/* =============================================
   aistations.org — Global Stylesheet
   ============================================= */

@import url('https://fonts.googleapis.com/css2?family=DM+Serif+Display:ital@0;1&family=DM+Mono:wght@300;400;500&family=Syne:wght@400;600;700;800&display=swap');

:root {
  --ink: #080807;
  --paper: #ffffff;
  --cream: #f0ece4;
  --accent: #a83200;
  --accent2: #0f2a52;
  --muted: #3a3530;
  --line: rgba(8,8,7,0.15);
  --gold: #8a6820;
  --green: #145030;
  --purple: #321a58;

  --font-display: 'DM Serif Display', serif;
  --font-mono: 'DM Mono', monospace;
  --font-sans: 'Syne', sans-serif;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }

body {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: 14px;
  line-height: 1.7;
  overflow-x: hidden;
}

body::before {
  content: '';
  position: fixed;
  inset: 0;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 512 512' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)' opacity='0.035'/%3E%3C/svg%3E");
  pointer-events: none;
  z-index: 9999;
  opacity: 0.4;
}

/* ─── NAV ─── */
nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 18px 48px;
  background: rgba(255,255,255,0.96);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}

.nav-logo {
  font-family: var(--font-display);
  font-size: 18px;
  color: var(--ink);
  text-decoration: none;
  letter-spacing: 0.01em;
}
.nav-logo span { color: var(--accent); }

.nav-links { display: flex; gap: 28px; list-style: none; align-items: center; }
.nav-links a {
  text-decoration: none;
  color: var(--muted);
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  transition: color 0.2s;
  padding: 4px 0;
  border-bottom: 1px solid transparent;
}
.nav-links a:hover, .nav-links a.active { color: var(--ink); border-bottom-color: var(--accent); }

.nav-lang { display: flex; gap: 6px; }
.lang-btn {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.1em;
  padding: 4px 10px;
  border: 1px solid var(--line);
  background: transparent;
  cursor: pointer;
  color: var(--muted);
  transition: all 0.2s;
}
.lang-btn.active, .lang-btn:hover { background: var(--ink); color: var(--paper); border-color: var(--ink); }

/* ─── PAGE WRAPPER ─── */
.page-wrap {
  max-width: 1200px;
  margin: 0 auto;
  padding: 120px 48px 80px;
}

/* ─── PAGE HEADER ─── */
.page-header {
  padding-bottom: 48px;
  border-bottom: 1px solid var(--line);
  margin-bottom: 64px;
}
.page-eyebrow {
  font-size: 11px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 16px;
}
.page-title {
  font-family: var(--font-display);
  font-size: clamp(40px, 5vw, 72px);
  line-height: 1.0;
  letter-spacing: -0.02em;
  margin-bottom: 20px;
}
.page-subtitle {
  font-size: 14px;
  color: var(--muted);
  max-width: 560px;
  line-height: 1.9;
}

/* ─── SECTION TITLE ─── */
.section-heading {
  display: flex;
  align-items: baseline;
  gap: 16px;
  margin-bottom: 40px;
}
.section-heading h2 {
  font-family: var(--font-display);
  font-size: 28px;
  letter-spacing: -0.01em;
}
.section-heading::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--line);
}

/* ─── CARDS ─── */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  margin-bottom: 64px;
}

.card {
  background: var(--paper);
  padding: 32px 28px;
  text-decoration: none;
  color: inherit;
  display: block;
  transition: background 0.2s;
  position: relative;
  overflow: hidden;
}
.card::before {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 3px; height: 0;
  background: var(--accent);
  transition: height 0.3s;
}
.card:hover { background: var(--cream); }
.card:hover::before { height: 100%; }

.card-tag {
  display: inline-block;
  font-size: 10px;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 14px;
  padding: 3px 8px;
  border: 1px solid rgba(184,56,0,0.4);
}
.card-tag.blue { color: var(--accent2); border-color: rgba(20,48,90,0.4); }
.card-tag.green { color: var(--green); border-color: rgba(26,92,58,0.4); }
.card-tag.purple { color: var(--purple); border-color: rgba(61,34,96,0.4); }

.card-title {
  font-family: var(--font-display);
  font-size: 20px;
  line-height: 1.3;
  margin-bottom: 10px;
}
.card-desc {
  font-size: 12px;
  color: var(--muted);
  line-height: 1.8;
  margin-bottom: 18px;
}
.card-meta {
  font-size: 10px;
  letter-spacing: 0.08em;
  color: var(--muted);
  display: flex;
  gap: 12px;
  align-items: center;
}
.card-meta .dot { opacity: 0.4; }

/* ─── ARTICLE / POST ─── */
.article-wrap {
  max-width: 740px;
  margin: 0 auto;
  padding: 120px 48px 80px;
}
.article-header { margin-bottom: 56px; border-bottom: 1px solid var(--line); padding-bottom: 40px; }
.article-header .page-eyebrow { margin-bottom: 20px; }
.article-header .page-title { font-size: clamp(32px, 4vw, 56px); margin-bottom: 24px; }
.article-body { font-size: 15px; line-height: 1.9; color: #111108; }
.article-body h2 {
  font-family: var(--font-display);
  font-size: 28px;
  margin: 48px 0 20px;
  color: var(--ink);
}
.article-body h3 {
  font-family: var(--font-sans);
  font-size: 16px;
  font-weight: 700;
  margin: 32px 0 12px;
  color: var(--ink);
}
.article-body p { margin-bottom: 20px; }
.article-body code {
  font-family: var(--font-mono);
  font-size: 12px;
  background: var(--cream);
  padding: 2px 6px;
  border: 1px solid var(--line);
}
.article-body pre {
  background: var(--ink);
  color: #e8e4dc;
  padding: 24px 28px;
  overflow-x: auto;
  margin: 28px 0;
  font-size: 13px;
  line-height: 1.6;
  border-left: 3px solid var(--accent);
}
.article-body pre code { background: none; border: none; padding: 0; color: inherit; font-size: inherit; }
.article-body blockquote {
  border-left: 3px solid var(--accent);
  margin: 28px 0;
  padding: 16px 24px;
  background: var(--cream);
  font-style: italic;
  color: var(--muted);
}
.article-body ul, .article-body ol {
  margin: 16px 0 20px 24px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.article-body img { width: 100%; margin: 28px 0; border: 1px solid var(--line); }

/* ─── COURSE LEVELS ─── */
.level-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 10px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  padding: 4px 10px;
  font-family: var(--font-mono);
}
.level-badge.beginner { background: rgba(26,92,58,0.1); color: var(--green); border: 1px solid rgba(26,92,58,0.35); }
.level-badge.intermediate { background: rgba(20,48,90,0.1); color: var(--accent2); border: 1px solid rgba(20,48,90,0.35); }
.level-badge.advanced { background: rgba(184,56,0,0.1); color: var(--accent); border: 1px solid rgba(184,56,0,0.35); }

/* ─── PROGRESS TRACK ─── */
.course-track {
  display: flex;
  flex-direction: column;
  gap: 0;
  border: 1px solid var(--line);
  margin-bottom: 64px;
}
.track-item {
  display: grid;
  grid-template-columns: 48px 1fr auto;
  gap: 24px;
  align-items: center;
  padding: 20px 24px;
  border-bottom: 1px solid var(--line);
  text-decoration: none;
  color: inherit;
  transition: background 0.2s;
}
.track-item:last-child { border-bottom: none; }
.track-item:hover { background: var(--cream); }
.track-num {
  font-family: var(--font-display);
  font-size: 24px;
  color: rgba(10,10,5,0.2);
  text-align: center;
  line-height: 1;
}
.track-item:hover .track-num { color: var(--accent); }
.track-title { font-family: var(--font-sans); font-size: 14px; font-weight: 600; margin-bottom: 4px; }
.track-desc { font-size: 12px; color: var(--muted); }

/* ─── BUTTONS ─── */
.btn-primary {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 12px 24px; background: var(--ink); color: var(--paper);
  text-decoration: none; font-size: 11px; letter-spacing: 0.12em;
  text-transform: uppercase; transition: background 0.2s, transform 0.2s;
  border: none; cursor: pointer; font-family: var(--font-mono);
}
.btn-primary:hover { background: var(--accent); transform: translateY(-2px); }
.btn-outline {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 12px 24px; border: 1px solid var(--ink); color: var(--ink);
  text-decoration: none; font-size: 11px; letter-spacing: 0.12em;
  text-transform: uppercase; transition: all 0.2s; background: transparent;
  cursor: pointer; font-family: var(--font-mono);
}
.btn-outline:hover { background: var(--ink); color: var(--paper); }

/* ─── FOOTER ─── */
footer {
  background: var(--ink);
  color: rgba(248,245,239,0.6);
  padding: 32px 48px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 11px;
  letter-spacing: 0.08em;
  margin-top: 80px;
}
footer a { color: rgba(248,245,239,0.6); text-decoration: none; }
footer a:hover { color: var(--paper); }

/* ─── LANGUAGE ─── */
[data-lang="vi"] { display: none; }
body.vi [data-lang="en"] { display: none; }
body.vi [data-lang="vi"] { display: revert; }

/* ─── REVEAL ANIMATION ─── */
.reveal { opacity: 0; transform: translateY(24px); transition: opacity 0.6s, transform 0.6s; }
.reveal.visible { opacity: 1; transform: none; }

/* ─── RESPONSIVE ─── */
@media (max-width: 768px) {
  nav { padding: 16px 20px; }
  .nav-links { gap: 16px; }
  .nav-links a { font-size: 10px; }
  .page-wrap, .article-wrap { padding: 100px 20px 60px; }
  footer { padding: 24px 20px; flex-direction: column; gap: 8px; text-align: center; }
}