/* ==========================================================================
   Design tokens
   ========================================================================== */
:root {
  --bg: #ffffff;
  --bg-alt: #f6f7f9;
  --surface: #ffffff;
  --border: #e5e7eb;
  --text: #16181d;
  --text-muted: #5b6470;
  --accent: #4f46e5;
  --accent-hover: #4338ca;
  --accent-soft: #eef0fe;
  --tag-bg: #f1f2f6;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'SFMono-Regular', Consolas, monospace;
  --radius: 12px;
  --shadow: 0 1px 2px rgba(16, 24, 40, 0.04), 0 1px 3px rgba(16, 24, 40, 0.06);
  --max-width: 1100px;
}

[data-theme="dark"] {
  --bg: #0d0f14;
  --bg-alt: #12151c;
  --surface: #171a22;
  --border: #262a35;
  --text: #eef0f4;
  --text-muted: #9aa2b1;
  --accent: #818cf8;
  --accent-hover: #a5b0fb;
  --accent-soft: #1c1f3a;
  --tag-bg: #1d2029;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 4px 12px rgba(0, 0, 0, 0.25);
}

/* ==========================================================================
   Reset & base
   ========================================================================== */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  transition: background 0.25s ease, color 0.25s ease;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
ul, ol { margin: 0; padding: 0; list-style: none; }
h1, h2, h3, p { margin: 0; }

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

.skip-link {
  position: absolute;
  left: -999px;
  top: auto;
}
.skip-link:focus {
  left: 16px;
  top: 16px;
  background: var(--accent);
  color: #fff;
  padding: 8px 16px;
  border-radius: 8px;
  z-index: 200;
}

/* ==========================================================================
   Buttons
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 12px 22px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.95rem;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.15s ease, background 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}
.btn:hover { transform: translateY(-1px); }
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: var(--accent-hover); }
.btn-outline { background: transparent; color: var(--text); border-color: var(--border); }
.btn-outline:hover { border-color: var(--accent); color: var(--accent); }
.btn-sm { padding: 8px 16px; font-size: 0.85rem; }

/* ==========================================================================
   Header
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
}
.logo {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 1.15rem;
}
.logo-dot { color: var(--accent); }

.nav {
  display: flex;
  gap: 28px;
}
.nav a {
  font-size: 0.92rem;
  font-weight: 500;
  color: var(--text-muted);
  transition: color 0.15s ease;
}
.nav a:hover { color: var(--text); }

.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.theme-toggle {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text);
  width: 38px;
  height: 38px;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
}
.theme-toggle .icon-moon { display: none; }
[data-theme="dark"] .theme-toggle .icon-sun { display: none; }
[data-theme="dark"] .theme-toggle .icon-moon { display: block; }

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 4px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}
.nav-toggle span {
  width: 20px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
}

/* ==========================================================================
   Hero
   ========================================================================== */
.hero {
  padding: 96px 0 72px;
  background: radial-gradient(circle at 20% 0%, var(--accent-soft), transparent 55%);
}
.hero-inner { max-width: 760px; }
.eyebrow {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 14px;
}
.hero h1 {
  font-size: clamp(2.2rem, 5vw, 3.4rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 18px;
}
.hero-sub {
  font-size: 1.15rem;
  color: var(--text-muted);
  max-width: 60ch;
  margin-bottom: 28px;
}
.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  font-size: 0.92rem;
  color: var(--text-muted);
  margin-bottom: 32px;
}
.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-bottom: 56px;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  border-top: 1px solid var(--border);
  padding-top: 32px;
}
.stat { display: flex; flex-direction: column; gap: 4px; }
.stat-num {
  font-family: var(--font-mono);
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--accent);
}
.stat-label {
  font-size: 0.82rem;
  color: var(--text-muted);
}

/* ==========================================================================
   Sections
   ========================================================================== */
.section { padding: 84px 0; }
.section-alt { background: var(--bg-alt); }
.section-eyebrow {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 10px;
}
.section-title {
  font-size: clamp(1.6rem, 3vw, 2.1rem);
  font-weight: 700;
  letter-spacing: -0.01em;
  margin-bottom: 36px;
}
.section-note {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-top: -20px;
  margin-bottom: 32px;
  max-width: 68ch;
}

/* About */
.about-grid {
  display: grid;
  gap: 20px;
  max-width: 76ch;
}
.about-text { color: var(--text-muted); font-size: 1.02rem; }

/* Skills */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
}
.skill-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  box-shadow: var(--shadow);
}
.skill-card h3 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 14px;
}
.tag-list { display: flex; flex-wrap: wrap; gap: 8px; }
.tag {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  background: var(--tag-bg);
  color: var(--text-muted);
  padding: 5px 10px;
  border-radius: 6px;
}

/* Timeline */
.timeline {
  position: relative;
  padding-left: 28px;
  border-left: 2px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 44px;
}
.timeline-item { position: relative; }
.timeline-marker {
  position: absolute;
  left: -34px;
  top: 4px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 4px var(--accent-soft);
}
.timeline-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px;
  margin-bottom: 4px;
}
.timeline-head h3 { font-size: 1.08rem; font-weight: 700; }
.timeline-company { font-weight: 500; color: var(--text-muted); }
.timeline-date {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--accent);
  white-space: nowrap;
}
.timeline-loc {
  font-size: 0.88rem;
  color: var(--text-muted);
  margin-bottom: 12px;
}
.timeline-content ul { display: flex; flex-direction: column; gap: 8px; }
.timeline-content li {
  position: relative;
  padding-left: 18px;
  color: var(--text-muted);
  font-size: 0.95rem;
}
.timeline-content li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.6em;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--border);
}

/* Case studies */
.case-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 24px;
}
.case-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 26px;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.case-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}
.case-head h3 { font-size: 1.15rem; font-weight: 700; }
.case-tag {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 4px 10px;
  border-radius: 999px;
  white-space: nowrap;
}
.case-role {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
  margin-bottom: 4px;
}
.case-card p { font-size: 0.93rem; color: var(--text-muted); }
.case-card p strong { color: var(--text); }
.case-card .tag-list { margin-top: 8px; }

/* Education */
.edu-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  max-width: 480px;
  box-shadow: var(--shadow);
}
.edu-card h3 { font-size: 1.05rem; font-weight: 700; margin-bottom: 6px; }
.edu-card p { color: var(--text-muted); font-size: 0.93rem; }

/* Contact / CTA */
.section-cta { text-align: center; }
.cta-inner { display: flex; flex-direction: column; align-items: center; }
.cta-text {
  color: var(--text-muted);
  max-width: 52ch;
  margin: 0 auto 32px;
}
.contact-links {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 14px;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 28px 0;
}
.footer-inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 12px;
  font-size: 0.85rem;
  color: var(--text-muted);
}
.footer-inner a:hover { color: var(--accent); }

/* ==========================================================================
   Responsive
   ========================================================================== */
@media (max-width: 860px) {
  .hero-stats { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 720px) {
  .nav {
    position: absolute;
    top: 68px;
    left: 0;
    right: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    padding: 16px 24px;
    gap: 16px;
    display: none;
  }
  .nav.open { display: flex; }
  .nav-toggle { display: flex; }
  .header-actions .btn-sm { display: none; }
}