/*
 * index.css — Homepage styles
 * Shihui Ruan · Portfolio
 *
 * Sections:
 *  1.  Design tokens — light (default) + dark override
 *  2.  Reset & base
 *  3.  Accessibility utilities
 *  4.  Scroll progress bar
 *  5.  Topbar & navigation
 *  6.  Mobile menu
 *  7.  Cursor glow (homepage only)
 *  8.  Layout helpers
 *  9.  Hero section
 * 10.  About section
 * 11.  Approach / Steps cards
 * 12.  Work list
 * 13.  Contact section
 * 14.  Footer
 * 15.  Reveal & boot animations
 * 16.  Responsive overrides
 */


/* ══════════════════════════════════════════════════════
   1. DESIGN TOKENS
   All contrast ratios verified against WCAG AA (4.5:1 body text)
   ══════════════════════════════════════════════════════ */
:root {
  /* backgrounds */
  --bg:        #FAFAF8;   /* page  — warm white */
  --bg-alt:    #F2F1EE;   /* cards / surfaces */
  --surface:   #FFFFFF;
  --border:    #E4E2DE;
  --border-str:#C9C7C1;   /* stronger border for interactive states */

  /* text — all on var(--bg) #FAFAF8 ≥ WCAG AA */
  --text:      #1C1B18;   /* ~17:1 ✓ */
  --text-2:    #5C5A54;   /* ~6.5:1 ✓ */
  --text-3:    #96948F;   /* ~3:1 — decorative / UI labels only */

  /* accent (amber) — 5.1:1 on #FAFAF8 ✓ */
  --accent:    #A3620A;
  --accent-2:  #7C4909;   /* hover / pressed */
  --on-accent: #FFFFFF;

  /* homepage-specific */
  --glow:   rgba(163, 98, 10, 0.05);  /* cursor radial tint */
  --orb:    rgba(163, 98, 10, 0.11);  /* hero decorative orb */

  /* typography */
  --font-display: "Bricolage Grotesque", system-ui, sans-serif;
  --font-body:    "DM Sans", system-ui, sans-serif;
  --radius: 12px;

  /* cursor position for glow (updated by index.js) */
  --mx: 50%;
  --my: 35%;
}

[data-theme="dark"] {
  --bg:        #111110;
  --bg-alt:    #1A1916;
  --surface:   #222120;
  --border:    #2E2C28;
  --border-str:#46443E;

  --text:      #EDEBE7;   /* ~15:1 on dark bg ✓ */
  --text-2:    #A8A59F;   /* ~7:1 ✓ */
  --text-3:    #6A6760;

  --accent:    #F0A932;   /* brighter amber for dark mode, ~5.5:1 ✓ */
  --accent-2:  #D4902C;
  --on-accent: #111110;

  --glow:   rgba(240, 169, 50, 0.07);
  --orb:    rgba(240, 169, 50, 0.18);
}


/* ══════════════════════════════════════════════════════
   2. RESET & BASE
   ══════════════════════════════════════════════════════ */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  /* keeps color-scheme hint for browser chrome (scrollbar etc.) */
  color-scheme: light dark;
}
[data-theme="light"] { color-scheme: light; }
[data-theme="dark"]  { color-scheme: dark; }

body {
  background-color: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  transition: background-color 0.4s ease, color 0.4s ease;
}


/* ══════════════════════════════════════════════════════
   3. ACCESSIBILITY UTILITIES
   ══════════════════════════════════════════════════════ */
.skip-link {
  position: absolute;
  top: -100%;
  left: 16px;
  z-index: 200;
  padding: 10px 20px;
  background: var(--accent);
  color: var(--on-accent);
  font-family: var(--font-body);
  font-weight: 600;
  font-size: 0.9rem;
  border-radius: 0 0 var(--radius) var(--radius);
  text-decoration: none;
  transition: top 0.2s ease;
}
.skip-link:focus { top: 0; }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 4px;
}


/* ══════════════════════════════════════════════════════
   4. SCROLL PROGRESS BAR
   ══════════════════════════════════════════════════════ */
#scroll-bar {
  position: fixed;
  top: 0; left: 0;
  width: 0%;
  height: 2px;
  background: var(--accent);
  z-index: 100;
  transition: width 0.1s linear;
  transform-origin: left;
}


/* ══════════════════════════════════════════════════════
   5. TOPBAR & NAVIGATION
   ══════════════════════════════════════════════════════ */
.topbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 60;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px clamp(20px, 4vw, 44px);
  background: color-mix(in srgb, var(--bg) 84%, transparent);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.35s ease, background-color 0.4s ease;
}
.topbar.scrolled { border-bottom-color: var(--border); }

.brand {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.05rem;
  letter-spacing: -0.01em;
  color: var(--text);
  text-decoration: none;
}
.brand .mark { color: var(--accent); }

/* Desktop nav — hidden on mobile, shown ≥860px */
.main-nav {
  display: none;
  gap: 28px;
}
.main-nav a {
  font-size: 0.9rem;
  color: var(--text-2);
  text-decoration: none;
  position: relative;
  padding: 4px 0;
  transition: color 0.22s ease;
}
.main-nav a::after {
  content: "";
  position: absolute; left: 0; bottom: -2px;
  width: 0; height: 2px;
  border-radius: 2px;
  background: var(--accent);
  transition: width 0.25s ease;
}
.main-nav a:hover,
.main-nav a[aria-current="page"] { color: var(--text); }
.main-nav a:hover::after,
.main-nav a[aria-current="page"]::after { width: 100%; }

.topbar-right {
  display: flex;
  align-items: center;
  gap: 8px;
}

/* Theme button */
.theme-btn {
  width: 38px; height: 38px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--border);
  background: var(--bg-alt);
  color: var(--text);
  border-radius: 999px;
  cursor: pointer;
  transition: border-color 0.22s ease, color 0.22s ease, background-color 0.4s ease;
}
.theme-btn:hover { border-color: var(--accent); color: var(--accent); }
.theme-btn svg   { width: 17px; height: 17px; display: block; }

/* Icon visibility: light theme → show moon, dark theme → show sun */
.ico-sun  { display: none; }
.ico-moon { display: block; }
[data-theme="dark"] .ico-sun  { display: block; }
[data-theme="dark"] .ico-moon { display: none; }


/* ══════════════════════════════════════════════════════
   6. MOBILE MENU
   ══════════════════════════════════════════════════════ */
.menu-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 38px; height: 38px;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  cursor: pointer;
  transition: border-color 0.22s ease, color 0.22s ease;
}
.menu-toggle:hover { border-color: var(--accent); color: var(--accent); }
.menu-toggle svg  { display: block; }

@media (min-width: 860px) {
  .main-nav  { display: flex; } /* show as horizontal row */
  .menu-toggle { display: none; }
}

/* Mobile nav overlay (below topbar, full-width) */
@media (max-width: 859px) {
  .main-nav {
    /* hidden until .is-open */
    flex-direction: column;
    position: fixed;
    top: 58px; left: 0; right: 0;
    background: color-mix(in srgb, var(--bg) 96%, transparent);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    padding: 8px 0 16px;
    gap: 0;
    z-index: 55;
    /* hidden by default */
    display: none;
  }
  .main-nav.is-open { display: flex; }
  .main-nav a {
    padding: 12px clamp(20px, 5vw, 44px);
    font-size: 1rem;
  }
  .main-nav a::after { display: none; } /* underlines off in mobile menu */
}


/* ══════════════════════════════════════════════════════
   7. CURSOR GLOW (homepage only)
   Updated by index.js: sets --mx / --my on <html>
   ══════════════════════════════════════════════════════ */
.cursor-glow {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background: radial-gradient(
    600px circle at var(--mx) var(--my),
    var(--glow),
    transparent 65%
  );
}


/* ══════════════════════════════════════════════════════
   8. LAYOUT HELPERS
   ══════════════════════════════════════════════════════ */
main { position: relative; z-index: 10; }

.wrap {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 clamp(20px, 5vw, 44px);
}

section {
  padding: clamp(80px, 12vw, 130px) 0;
  scroll-margin-top: 80px;
  position: relative;
}

.eyebrow {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 36px;
}
.eyebrow .idx  { color: var(--text-3); font-weight: 500; }
.eyebrow::after {
  content: "";
  flex: 1;
  height: 1px;
  background: var(--border);
  max-width: 90px;
}

/* shared button */
.btn {
  font-family: var(--font-body);
  font-size: 0.95rem;
  font-weight: 600;
  text-decoration: none;
  padding: 13px 24px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  color: var(--text);
  background: var(--bg-alt);
  display: inline-flex;
  align-items: center;
  gap: 8px;
  transition: transform 0.18s ease, border-color 0.22s ease, background-color 0.22s ease, color 0.22s ease;
}
.btn:hover         { transform: translateY(-2px); border-color: var(--accent); }
.btn.primary       { background: var(--accent); color: var(--on-accent); border-color: var(--accent); }
.btn.primary:hover { background: var(--accent-2); border-color: var(--accent-2); transform: translateY(-2px); }


/* ══════════════════════════════════════════════════════
   9. HERO
   ══════════════════════════════════════════════════════ */
.hero {
  min-height: 100vh;
  min-height: 100svh;
  display: flex;
  align-items: center;
  padding-top: 72px;
  position: relative;
  overflow: hidden;
}

/* Decorative orb — CSS gradient, parallax via index.js */
.orb {
  position: absolute;
  top: 6%; right: -8%;
  width: min(48vw, 560px);
  height: min(48vw, 560px);
  border-radius: 50%;
  background: radial-gradient(circle, var(--orb), transparent 68%);
  filter: blur(12px);
  z-index: 0;
  pointer-events: none;
  will-change: transform;
}

.hero-inner {
  position: relative;
  z-index: 2;
  width: 100%;
}

.kicker {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  font-size: 0.82rem;
  font-weight: 500;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-2);
  margin-bottom: 26px;
}
.pin {
  width: 7px; height: 7px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 4px color-mix(in srgb, var(--accent) 20%, transparent);
  flex-shrink: 0;
}

.hero h1 {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(2.7rem, 8.5vw, 6rem);
  line-height: 1.02;
  letter-spacing: -0.025em;
  margin-bottom: 28px;
  max-width: 14ch;
}
.hero h1 .accent { color: var(--accent); }

.hero .sub {
  font-size: clamp(1rem, 2.2vw, 1.25rem);
  color: var(--text-2);
  max-width: 540px;
  margin-bottom: 40px;
  line-height: 1.6;
}

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


/* ══════════════════════════════════════════════════════
   10. ABOUT
   ══════════════════════════════════════════════════════ */
.about-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 48px;
}

.about-lead {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(1.5rem, 3.5vw, 2.1rem);
  line-height: 1.3;
  letter-spacing: -0.01em;
  margin-bottom: 22px;
}
.about-lead .accent { color: var(--accent); }

.about-body {
  color: var(--text-2);
  font-size: 1.02rem;
  line-height: 1.75;
}

/* Metrics 2×2 grid */
.metrics {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}
.metric {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px 20px;
  transition: border-color 0.22s ease;
}
.metric:hover { border-color: var(--border-str); }

.metric .num {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 2.4rem;
  line-height: 1;
  color: var(--text);
}
.metric .num .u { color: var(--accent); font-size: 1.6rem; }

.metric .lbl {
  font-size: 0.82rem;
  color: var(--text-3);
  margin-top: 8px;
  line-height: 1.4;
}


/* ══════════════════════════════════════════════════════
   11. APPROACH / STEPS
   ══════════════════════════════════════════════════════ */
.steps {
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
}

.step {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 28px 26px;
  transition: transform 0.25s ease, border-color 0.25s ease;
}
.step:hover { transform: translateY(-3px); border-color: var(--border-str); }

.step .sn {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1rem;
  color: var(--accent);
  margin-bottom: 14px;
}
.step h3 {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.45rem;
  letter-spacing: -0.01em;
  margin-bottom: 10px;
}
.step p {
  color: var(--text-2);
  font-size: 0.97rem;
  line-height: 1.65;
  margin-bottom: 18px;
}
.tags {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}
.tags span {
  font-size: 0.76rem;
  font-weight: 500;
  color: var(--text-3);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 3px 11px;
}


/* ══════════════════════════════════════════════════════
   12. WORK LIST
   ══════════════════════════════════════════════════════ */
.work-list { display: flex; flex-direction: column; }

.proj {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
  padding: 34px 0;
  border-top: 1px solid var(--border);
  text-decoration: none;
  color: inherit;
  border-radius: 0;
  position: relative;
  transition: padding-left 0.3s ease, padding-right 0.3s ease, background-color 0.25s ease;
}
.proj:last-child { border-bottom: 1px solid var(--border); }
.proj:hover {
  background: var(--bg-alt);
  padding-left: 20px;
  padding-right: 20px;
  border-radius: var(--radius);
}

.proj .pn {
  font-size: 0.84rem;
  font-weight: 600;
  color: var(--text-3);
  transition: color 0.22s ease;
}
.proj:hover .pn { color: var(--accent); }

.proj h3 {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(1.4rem, 3.4vw, 2rem);
  line-height: 1.15;
  letter-spacing: -0.015em;
  margin-bottom: 8px;
  transition: color 0.22s ease;
}
.proj:hover h3 { color: var(--accent); }

.proj .pd {
  color: var(--text-2);
  font-size: 0.96rem;
  line-height: 1.6;
  max-width: 540px;
}

.ptags {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  align-self: start;
}
.ptags span {
  font-size: 0.76rem;
  color: var(--text-3);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 3px 11px;
  white-space: nowrap;
}


/* ══════════════════════════════════════════════════════
   13. CONTACT
   ══════════════════════════════════════════════════════ */
.contact h2 {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(2rem, 6.5vw, 4.4rem);
  line-height: 1.05;
  letter-spacing: -0.025em;
  margin-bottom: 34px;
}
.contact h2 a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 3px solid color-mix(in srgb, var(--accent) 30%, transparent);
  transition: border-color 0.22s ease;
}
.contact h2 a:hover { border-bottom-color: var(--accent); }

.links { display: flex; gap: 10px; flex-wrap: wrap; }
.links a {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-2);
  text-decoration: none;
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 10px 20px;
  transition: transform 0.18s ease, border-color 0.22s ease, color 0.22s ease;
}
.links a:hover { transform: translateY(-2px); border-color: var(--accent); color: var(--text); }


/* ══════════════════════════════════════════════════════
   14. FOOTER
   ══════════════════════════════════════════════════════ */
.footer {
  border-top: 1px solid var(--border);
  padding: 28px clamp(20px, 5vw, 44px);
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px;
  font-size: 0.82rem;
  color: var(--text-3);
  position: relative;
  z-index: 10;
}
.footer .accent { color: var(--accent); }


/* ══════════════════════════════════════════════════════
   15. ANIMATIONS
   ══════════════════════════════════════════════════════ */

/* Boot — hero elements fade up on page load (triggered by index.js) */
.boot {
  opacity: 0;
  transform: translateY(16px);
}
.boot.on {
  animation: rise 0.7s cubic-bezier(0.2, 0, 0.1, 1) forwards;
}
@keyframes rise {
  to { opacity: 1; transform: translateY(0); }
}

/* Scroll reveal — triggered by IntersectionObserver in index.js */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s ease, transform 0.7s cubic-bezier(0.2, 0, 0.1, 1);
}
.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* Honour prefers-reduced-motion */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    transition-duration: 0.001ms !important;
  }
  .reveal, .boot { opacity: 1 !important; transform: none !important; }
  .orb           { display: none; }
  .cursor-glow   { display: none; }
}


/* ══════════════════════════════════════════════════════
   16. RESPONSIVE
   ══════════════════════════════════════════════════════ */

/* ── Tablet ≥ 640px ── */
@media (min-width: 640px) {
  .steps { grid-template-columns: 1fr 1fr; }
}

/* ── Desktop ≥ 860px ── */
@media (min-width: 860px) {
  .about-grid {
    grid-template-columns: 1.4fr 1fr;
    gap: 64px;
    align-items: start;
  }
  .proj {
    grid-template-columns: 64px 1fr auto;
    gap: 32px;
    align-items: baseline;
  }
  .proj:hover { border-radius: var(--radius); }
}