/* ===== Tuhoc.cc /duan — design tokens ===== */
:root {
  --bg: #07081a;
  --bg-2: #0c0e2b;
  --surface: rgba(255,255,255,0.04);
  --surface-2: rgba(255,255,255,0.06);
  --border: rgba(255,255,255,0.08);
  --border-strong: rgba(255,255,255,0.14);
  --text: #eaeeff;
  --text-dim: #aab1d9;
  --text-muted: #6b7299;
  --primary: #5F2DED;
  --primary-2: #7c3aff;
  --pink: #F2277E;
  --cyan: #00d4ff;
  --green: #2EC14A;
  --gold: #ffd166;
  --grad-brand: linear-gradient(135deg, #5F2DED 0%, #F2277E 100%);
  --grad-cool: linear-gradient(135deg, #3b6bff 0%, #7c3aff 50%, #00d4ff 100%);
  --grad-warm: linear-gradient(135deg, #ffb46b 0%, #F2277E 100%);
  --font-sans: 'Plus Jakarta Sans','Inter',system-ui,-apple-system,sans-serif;
  --font-mono: 'JetBrains Mono','Fira Code',ui-monospace,monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }
button { font-family: inherit; cursor: pointer; border: 0; background: none; color: inherit; }

/* ===== Background fx ===== */
.bg-fx {
  position: fixed; inset: 0; z-index: -1; pointer-events: none;
  background:
    radial-gradient(1000px 600px at 80% -10%, rgba(95,45,237,0.25), transparent 60%),
    radial-gradient(800px 600px at 0% 30%, rgba(242,39,126,0.18), transparent 60%),
    radial-gradient(900px 700px at 50% 100%, rgba(0,212,255,0.12), transparent 60%),
    var(--bg);
}
.bg-fx::before {
  content: ""; position: absolute; inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,0.025) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.025) 1px, transparent 1px);
  background-size: 60px 60px;
  mask-image: radial-gradient(ellipse 80% 60% at 50% 30%, #000 30%, transparent 80%);
}

/* ===== Container ===== */
.container { width: 100%; max-width: 1180px; padding: 0 24px; margin: 0 auto; }

/* ===== Topbar ===== */
.topbar {
  position: sticky; top: 0; z-index: 50;
  padding: 14px 0;
  background: rgba(7,8,26,0.85);
  backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid var(--border);
}
.topbar-inner {
  display: flex; align-items: center; justify-content: space-between; gap: 24px;
  position: relative;
}
.logo {
  display: flex; align-items: center; gap: 10px;
  font-weight: 800; font-size: 18px; letter-spacing: -0.02em; color: var(--text);
  flex-shrink: 0;
}
.logo-mark {
  position: relative;
  width: 36px; height: 36px;
  border-radius: 10px;
  background: conic-gradient(from 210deg, #3b6bff, #7c3aff, #F2277E, #00d4ff, #3b6bff);
  display: grid; place-items: center;
  font-family: var(--font-mono); font-weight: 700;
  color: #fff; font-size: 17px;
  box-shadow: 0 6px 20px rgba(95,45,237,0.5);
}
.logo-mark::before {
  content: ""; position: absolute; inset: 3px;
  border-radius: 7px; background: var(--bg);
}
.logo-mark > span { position: relative; z-index: 1; }
.logo b {
  background: var(--grad-brand);
  -webkit-background-clip: text; background-clip: text; color: transparent;
}

/* ===== Nav with dropdowns ===== */
.topbar-nav {
  display: flex; gap: 4px; align-items: center;
}
.nav-item {
  position: relative;
}
.nav-link {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 10px 16px;
  border-radius: 10px;
  font-size: 14.5px; font-weight: 600; color: var(--text-dim);
  white-space: nowrap;
  transition: color .2s, background .2s;
}
.nav-link:hover { color: var(--text); background: rgba(255,255,255,0.05); }
.nav-link .caret {
  font-size: 10px;
  opacity: .6;
  transition: transform .2s ease;
}
.nav-item:hover .nav-link .caret,
.nav-item.sub-open .nav-link .caret {
  transform: rotate(-180deg);
  opacity: 1;
}

.sub-menu {
  position: absolute;
  top: calc(100% + 8px);
  left: 0;
  min-width: 260px;
  list-style: none;
  padding: 8px;
  margin: 0;
  background: rgba(15,17,42,0.96);
  border: 1px solid var(--border-strong);
  border-radius: 14px;
  backdrop-filter: blur(20px) saturate(180%);
  box-shadow: 0 24px 48px -12px rgba(0,0,0,0.6), 0 0 0 1px rgba(255,255,255,0.04) inset;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-6px);
  transition: opacity .2s ease, transform .2s ease, visibility .2s;
  z-index: 60;
}
.nav-item:hover > .sub-menu,
.nav-item.sub-open > .sub-menu {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.sub-menu li { padding: 0; margin: 0; list-style: none; }
.sub-menu li a {
  display: flex; align-items: center; gap: 10px;
  padding: 10px 12px;
  border-radius: 8px;
  font-size: 13.5px; font-weight: 500;
  color: var(--text-dim);
  transition: color .2s, background .2s;
}
.sub-menu li a:hover {
  color: var(--text);
  background: rgba(124,58,255,0.12);
}
.sub-menu .sm-icon {
  font-size: 14px;
  opacity: .9;
  flex-shrink: 0;
}
.sm-divider {
  height: 1px;
  background: var(--border);
  margin: 6px 8px;
}

/* Right-edge dropdowns flip if would overflow */
.nav-item:nth-last-child(1) .sub-menu,
.nav-item:nth-last-child(2) .sub-menu {
  left: auto;
  right: 0;
}

/* Menu toggle (mobile) */
.menu-toggle {
  display: none;
  width: 40px; height: 40px;
  border-radius: 10px;
  background: var(--surface);
  border: 1px solid var(--border-strong);
  flex-direction: column; gap: 4px;
  align-items: center; justify-content: center;
}
.menu-toggle span {
  display: block; width: 18px; height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform .25s ease, opacity .2s ease;
}
.menu-toggle.open span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.menu-toggle.open span:nth-child(2) { opacity: 0; }
.menu-toggle.open span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

@media (max-width: 900px) {
  .menu-toggle { display: inline-flex; }
  .topbar-nav {
    position: absolute;
    top: calc(100% + 12px);
    left: 0; right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 4px;
    padding: 12px;
    background: rgba(15,17,42,0.96);
    border: 1px solid var(--border-strong);
    border-radius: 14px;
    backdrop-filter: blur(20px) saturate(180%);
    box-shadow: 0 24px 48px -12px rgba(0,0,0,0.6);
    max-height: calc(100vh - 120px);
    overflow-y: auto;
    opacity: 0; visibility: hidden;
    transform: translateY(-6px);
    transition: opacity .2s ease, transform .2s ease, visibility .2s;
  }
  .topbar-nav.open {
    opacity: 1; visibility: visible; transform: translateY(0);
  }
  .nav-item { width: 100%; }
  .nav-link {
    width: 100%;
    justify-content: space-between;
    padding: 12px 14px;
  }
  .sub-menu {
    position: static;
    background: transparent;
    border: 0;
    box-shadow: none;
    padding: 4px 8px 8px 24px;
    min-width: 0;
    opacity: 1;
    visibility: visible;
    transform: none;
    display: none;
    backdrop-filter: none;
  }
  .nav-item.sub-open > .sub-menu { display: block; }
  .nav-item:hover > .sub-menu { display: none; }
  .nav-item.sub-open:hover > .sub-menu { display: block; }
  .nav-item:nth-last-child(1) .sub-menu,
  .nav-item:nth-last-child(2) .sub-menu {
    left: 0; right: 0;
  }
}

/* ===== Main ===== */
.main { padding: 60px 0 80px; }

/* ===== Hero ===== */
.hero { text-align: center; max-width: 760px; margin: 0 auto 56px; }
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 6px 14px;
  border-radius: 999px;
  font-size: 12px; font-weight: 600; letter-spacing: 0.08em;
  text-transform: uppercase;
  background: rgba(124,58,255,0.12);
  border: 1px solid rgba(124,58,255,0.3);
  color: #c4b5fd;
}
.hero h1 {
  font-size: clamp(34px, 5vw, 54px);
  line-height: 1.1; letter-spacing: -0.025em; font-weight: 800;
  margin: 18px 0 18px;
}
.hero h1 .grad {
  background: var(--grad-brand);
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.hero .lead {
  font-size: 17px; color: var(--text-dim); max-width: 620px; margin: 0 auto 18px;
}
.hero-hint {
  display: inline-flex; align-items: center; gap: 10px;
  padding: 10px 18px;
  border-radius: 999px;
  background: rgba(124,58,255,0.10);
  border: 1px solid rgba(124,58,255,0.25);
  font-size: 13.5px;
  color: var(--text-dim);
  max-width: 100%;
}
.hh-icon { font-size: 16px; }

/* ===== Dự án block ===== */
.duan-block {
  margin: 0 auto 60px;
  padding: 36px 32px;
  background: rgba(12,14,43,0.5);
  border: 1px solid var(--border-strong);
  border-radius: 22px;
  backdrop-filter: blur(10px);
  scroll-margin-top: 90px;
}
.block-head {
  margin-bottom: 28px;
}
.block-tag {
  display: inline-block;
  font-family: var(--font-mono); font-size: 11px; font-weight: 700;
  letter-spacing: 0.16em; text-transform: uppercase;
  padding: 5px 12px; border-radius: 6px;
  background: rgba(124,58,255,0.18);
  border: 1px solid rgba(124,58,255,0.4);
  color: #c4b5fd;
  margin-bottom: 14px;
}
.block-head h2 {
  font-size: clamp(22px, 3vw, 30px);
  font-weight: 800; letter-spacing: -0.02em;
  margin: 0 0 8px;
}
.block-head p {
  font-size: 15px;
  color: var(--text-dim);
  margin: 0;
  max-width: 640px;
}

.block-links {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 14px;
}
.link-card {
  display: flex; align-items: center; gap: 14px;
  padding: 16px 18px;
  background: var(--surface);
  border: 1px solid var(--border-strong);
  border-radius: 14px;
  transition: transform .25s ease, border-color .25s ease, box-shadow .25s ease;
}
.link-card:hover {
  transform: translateY(-3px);
  border-color: rgba(124,58,255,0.5);
  box-shadow: 0 16px 32px -12px rgba(95,45,237,0.4);
}
.lc-icon {
  flex-shrink: 0;
  width: 44px; height: 44px;
  border-radius: 12px;
  display: grid; place-items: center;
  font-size: 22px;
}
.link-figma .lc-icon { background: linear-gradient(135deg, rgba(255,124,90,.20), rgba(242,39,126,.20)); }
.link-demo .lc-icon { background: linear-gradient(135deg, rgba(0,212,255,.20), rgba(91,140,255,.20)); }
.link-code .lc-icon { background: linear-gradient(135deg, rgba(124,58,255,.22), rgba(91,140,255,.18)); }
.link-discord .lc-icon { background: linear-gradient(135deg, rgba(46,193,74,.20), rgba(0,212,255,.18)); }
.link-mirror .lc-icon { background: linear-gradient(135deg, rgba(255,209,102,.18), rgba(242,39,126,.18)); }
.lc-text { display: flex; flex-direction: column; gap: 2px; min-width: 0; }
.lc-text b {
  font-size: 14.5px; font-weight: 700; color: var(--text);
  letter-spacing: -0.005em;
}
.lc-text span {
  font-size: 12.5px; color: var(--text-muted);
}

.block-extra {
  margin-top: 22px;
  padding-top: 22px;
  border-top: 1px solid var(--border);
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 14px;
}
.extra-badge {
  grid-column: 1 / -1;
  display: inline-flex; align-items: center; gap: 8px;
  padding: 6px 12px; border-radius: 999px;
  font-size: 12px; font-weight: 700; letter-spacing: 0.05em;
  background: rgba(242,39,126,0.15);
  border: 1px solid rgba(242,39,126,0.35);
  color: #ffaecf;
  width: fit-content;
  margin-bottom: 4px;
}

/* ===== Info section ===== */
.info {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 18px;
  padding: 32px;
  background: rgba(12,14,43,0.5);
  border: 1px solid var(--border);
  border-radius: 22px;
  backdrop-filter: blur(10px);
  margin-top: 24px;
}
.info-card {
  display: flex; gap: 14px; align-items: flex-start;
}
.info-icon {
  flex-shrink: 0;
  width: 44px; height: 44px;
  border-radius: 12px;
  background: rgba(124,58,255,0.15);
  border: 1px solid rgba(124,58,255,0.3);
  display: grid; place-items: center;
  font-size: 22px;
}
.info-card h4 {
  font-size: 15px; font-weight: 700; margin: 0 0 4px; color: var(--text);
}
.info-card p {
  font-size: 13.5px; color: var(--text-dim); line-height: 1.5; margin: 0;
}
.info-card a { color: #c4b5fd; font-weight: 500; }
.info-card a:hover { text-decoration: underline; }

/* ===== Footer ===== */
.footer {
  border-top: 1px solid var(--border);
  padding: 28px 0;
  background: rgba(0,0,0,0.3);
  font-size: 13px; color: var(--text-muted);
}
.footer-inner {
  display: flex; align-items: center; justify-content: space-between;
  flex-wrap: wrap; gap: 12px;
}
.footer a { color: var(--text-dim); }
.footer a:hover { color: var(--text); }

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .main { padding: 36px 0 60px; }
  .hero { margin-bottom: 36px; }
  .duan-block { padding: 26px 22px; margin-bottom: 30px; }
  .block-links { gap: 10px; }
  .link-card { padding: 12px 14px; }
  .info { padding: 22px; gap: 22px; }
}