:root {
  color-scheme: light dark;
  --font-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'Fira Code', 'SFMono-Regular', ui-monospace, monospace;
  --max-width: min(1120px, 90vw);
  --radius-lg: 28px;
  --radius-md: 18px;
  --radius-sm: 12px;
  --shadow-soft: 0 28px 60px -32px rgba(15, 23, 42, 0.55);
  --shadow-pop: 0 20px 40px -25px rgba(0, 0, 0, 0.38);
  --transition-base: 240ms ease;
  --transition-slow: 420ms cubic-bezier(0.23, 1, 0.32, 1);

  /* Dark theme defaults */
  --bg-page: #070c1b;
  --bg-surface: rgba(13, 18, 35, 0.92);
  --bg-muted: rgba(17, 24, 47, 0.6);
  --bg-elevated: rgba(27, 36, 64, 0.9);
  --gradient-soft: radial-gradient(circle at 12% 15%, rgba(111, 179, 255, 0.18), transparent 60%),
                   radial-gradient(circle at 82% 0%, rgba(140, 99, 255, 0.16), transparent 55%),
                   linear-gradient(160deg, rgba(10, 15, 32, 0.88), rgba(7, 10, 26, 0.94));

  --text-primary: #f5f7ff;
  --text-secondary: #d8dcff;
  --text-muted: #9aa4d6;
  --accent: #6d8cff;
  --accent-soft: rgba(109, 140, 255, 0.18);
  --border: rgba(109, 140, 255, 0.28);
}

/* Light theme overrides */
[data-theme='light'] {
  color-scheme: light;
  --bg-page: #f5f7fb;
  --bg-surface: rgba(255, 255, 255, 0.95);
  --bg-muted: rgba(233, 237, 251, 0.7);
  --bg-elevated: rgba(248, 249, 254, 0.98);
  --gradient-soft: radial-gradient(circle at 15% 18%, rgba(109, 140, 255, 0.16), transparent 55%),
                   radial-gradient(circle at 88% 12%, rgba(93, 228, 198, 0.12), transparent 58%),
                   linear-gradient(180deg, rgba(255, 255, 255, 0.92), rgba(246, 248, 255, 0.94));

  --text-primary: #0f172a;
  --text-secondary: #273554;
  --text-muted: #647084;
  --accent: #3a60ff;
  --accent-soft: rgba(58, 96, 255, 0.12);
  --border: rgba(58, 96, 255, 0.2);
}

[data-theme='dark'] { color-scheme: dark; }

*,
*::before,
*::after { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-sans);
  background: var(--gradient-soft);
  background-color: var(--bg-page);
  color: var(--text-primary);
  min-height: 100vh;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

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

button {
  font-family: inherit;
  font-size: 1rem;
  cursor: pointer;
}

p { margin: 0; }

h1,h2,h3,h4,h5,h6 {
  margin: 0;
  font-weight: 600;
  color: var(--text-primary);
}

::selection { background: var(--accent); color: #fff; }

@media (prefers-reduced-motion: reduce) {
  *,*::before,*::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* Layout */
.container { width: var(--max-width); margin: 0 auto; padding: 0 clamp(1rem, 4vw, 2rem); }

.skip-link {
  position: absolute; top: -999px; left: 1rem;
  background: var(--accent); color: #fff;
  padding: 0.7rem 1.3rem; border-radius: var(--radius-sm);
  font-weight: 600; transition: transform var(--transition-base);
  z-index: 999;
}
.skip-link:focus { top: 1rem; transform: translateY(0); }

/* Header */
.site-header {
  position: sticky; top: 0; z-index: 998;
  backdrop-filter: blur(18px);
  background: linear-gradient(180deg, rgba(4, 7, 18, 0.82), rgba(4, 7, 18, 0.72));
  border-bottom: 1px solid rgba(255, 255, 255, 0.04);
}
[data-theme='light'] .site-header {
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.9), rgba(245, 247, 251, 0.82));
  border-bottom-color: rgba(15, 23, 42, 0.08);
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  gap: clamp(1rem, 3vw, 2rem); padding: 1rem 0;
}

.brand { display: inline-flex; align-items: center; gap: 0.85rem; font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase; font-size: 1rem; }
.brand-icon { width: 2.6rem; height: 2.6rem; border-radius: 18px; background: linear-gradient(145deg, var(--accent), rgba(255,255,255,0)); box-shadow: 0 18px 36px -22px var(--accent); }

.primary-nav { display: flex; align-items: center; }
.primary-nav ul {
  list-style: none; display: flex; align-items: center;
  gap: clamp(0.6rem,1.8vw,1.7rem); margin: 0; padding: 0;
}
.nav-link {
  position: relative; display: inline-flex; align-items: center;
  padding: 0.35rem 0; font-weight: 500; font-size: 0.95rem;
  color: var(--text-muted); letter-spacing: 0.02em; transition: color var(--transition-base);
}
.nav-link::after {
  content: ''; position: absolute; left: 0; bottom: -0.35rem;
  width: 100%; height: 2px; border-radius: 12px; background: var(--accent);
  transform: scaleX(0); transform-origin: right; transition: transform var(--transition-base);
}
.nav-link:hover,.nav-link:focus-visible { color: var(--accent); }
.nav-link:hover::after,.nav-link:focus-visible::after { transform: scaleX(1); transform-origin: left; }

/* Mobile nav button */
.nav-toggle {
  display: none; width: 2.75rem; height: 2.75rem; border-radius: 999px;
  border: 1px solid rgba(255,255,255,0.12); background: var(--bg-muted);
  align-items: center; justify-content: center; padding: 0;
  transition: background var(--transition-base), transform var(--transition-base);
}
[data-theme='light'] .nav-toggle { border-color: rgba(15, 23, 42, 0.12); }
.nav-toggle:hover,.nav-toggle:focus-visible { background: var(--accent-soft); transform: translateY(-2px); }
.nav-toggle-bar { position: relative; width: 1.35rem; height: 2px; background: var(--text-primary); border-radius: 999px; }
.nav-toggle-bar::before,.nav-toggle-bar::after {
  content: ''; position: absolute; left: 0; width: 1.35rem; height: 2px; border-radius: 999px; background: currentColor;
  transition: transform var(--transition-base), top var(--transition-base);
}
.nav-toggle-bar::before { top: -6px; }
.nav-toggle-bar::after { top: 6px; }
.nav-toggle[aria-expanded='true'] .nav-toggle-bar { background: transparent; }
.nav-toggle[aria-expanded='true'] .nav-toggle-bar::before { top: 0; transform: rotate(45deg); }
.nav-toggle[aria-expanded='true'] .nav-toggle-bar::after { top: 0; transform: rotate(-45deg); }

/* Header actions */
.header-actions { display: flex; align-items: center; gap: 0.85rem; }
.btn {
  display: inline-flex; align-items: center; gap: 0.45rem; font-weight: 600;
  border-radius: var(--radius-sm); padding: 0.65rem 1.2rem; border: 1px solid transparent;
  transition: transform var(--transition-base), box-shadow var(--transition-base);
}
.btn-ghost { border-color: var(--border); background: transparent; color: var(--text-primary); }
.btn-ghost:hover,.btn-ghost:focus-visible { transform: translateY(-2px); box-shadow: 0 12px 28px -18px var(--accent); }

/* Theme toggle */
.theme-toggle {
  position: relative; border: 1px solid var(--border); border-radius: 999px;
  padding: 0.25rem 0.3rem; background: var(--bg-muted);
  display: inline-flex; align-items: center; gap: 0.7rem; min-width: 3.6rem;
}
.theme-toggle-track { position: relative; display: inline-flex; align-items: center; gap: 0.7rem; padding: 0.3rem 0.35rem; }
.theme-toggle-thumb {
  position: absolute; width: 1.6rem; height: 1.6rem; border-radius: 999px; background: var(--accent);
  top: 50%; left: 0.1rem; transform: translate(0,-50%);
  box-shadow: 0 12px 24px -18px var(--accent); transition: transform var(--transition-slow), background var(--transition-base);
}
.theme-toggle i { font-size: 0.95rem; opacity: 0.5; transition: opacity var(--transition-base); }
.theme-toggle i.is-active { opacity: 1; }
.theme-toggle-text { font-weight: 600; letter-spacing: 0.02em; color: var(--text-secondary); }
[data-theme='dark'] .theme-toggle-thumb { transform: translate(1.65rem, -50%); }

/* Sections */
.section { position: relative; padding: clamp(4rem, 11vh, 6.5rem) 0; scroll-margin-top: 5.5rem; }
.section::before {
  content: ''; position: absolute; inset: 12% auto auto 8%; width: 14rem; height: 14rem;
  background: radial-gradient(circle, var(--accent-soft), transparent 70%); opacity: 0.18; z-index: -1;
}
.section:nth-of-type(even)::before { left: auto; right: 10%; }

.section-head { max-width: 640px; margin-bottom: clamp(2.5rem, 6vw, 3.5rem); }
.section-tag { display: inline-flex; gap: 0.4rem; font-size: 0.85rem; text-transform: uppercase; letter-spacing: 0.18em; color: var(--text-muted); }
.section-title { font-size: clamp(1.85rem, 2.8vw, 2.45rem); margin-top: 0.5rem; margin-bottom: 0.7rem; line-height: 1.25; }
.section-intro { color: var(--text-secondary); font-size: 1.05rem; }

/* Hero */
.hero { padding-top: clamp(6rem, 16vh, 8.5rem); }
.hero-layout { display: grid; grid-template-columns: repeat(12, 1fr); gap: clamp(2rem, 6vw, 3rem); align-items: center; }
.hero-copy { grid-column: span 7; display: flex; flex-direction: column; gap: 1.4rem; }
.hero-title { font-size: clamp(2.4rem, 4vw, 3.1rem); line-height: 1.1; }

.typewriter {
  font-family: var(--font-mono); font-size: 0.95rem; background: var(--bg-elevated);
  border-radius: var(--radius-md); padding: 1.3rem 1.4rem; min-height: 7.5rem;
  border: 1px solid rgba(255,255,255,0.06); box-shadow: var(--shadow-soft);
}
.cursor { animation: blink 1.2s steps(1) infinite; }
@keyframes blink { 0%,50%{opacity:1} 50.01%,100%{opacity:0} }

.hero-highlights { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 1rem; }
.highlight-card {
  background: var(--bg-elevated); border-radius: var(--radius-md); padding: 1rem 1.2rem;
  border: 1px solid rgba(255,255,255,0.06);
}
.highlight-label { font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.18em; color: var(--text-muted); }
.highlight-text { font-weight: 500; margin-top: 0.4rem; }

.hero-portrait { grid-column: span 5; position: relative; justify-self: center; }
.portrait-frame {
  position: absolute; inset: -1.5rem -1.5rem auto auto; width: 100%; height: 100%;
  border-radius: var(--radius-lg); border: 1px solid rgba(255,255,255,0.08); transform: rotate(6deg); z-index: -1;
}
.hero-portrait img { width: min(360px, 100%); border-radius: var(--radius-lg); box-shadow: var(--shadow-soft); }

/* Cards */
.card { background: var(--bg-surface); border-radius: var(--radius-lg); padding: clamp(1.6rem, 4vw, 2.4rem); border: 1px solid rgba(255,255,255,0.06); box-shadow: var(--shadow-soft); }
.card-grid { display: grid; gap: clamp(1.4rem, 3vw, 2rem); grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); }
.card.placeholder { text-align: left; border-style: dashed; border-color: var(--border); color: var(--text-secondary); }
.link-button { margin-top: 1rem; background: var(--accent); color: #fff; border: none; padding: 0.6rem 1.1rem; border-radius: var(--radius-sm); }
.link-button:hover,.link-button:focus-visible { transform: translateY(-2px); box-shadow: 0 12px 28px -18px var(--accent); }
.card.spotlight { background: linear-gradient(135deg, rgba(109,140,255,0.18), rgba(93,228,198,0.15)); border-color: rgba(109,140,255,0.22); color: var(--text-primary); font-size: 1.05rem; }

/* Timeline */
.timeline { position: relative; display: grid; gap: 1.4rem; padding-left: 1.8rem; }
.timeline::before { content: ''; position: absolute; top: 0.5rem; bottom: 0.5rem; left: 0.4rem; width: 2px; background: var(--border); }
.timeline-item { position: relative; display: grid; grid-template-columns: auto 1fr; gap: 1rem; align-items: start; }
.timeline-marker { width: 0.9rem; height: 0.9rem; border-radius: 999px; background: var(--accent); box-shadow: 0 0 0 6px var(--accent-soft); margin-top: 0.45rem; }
.timeline-content { background: var(--bg-surface); border-radius: var(--radius-md); padding: 1.3rem 1.5rem; border: 1px solid rgba(255,255,255,0.06); box-shadow: var(--shadow-soft); }
.timeline-content h3 { font-size: 1.15rem; margin-bottom: 0.35rem; }
.meta { color: var(--text-muted); font-size: 0.9rem; }

/* Contact form */
.contact-form { background: var(--bg-surface); border-radius: var(--radius-lg); padding: clamp(1.8rem, 4vw, 2.4rem); border: 1px solid rgba(255,255,255,0.06); box-shadow: var(--shadow-soft); }
.field { display: flex; flex-direction: column; gap: 0.45rem; margin-bottom: 1.1rem; }
.field label { font-weight: 600; color: var(--text-secondary); }
.field input,.field textarea {
  padding: 0.85rem 1rem; border-radius: var(--radius-sm);
  border: 1px solid rgba(255,255,255,0.08); background: var(--bg-muted);
  color: var(--text-primary); font-family: inherit;
}
.field textarea { min-height: 8rem; resize: vertical; }
.field input:focus,.field textarea:focus { outline: 2px solid var(--accent); outline-offset: 2px; }

.btn-primary {
  background: var(--accent); color: #fff; border: none;
  padding: 0.75rem 1.4rem; border-radius: var(--radius-sm); font-weight: 600;
}
.btn-primary:hover,.btn-primary:focus-visible { transform: translateY(-2px); box-shadow: 0 12px 28px -18px var(--accent); }

/* Footer */
.site-footer { padding: 2.4rem 0; background: rgba(4, 7, 18, 0.85); border-top: 1px solid rgba(255,255,255,0.04); }
[data-theme='light'] .site-footer { background: rgba(255,255,255,0.92); border-top-color: rgba(15,23,42,0.08); }
.footer-inner { display: flex; align-items: center; justify-content: space-between; gap: 1.5rem; }
.social-links { display: inline-flex; gap: 0.75rem; }
.social-link {
  width: 2.4rem; height: 2.4rem; border-radius: 999px; display: inline-flex; align-items: center; justify-content: center;
  background: var(--bg-muted); color: var(--text-primary); border: 1px solid rgba(255,255,255,0.08);
  transition: transform var(--transition-base), background var(--transition-base);
}
.social-link:hover,.social-link:focus-visible { transform: translateY(-3px); background: var(--accent); color: #fff; }

.back-to-top {
  width: 2.9rem; height: 2.9rem; border-radius: 999px; border: none; background: var(--accent); color: #fff;
  display: inline-flex; align-items: center; justify-content: center; box-shadow: 0 20px 40px -24px var(--accent);
  transition: transform var(--transition-base);
}
.back-to-top:hover,.back-to-top:focus-visible { transform: translateY(-3px); }
.back-to-top[hidden] { display: none; }

/* Reveal on scroll */
.section[data-section] { transition: opacity var(--transition-slow), transform var(--transition-slow); }
.js-enabled .section[data-section] { opacity: 0; transform: translateY(40px); }
.js-enabled .section[data-section].is-visible { opacity: 1; transform: translateY(0); }

/* Responsive */
@media (max-width: 1024px) {
  .hero-copy { grid-column: 1 / span 12; }
  .hero-portrait { grid-column: 1 / span 12; order: -1; margin-bottom: 2.5rem; }
  .hero-portrait img { width: min(320px, 85vw); margin: 0 auto; }
}
@media (max-width: 900px) {
  .primary-nav { position: relative; }
  .nav-toggle { display: inline-flex; }
  .primary-nav ul {
    position: absolute; inset: 100% auto auto 50%; transform: translateX(-50%);
    flex-direction: column; background: var(--bg-surface); padding: 1.4rem; border-radius: var(--radius-md);
    border: 1px solid rgba(255,255,255,0.06); box-shadow: var(--shadow-pop);
    opacity: 0; pointer-events: none; transition: opacity var(--transition-base), transform var(--transition-base); z-index: 10;
  }
  [data-theme='light'] .primary-nav ul { border-color: rgba(15, 23, 42, 0.08); }
  .primary-nav ul[data-open='true'] { opacity: 1; pointer-events: auto; transform: translate(-50%, 0.6rem); }

  .header-inner { align-items: center; flex-wrap: wrap; row-gap: 0.85rem; }
  .header-actions { width: 100%; justify-content: flex-end; }
  .section { padding: clamp(3.2rem, 12vh, 4.6rem) 0; }
}
@media (max-width: 640px) {
  .container { padding: 0 1rem; }
  .header-inner { padding: 0.8rem 0; }
  .hero-title { font-size: clamp(2.1rem, 8vw, 2.7rem); }
  .section-title { font-size: clamp(1.65rem, 6vw, 2.15rem); }
  .timeline { padding-left: 1.2rem; }
  .timeline-item { grid-template-columns: 1fr; }
  .timeline-marker { display: none; }
  .timeline-content { padding: 1.1rem 1.2rem; }
  .contact-form { padding: 1.4rem; }
  .footer-inner { flex-direction: column; align-items: flex-start; }
}