/* Base Theme and Utilities */
:root {
  --color-bg: #0b0f17;
  --color-surface: #111827;
  --color-elevated: #0f172a;
  --color-primary: #38bdf8;
  --color-primary-600: #0ea5e9;
  --color-secondary: #a78bfa;
  --color-text: #e5e7eb;
  --color-text-dim: #9ca3af;
  --color-border: #1f2937;

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;

  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;
  --space-10: 40px;
  --space-12: 48px;
  --space-16: 64px;

  --container-max: 1120px;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.2);
  --shadow-md: 0 6px 20px rgba(2,6,23,0.35);
  --shadow-lg: 0 18px 40px rgba(2,6,23,0.5);
}

* { box-sizing: border-box; }
html, body { height: 100%; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  padding-top: 64px;
  background: radial-gradient(1200px 800px at 80% -10%, rgba(56,189,248,0.08), transparent 60%),
              radial-gradient(1000px 700px at -10% 10%, rgba(167,139,250,0.07), transparent 60%),
              var(--color-bg);
  color: var(--color-text);
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Arial, "Apple Color Emoji", "Segoe UI Emoji";
  line-height: 1.65;
}

img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }

/* Layout */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-5);
}

section { padding: var(--space-16) 0; }

/* Ensure anchored headings are visible below sticky header */
section, [id] { scroll-margin-top: 80px; }

.grid {
  display: grid;
  gap: var(--space-8);
}

/* Header */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(11,15,23,0.7);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--color-border);
}
.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  font-weight: 700;
  letter-spacing: 0.3px;
}
.brand .dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  box-shadow: 0 0 20px rgba(56,189,248,0.6);
}
.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-6);
}
.nav-links a {
  color: var(--color-text-dim);
  font-weight: 500;
}
.nav-links a:hover,
.nav-links a.active { color: var(--color-text); }

.nav-cta {
  padding: 10px 14px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: linear-gradient(180deg, rgba(255,255,255,0.02), rgba(255,255,255,0));
}
.nav-cta:hover { border-color: #273244; }

/* Mobile nav */
.nav-toggle { display: none; }
.mobile-menu { display: none; }
@media (max-width: 800px) {
  .nav-links { display: none; }
  .nav-toggle { display: inline-flex; }
  .mobile-menu {
    position: fixed;
    top: 64px; left: 0; right: 0;
    background: rgba(11,15,23,0.95);
    border-bottom: 1px solid var(--color-border);
  }
  .mobile-menu.open { display: block; }
  .mobile-menu a {
    display: block;
    padding: 14px var(--space-5);
    color: var(--color-text-dim);
    border-top: 1px solid var(--color-border);
  }
  .mobile-menu a:hover { color: var(--color-text); }
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 12px 18px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  border: 1px solid var(--color-border);
  background: linear-gradient(180deg, rgba(255,255,255,0.04), rgba(255,255,255,0));
  color: var(--color-text);
}
.btn-primary {
  border: none;
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  color: #0b0f17;
  box-shadow: var(--shadow-md);
}
.btn-primary:hover { filter: brightness(1.05); }
.btn-ghost:hover { border-color: #2a3345; }

/* Hero */
.hero {
  padding-top: 96px;
  padding-bottom: var(--space-16);
}
.hero .eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 6px 10px;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  color: var(--color-text-dim);
  background: rgba(17,24,39,0.6);
}
.hero h1 {
  margin: 18px 0 10px;
  font-size: clamp(28px, 6vw, 48px);
  line-height: 1.15;
}
.hero .subtitle {
  font-size: clamp(16px, 2.4vw, 20px);
  color: var(--color-text-dim);
  max-width: 760px;
}
.hero .actions {
  margin-top: var(--space-6);
  display: flex;
  gap: var(--space-4);
  flex-wrap: wrap;
}

/* Cards */
.card {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: linear-gradient(180deg, rgba(255,255,255,0.02), rgba(255,255,255,0));
  box-shadow: var(--shadow-sm);
}
.card:hover { box-shadow: var(--shadow-md); }
.card-body { padding: var(--space-6); }
.card-title { font-weight: 700; margin: 0 0 var(--space-2); }
.card-meta {
  color: var(--color-text-dim);
  font-size: 14px;
  line-height: 1.5;
}

/* Metric Highlight */
.metric {
  color: var(--color-primary);
  font-weight: 600;
  transition: color 0.2s ease, filter 0.2s ease;
}
.card:hover .metric {
  color: var(--color-primary);
  filter: brightness(1.2);
}

/* Sections */
.section-title {
  font-size: 24px;
  margin: 0 0 var(--space-6);
}
.projects-grid { grid-template-columns: repeat(3, 1fr); }
@media (max-width: 1000px) { .projects-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 640px) { .projects-grid { grid-template-columns: 1fr; } }

/* Lists & badges */
.badges { display: flex; gap: var(--space-3); flex-wrap: wrap; }
.badge {
  font-size: 12px;
  color: var(--color-text-dim);
  border: 1px solid var(--color-border);
  padding: 6px 10px;
  border-radius: 999px;
  background: rgba(17,24,39,0.5);
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--color-border);
  background: rgba(11,15,23,0.6);
}
.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-6);
  padding: var(--space-8) 0;
}
.socials {
  display: flex;
  gap: var(--space-4);
  color: var(--color-text-dim);
}
.site-footer .muted {
  font-size: 14px;
  color: rgba(229,231,235,0.6);
}
.site-footer a:hover {
  color: var(--color-primary);
}

/* Utilities */
.muted { color: var(--color-text-dim); }
.surface {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
}
.stack-sm > * + * { margin-top: var(--space-3); }
.stack-md > * + * { margin-top: var(--space-4); }
.stack-lg > * + * { margin-top: var(--space-6); }
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 1px, 1px);
  white-space: nowrap;
  border: 0;
}

/* Responsive tweaks */
.projects-grid .card-body p {
  margin-top: var(--space-3);
  line-height: 1.7;
}
@media (max-width: 480px) {
  .card-body { padding: var(--space-4); }
  .card-meta { font-size: 13px; }
  .card-title { font-size: 16px; }
  .hero .subtitle { font-size: 15px; }
  .section-title { font-size: 20px; }
}

/* Button glow */
.btn-primary {
  box-shadow: 0 0 20px rgba(56,189,248,0.25);
}
.btn-primary:hover {
  box-shadow: 0 0 24px rgba(56,189,248,0.4);
}