/* ==========================================================================
   C2CAD-Bench — Design System
   Modern academic bench site: light-first, dark-mode ready.
   ========================================================================== */

:root {
  /* Typography */
  --font-sans: "Inter", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-display: "Sora", "Inter", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", Consolas, monospace;

  /* Brand palette */
  --accent: #1f3a5f;
  --accent-strong: #14273f;
  --accent-soft: rgba(31, 58, 95, 0.06);
  --accent-ring: rgba(31, 58, 95, 0.22);
  --accent-2: #5b6b7c;
  --accent-2-soft: rgba(91, 107, 124, 0.09);
  --accent-3: #8a6d3b;
  --gradient: var(--accent);
  --gradient-soft: rgba(31, 58, 95, 0.06);

  /* Surfaces */
  --bg: #ffffff;
  --bg-soft: #f5f6fb;
  --bg-deep: #eef0f8;
  --bg-elev: #ffffff;
  --bg-glass: rgba(255, 255, 255, 0.78);
  --bg-code: #0d1224;

  /* Ink */
  --ink: #0b1020;
  --ink-soft: #2a3350;
  --muted: #5a647c;
  --muted-2: #7a849c;

  /* Lines */
  --border: #e6e8f2;
  --border-strong: #d5d9ea;

  /* Status */
  --good: #059669;
  --good-bg: rgba(5, 150, 105, 0.1);
  --warn: #d97706;
  --warn-bg: rgba(217, 119, 6, 0.11);
  --bad: #9b2c2c;
  --bad-bg: rgba(225, 29, 72, 0.1);

  /* Effects */
  --radius-xs: 8px;
  --radius-sm: 12px;
  --radius: 18px;
  --radius-lg: 26px;
  --radius-full: 999px;
  --shadow-xs: 0 1px 2px rgba(11, 16, 32, 0.05);
  --shadow-sm: 0 2px 8px rgba(11, 16, 32, 0.05);
  --shadow-md: 0 12px 32px -12px rgba(11, 16, 32, 0.18);
  --shadow-lg: 0 30px 60px -24px rgba(11, 16, 32, 0.26);
  --shadow-glow: 0 18px 50px -18px rgba(79, 70, 229, 0.55);
  --transition: 180ms cubic-bezier(0.22, 0.61, 0.36, 1);

  /* Layout */
  --nav-h: 70px;
  --container: 1200px;
  --container-wide: 1320px;

  color-scheme: light;
}

[data-theme="dark"] {
  --accent: #9db8d6;
  --accent-strong: #c3d6ea;
  --accent-soft: rgba(157, 184, 214, 0.09);
  --accent-ring: rgba(157, 184, 214, 0.22);
  --accent-2: #a8a396;
  --accent-2-soft: rgba(168, 163, 150, 0.1);
  --accent-3: #c2a878;
  --gradient: var(--accent);
  --gradient-soft: rgba(157, 184, 214, 0.09);

  --bg: #080b15;
  --bg-soft: #0d1120;
  --bg-deep: #111629;
  --bg-elev: #111628;
  --bg-glass: rgba(10, 14, 27, 0.72);
  --bg-code: #060913;

  --ink: #f1f3ff;
  --ink-soft: #cbd1ea;
  --muted: #9aa3c0;
  --muted-2: #7e88a8;

  --border: #202944;
  --border-strong: #2c3758;

  --good: #34d399;
  --good-bg: rgba(52, 211, 153, 0.12);
  --warn: #fbbf24;
  --warn-bg: rgba(251, 191, 36, 0.12);
  --bad: #cf9191;
  --bad-bg: rgba(251, 113, 133, 0.12);

  --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-sm: 0 2px 10px rgba(0, 0, 0, 0.35);
  --shadow-md: 0 16px 36px -16px rgba(0, 0, 0, 0.6);
  --shadow-lg: 0 34px 70px -26px rgba(0, 0, 0, 0.72);
  --shadow-glow: 0 20px 55px -18px rgba(129, 140, 248, 0.4);

  color-scheme: dark;
}

/* --------------------------------------------------------------------------
   Reset & base
   -------------------------------------------------------------------------- */

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-h) + 28px);
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.68;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
  transition: background-color 220ms ease, color 220ms ease;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.18;
  letter-spacing: -0.02em;
  color: var(--ink);
}

p {
  margin: 0;
}

a {
  color: inherit;
  text-decoration: none;
}

img,
svg,
canvas {
  display: block;
  max-width: 100%;
}

button,
input,
select,
textarea {
  font: inherit;
  color: inherit;
}

button {
  background: none;
  border: 0;
  cursor: pointer;
}

ul,
ol {
  margin: 0;
  padding: 0;
  list-style: none;
}

pre,
code,
kbd {
  font-family: var(--font-mono);
}

::selection {
  background: var(--accent);
  color: #ffffff;
}

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 6px;
}

/* Scrollbars */
* {
  scrollbar-width: thin;
  scrollbar-color: var(--border-strong) transparent;
}

*::-webkit-scrollbar {
  width: 10px;
  height: 10px;
}

*::-webkit-scrollbar-thumb {
  background: var(--border-strong);
  border-radius: 999px;
  border: 2px solid var(--bg);
}

*::-webkit-scrollbar-track {
  background: transparent;
}

/* --------------------------------------------------------------------------
   Layout helpers
   -------------------------------------------------------------------------- */

.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: 24px;
}

.container-wide {
  max-width: var(--container-wide);
}

.section {
  position: relative;
  padding: 96px 0;
}

.section--tight {
  padding: 72px 0;
}

.section--soft {
  background: var(--bg-soft);
  border-block: 1px solid var(--border);
}

.section--deep {
  background: var(--bg-deep);
}

.section-head {
  max-width: 760px;
  margin-bottom: 46px;
}

.section-head--center {
  margin-inline: auto;
  text-align: center;
}

.section-head--split {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 32px;
  max-width: none;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
}

.eyebrow::before {
  content: "";
  width: 22px;
  height: 2px;
  border-radius: 2px;
  background: var(--gradient);
}

.section-title {
  margin: 10px 0 14px;
  font-size: clamp(1.7rem, 3.3vw, 2.55rem);
  font-weight: 700;
}

.section-lead {
  max-width: 680px;
  color: var(--muted);
  font-size: 1.04rem;
}

.section-head--center .section-lead {
  margin-inline: auto;
}

.text-gradient {
  color: var(--accent);
}

.muted {
  color: var(--muted);
}

.mono {
  font-family: var(--font-mono);
}

.text-good {
  color: var(--good);
}

.text-warn {
  color: var(--warn);
}

.text-bad {
  color: var(--bad);
}

.icon {
  width: 1.15em;
  height: 1.15em;
  flex: 0 0 auto;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.visually-hidden {
  position: absolute !important;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.spinner {
  width: 26px;
  height: 26px;
  border: 2px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

/* Provider markers (shared by scoreboard and visualizer) */
.provider-dot {
  display: inline-block;
  width: 7px;
  height: 7px;
  flex: 0 0 auto;
  border-radius: 50%;
  background: #94a3b8;
}

.dot-gemini {
  background: #3b5f8a;
}

.dot-claude {
  background: #8a5a3b;
}

.dot-deepseek {
  background: #3f6b6b;
}

.dot-openai {
  background: #4f6b4f;
}

.dot-mistral {
  background: #8a4d4d;
}

.dot-kimi {
  background: #6b6459;
}

.dot-custom {
  background: #77746d;
}

.dot-qwen {
  background: #5b6b7c;
}

.dot-xiaomi {
  background: #8a6d3b;
}

.dot-tencent {
  background: #3f6b8a;
}

.dot-stepfun {
  background: #55603f;
}

.dot-deepinfra {
  background: #6b6459;
}

.dot-zhipu {
  background: #7a5c43;
}

/* --------------------------------------------------------------------------
   Buttons & badges
   -------------------------------------------------------------------------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  min-height: 44px;
  padding: 10px 20px;
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 14px;
  font-weight: 600;
  line-height: 1;
  white-space: nowrap;
  cursor: pointer;
  transition: transform var(--transition), background var(--transition),
    border-color var(--transition), box-shadow var(--transition), color var(--transition);
}

.btn:hover {
  transform: translateY(-1px);
}

.btn:active {
  transform: translateY(0);
}

.btn-primary {
  background: var(--accent);
  color: #ffffff;
  box-shadow: 0 10px 24px -12px var(--accent);
}

.btn-primary:hover {
  background: var(--accent-strong);
  box-shadow: 0 14px 30px -12px var(--accent);
}

.btn-gradient {
  background: var(--gradient);
  color: #ffffff;
  box-shadow: var(--shadow-glow);
}

.btn-gradient:hover {
  filter: brightness(1.05);
}

.btn-ghost {
  background: var(--bg-elev);
  border-color: var(--border);
  color: var(--ink-soft);
  box-shadow: var(--shadow-xs);
}

.btn-ghost:hover {
  border-color: var(--border-strong);
  color: var(--ink);
  box-shadow: var(--shadow-sm);
}

.btn-soft {
  background: var(--accent-soft);
  color: var(--accent);
}

.btn-soft:hover {
  background: var(--accent);
  color: #ffffff;
}

.btn-sm {
  min-height: 36px;
  padding: 8px 14px;
  font-size: 13px;
}

.btn-lg {
  min-height: 52px;
  padding: 14px 26px;
  font-size: 15px;
  border-radius: 14px;
}

.btn-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 5px 12px;
  border-radius: var(--radius-full);
  background: var(--accent-soft);
  border: 1px solid var(--accent-ring);
  color: var(--accent);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.02em;
}

.badge-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 4px var(--accent-soft);
}

/* --------------------------------------------------------------------------
   Cards
   -------------------------------------------------------------------------- */

.card {
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
}

.card-hover {
  transition: transform var(--transition), box-shadow var(--transition),
    border-color var(--transition);
}

.card-hover:hover {
  transform: translateY(-4px);
  border-color: var(--border-strong);
  box-shadow: var(--shadow-md);
}

/* --------------------------------------------------------------------------
   Header / navigation
   -------------------------------------------------------------------------- */

.scroll-progress {
  position: fixed;
  inset: 0 auto auto 0;
  width: 0;
  height: 3px;
  z-index: 1200;
  background: var(--gradient);
  box-shadow: 0 0 12px var(--accent-ring);
  pointer-events: none;
}

.site-header {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 1000;
  height: var(--nav-h);
  background: var(--bg-glass);
  border-bottom: 1px solid transparent;
  -webkit-backdrop-filter: blur(16px) saturate(160%);
  backdrop-filter: blur(16px) saturate(160%);
  transition: border-color var(--transition), box-shadow var(--transition);
}

.site-header.is-scrolled {
  border-bottom-color: var(--border);
  box-shadow: var(--shadow-sm);
}

.nav-inner {
  display: flex;
  align-items: center;
  gap: 22px;
  height: 100%;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  font-family: var(--font-display);
  font-size: 1.06rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  white-space: nowrap;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 36px;
  height: 36px;
  border-radius: 11px;
  background: var(--gradient);
  color: #ffffff;
  box-shadow: 0 8px 18px -8px var(--accent);
}

.brand-mark .icon {
  width: 19px;
  height: 19px;
  stroke-width: 1.7;
}

.brand-sub {
  display: block;
  margin-top: -2px;
  font-family: var(--font-sans);
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--muted-2);
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 18px;
  margin-left: auto;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 2px;
}

.nav-link {
  padding: 8px 13px;
  border-radius: var(--radius-full);
  font-size: 13.5px;
  font-weight: 550;
  color: var(--muted);
  transition: color var(--transition), background var(--transition);
}

.nav-link:hover {
  color: var(--ink);
  background: var(--bg-soft);
}

.nav-link.is-active {
  color: var(--accent);
  background: var(--accent-soft);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

.icon-btn {
  display: inline-grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  border: 1px solid var(--border);
  background: var(--bg-elev);
  color: var(--muted);
  transition: color var(--transition), background var(--transition),
    border-color var(--transition), transform var(--transition);
}

.icon-btn:hover {
  transform: translateY(-1px);
  color: var(--ink);
  border-color: var(--border-strong);
}

.icon-btn .icon {
  width: 18px;
  height: 18px;
}

.nav-toggle {
  display: none;
  width: 42px;
  height: 42px;
  place-items: center;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--bg-elev);
  color: var(--ink);
  margin-left: auto;
}

.nav-toggle .icon-close {
  display: none;
}

.nav-toggle[aria-expanded="true"] .icon-menu {
  display: none;
}

.nav-toggle[aria-expanded="true"] .icon-close {
  display: block;
}

.theme-toggle .icon-moon {
  display: none;
}

[data-theme="dark"] .theme-toggle .icon-sun {
  display: none;
}

[data-theme="dark"] .theme-toggle .icon-moon {
  display: block;
}

/* --------------------------------------------------------------------------
   Footer
   -------------------------------------------------------------------------- */

.site-footer {
  padding: 68px 0 30px;
  background: var(--bg-soft);
  border-top: 1px solid var(--border);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2.2fr 1fr 1fr;
  gap: 44px;
}

.footer-brand .brand {
  margin-bottom: 16px;
}

.footer-about {
  max-width: 420px;
  color: var(--muted);
  font-size: 14px;
}

.footer-title {
  margin-bottom: 14px;
  font-family: var(--font-display);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted-2);
}

.footer-links {
  display: flex;
  flex-direction: column;
  gap: 9px;
}

.footer-links a {
  width: fit-content;
  color: var(--muted);
  font-size: 14px;
  transition: color var(--transition);
}

.footer-links a:hover {
  color: var(--accent);
}

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  margin-top: 44px;
  padding-top: 22px;
  border-top: 1px solid var(--border);
  color: var(--muted-2);
  font-size: 13px;
}

.footer-bottom a {
  color: var(--muted);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.footer-bottom a:hover {
  color: var(--accent);
}

/* --------------------------------------------------------------------------
   Reveal animation
   -------------------------------------------------------------------------- */

.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 620ms cubic-bezier(0.22, 0.61, 0.36, 1),
    transform 620ms cubic-bezier(0.22, 0.61, 0.36, 1);
}

.reveal.is-visible {
  opacity: 1;
  transform: none;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .reveal {
    opacity: 1;
    transform: none;
  }
}

/* --------------------------------------------------------------------------
   Lightbox
   -------------------------------------------------------------------------- */

.lightbox {
  position: fixed;
  inset: 0;
  z-index: 2000;
  display: grid;
  place-items: center;
  padding: 28px;
  background: rgba(4, 7, 18, 0.86);
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
  opacity: 0;
  visibility: hidden;
  transition: opacity 220ms ease, visibility 220ms ease;
}

.lightbox.is-open {
  opacity: 1;
  visibility: visible;
}

.lightbox-inner {
  display: flex;
  flex-direction: column;
  gap: 14px;
  max-width: min(1120px, 94vw);
  transform: scale(0.97);
  transition: transform 220ms ease;
}

.lightbox.is-open .lightbox-inner {
  transform: scale(1);
}

.lightbox img {
  max-height: 78vh;
  width: auto;
  margin-inline: auto;
  border-radius: 12px;
  background: #ffffff;
  box-shadow: 0 40px 90px -30px rgba(0, 0, 0, 0.7);
}

.lightbox-caption {
  color: #e7eaf7;
  font-size: 13.5px;
  text-align: center;
}

.lightbox-close {
  position: fixed;
  top: 22px;
  right: 24px;
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1px solid rgba(255, 255, 255, 0.18);
  background: rgba(255, 255, 255, 0.1);
  color: #ffffff;
  transition: background var(--transition), transform var(--transition);
}

.lightbox-close:hover {
  background: rgba(255, 255, 255, 0.2);
  transform: rotate(90deg);
}

body.has-lightbox {
  overflow: hidden;
}

/* --------------------------------------------------------------------------
   Responsive
   -------------------------------------------------------------------------- */

@media (max-width: 1040px) {
  .nav-links {
    gap: 0;
  }

  .nav-link {
    padding: 8px 10px;
    font-size: 13px;
  }
}

@media (max-width: 920px) {
  .nav-toggle {
    display: grid;
  }

  .nav-menu {
    position: absolute;
    top: calc(var(--nav-h) + 8px);
    left: 16px;
    right: 16px;
    flex-direction: column;
    align-items: stretch;
    gap: 10px;
    padding: 14px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: var(--bg-elev);
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-8px);
    transition: opacity var(--transition), transform var(--transition),
      visibility var(--transition);
  }

  .nav-menu.is-open {
    opacity: 1;
    visibility: visible;
    transform: none;
  }

  .nav-links {
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
  }

  .nav-link {
    padding: 11px 14px;
    font-size: 14px;
    border-radius: var(--radius-sm);
  }

  .nav-actions {
    padding-top: 10px;
    border-top: 1px solid var(--border);
  }

  .nav-actions .btn {
    flex: 1;
  }

  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }

  .footer-brand {
    grid-column: 1 / -1;
  }
}

@media (max-width: 640px) {
  :root {
    --nav-h: 64px;
  }

  .container {
    padding-inline: 18px;
  }

  .section {
    padding: 70px 0;
  }

  .section--tight {
    padding: 54px 0;
  }

  .brand {
    font-size: 0.98rem;
  }

  .brand-mark {
    width: 33px;
    height: 33px;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 30px;
  }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }
}