/* CyberA4U Arena — Lunar Silver (parity with platform) */

:root {
  --color-obsidian: #050609;
  --color-carbon: #0a0b0f;
  --color-graphite: #101116;
  --color-slate: #15171d;
  --color-steel: #1a1d23;
  --color-iron: #343943;
  --color-ink: #f8f8fa;
  --color-ink-dim: #e4e5e8;
  --color-ink-mute: #9a9faa;
  --color-ink-faint: #777d88;
  --color-signal: #e2e8f0;
  --color-signal-hi: #ffffff;
  --color-signal-dim: #94a3b8;
  --color-signal-glow: rgb(226 232 240 / 16%);
  --color-cyan: #cbd5e1;
  --color-ctf: #34d399;
  --color-success: #34d399;
  --color-error: #fb7185;
  --color-warn: #fbbf24;
  --color-hairline: #24262d;
  --color-hairline-strong: #343943;
  --color-hairline-weak: #1b1e24;
  --font-display: "Sora", system-ui, sans-serif;
  --font-sans: "Source Sans 3", system-ui, sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, monospace;
  --radius-6: 12px;
  --radius-8: 16px;
  --radius-pill: 999px;
  --ease-out-expo: cubic-bezier(0.16, 1, 0.3, 1);
  --shadow-card: 0 12px 40px rgba(0, 0, 0, 0.35);
  --shadow-glow: 0 0 0 1px var(--color-hairline), 0 0 32px var(--color-signal-glow);
  --nav-h: 4.25rem;
  --shell: 1400px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  color-scheme: dark;
}

body.s4f-arena,
body {
  margin: 0 !important;
  min-height: 100vh;
  background: var(--color-obsidian) !important;
  color: var(--color-ink) !important;
  font-family: var(--font-sans) !important;
  font-size: 16px;
  line-height: 1.55;
  padding-top: calc(var(--nav-h) + 1rem) !important;
}

h1, h2, h3, h4, h5, h6,
.s4f-title,
.challenge-name,
.navbar-brand {
  font-family: var(--font-display) !important;
  color: var(--color-ink) !important;
  letter-spacing: -0.02em;
}

a {
  color: var(--color-signal-hi);
  text-decoration: none;
  transition: color 150ms var(--ease-out-expo);
}
a:hover {
  color: var(--color-ink);
}

/* Atmosphere */
.s4f-atmosphere {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background:
    radial-gradient(ellipse 80% 50% at 20% -10%, rgb(226 232 240 / 0.22), transparent 55%),
    radial-gradient(ellipse 60% 40% at 90% 10%, rgb(148 163 184 / 0.1), transparent 50%),
    radial-gradient(ellipse 50% 40% at 50% 100%, rgb(226 232 240 / 0.08), transparent 55%),
    var(--color-obsidian);
}
.s4f-grid {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  opacity: 0.035;
  background-image:
    linear-gradient(var(--color-signal-hi) 1px, transparent 1px),
    linear-gradient(90deg, var(--color-signal-hi) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(ellipse at center, black 20%, transparent 75%);
}

/* Do NOT put z-index on .s4f-main — it creates a stacking context that traps
   Bootstrap's #challenge-window (fixed, z-index 1055) BELOW body-level
   .modal-backdrop (1050) and .s4f-nav-shell (1040). Clicks then hit the
   backdrop; the close control sits under the fixed nav. */
.s4f-main,
.s4f-nav,
.s4f-footer {
  position: relative;
  z-index: auto;
}

.s4f-shell {
  width: min(100% - 2.5rem, var(--shell));
  margin-inline: auto;
}
.s4f-narrow {
  max-width: 36rem;
}
.s4f-section {
  padding-bottom: 4rem;
}

/* Nav — full-bleed chrome; inner bar is content-width only */
.s4f-nav-shell {
  position: fixed !important;
  top: 0;
  left: 0;
  right: 0;
  width: 100% !important;
  max-width: none !important;
  margin: 0 !important;
  padding: 0 !important;
  z-index: 1040;
  pointer-events: none;
  box-sizing: border-box;
  /* Match platform .shell-nav > nav: solid surface-2 / carbon */
  background: var(--color-carbon) !important;
  backdrop-filter: none;
  -webkit-backdrop-filter: none;
  border-bottom: 1px solid var(--color-hairline);
  box-shadow: 0 16px 40px rgb(0 0 0 / 55%);
}
.s4f-nav-shell .s4f-nav,
.s4f-nav-shell .s4f-nav-bar,
.s4f-nav-shell a,
.s4f-nav-shell button {
  pointer-events: auto;
}
.s4f-nav.navbar,
nav.s4f-nav {
  background: transparent !important;
  border: 0 !important;
  padding: 0 !important;
  margin: 0 !important;
  box-shadow: none !important;
  width: 100% !important;
  max-width: none !important;
  display: block !important;
}
/* Defeat Bootstrap/CTFd container wrappers if core injects them */
.s4f-nav-shell .container,
.s4f-nav-shell .container-sm,
.s4f-nav-shell .container-md,
.s4f-nav-shell .container-lg,
.s4f-nav-shell .container-xl,
.s4f-nav-shell .container-xxl,
.s4f-nav-shell .container-fluid {
  width: 100% !important;
  max-width: none !important;
  margin-inline: 0 !important;
  padding-inline: 0 !important;
}
.s4f-nav-bar {
  display: flex;
  flex-wrap: nowrap;
  align-items: center;
  gap: 0.75rem;
  width: 100%;
  max-width: 1440px;
  margin-inline: auto;
  min-height: var(--nav-h);
  padding: 0 0.85rem 0 1rem;
  border-radius: 0;
  border: 0;
  background: transparent !important;
  backdrop-filter: none;
  -webkit-backdrop-filter: none;
  box-shadow: none;
  box-sizing: border-box;
}
.s4f-nav-collapse {
  flex: 1 1 auto;
  display: flex !important;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.35rem;
  width: auto;
}
.s4f-nav-spacer {
  flex: 1 1 auto;
  min-width: 0.5rem;
}
.s4f-nav-links,
.s4f-nav-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.15rem;
  margin: 0 !important;
}
.s4f-btn-nav {
  min-height: 2.25rem !important;
  padding: 0.35rem 0.9rem !important;
  font-size: 12px !important;
  margin-left: 0.25rem;
}
.s4f-logo {
  display: inline-flex !important;
  align-items: center;
  gap: 0.65rem;
  text-decoration: none !important;
  color: var(--color-ink) !important;
  margin: 0 !important;
  padding: 0 !important;
  flex-shrink: 0;
}
.s4f-logo-img {
  display: block;
  height: 40px;
  width: auto;
  max-width: min(11.5rem, 46vw);
  object-fit: contain;
  object-position: left center;
}
@media (min-width: 640px) {
  .s4f-logo-img {
    height: 44px;
    max-width: min(14rem, 50vw);
  }
}
@media (min-width: 992px) {
  .s4f-logo-img {
    height: 48px;
    max-width: min(16rem, 40vw);
  }
}
.s4f-logo-text {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 0.95rem;
  letter-spacing: -0.02em;
}
.s4f-logo-text span {
  color: var(--color-signal);
}
.s4f-logo-text em {
  font-style: normal;
  color: var(--color-ink-mute);
  font-weight: 500;
  margin-left: 0.35rem;
  font-size: 0.8rem;
}
.s4f-toggler {
  border: 1px solid var(--color-hairline-strong) !important;
  border-radius: 8px;
  margin-left: auto;
}
.s4f-nav .nav-link {
  font-size: 13px !important;
  font-weight: 500;
  color: var(--color-ink-mute) !important;
  padding: 0.45rem 0.75rem !important;
  border-radius: 8px;
  position: relative;
  white-space: nowrap;
}
.s4f-nav .nav-link:hover,
.s4f-nav .nav-link.active {
  color: var(--color-ink) !important;
}
.s4f-nav .nav-link::after {
  content: "";
  position: absolute;
  left: 0.75rem;
  right: 0.75rem;
  bottom: 0.2rem;
  height: 2px;
  border-radius: 2px;
  background: transparent;
  transition: background 150ms var(--ease-out-expo);
}
.s4f-nav .nav-link:hover::after,
.s4f-nav .nav-item.active .nav-link::after {
  background: var(--color-signal);
}
.s4f-platform-link {
  color: var(--color-cyan) !important;
}
.s4f-badge {
  display: inline-grid;
  place-items: center;
  min-width: 1.1rem;
  height: 1.1rem;
  padding: 0 0.3rem;
  margin-left: 0.25rem;
  border-radius: var(--radius-pill);
  background: var(--color-error);
  color: #fff;
  font-family: var(--font-mono);
  font-size: 10px;
}

/* Buttons */
.s4f-btn,
.btn.s4f-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  min-height: 2.75rem;
  padding: 0.55rem 1.25rem;
  border-radius: var(--radius-pill) !important;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 150ms var(--ease-out-expo), box-shadow 150ms var(--ease-out-expo), background 150ms var(--ease-out-expo);
  text-decoration: none !important;
}
.s4f-btn-primary,
.btn.s4f-btn-primary,
.btn-primary {
  background: linear-gradient(135deg, #9d74f8, var(--color-signal)) !important;
  border-color: transparent !important;
  color: #fff !important;
  box-shadow: 0 8px 24px var(--color-signal-glow);
}
.s4f-btn-primary:hover,
.btn.s4f-btn-primary:hover,
.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 12px 32px var(--color-signal-glow);
  color: #fff !important;
}
.s4f-btn-ghost,
.btn.s4f-btn-ghost {
  background: rgba(16, 19, 40, 0.72) !important;
  border-color: var(--color-hairline-strong) !important;
  color: var(--color-ink) !important;
  backdrop-filter: blur(12px);
}
.s4f-btn-ghost:hover {
  border-color: var(--color-signal) !important;
  color: var(--color-signal-hi) !important;
}
.s4f-btn-sm,
.btn.s4f-btn-sm {
  min-height: 2.15rem;
  padding: 0.35rem 0.9rem;
  font-size: 0.8rem;
}

/* Hero */
.s4f-hero {
  padding: 1.5rem 0 2rem;
  animation: s4f-fade-up 0.55s var(--ease-out-expo) both;
}
.s4f-hero-center {
  text-align: center;
  padding-top: 4rem;
  padding-bottom: 4rem;
}
.s4f-eyebrow {
  margin: 0 0 0.65rem;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-signal);
}
.s4f-title {
  margin: 0;
  font-size: clamp(1.85rem, 4vw, 2.75rem);
  font-weight: 650;
  line-height: 1.15;
}
.s4f-lead {
  margin: 0.75rem 0 0;
  max-width: 36rem;
  color: var(--color-ink-mute);
  font-size: 1.02rem;
}
.s4f-hero-center .s4f-lead {
  margin-inline: auto;
}
.s4f-cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.5rem;
  justify-content: center;
}

/* Challenge board */
.s4f-loading {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.75rem;
  padding: 4rem 1rem;
  color: var(--color-ink-mute);
  font-family: var(--font-mono);
  font-size: 12px;
}
.s4f-hero-row {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: 1.25rem;
}
.s4f-hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
}
.s4f-stats-bar {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.75rem;
  margin-bottom: 1.25rem;
}
@media (min-width: 768px) {
  .s4f-stats-bar {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}
.s4f-stat {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  padding: 0.9rem 1rem;
  border-radius: var(--radius-8);
  border: 1px solid var(--color-hairline);
  background: rgba(16, 19, 40, 0.72);
  backdrop-filter: blur(12px);
}
.s4f-stat-wide {
  min-width: 0;
}
.s4f-stat-label {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-ink-faint);
}
.s4f-stat-value {
  font-family: var(--font-display);
  font-size: 1.35rem;
  font-weight: 650;
  color: var(--color-ink);
  letter-spacing: -0.02em;
}
.s4f-stat-value.is-ctf { color: var(--color-ctf); }
.s4f-stat-value.is-signal { color: var(--color-signal-hi); }
.s4f-stat-meta {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--color-ink-mute);
}
.s4f-progress {
  height: 6px;
  border-radius: 999px;
  background: rgba(167, 139, 250, 0.12);
  overflow: hidden;
}
.s4f-progress-fill {
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--color-signal), var(--color-ctf));
  transition: width 280ms var(--ease-out-expo);
}
.s4f-toolbar {
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
  margin-bottom: 1.5rem;
  padding: 1rem;
  border-radius: var(--radius-8);
  border: 1px solid var(--color-hairline);
  background: rgba(10, 12, 26, 0.55);
}
.s4f-search {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  padding: 0.65rem 0.9rem;
  border-radius: 10px;
  border: 1px solid var(--color-hairline-strong);
  background: var(--color-carbon);
  color: var(--color-ink-faint);
}
.s4f-search input {
  flex: 1;
  border: 0;
  outline: 0;
  background: transparent;
  color: var(--color-ink);
  font-size: 0.95rem;
}
.s4f-kbd {
  font-family: var(--font-mono);
  font-size: 10px;
  color: var(--color-ink-faint);
  border: 1px solid var(--color-hairline);
  border-radius: 6px;
  padding: 0.15rem 0.4rem;
  background: rgba(16, 19, 40, 0.8);
}
.s4f-filter-pills,
.s4f-cat-scroll {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
}
.s4f-cat-scroll {
  overflow-x: auto;
  flex-wrap: nowrap;
  padding-bottom: 0.15rem;
  scrollbar-width: thin;
}
.s4f-pill,
.s4f-chip-btn {
  appearance: none;
  border: 1px solid var(--color-hairline);
  background: transparent;
  color: var(--color-ink-mute);
  border-radius: var(--radius-pill);
  padding: 0.4rem 0.85rem;
  font-size: 12px;
  font-family: var(--font-mono);
  letter-spacing: 0.04em;
  cursor: pointer;
  white-space: nowrap;
  transition: border-color 150ms var(--ease-out-expo), background 150ms var(--ease-out-expo), color 150ms var(--ease-out-expo);
}
.s4f-pill.active,
.s4f-chip-btn.active,
.s4f-pill:hover,
.s4f-chip-btn:hover {
  border-color: var(--color-signal);
  color: var(--color-ink);
  background: rgb(226 232 240 / 0.16);
}
.s4f-category {
  margin-top: 2rem;
  animation: s4f-fade-up 0.5s var(--ease-out-expo) both;
}
.s4f-category-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 0.85rem;
}
.s4f-category-title {
  margin: 0;
  font-size: 1.15rem;
  font-weight: 600;
}
.s4f-category-count {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--color-ink-faint);
}
.s4f-challenge-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 300px), 1fr));
  gap: 1.15rem;
}
.s4f-page-meta {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  margin: 0.35rem 0 0.85rem;
}
.s4f-page-meta-text {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--color-ink-faint);
}
.s4f-challenge-card,
a.s4f-challenge-card,
button.s4f-challenge-card,
.challenge-button.s4f-challenge-card {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  gap: 0;
  width: 100%;
  min-width: 0;
  min-height: 17.5rem;
  padding: 0;
  text-align: left;
  text-decoration: none !important;
  border-radius: 14px !important;
  border: 1px solid rgba(61, 69, 96, 0.85) !important;
  background: #1a1d2e !important;
  color: var(--color-ink) !important;
  box-shadow: 0 8px 28px rgba(0, 0, 0, 0.28);
  transition:
    border-color 220ms var(--ease-out-expo),
    transform 220ms var(--ease-out-expo),
    box-shadow 220ms var(--ease-out-expo);
  cursor: pointer;
  position: relative;
  overflow: hidden;
}
.s4f-challenge-card::after {
  display: none;
}
.s4f-challenge-card:hover,
.s4f-thm-card:hover,
.s4f-challenge-card:focus-visible {
  border-color: rgba(148, 163, 184, 0.5) !important;
  transform: translateY(-4px);
  box-shadow: 0 14px 36px rgba(0, 0, 0, 0.38);
  color: var(--color-ink) !important;
}
.s4f-challenge-card.is-solved,
.challenge-button.challenge-solved,
.s4f-challenge-card.challenge-solved {
  border-color: rgba(52, 211, 153, 0.35) !important;
  background:
    linear-gradient(160deg, rgba(52, 211, 153, 0.08), transparent 42%),
    #1a1d2e !important;
}
.s4f-thm-card-body {
  display: flex;
  flex-direction: column;
  flex: 1;
  gap: 0.7rem;
  padding: 1.15rem 1.15rem 0.9rem;
  min-height: 12.5rem;
  position: relative;
  z-index: 1;
}
.s4f-thm-card .s4f-challenge-name {
  margin: 0;
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 650;
  line-height: 1.3;
  min-width: 0;
  color: #f1f5f9;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  position: relative;
  z-index: 3;
}
/* Art stage — hover blurb lives here only, never over the title */
.s4f-thm-stage {
  position: relative;
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 7.25rem;
  margin-top: 0.15rem;
}
.s4f-thm-art {
  width: 6.5rem;
  height: 6.5rem;
  border-radius: 50%;
  border: 2px solid rgba(61, 69, 96, 0.95);
  background:
    radial-gradient(circle at 35% 30%, rgba(255, 255, 255, 0.1), transparent 55%),
    #121526;
  overflow: hidden;
  flex-shrink: 0;
  display: grid;
  place-items: center;
  transition:
    transform 900ms var(--ease-out-expo),
    border-color 900ms ease,
    opacity 900ms ease;
}
.s4f-thm-card:hover .s4f-thm-art,
.s4f-thm-card:focus-visible .s4f-thm-art {
  transform: scale(0.88);
  opacity: 0.22;
  border-color: rgba(148, 163, 184, 0.28);
}
.s4f-thm-logo {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
/* Description only on hover — fades in over the art stage, below the title */
.s4f-thm-hover {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0.55rem 0.35rem;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transform: translateY(10px);
  transition:
    opacity 900ms ease,
    transform 1000ms var(--ease-out-expo),
    visibility 900ms ease;
  z-index: 2;
}
.s4f-thm-card:hover .s4f-thm-hover,
.s4f-thm-card:focus-visible .s4f-thm-hover {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.s4f-thm-desc {
  margin: 0;
  max-width: 100%;
  padding: 0.7rem 0.8rem;
  border-radius: 10px;
  background: rgba(8, 10, 20, 0.88);
  border: 1px solid rgba(100, 116, 139, 0.32);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.35);
  font-size: 0.84rem;
  line-height: 1.45;
  color: rgba(226, 232, 240, 0.96);
  text-align: center;
  display: -webkit-box;
  -webkit-line-clamp: 4;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.s4f-thm-card-foot {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  flex-wrap: wrap;
  width: 100%;
  padding: 0.7rem 1.05rem 0.85rem;
  border-top: 1px solid rgba(61, 69, 96, 0.65);
  background: rgba(12, 14, 24, 0.45);
  position: relative;
  z-index: 1;
}
.s4f-thm-flag {
  display: inline-grid;
  place-items: center;
  width: 1.65rem;
  height: 1.65rem;
  border-radius: 7px;
  background: rgba(51, 65, 85, 0.55);
  color: #e2e8f0;
  font-size: 0.7rem;
}
.s4f-thm-diff {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.02em;
}
.s4f-thm-diff.diff-easy { color: #4ade80; }
.s4f-thm-diff.diff-medium { color: #fbbf24; }
.s4f-thm-diff.diff-hard { color: #fb7185; }
.s4f-thm-diff.diff-expert { color: #c084fc; }
.s4f-thm-diff.diff-practice { color: #94a3b8; }
.s4f-thm-bars {
  display: inline-flex;
  align-items: flex-end;
  gap: 2px;
  height: 12px;
}
.s4f-thm-bars i {
  display: block;
  width: 3px;
  border-radius: 1px;
  background: rgba(148, 163, 184, 0.35);
}
.s4f-thm-bars i:nth-child(1) { height: 4px; }
.s4f-thm-bars i:nth-child(2) { height: 7px; }
.s4f-thm-bars i:nth-child(3) { height: 10px; }
.s4f-thm-bars i:nth-child(4) { height: 12px; }
.s4f-thm-diff.diff-easy .s4f-thm-bars i.on,
.s4f-room-meta-item.diff-easy .s4f-thm-bars i.on { background: #4ade80; }
.s4f-thm-diff.diff-medium .s4f-thm-bars i.on,
.s4f-room-meta-item.diff-medium .s4f-thm-bars i.on { background: #fbbf24; }
.s4f-thm-diff.diff-hard .s4f-thm-bars i.on,
.s4f-room-meta-item.diff-hard .s4f-thm-bars i.on { background: #fb7185; }
.s4f-thm-diff.diff-expert .s4f-thm-bars i.on,
.s4f-room-meta-item.diff-expert .s4f-thm-bars i.on { background: #c084fc; }
.s4f-thm-diff.diff-practice .s4f-thm-bars i.on,
.s4f-room-meta-item.diff-practice .s4f-thm-bars i.on { background: #94a3b8; }
.s4f-thm-time {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-family: var(--font-mono);
  font-size: 11px;
  color: rgba(226, 232, 240, 0.88);
}
.s4f-thm-pts {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 11px;
  color: #67e8f9;
  font-weight: 600;
}
.s4f-thm-solved {
  color: #34d399;
  font-size: 0.85rem;
}
.s4f-pagination {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  margin-top: 1.75rem;
}
.s4f-page-btn {
  min-width: 2.25rem;
  height: 2.25rem;
  padding: 0 0.7rem;
  border-radius: 8px;
  border: 1px solid rgba(61, 69, 96, 0.9);
  background: rgba(16, 19, 40, 0.85);
  color: #e2e8f0;
  font-family: var(--font-mono);
  font-size: 11px;
  cursor: pointer;
  transition: background 160ms ease, border-color 160ms ease;
}
.s4f-page-btn:hover:not(:disabled) {
  border-color: rgba(148, 163, 184, 0.55);
  background: rgba(30, 36, 58, 0.95);
}
.s4f-page-btn.active {
  border-color: var(--color-signal);
  color: var(--color-signal-hi);
  background: rgba(226, 232, 240, 0.08);
}
.s4f-page-btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}
@media (prefers-reduced-motion: reduce) {
  .s4f-challenge-card,
  .s4f-thm-art,
  .s4f-thm-hover {
    transition: none !important;
  }
  .s4f-thm-card:hover {
    transform: none;
  }
}
/* Legacy class hooks kept for any leftover markup */
.s4f-challenge-card-top,
.s4f-challenge-cat-badge,
.s4f-challenge-pts,
.s4f-challenge-card-foot,
.s4f-challenge-solves,
.s4f-challenge-solved-pill,
.s4f-challenge-open {
  display: none;
}
.s4f-challenge-cat {
  font-family: var(--font-mono);
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-ink-faint);
}
.s4f-profile-bridge {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1rem;
}

/* Arena public / private profile card */
.s4f-profile-hero {
  padding-bottom: 0.5rem;
}
.s4f-profile-card {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  padding: 1.5rem 0 0.5rem;
}
.s4f-profile-identity {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-start;
  gap: 1.25rem 1.75rem;
}
.s4f-profile-avatar {
  position: relative;
  width: 6.5rem;
  height: 6.5rem;
  border-radius: 22%;
  overflow: hidden;
  flex-shrink: 0;
  background: linear-gradient(145deg, var(--color-slate), var(--color-graphite));
  border: 1px solid var(--color-hairline-strong);
  box-shadow: var(--shadow-glow);
}
.s4f-profile-avatar-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
.s4f-profile-avatar-fallback {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  font-family: var(--font-display);
  font-size: 2rem;
  font-weight: 600;
  color: var(--color-signal-hi);
  background: radial-gradient(circle at 30% 20%, rgb(226 232 240 / 0.35), transparent 60%);
}
.s4f-profile-meta {
  flex: 1 1 16rem;
  min-width: 0;
}
.s4f-profile-name {
  margin: 0.15rem 0 0.65rem !important;
  font-size: clamp(1.75rem, 3vw, 2.35rem) !important;
}
.s4f-profile-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
  margin-bottom: 0.65rem;
}
.s4f-role-pill,
.s4f-meta-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  min-height: 1.65rem;
  padding: 0.2rem 0.7rem;
  border-radius: var(--radius-pill);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  border: 1px solid var(--color-hairline);
  color: var(--color-ink-dim);
  background: rgba(16, 19, 40, 0.75);
}
.s4f-role-pill[data-role="teacher"] {
  color: var(--color-cyan);
  border-color: rgb(148 163 184 / 0.35);
  background: rgb(148 163 184 / 0.08);
}
.s4f-role-pill[data-role="student"] {
  color: var(--color-signal-hi);
  border-color: rgba(196, 181, 253, 0.35);
  background: rgb(226 232 240 / 0.1);
}
.s4f-role-pill[data-role="admin"],
.s4f-role-pill[data-role="mod"] {
  color: var(--color-warn);
  border-color: rgba(251, 191, 36, 0.35);
  background: rgba(251, 191, 36, 0.08);
}
.s4f-profile-bio {
  margin: 0 0 0.85rem;
  max-width: 42rem;
  color: var(--color-ink-mute);
  font-size: 0.95rem;
}
.s4f-profile-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem 1.5rem;
  margin: 0.35rem 0 0.25rem;
}
.s4f-stat {
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
  min-width: 4.5rem;
}
.s4f-stat strong {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--color-ink);
  letter-spacing: -0.02em;
}
.s4f-stat span {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-ink-faint);
}
.s4f-profile-courses {
  margin-top: 0.25rem;
  padding: 1.1rem 1.2rem;
  border: 1px solid var(--color-hairline);
  border-radius: var(--radius-8);
  background: rgba(10, 12, 26, 0.55);
}
.s4f-profile-courses-title {
  margin: 0 0 0.75rem !important;
  font-size: 1rem !important;
  color: var(--color-ink-dim) !important;
}
.s4f-course-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.45rem;
}
.s4f-course-list a {
  display: block;
  padding: 0.65rem 0.85rem;
  border-radius: var(--radius-6);
  border: 1px solid var(--color-hairline-weak);
  background: rgba(23, 26, 50, 0.65);
  color: var(--color-ink) !important;
  font-weight: 600;
  transition: border-color 150ms var(--ease-out-expo), background 150ms var(--ease-out-expo);
}
.s4f-course-list a:hover {
  border-color: var(--color-hairline-strong);
  background: rgba(34, 38, 74, 0.8);
  color: var(--color-signal-hi) !important;
}
.s4f-profile-team {
  margin: 0;
}
.s4f-profile-fields {
  color: var(--color-ink-mute);
  font-size: 0.9rem;
}
.s4f-ink-mute {
  color: var(--color-ink-faint);
}

@media (max-width: 640px) {
  .s4f-profile-avatar {
    width: 5.25rem;
    height: 5.25rem;
  }
}
[x-cloak] { display: none !important; }

@media (max-width: 900px) {
  .s4f-footer-grid {
    grid-template-columns: 1fr;
  }
  .s4f-footer-cols {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 768px) {
  body {
    padding-top: calc(var(--nav-h) + 0.75rem) !important;
  }
  .s4f-nav-shell {
    padding-inline: 0 !important;
  }
  .s4f-footer-cols {
    grid-template-columns: 1fr 1fr;
  }
}

/* ── Challenge modal (Arena detail) ─────────────────────────── */
.modal-backdrop {
  z-index: 1050 !important;
}
.modal-backdrop.show {
  background: rgba(5, 6, 15, 0.78) !important;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}
#challenge-window.modal,
.s4f-modal.modal {
  --bs-modal-margin: 1.25rem;
  z-index: 1055 !important;
  padding: 0 !important;
}
#challenge-window .modal-dialog,
.s4f-modal .modal-dialog,
.s4f-chal-dialog.modal-dialog {
  max-width: min(760px, calc(100vw - 1.5rem)) !important;
  width: 100%;
  margin: 1.5rem auto !important;
  pointer-events: auto;
}
.modal-content,
.s4f-modal .modal-content,
.s4f-chal.modal-content,
.s4f-modal-content {
  background:
    linear-gradient(165deg, rgb(226 232 240 / 0.07), transparent 38%),
    var(--color-graphite) !important;
  border: 1px solid var(--color-hairline-strong) !important;
  border-radius: 18px !important;
  color: var(--color-ink) !important;
  box-shadow: var(--shadow-glow), 0 28px 80px rgba(0, 0, 0, 0.55);
  overflow: hidden;
}
.s4f-chal.is-solved {
  border-color: rgba(52, 211, 153, 0.35) !important;
  background:
    linear-gradient(165deg, rgba(52, 211, 153, 0.08), transparent 40%),
    var(--color-graphite) !important;
}
.modal-header,
.modal-footer {
  border-color: var(--color-hairline) !important;
}
.btn-close {
  filter: invert(1) grayscale(1);
  opacity: 0.7;
}

/* Header */
.s4f-chal-head {
  position: relative;
  padding: 1.25rem 1.35rem 0;
  border-bottom: 1px solid var(--color-hairline);
  background: rgba(10, 12, 26, 0.45);
}
.s4f-chal-head-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.75rem;
}
.s4f-chal-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.45rem;
  min-width: 0;
}
.s4f-chal-cat {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-signal-hi);
  border: 1px solid var(--color-hairline);
  border-radius: 6px;
  padding: 0.22rem 0.5rem;
  background: rgb(226 232 240 / 0.12);
}
.s4f-chal-pts,
.s4f-chal .challenge-value {
  font-family: var(--font-mono) !important;
  font-size: 11px !important;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--color-cyan) !important;
}
.s4f-chal-solves-count {
  font-family: var(--font-mono);
  font-size: 10px;
  color: var(--color-ink-faint);
}
.s4f-chal-solved-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-family: var(--font-mono);
  font-size: 10px;
  color: var(--color-ctf);
  border: 1px solid rgba(52, 211, 153, 0.35);
  border-radius: var(--radius-pill);
  padding: 0.2rem 0.55rem;
  background: rgba(52, 211, 153, 0.1);
}
.s4f-chal-close {
  flex-shrink: 0;
  display: grid;
  place-items: center;
  width: 2.25rem;
  height: 2.25rem;
  border-radius: 10px;
  border: 1px solid var(--color-hairline);
  background: rgba(16, 19, 40, 0.7);
  color: var(--color-ink-mute);
  cursor: pointer;
  transition: border-color 150ms var(--ease-out-expo), color 150ms var(--ease-out-expo), background 150ms var(--ease-out-expo);
}
.s4f-chal-close:hover {
  border-color: var(--color-hairline-strong);
  color: var(--color-ink);
  background: rgba(248, 113, 113, 0.12);
}
.s4f-chal-title,
.s4f-chal .challenge-name {
  margin: 0.85rem 0 0;
  font-size: clamp(1.35rem, 3vw, 1.7rem) !important;
  font-weight: 650;
  line-height: 1.25;
  letter-spacing: -0.02em;
  text-align: left !important;
}
.s4f-chal-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: 0.75rem;
}
.s4f-chal-tag,
.s4f-chal .challenge-tag,
.challenge-tag.badge,
.badge.bg-info {
  display: inline-flex;
  align-items: center;
  padding: 0.2rem 0.55rem;
  border-radius: 6px;
  border: 1px solid var(--color-hairline);
  background: rgb(148 163 184 / 0.08) !important;
  color: var(--color-cyan) !important;
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 500;
  letter-spacing: 0.04em;
}
.s4f-chal-byline {
  margin-top: 0.55rem;
  font-size: 0.85rem;
  color: var(--color-ink-mute);
}
.s4f-chal-byline p {
  margin: 0;
}
.s4f-chal-ratings {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  margin-top: 0.45rem;
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--color-ink-mute);
}
.s4f-chal-ratings-pct {
  color: var(--color-ink-faint);
}

/* Tabs */
.s4f-chal-tabs {
  margin-top: 1rem;
}
.s4f-chal-tablist.nav-tabs,
.s4f-chal .nav-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin: 0;
  padding: 0 0 0.85rem;
  border-bottom: 1px solid var(--color-hairline) !important;
}
.s4f-chal .nav-tabs .nav-link,
.nav-tabs .nav-link {
  margin: 0;
  padding: 0.4rem 0.85rem !important;
  border: 1px solid var(--color-hairline) !important;
  border-radius: var(--radius-pill) !important;
  background: transparent !important;
  color: var(--color-ink-mute) !important;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  box-shadow: none !important;
}
.s4f-chal .nav-tabs .nav-link:hover {
  color: var(--color-ink) !important;
  border-color: var(--color-hairline-strong) !important;
}
.s4f-chal .nav-tabs .nav-link.active,
.nav-tabs .nav-link.active {
  color: var(--color-ink) !important;
  background: rgb(226 232 240 / 0.16) !important;
  border-color: var(--color-signal) !important;
  box-shadow: none !important;
}

/* Body */
.s4f-chal-body.modal-body {
  padding: 1.15rem 1.35rem 1.5rem !important;
  max-height: min(70vh, 720px);
  overflow-y: auto;
  overscroll-behavior: contain;
}
.s4f-chal-section {
  margin-bottom: 1.35rem;
}
.s4f-chal-section:last-child {
  margin-bottom: 0;
}
.s4f-chal-section-label {
  margin: 0 0 0.55rem;
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 500;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-ink-faint);
}
.s4f-chal-desc,
.s4f-chal .challenge-desc,
.challenge-desc {
  display: block;
  color: var(--color-ink-dim);
  line-height: 1.7;
  font-size: 0.98rem;
  overflow-wrap: anywhere;
}
.s4f-chal-desc img,
.challenge-desc img {
  max-width: 100%;
  height: auto;
  border-radius: 10px;
  border: 1px solid var(--color-hairline);
  margin: 0.75rem 0;
}
.s4f-chal-desc pre,
.s4f-chal-desc code,
.challenge-desc pre,
.challenge-desc code {
  font-family: var(--font-mono);
  font-size: 0.85em;
}
.s4f-chal-desc pre,
.challenge-desc pre {
  padding: 0.85rem 1rem;
  border-radius: 10px;
  border: 1px solid var(--color-hairline);
  background: var(--color-carbon);
  overflow-x: auto;
}
.s4f-chal-desc p:last-child,
.challenge-desc p:last-child {
  margin-bottom: 0;
}
.s4f-chal-conn {
  padding: 0.85rem 1rem;
  border-radius: 12px;
  border: 1px dashed var(--color-hairline-strong);
  background: rgb(148 163 184 / 0.06);
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--color-cyan);
  word-break: break-all;
}
.s4f-chal-conn code {
  color: inherit;
  background: transparent;
}
.s4f-chal-files {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}
.s4f-chal-file {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  max-width: 100%;
  padding: 0.55rem 0.85rem;
  border-radius: var(--radius-pill);
  border: 1px solid var(--color-hairline);
  background: rgba(16, 19, 40, 0.85);
  color: var(--color-ink) !important;
  font-family: var(--font-mono);
  font-size: 12px;
  text-decoration: none !important;
  transition: border-color 150ms var(--ease-out-expo), background 150ms var(--ease-out-expo), color 150ms var(--ease-out-expo);
}
.s4f-chal-file span {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  max-width: 16rem;
}
.s4f-chal-file:hover {
  border-color: var(--color-signal);
  color: var(--color-signal-hi) !important;
  background: rgb(226 232 240 / 0.12);
}
.s4f-chal-file i {
  color: var(--color-cyan);
  flex-shrink: 0;
}

/* Hints */
.s4f-chal-hints {
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
}
.s4f-chal-hint-details {
  border-radius: 12px;
  border: 1px solid var(--color-hairline);
  background: rgba(10, 12, 26, 0.55);
  overflow: hidden;
}
.s4f-chal-hint-details summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 0.85rem 1rem;
  cursor: pointer;
  list-style: none;
  user-select: none;
}
.s4f-chal-hint-details summary::-webkit-details-marker {
  display: none;
}
.s4f-chal-hint-title {
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--color-ink);
}
.s4f-chal-hint-cost {
  flex-shrink: 0;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.04em;
  color: var(--color-warn);
  border: 1px solid rgba(251, 191, 36, 0.35);
  border-radius: var(--radius-pill);
  padding: 0.2rem 0.55rem;
  background: rgba(251, 191, 36, 0.1);
}
.s4f-chal-hint-cost.is-unlocked {
  color: var(--color-ctf);
  border-color: rgba(52, 211, 153, 0.35);
  background: rgba(52, 211, 153, 0.1);
}
.s4f-chal-hint-body {
  padding: 0 1rem 1rem;
  color: var(--color-ink-dim);
  line-height: 1.65;
  border-top: 1px solid var(--color-hairline-weak);
}
.s4f-chal-hint-body:empty {
  display: none;
}

/* Flag submit */
.s4f-chal-submit-wrap {
  margin-top: 0.25rem;
  padding: 1.1rem 1.15rem;
  border-radius: 14px;
  border: 1px solid var(--color-hairline-strong);
  background:
    linear-gradient(135deg, rgb(226 232 240 / 0.1), transparent 55%),
    rgba(10, 12, 26, 0.72);
  box-shadow: inset 0 1px 0 rgba(196, 181, 253, 0.06);
}
.s4f-chal-submit-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 0.65rem;
}
.s4f-chal-submit-head .s4f-chal-section-label {
  margin: 0;
  color: var(--color-signal-hi);
}
.s4f-chal-attempts {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--color-ink-faint);
}
.s4f-chal-submit {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 0.65rem;
  align-items: stretch;
}
.s4f-chal-input,
.s4f-chal .challenge-input,
.challenge-input.form-control,
.form-control,
.form-select {
  background: var(--color-carbon) !important;
  border: 1px solid var(--color-hairline-strong) !important;
  color: var(--color-ink) !important;
  border-radius: 12px !important;
  min-height: 3rem;
  font-family: var(--font-mono) !important;
  font-size: 0.95rem !important;
  padding: 0.65rem 1rem !important;
}
.form-control:focus,
.form-select:focus,
.challenge-input:focus,
.s4f-chal-input:focus {
  border-color: var(--color-signal) !important;
  box-shadow: 0 0 0 3px var(--color-signal-glow) !important;
  outline: none;
}
.s4f-chal-submit-btn {
  min-width: 7.5rem;
  min-height: 3rem !important;
  border-radius: 12px !important;
  white-space: nowrap;
}
.s4f-chal-notify {
  margin-top: 0.85rem;
}
.s4f-chal-reset {
  margin-top: 1rem;
  padding-top: 0.9rem;
  border-top: 1px solid var(--color-hairline);
}
.s4f-chal-reset-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem;
}
.s4f-chal-reset-btn {
  display: inline-flex !important;
  align-items: center;
  gap: 0.45rem;
  min-height: 2.35rem !important;
  padding: 0.4rem 0.95rem !important;
  font-family: var(--font-mono) !important;
  font-size: 0.78rem !important;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}
.s4f-chal-reset-btn:disabled {
  opacity: 0.55;
  cursor: wait;
}
.s4f-chal-reset-hint {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--color-ink-faint);
}
.s4f-chal-alert.alert {
  margin: 0;
  padding: 0.9rem 1rem;
  border-radius: 12px;
  border-width: 1px;
  border-style: solid;
  text-align: left;
}
.alert-success,
.s4f-chal-alert.alert-success {
  background: rgba(52, 211, 153, 0.12) !important;
  border-color: rgba(52, 211, 153, 0.35) !important;
  color: var(--color-ctf) !important;
}
.alert-danger,
.s4f-chal-alert.alert-danger {
  background: rgba(248, 113, 113, 0.12) !important;
  border-color: rgba(248, 113, 113, 0.35) !important;
  color: var(--color-error) !important;
}
.alert-info,
.s4f-chal-alert.alert-info {
  background: rgb(148 163 184 / 0.1) !important;
  border-color: rgb(148 163 184 / 0.3) !important;
  color: var(--color-cyan) !important;
}
.alert-warning,
.s4f-chal-alert.alert-warning {
  background: rgba(251, 191, 36, 0.1) !important;
  border-color: rgba(251, 191, 36, 0.35) !important;
  color: var(--color-warn) !important;
}
.s4f-chal-alert-actions,
.s4f-chal-share,
.s4f-chal-rate {
  margin-top: 0.85rem;
}
.s4f-chal-share-group {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}
.s4f-chal-rate-label {
  margin: 0 0 0.5rem;
  font-size: 0.9rem;
  color: var(--color-ink-dim);
}
.s4f-chal-rate-btns {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 0.65rem;
}
.s4f-chal-rate-btn {
  display: grid;
  place-items: center;
  width: 2.5rem;
  height: 2.5rem;
  border-radius: 10px;
  border: 1px solid var(--color-hairline);
  background: transparent;
  color: var(--color-ink-mute);
  cursor: pointer;
}
.s4f-chal-rate-btn.is-active {
  border-color: var(--color-ctf);
  color: var(--color-ctf);
  background: rgba(52, 211, 153, 0.12);
}
.s4f-chal-rate-btn.is-down.is-active {
  border-color: var(--color-error);
  color: var(--color-error);
  background: rgba(248, 113, 113, 0.12);
}
.s4f-chal-rate-review {
  margin-bottom: 0.65rem;
}
.s4f-chal-rate-thanks {
  margin-top: 0.45rem;
  color: var(--color-ctf);
}
.s4f-chal-eye {
  border: 0;
  background: transparent;
  color: var(--color-ink-mute);
  padding: 0 0.35rem;
  cursor: pointer;
}

/* Kill leftover CTFd/Bootstrap chrome inside challenge modal */
.s4f-chal .btn-info,
.s4f-chal .btn-outline-info,
.s4f-chal .btn-outline-secondary {
  background: rgba(16, 19, 40, 0.72) !important;
  border: 1px solid var(--color-hairline-strong) !important;
  color: var(--color-ink) !important;
  border-radius: var(--radius-pill) !important;
}
.s4f-chal .text-muted {
  color: var(--color-ink-mute) !important;
}
.s4f-chal .row {
  --bs-gutter-x: 0;
}

@media (max-width: 640px) {
  #challenge-window .modal-dialog,
  .s4f-modal .modal-dialog,
  .s4f-chal-dialog.modal-dialog {
    max-width: 100% !important;
    margin: 0 !important;
    min-height: 100%;
  }
  #challenge-window.modal.show .modal-dialog {
    transform: none;
  }
  .s4f-chal.modal-content {
    min-height: 100dvh;
    border-radius: 0 !important;
    border-left: 0 !important;
    border-right: 0 !important;
  }
  .s4f-chal-body.modal-body {
    max-height: none;
  }
  .s4f-chal-submit {
    grid-template-columns: 1fr;
  }
  .s4f-chal-submit-btn {
    width: 100%;
  }
  .s4f-chal-head,
  .s4f-chal-body.modal-body {
    padding-inline: 1rem !important;
  }
}

/* Scoreboard */
.s4f-score-graph {
  min-height: 3rem;
  margin-bottom: 1.5rem;
  padding: 1rem;
  border-radius: var(--radius-8);
  border: 1px solid var(--color-hairline);
  background: rgba(16, 19, 40, 0.55);
}
.s4f-table-wrap {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border-radius: var(--radius-8);
  border: 1px solid var(--color-hairline);
  background: rgba(16, 19, 40, 0.72);
  box-shadow: var(--shadow-card);
}
.s4f-table,
table.table {
  --bs-table-bg: transparent;
  --bs-table-color: var(--color-ink);
  --bs-table-striped-bg: rgba(167, 139, 250, 0.04);
  --bs-table-striped-color: var(--color-ink);
  --bs-table-hover-bg: rgb(226 232 240 / 0.08);
  margin: 0;
  color: var(--color-ink) !important;
}
.s4f-table thead th,
.table thead th {
  font-family: var(--font-mono) !important;
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-ink-mute) !important;
  border-bottom-color: var(--color-hairline) !important;
  background: rgba(10, 12, 26, 0.6) !important;
  padding: 0.85rem 1rem !important;
}
.s4f-table td,
.s4f-table th,
.table td,
.table th {
  border-color: var(--color-hairline-weak) !important;
  padding: 0.85rem 1rem !important;
}
.s4f-place {
  font-family: var(--font-mono);
  color: var(--color-signal-hi) !important;
}
.s4f-score {
  font-family: var(--font-mono);
  color: var(--color-ctf) !important;
  font-weight: 600;
}
.s4f-chip,
.badge.bg-secondary {
  display: inline-block;
  margin-left: 0.4rem;
  padding: 0.15rem 0.5rem;
  border-radius: 6px;
  border: 1px solid var(--color-hairline);
  background: rgb(226 232 240 / 0.12) !important;
  color: var(--color-ink-dim) !important;
  font-family: var(--font-mono);
  font-size: 10px;
}
.s4f-pills .nav-link,
.s4f-side-pills .nav-link {
  border-radius: var(--radius-pill) !important;
  color: var(--color-ink-mute) !important;
  border: 1px solid var(--color-hairline) !important;
  background: transparent !important;
  margin: 0.2rem;
  font-size: 13px;
}
.s4f-pills .nav-link.active,
.s4f-side-pills .nav-link.active {
  background: rgb(226 232 240 / 0.18) !important;
  border-color: var(--color-signal) !important;
  color: var(--color-ink) !important;
}
.s4f-panel {
  padding: 1.25rem;
  border-radius: var(--radius-8);
  border: 1px solid var(--color-hairline);
  background: rgba(16, 19, 40, 0.72);
}
.s4f-empty {
  text-align: center;
  padding: 3rem 1rem;
  color: var(--color-ink-mute);
}
.s4f-empty .s4f-btn {
  margin-top: 1rem;
}

/* Footer — platform parity */
.s4f-footer,
footer.s4f-footer,
footer.footer {
  position: relative;
  margin-top: 4rem;
  padding: 3.5rem 0 2rem;
  border-top: 1px solid var(--color-hairline) !important;
  background: linear-gradient(180deg, #0a0b0f 0%, #050609 100%) !important;
  overflow: hidden;
}
.s4f-footer-glow {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: radial-gradient(ellipse 48% 70% at 0% 100%, rgb(226 232 240 / 0.12), transparent 55%);
}
.s4f-footer-grid {
  position: relative;
  display: grid;
  gap: 2.5rem;
  grid-template-columns: 1.2fr 2fr;
}
.s4f-footer-brand-col {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  max-width: 22rem;
}
.s4f-footer-tag {
  margin: 0;
  font-size: 0.9rem;
  line-height: 1.6;
  color: var(--color-ink-mute);
}
.s4f-footer-status {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  margin: 0;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-ink-faint);
}
.s4f-footer-cols {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1.5rem;
}
.s4f-footer-heading {
  margin: 0 0 1rem;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-ink-mute);
}
.s4f-footer-col ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}
.s4f-footer-col a {
  display: inline-flex;
  align-items: center;
  min-height: 2.15rem;
  color: var(--color-ink-dim);
  font-size: 0.9rem;
  text-decoration: none;
  transition: color 150ms var(--ease-out-expo);
}
.s4f-footer-col a:hover {
  color: var(--color-signal);
}
.s4f-footer-bottom {
  position: relative;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  margin-top: 2.5rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--color-hairline);
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--color-ink-faint);
}
.s4f-footer-bottom a {
  color: var(--color-ink-mute);
  text-decoration: none;
}
.s4f-footer-bottom a:hover {
  color: var(--color-signal);
}
.s4f-status-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--color-signal);
  box-shadow: 0 0 8px var(--color-signal);
  animation: s4f-pulse 2s ease-in-out infinite;
}

/* Back to top */
.s4f-totop {
  position: fixed;
  right: 1.25rem;
  bottom: 1.25rem;
  z-index: 30;
  display: grid;
  place-items: center;
  width: 2.75rem;
  height: 2.75rem;
  border-radius: 999px;
  border: 1px solid var(--color-hairline-strong);
  background: rgba(10, 12, 26, 0.85);
  color: var(--color-signal-hi);
  backdrop-filter: blur(12px);
  box-shadow: var(--shadow-card);
  text-decoration: none;
  opacity: 0;
  pointer-events: none;
  transform: translateY(8px);
  transition: opacity 180ms var(--ease-out-expo), transform 180ms var(--ease-out-expo);
}
.s4f-totop.is-visible {
  opacity: 1;
  pointer-events: auto;
  transform: translateY(0);
}

/* Hide contest-only chrome */
#ctf_timer,
.countdown,
[data-countdown],
a[href*="/teams"],
a[href*="/register"],
.theme-switch,
.navbar .dropdown:has(.fa-language),
li.nav-item:has(.theme-switch),
li.nav-item:has(.fa-language) {
  display: none !important;
}

/* Bootstrap dark overrides leftovers */
.jumbotron,
.bg-dark,
.navbar-dark.bg-dark {
  background: transparent !important;
}
.text-muted {
  color: var(--color-ink-mute) !important;
}
.min-vh-50 {
  min-height: 40vh;
}
.spinner,
.fa-spin {
  color: var(--color-signal-hi);
}

@keyframes s4f-fade-up {
  from {
    opacity: 0;
    transform: translateY(12px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}
@keyframes s4f-pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.45; }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

@media (max-width: 991.98px) {
  .s4f-nav-bar {
    flex-wrap: wrap;
    padding-block: 0.55rem;
    gap: 0.5rem;
  }
  .s4f-nav-collapse {
    display: none !important;
    flex-basis: 100%;
    flex-direction: column;
    align-items: stretch;
    gap: 0.35rem;
    padding: 0.75rem 0 0.35rem;
    border-top: 1px solid var(--color-hairline);
    margin-top: 0.55rem;
  }
  .s4f-nav-collapse.show {
    display: flex !important;
  }
  .s4f-nav-links,
  .s4f-nav-actions {
    flex-direction: column;
    align-items: stretch;
    width: 100%;
  }
  .s4f-nav-spacer {
    display: none;
  }
  .s4f-btn-nav {
    width: 100%;
    margin: 0.35rem 0 0;
    min-height: 44px;
  }
  .s4f-shell,
  .s4f-main .container,
  .s4f-main .container-fluid {
    padding-inline: 0.85rem !important;
    max-width: 100% !important;
  }
  .s4f-chal-dialog {
    margin: 0.5rem;
    max-width: calc(100vw - 1rem);
  }
}

@media (min-width: 992px) {
  .s4f-nav-collapse {
    display: flex !important;
  }
  .s4f-toggler {
    display: none !important;
  }
}

/* —— THM-style challenge room page —— */
.s4f-main > .s4f-room-hero {
  position: relative;
  z-index: 1;
  margin: -0.5rem 0 0;
  padding: 1.5rem 0 0;
  background:
    radial-gradient(ellipse 70% 80% at 8% 0%, rgba(226, 232, 240, 0.1), transparent 55%),
    linear-gradient(180deg, #14182b 0%, #0c0f1c 100%) !important;
  border-bottom: 1px solid rgba(61, 69, 96, 0.85);
}
.s4f-room-hero.is-solved {
  background:
    radial-gradient(ellipse 70% 55% at 10% 0%, rgba(52, 211, 153, 0.12), transparent 48%),
    linear-gradient(180deg, #12162a 0%, #0b0e1a 100%) !important;
}
.s4f-room-crumb {
  display: flex !important;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.4rem;
  margin: 0 0 1.35rem !important;
  font-family: var(--font-mono) !important;
  font-size: 11px !important;
  color: rgba(148, 163, 184, 0.95) !important;
}
.s4f-room-crumb a {
  color: rgba(186, 198, 216, 0.98) !important;
  text-decoration: none !important;
}
.s4f-room-crumb a:hover {
  color: #f8fafc !important;
}
.s4f-room-crumb .is-current {
  color: #f1f5f9 !important;
  max-width: 28rem;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.s4f-room-hero-row {
  display: grid !important;
  grid-template-columns: 8.5rem minmax(0, 1fr) !important;
  gap: 1.5rem 1.85rem !important;
  align-items: center !important;
  padding-bottom: 1.65rem !important;
}
.s4f-room-art {
  width: 8.25rem !important;
  height: 8.25rem !important;
  border-radius: 20px !important;
  border: 1px solid rgba(148, 163, 184, 0.35) !important;
  background:
    radial-gradient(circle at 35% 28%, rgba(255, 255, 255, 0.12), transparent 55%),
    #15192c !important;
  overflow: hidden !important;
  display: grid !important;
  place-items: center !important;
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.45) !important;
  flex-shrink: 0;
}
.s4f-room-art img {
  width: 100% !important;
  height: 100% !important;
  object-fit: cover !important;
  display: block !important;
}
.s4f-room-kicker {
  margin: 0 0 0.4rem !important;
  font-family: var(--font-mono) !important;
  font-size: 11px !important;
  letter-spacing: 0.14em !important;
  text-transform: uppercase !important;
  color: rgba(148, 163, 184, 0.98) !important;
}
.s4f-room-title {
  margin: 0 0 0.6rem !important;
  font-family: var(--font-display) !important;
  font-size: clamp(1.7rem, 3.2vw, 2.45rem) !important;
  font-weight: 700 !important;
  line-height: 1.15 !important;
  color: #f8fafc !important;
  letter-spacing: -0.02em !important;
}
.s4f-room-lead {
  margin: 0 0 1.1rem !important;
  max-width: 44rem;
  font-size: 1.02rem !important;
  line-height: 1.55 !important;
  color: rgba(203, 213, 225, 0.95) !important;
}
.s4f-room-meta {
  display: flex !important;
  flex-wrap: wrap !important;
  gap: 0.55rem 1.15rem !important;
  margin: 0 0 1.15rem !important;
  align-items: center !important;
}
.s4f-room-meta-item {
  display: inline-flex !important;
  align-items: center !important;
  gap: 0.4rem !important;
  font-family: var(--font-mono) !important;
  font-size: 12px !important;
  color: rgba(226, 232, 240, 0.92) !important;
  padding: 0.28rem 0.55rem;
  border-radius: 8px;
  background: rgba(15, 18, 32, 0.55);
  border: 1px solid rgba(61, 69, 96, 0.65);
}
.s4f-room-meta-item.diff-easy { color: #4ade80 !important; border-color: rgba(74, 222, 128, 0.28); }
.s4f-room-meta-item.diff-medium { color: #fbbf24 !important; border-color: rgba(251, 191, 36, 0.28); }
.s4f-room-meta-item.diff-hard { color: #fb7185 !important; border-color: rgba(251, 113, 133, 0.28); }
.s4f-room-meta-item.diff-expert { color: #c084fc !important; border-color: rgba(192, 132, 252, 0.28); }
.s4f-room-meta-item.diff-practice { color: #94a3b8 !important; }
.s4f-room-meta-item.is-solved {
  color: #34d399 !important;
  border-color: rgba(52, 211, 153, 0.35);
  background: rgba(52, 211, 153, 0.08);
}
.s4f-room-actions {
  display: flex !important;
  flex-wrap: wrap !important;
  align-items: center !important;
  gap: 0.75rem 1rem !important;
}
.s4f-room-tags {
  display: flex !important;
  flex-wrap: wrap !important;
  gap: 0.4rem !important;
}
.s4f-room-progress-bar {
  position: relative !important;
  margin-top: 0.15rem !important;
  border-top: 1px solid rgba(61, 69, 96, 0.7) !important;
  background: rgba(8, 10, 18, 0.72) !important;
  overflow: hidden !important;
}
.s4f-room-progress-inner {
  display: flex !important;
  align-items: center !important;
  justify-content: flex-end !important;
  gap: 0.65rem !important;
  min-height: 2.45rem !important;
  font-family: var(--font-mono) !important;
  font-size: 12px !important;
  color: rgba(226, 232, 240, 0.9) !important;
  position: relative;
  z-index: 1;
}
.s4f-room-progress-fill {
  position: absolute !important;
  left: 0 !important;
  top: 0 !important;
  bottom: 0 !important;
  background: linear-gradient(90deg, rgba(52, 211, 153, 0.4), rgba(148, 163, 184, 0.22)) !important;
  pointer-events: none;
  transition: width 400ms var(--ease-out-expo);
}
.s4f-room-layout {
  position: relative;
  z-index: 1;
  display: grid !important;
  grid-template-columns: minmax(0, 1fr) 17.5rem !important;
  gap: 1.5rem !important;
  padding: 1.85rem 0 3.25rem !important;
  align-items: start !important;
}
.s4f-room-panel {
  border: 1px solid rgba(61, 69, 96, 0.9) !important;
  border-radius: 16px !important;
  background: linear-gradient(165deg, rgba(24, 28, 46, 0.98), rgba(14, 17, 30, 0.98)) !important;
  padding: 1.45rem 1.5rem 1.6rem !important;
  box-shadow: 0 14px 36px rgba(0, 0, 0, 0.32) !important;
}
.s4f-room-panel .s4f-chal-section + .s4f-chal-section {
  margin-top: 1.35rem;
  padding-top: 1.25rem;
  border-top: 1px solid rgba(61, 69, 96, 0.55);
}
.s4f-room-desc {
  font-size: 1rem !important;
  line-height: 1.65 !important;
  color: rgba(226, 232, 240, 0.92) !important;
}
.s4f-room-side {
  display: flex !important;
  flex-direction: column !important;
  gap: 0.9rem !important;
  position: sticky !important;
  top: 5.75rem !important;
}
.s4f-room-side-card {
  border: 1px solid rgba(61, 69, 96, 0.9) !important;
  border-radius: 16px !important;
  background: linear-gradient(165deg, rgba(24, 28, 46, 0.98), rgba(14, 17, 30, 0.98)) !important;
  padding: 1.15rem 1.2rem !important;
  box-shadow: 0 10px 28px rgba(0, 0, 0, 0.28) !important;
}
.s4f-room-side-card h3 {
  margin: 0 0 0.95rem !important;
  font-family: var(--font-display) !important;
  font-size: 0.95rem !important;
  font-weight: 650 !important;
  color: #f1f5f9 !important;
}
.s4f-room-dl {
  margin: 0 !important;
  display: grid !important;
  gap: 0.65rem !important;
}
.s4f-room-dl > div {
  display: flex !important;
  justify-content: space-between !important;
  gap: 0.75rem !important;
  font-size: 12px !important;
  padding-bottom: 0.55rem;
  border-bottom: 1px solid rgba(61, 69, 96, 0.45);
}
.s4f-room-dl > div:last-child {
  border-bottom: 0;
  padding-bottom: 0;
}
.s4f-room-dl dt {
  font-family: var(--font-mono) !important;
  color: rgba(148, 163, 184, 0.98) !important;
}
.s4f-room-dl dd {
  margin: 0 !important;
  font-family: var(--font-mono) !important;
  color: #e2e8f0 !important;
  text-align: right !important;
  font-weight: 600;
}
.s4f-room-side-link {
  width: 100% !important;
  justify-content: center !important;
  text-align: center !important;
}
.s4f-room-panel .s4f-chal-submit-wrap {
  margin-top: 0.35rem;
  padding: 1.1rem 1.15rem !important;
  border-radius: 12px !important;
  border: 1px solid rgba(100, 116, 139, 0.35) !important;
  background: rgba(8, 10, 20, 0.55) !important;
}
@media (max-width: 959.98px) {
  .s4f-room-hero-row {
    grid-template-columns: 1fr !important;
  }
  .s4f-room-art {
    width: 5.75rem !important;
    height: 5.75rem !important;
  }
  .s4f-room-layout {
    grid-template-columns: 1fr !important;
  }
  .s4f-room-side {
    position: static !important;
  }
}