/* ══════════════════════════════════════
   AIUsage.in — Main Stylesheet
   Ultra-Light Theme | Dark Black Text
   .NET 8 / ASP.NET Core
══════════════════════════════════════ */

:root {
  /* Ultra-light backgrounds */
  --bg:           #ffffff;
  --bg2:          #f8f9fc;
  --bg3:          #f0f4ff;
  --surface:      #ffffff;
  --border:       #e2e8f0;
  --border2:      #cbd5e1;

  /* Accents */
  --accent:       #1d4ed8;
  --accent2:      #7c3aed;
  --accent3:      #059669;
  --accent-light: #eff6ff;
  --accent-hover: #1e40af;

  /* Text — deep black family */
  --text:         #0a0f1e;
  --text-muted:   #374151;
  --text-dim:     #6b7280;
  --text-light:   #9ca3af;

  /* Status */
  --danger:       #dc2626;
  --warning:      #d97706;
  --success:      #059669;

  /* Typography */
  --heading: 'Syne', sans-serif;
  --body:    'DM Sans', sans-serif;
  --mono:    'DM Mono', monospace;

  /* Shadows */
  --shadow:    0 1px 8px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 20px rgba(0,0,0,0.09);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.13);
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--body);
  font-size: 16px;
  line-height: 1.75;
  overflow-x: hidden;
  padding-bottom: 72px;
  -webkit-font-smoothing: antialiased;
}

/* ══ SCROLLBAR ══ */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--bg2); }
::-webkit-scrollbar-thumb { background: var(--border2); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-dim); }

/* ══════════════════════════
   AD BLOCKS
══════════════════════════ */
.ad-block {
  background: #fafbff;
  border: 1.5px dashed #c7d7f0;
  border-radius: 10px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  color: var(--text-dim);
  font-family: var(--mono);
  font-size: .68rem;
  letter-spacing: .5px;
  text-transform: uppercase;
  position: relative;
  overflow: hidden;
}
.ad-label {
  font-size: .58rem;
  color: var(--text-light);
  background: #eef2ff;
  border-radius: 4px;
  padding: .18rem .5rem;
  margin-bottom: .35rem;
  display: flex;
  align-items: center;
  gap: .3rem;
}
.ad-label::before { content: '📢'; font-size: .6rem; }
.ad-size { font-size: .7rem; font-weight: 600; color: var(--text-dim); }

.ad-sidebar-fixed {
  position: fixed; top: 50%; transform: translateY(-50%);
  width: 160px; z-index: 500;
}
.ad-sidebar-fixed.left  { left: 6px; }
.ad-sidebar-fixed.right { right: 6px; }
.ad-sidebar-fixed .ad-block { width: 160px; height: 600px; }
@media (max-width: 1439px) { .ad-sidebar-fixed { display: none; } }

.ad-strip {
  width: 100%;
  padding: .5rem 1rem;
  background: var(--bg2);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  display: flex;
  justify-content: center;
  align-items: center;
}
.ad-strip .ad-block { width: 100%; max-width: 728px; height: 90px; flex-direction: row; gap: .75rem; }

.ad-card-inline {
  background: var(--bg2);
  border: 1.5px dashed #c7d7f0;
  border-radius: 12px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 200px;
}
.ad-rect-wrap { display: flex; justify-content: center; margin: 2rem 0; }
.ad-billboard-wrap { display: flex; justify-content: center; padding: 2rem 1rem; background: var(--bg2); }
.ad-billboard-wrap .ad-block { width: 100%; max-width: 970px; height: 250px; }

.ad-sticky-bottom {
  position: fixed; bottom: 0; left: 0; right: 0; z-index: 900;
  background: #fff;
  border-top: 2px solid var(--border);
  padding: .4rem;
  display: flex; justify-content: center; align-items: center;
  box-shadow: 0 -4px 20px rgba(0,0,0,.07);
}
.ad-sticky-close {
  position: absolute; right: .75rem;
  background: var(--bg2); border: 1px solid var(--border);
  color: var(--text-dim); width: 26px; height: 26px;
  border-radius: 50%; cursor: pointer; font-size: .85rem;
  display: flex; align-items: center; justify-content: center;
  transition: all .2s;
}
.ad-sticky-close:hover { background: var(--border); color: var(--text); }

/* ══════════════════════════
   NAVIGATION
══════════════════════════ */
nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  background: rgba(255,255,255,.97);
  backdrop-filter: blur(20px);
  border-bottom: 1.5px solid var(--border);
  padding: 0 2rem;
  display: flex; align-items: center; justify-content: space-between;
  height: 66px;
  box-shadow: var(--shadow);
}

/* Logo with icon */
.nav-logo {
  display: flex; align-items: center; gap: .55rem;
  text-decoration: none;
}
.nav-logo-icon {
  width: 36px; height: 36px;
  background: linear-gradient(135deg, var(--accent) 0%, var(--accent2) 100%);
  border-radius: 9px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.1rem;
  box-shadow: 0 2px 8px rgba(29,78,216,.3);
  flex-shrink: 0;
}
.nav-logo-text {
  font-family: var(--heading);
  font-size: 1.3rem;
  font-weight: 800;
  color: var(--text);
  letter-spacing: -.5px;
  line-height: 1;
}
.nav-logo-text span { color: var(--accent); }
.nav-logo-text sub {
  font-size: .5rem;
  font-weight: 600;
  color: var(--text-dim);
  vertical-align: super;
  letter-spacing: 0;
  font-family: var(--body);
}

.nav-links { display: flex; gap: .15rem; align-items: center; }
.nav-links a {
  color: var(--text-muted); text-decoration: none; font-size: .85rem;
  font-weight: 500; padding: .4rem .8rem; border-radius: 6px; transition: all .2s;
}
.nav-links a:hover { color: var(--accent); background: var(--accent-light); }
.hamburger { display: none; background: none; border: none; color: var(--text); font-size: 1.5rem; cursor: pointer; }

/* ══════════════════════════
   HERO
══════════════════════════ */
.hero {
  min-height: 92vh;
  display: flex; align-items: center; justify-content: center;
  flex-direction: column; text-align: center;
  padding: 7rem 2rem 4rem;
  position: relative; overflow: hidden;
  background: linear-gradient(170deg, #f0f7ff 0%, #ffffff 45%, #f5f0ff 100%);
}
.hero-dots {
  position: absolute; inset: 0;
  background-image: radial-gradient(circle, #c8d9f5 1px, transparent 1px);
  background-size: 28px 28px;
  opacity: .5;
}
.hero-glow {
  position: absolute;
  width: 700px; height: 700px;
  background: radial-gradient(circle, rgba(29,78,216,.06) 0%, transparent 70%);
  top: 50%; left: 50%; transform: translate(-50%,-50%);
  pointer-events: none;
}
.hero-badge {
  display: inline-flex; align-items: center; gap: .5rem;
  background: #eff6ff; border: 1.5px solid #bfdbfe;
  color: var(--accent); font-family: var(--mono); font-size: .72rem;
  padding: .4rem 1.1rem; border-radius: 100px; margin-bottom: 2rem;
  position: relative; animation: fadeUp .6s ease both;
  font-weight: 600;
}
.hero-badge::before {
  content: ''; width: 7px; height: 7px;
  background: var(--accent3); border-radius: 50%;
  animation: pulse 2s infinite;
}
@keyframes pulse { 0%,100%{opacity:1;transform:scale(1)} 50%{opacity:.5;transform:scale(1.5)} }
@keyframes fadeUp { from{opacity:0;transform:translateY(24px)} to{opacity:1;transform:translateY(0)} }

.hero h1 {
  font-family: var(--heading);
  font-size: clamp(2.5rem, 6vw, 5rem);
  font-weight: 800; line-height: 1.08; letter-spacing: -2px;
  margin-bottom: 1.5rem;
  animation: fadeUp .6s .1s ease both;
  color: var(--text);
}
.hero h1 .hl {
  background: linear-gradient(135deg, var(--accent) 0%, var(--accent2) 100%);
  -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
}
.hero-sub {
  max-width: 580px; color: var(--text-muted); font-size: 1.1rem;
  font-weight: 400; margin-bottom: 2.5rem; animation: fadeUp .6s .2s ease both;
  line-height: 1.8;
}
.hero-ctas { display: flex; gap: 1rem; flex-wrap: wrap; justify-content: center; animation: fadeUp .6s .3s ease both; }

.btn-primary {
  background: var(--accent); color: #fff; border: none;
  padding: .875rem 2rem; border-radius: 9px; font-family: var(--body);
  font-size: .92rem; font-weight: 700; cursor: pointer; text-decoration: none;
  transition: all .22s; display: inline-flex; align-items: center; gap: .5rem;
  box-shadow: 0 4px 16px rgba(29,78,216,.3);
  letter-spacing: .01em;
}
.btn-primary:hover { background: var(--accent-hover); transform: translateY(-2px); box-shadow: 0 8px 28px rgba(29,78,216,.35); }

.btn-secondary {
  background: #fff; color: var(--text); border: 2px solid var(--border);
  padding: .875rem 2rem; border-radius: 9px; font-family: var(--body);
  font-size: .92rem; font-weight: 600; cursor: pointer; text-decoration: none;
  transition: all .22s; display: inline-flex; align-items: center; gap: .5rem;
  box-shadow: var(--shadow);
}
.btn-secondary:hover { border-color: var(--accent); color: var(--accent); transform: translateY(-2px); }

.hero-stats { display: flex; gap: 3rem; margin-top: 4rem; animation: fadeUp .6s .4s ease both; }
.stat { text-align: center; }
.stat-val { font-family: var(--heading); font-size: 2.2rem; font-weight: 800; color: var(--accent); }
.stat-lbl { font-size: .78rem; color: var(--text-dim); font-weight: 500; text-transform: uppercase; letter-spacing: .5px; }

/* ══════════════════════════
   SECTIONS
══════════════════════════ */
.section { padding: 5rem 2rem; max-width: 1060px; margin: 0 auto; }
.section-full { padding: 5rem 0; }
.section-bg-white { background: #fff; border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.section-bg-tint  { background: var(--bg2); border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.section-inner { max-width: 1060px; margin: 0 auto; padding: 0 2rem; }

.section-label {
  font-family: var(--mono); font-size: .7rem; color: var(--accent);
  letter-spacing: 2.5px; text-transform: uppercase; margin-bottom: .75rem;
  display: flex; align-items: center; gap: .6rem; font-weight: 600;
}
.section-label::before { content: ''; width: 18px; height: 2px; background: var(--accent); border-radius: 1px; }
.section-title {
  font-family: var(--heading);
  font-size: clamp(1.8rem, 3.5vw, 2.7rem);
  font-weight: 800; letter-spacing: -1px; margin-bottom: 1.2rem;
  line-height: 1.15; color: var(--text);
}
.section-desc { color: var(--text-muted); max-width: 580px; font-weight: 400; margin-bottom: 2.5rem; line-height: 1.8; }
.sub-heading {
  font-family: var(--heading); font-size: .85rem; color: var(--text-dim);
  margin-bottom: 1.1rem; text-transform: uppercase; letter-spacing: 1.5px; font-weight: 700;
}

/* ══════════════════════════
   WHAT IS AI
══════════════════════════ */
.ai-intro-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 4rem; align-items: center; }
.ai-visual {
  background: linear-gradient(135deg, #f0f7ff 0%, #f5f0ff 100%);
  border: 1.5px solid var(--border); border-radius: 20px;
  padding: 2.5rem; box-shadow: var(--shadow-md);
}
.ai-visual-inner { display: flex; flex-direction: column; align-items: center; gap: 1rem; }
.ai-brain {
  width: 110px; height: 110px;
  background: linear-gradient(135deg, rgba(29,78,216,.1), rgba(124,58,237,.1));
  border: 2px solid rgba(29,78,216,.2); border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 3.2rem; animation: float 4s ease-in-out infinite;
  box-shadow: 0 8px 32px rgba(29,78,216,.12);
}
@keyframes float { 0%,100%{transform:translateY(0)} 50%{transform:translateY(-10px)} }
.ai-connections { display: flex; gap: .5rem; flex-wrap: wrap; justify-content: center; }
.conn-pill {
  background: #eff6ff; border: 1px solid #bfdbfe;
  color: var(--accent); font-family: var(--mono); font-size: .68rem;
  padding: .25rem .65rem; border-radius: 100px; font-weight: 600;
}
.ai-text p { color: var(--text-muted); margin-bottom: 1.2rem; font-weight: 400; line-height: 1.8; }
.code-box {
  width: 100%; background: #fff; border-radius: 10px;
  padding: 1rem; font-family: var(--mono); font-size: .72rem;
  color: var(--text-muted); border: 1.5px solid var(--border);
  line-height: 1.9;
}
.code-comment { color: var(--text-light); margin-bottom: .4rem; }
.code-arrow { color: var(--accent); font-weight: 700; }
.info-chips { display: flex; gap: .75rem; flex-wrap: wrap; margin-top: 1.5rem; }
.info-chip {
  background: #fff; border: 1.5px solid var(--border);
  border-radius: 10px; padding: .85rem 1.25rem; box-shadow: var(--shadow);
}
.chip-label { font-family: var(--mono); font-size: .62rem; color: var(--accent); margin-bottom: .2rem; font-weight: 700; letter-spacing: .5px; }
.chip-val { font-size: .875rem; color: var(--text); font-weight: 500; }

/* ══════════════════════════
   TYPE CARDS
══════════════════════════ */
.types-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(295px, 1fr)); gap: 1.25rem; }
.type-card {
  background: #fff; border: 1.5px solid var(--border);
  border-radius: 14px; padding: 1.75rem;
  position: relative; overflow: hidden;
  transition: all .25s; box-shadow: var(--shadow);
}
.type-card:hover { border-color: var(--accent); transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.type-card::before {
  content: ''; position: absolute; top: 0; left: 0; right: 0; height: 4px;
  background: var(--card-accent, var(--accent)); border-radius: 14px 14px 0 0;
}
.type-icon { font-size: 2.2rem; margin-bottom: .75rem; }
.type-tag {
  display: inline-block; background: var(--accent-light);
  color: var(--accent); font-family: var(--mono); font-size: .6rem;
  padding: .18rem .55rem; border-radius: 4px; margin-bottom: .6rem;
  letter-spacing: .5px; font-weight: 700;
}
.type-card h3 { font-family: var(--heading); font-size: 1.1rem; font-weight: 700; margin-bottom: .6rem; color: var(--text); }
.type-card p { color: var(--text-muted); font-size: .875rem; font-weight: 400; line-height: 1.7; }
.type-examples { margin-top: 1rem; display: flex; gap: .4rem; flex-wrap: wrap; }
.ex-badge {
  background: var(--bg2); border: 1px solid var(--border);
  color: var(--text-muted); font-size: .7rem; padding: .2rem .55rem;
  border-radius: 4px; font-family: var(--mono); font-weight: 500;
}

/* ══════════════════════════
   USE CASES
══════════════════════════ */
.use-cases-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(235px, 1fr)); gap: 1.25rem; }
.use-case {
  background: #fff; border: 1.5px solid var(--border); border-radius: 14px;
  padding: 1.5rem; transition: all .25s; box-shadow: var(--shadow);
}
.use-case:hover { border-color: var(--accent2); transform: translateY(-3px); box-shadow: var(--shadow-md); }
.use-number { font-family: var(--mono); font-size: .65rem; color: var(--text-light); margin-bottom: .6rem; font-weight: 600; }
.use-icon { font-size: 1.8rem; margin-bottom: .6rem; }
.use-case h3 { font-family: var(--heading); font-size: .95rem; font-weight: 700; margin-bottom: .4rem; color: var(--text); }
.use-case p { color: var(--text-muted); font-size: .85rem; font-weight: 400; line-height: 1.7; }

.tips-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 1rem; margin-top: 1.5rem; }
.tip { display: flex; gap: 1rem; align-items: flex-start; background: #f0fdf8; border: 1.5px solid #bbf7d0; border-radius: 10px; padding: 1.25rem; }
.tip-icon { font-size: 1.4rem; flex-shrink: 0; margin-top: .1rem; }
.tip-text h4 { font-size: .875rem; font-weight: 700; margin-bottom: .25rem; color: #065f46; }
.tip-text p { font-size: .82rem; color: var(--text-muted); font-weight: 400; line-height: 1.7; }

/* ══════════════════════════
   TIMELINE
══════════════════════════ */
.timeline { position: relative; padding-left: 2rem; }
.timeline::before {
  content: ''; position: absolute; left: 0; top: 0; bottom: 0; width: 3px;
  background: linear-gradient(to bottom, var(--accent), var(--accent2), #e2e8f0);
  border-radius: 2px;
}
.timeline-item { position: relative; margin-bottom: 2.25rem; }
.timeline-item::before {
  content: ''; position: absolute; left: -2.45rem; top: .4rem;
  width: 11px; height: 11px; background: var(--accent);
  border-radius: 50%; border: 3px solid #fff;
  box-shadow: 0 0 0 2px var(--accent);
}
.timeline-year { font-family: var(--mono); font-size: .72rem; color: var(--accent); font-weight: 700; margin-bottom: .25rem; letter-spacing: 1px; }
.timeline-item h3 { font-family: var(--heading); font-size: 1.05rem; font-weight: 700; margin-bottom: .3rem; color: var(--text); }
.timeline-item p { color: var(--text-muted); font-size: .875rem; font-weight: 400; line-height: 1.75; }
.timeline-creator {
  display: inline-flex; align-items: center; gap: .35rem;
  font-family: var(--mono); font-size: .68rem; color: var(--accent2);
  margin-top: .45rem; background: #faf5ff; padding: .2rem .6rem;
  border-radius: 4px; border: 1px solid #ddd6fe; font-weight: 500;
}

/* ══════════════════════════
   ARTICLES / SEARCH
══════════════════════════ */
.search-bar { max-width: 480px; margin: 0 auto 2.5rem; position: relative; }
.search-bar input {
  width: 100%; background: #fff; border: 2px solid var(--border);
  color: var(--text); padding: .875rem 1rem .875rem 3rem;
  border-radius: 10px; font-family: var(--body); font-size: .9rem;
  outline: none; transition: all .2s; box-shadow: var(--shadow);
  font-weight: 400;
}
.search-bar input::placeholder { color: var(--text-light); }
.search-bar input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(29,78,216,.1); }
.search-icon { position: absolute; left: 1rem; top: 50%; transform: translateY(-50%); color: var(--text-dim); }

.updates-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 1.25rem; }
.update-card {
  background: #fff; border: 1.5px solid var(--border); border-radius: 14px;
  overflow: hidden; transition: all .25s; cursor: pointer; box-shadow: var(--shadow);
  display: flex; flex-direction: column;
}
.update-card:hover { border-color: var(--accent); transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.update-header { padding: 1.4rem 1.4rem 0; }
.update-meta { display: flex; gap: .75rem; align-items: center; margin-bottom: .6rem; flex-wrap: wrap; }
.update-cat {
  font-family: var(--mono); font-size: .6rem; color: #fff;
  background: var(--accent); padding: .2rem .6rem; border-radius: 4px; font-weight: 700; letter-spacing: .3px;
}
.update-date { font-size: .75rem; color: var(--text-light); font-weight: 500; }
.update-card h3 { font-family: var(--heading); font-size: 1rem; font-weight: 700; line-height: 1.35; color: var(--text); }
.update-body { padding: .6rem 1.4rem 1rem; flex: 1; }
.update-body p { color: var(--text-muted); font-size: .875rem; font-weight: 400; line-height: 1.75; }
.update-footer {
  padding: .75rem 1.4rem 1.2rem;
  display: flex; align-items: center; justify-content: space-between;
  border-top: 1px solid var(--border); margin-top: auto;
}
.update-author { display: flex; align-items: center; gap: .5rem; }
.update-avatar {
  width: 26px; height: 26px; border-radius: 50%;
  background: linear-gradient(135deg, var(--accent), var(--accent2));
  display: flex; align-items: center; justify-content: center;
  font-size: .65rem; font-weight: 800; color: #fff;
}
.update-author-name { font-size: .78rem; color: var(--text-muted); font-weight: 500; }
.read-more { font-size: .78rem; color: var(--accent); font-weight: 700; }

/* Article body */
.article-body p { color: var(--text-muted); font-weight: 400; margin-bottom: 1rem; line-height: 1.85; }

/* ══════════════════════════
   FOOTER
══════════════════════════ */
footer {
  background: #0a0f1e;
  color: #e2e8f0;
  padding: 4rem 2rem 2.5rem;
  text-align: center;
}
.footer-brand { display: flex; align-items: center; justify-content: center; gap: .6rem; margin-bottom: .5rem; }
.footer-brand-icon {
  width: 34px; height: 34px;
  background: linear-gradient(135deg, #3b82f6, #8b5cf6);
  border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1rem;
}
.footer-logo { font-family: var(--heading); font-size: 1.8rem; font-weight: 800; color: #60a5fa; }
.footer-tagline { color: #94a3b8; font-size: .9rem; margin-bottom: 2rem; margin-top: .35rem; font-weight: 400; }
.footer-links { display: flex; gap: 2rem; justify-content: center; flex-wrap: wrap; margin-bottom: 1.5rem; }
.footer-links a { color: #94a3b8; text-decoration: none; font-size: .875rem; transition: color .2s; font-weight: 500; }
.footer-links a:hover { color: #60a5fa; }
.footer-email { color: #60a5fa; font-family: var(--mono); font-size: .85rem; margin-bottom: 1.5rem; }
.footer-copy { color: #475569; font-size: .78rem; }

/* ══════════════════════════
   TOAST
══════════════════════════ */
.toast {
  position: fixed; bottom: 5rem; right: 1.5rem; z-index: 9999;
  background: var(--success); color: #fff;
  padding: .85rem 1.5rem; border-radius: 10px;
  font-weight: 700; font-size: .875rem;
  transform: translateY(100px); opacity: 0; transition: all .3s;
  pointer-events: none; box-shadow: 0 8px 24px rgba(5,150,105,.3);
}
.toast.show { transform: translateY(0); opacity: 1; }

/* ══════════════════════════
   RESPONSIVE
══════════════════════════ */
@media (max-width: 960px) {
  .ai-intro-grid { grid-template-columns: 1fr; }
  .hero-stats { gap: 1.5rem; flex-wrap: wrap; justify-content: center; }
}
@media (max-width: 768px) {
  .hamburger { display: block; }
  .nav-links {
    display: none; position: absolute; top: 66px; left: 0; right: 0;
    background: #fff; border-bottom: 1.5px solid var(--border);
    flex-direction: column; padding: 1rem; gap: .25rem;
    box-shadow: var(--shadow-md);
  }
  .nav-links.open { display: flex; }
}