/* Lucas Yao — data-science portfolio (single-page) */

:root {
  --bg-deep: #070b14;
  --bg-panel: #0f1629;
  --bg-elevated: #151f38;
  --border: rgba(100, 180, 255, 0.12);
  --text: #e8eef8;
  --text-muted: #8b9bb8;
  --accent: #2dd4bf;
  --accent-dim: rgba(45, 212, 191, 0.15);
  --violet: #a78bfa;
  --rose: #fb7185;
  --font-sans: "DM Sans", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, monospace;
  --radius: 12px;
  --shadow: 0 24px 48px rgba(0, 0, 0, 0.35);
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 1.05rem;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg-deep);
  min-height: 100vh;
}

/* Subtle data-grid backdrop */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -2;
  background:
    radial-gradient(ellipse 120% 80% at 15% -20%, rgba(45, 212, 191, 0.08), transparent 50%),
    radial-gradient(ellipse 80% 60% at 100% 30%, rgba(167, 139, 250, 0.06), transparent 45%),
    var(--bg-deep);
}

body::after {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  opacity: 0.35;
  background-image:
    linear-gradient(rgba(100, 180, 255, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(100, 180, 255, 0.03) 1px, transparent 1px);
  background-size: 48px 48px;
  pointer-events: none;
}

a {
  color: var(--accent);
  text-decoration: none;
}
a:hover {
  text-decoration: underline;
  text-underline-offset: 3px;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  z-index: 100;
  padding: 0.75rem 1rem;
  background: var(--accent);
  color: var(--bg-deep);
  font-weight: 600;
}
.skip-link:focus {
  left: 1rem;
  top: 1rem;
}

/* —— Header —— */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  border-bottom: 1px solid var(--border);
  background: rgba(7, 11, 20, 0.85);
  backdrop-filter: blur(12px);
}

.header-inner {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0.85rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text);
  letter-spacing: -0.02em;
}
.brand span {
  color: var(--accent);
}

.nav-desktop {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}
.nav-desktop a {
  color: var(--text-muted);
  font-size: 0.9rem;
  padding: 0.4rem 0.75rem;
  border-radius: 8px;
  text-decoration: none;
}
.nav-desktop a:hover {
  color: var(--text);
  background: var(--accent-dim);
  text-decoration: none;
}

.nav-toggle {
  display: none;
  border: 1px solid var(--border);
  background: var(--bg-elevated);
  color: var(--text);
  padding: 0.45rem 0.65rem;
  border-radius: 8px;
  cursor: pointer;
  font-size: 1rem;
}

@media (max-width: 768px) {
  .nav-toggle {
    display: block;
  }
  .nav-desktop {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    flex-direction: column;
    padding: 1rem;
    background: var(--bg-panel);
    border-bottom: 1px solid var(--border);
  }
  .nav-desktop.is-open {
    display: flex;
  }
}

.btn-header {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  padding: 0.45rem 0.9rem;
  border-radius: 8px;
  border: 1px solid var(--accent);
  color: var(--accent);
  background: transparent;
  text-decoration: none;
  white-space: nowrap;
}
.btn-header:hover {
  background: var(--accent-dim);
  text-decoration: none;
}

/* —— Layout —— */
main {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 1.5rem 4rem;
}

section {
  padding: 4rem 0;
  border-bottom: 1px solid var(--border);
}
section:last-of-type {
  border-bottom: none;
}

.section-label {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--accent);
  margin: 0 0 0.75rem;
}

h1,
h2 {
  font-weight: 600;
  letter-spacing: -0.03em;
  line-height: 1.15;
}

/* —— Hero —— */
.hero {
  padding-top: 3rem;
  padding-bottom: 2rem;
  display: grid;
  gap: 2.5rem;
  align-items: center;
}
@media (min-width: 880px) {
  .hero {
    grid-template-columns: 1fr 320px;
    padding-top: 4rem;
  }
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 2.85rem);
  margin: 0 0 1rem;
}
.hero-lead {
  font-size: 1.15rem;
  color: var(--text-muted);
  max-width: 36ch;
  margin: 0 0 1.5rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.btn-primary {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  padding: 0.65rem 1.2rem;
  border-radius: 10px;
  border: none;
  background: var(--accent);
  color: var(--bg-deep);
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  display: inline-block;
}
.btn-primary:hover {
  filter: brightness(1.08);
  text-decoration: none;
}

.btn-ghost {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  padding: 0.65rem 1.2rem;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--bg-elevated);
  color: var(--text);
  text-decoration: none;
}
.btn-ghost:hover {
  border-color: var(--accent);
  text-decoration: none;
}

.stat-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 1rem;
  margin-top: 2rem;
}

.stat-card {
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem 1.1rem;
  box-shadow: var(--shadow);
}
.stat-card .k {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin: 0 0 0.35rem;
}
.stat-card .v {
  font-size: 1.05rem;
  font-weight: 600;
  margin: 0;
  color: var(--text);
}

/* Hero viz */
.hero-viz {
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  box-shadow: var(--shadow);
}
.hero-viz svg {
  width: 100%;
  height: auto;
  display: block;
}
.spark-line {
  fill: none;
  stroke: var(--accent);
  stroke-width: 2.5;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.spark-fill {
  fill: url(#sparkGrad);
  opacity: 0.25;
}
.hero-viz-caption {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-muted);
  margin: 0.75rem 0 0;
  text-align: center;
}

/* —— About —— */
.about-grid {
  display: grid;
  gap: 2rem;
}
@media (min-width: 720px) {
  .about-grid {
    grid-template-columns: 1fr 200px;
    align-items: start;
  }
}

.about-text p {
  margin: 0 0 1rem;
  color: var(--text-muted);
  max-width: 62ch;
}
.about-text p:last-child {
  margin-bottom: 0;
}

.avatar-wrap {
  justify-self: center;
  width: 200px;
  height: 200px;
  border-radius: 50%;
  overflow: hidden;
  border: 1px solid rgba(255, 255, 255, 0.12);
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.38);
  background: var(--bg-elevated);
}

/* Softer photo; framing shows head + shoulders (not zoomed on face only) */
.avatar-wrap img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  /* Higher % = shift crop down so shoulders / chest stay in the circle */
  object-position: center 48%;
  transform: scale(1);
  transform-origin: center center;
  filter: contrast(0.92) saturate(0.88) blur(0.45px);
  display: block;
}

/* —— Skills —— */
.skill-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}
.skill-pill {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  padding: 0.35rem 0.75rem;
  border-radius: 999px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  color: var(--text-muted);
}
.skill-pill strong {
  color: var(--accent);
  font-weight: 500;
}

/* —— Projects —— */
.projects-intro {
  color: var(--text-muted);
  max-width: 52ch;
  margin: 0 0 2rem;
}

.project-grid {
  display: grid;
  gap: 1.25rem;
}
@media (min-width: 640px) {
  .project-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

.project-card {
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.35rem 1.4rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  transition: border-color 0.2s, transform 0.2s;
}
.project-card:hover {
  border-color: rgba(45, 212, 191, 0.35);
  transform: translateY(-2px);
}

.project-card h3 {
  font-size: 1.1rem;
  margin: 0;
  color: var(--text);
}
.project-meta {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--violet);
  margin: 0;
}
.project-card p {
  margin: 0;
  font-size: 0.95rem;
  color: var(--text-muted);
  flex: 1;
}

.project-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}
.project-links a {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: 0.35rem 0.65rem;
  border-radius: 6px;
  border: 1px solid var(--border);
  color: var(--accent);
  text-decoration: none;
}
.project-links a:hover {
  background: var(--accent-dim);
  text-decoration: none;
}

/* —— Path (timeline) —— */
.timeline {
  display: grid;
  gap: 1.25rem;
}
@media (min-width: 800px) {
  .timeline {
    grid-template-columns: 1fr 1fr;
  }
}

.timeline-col h3 {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--rose);
  margin: 0 0 1rem;
}

.timeline-item {
  border-left: 2px solid var(--border);
  padding: 0 0 1.25rem 1.1rem;
  margin-left: 0.25rem;
}
.timeline-item:last-child {
  padding-bottom: 0;
}
.timeline-item h4 {
  margin: 0 0 0.25rem;
  font-size: 1rem;
}
.timeline-item .when {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
  margin: 0 0 0.5rem;
}
.timeline-item p {
  margin: 0;
  font-size: 0.9rem;
  color: var(--text-muted);
}

/* —— Contact —— */
.contact-block {
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
  text-align: center;
  box-shadow: var(--shadow);
}
.contact-block p {
  margin: 0 0 1.25rem;
  color: var(--text-muted);
}
.social-row {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.75rem;
}
.social-row a {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  padding: 0.5rem 1rem;
  border-radius: 8px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  color: var(--text);
  text-decoration: none;
}
.social-row a:hover {
  color: var(--accent);
  border-color: var(--accent);
  text-decoration: none;
}

/* —— Footer —— */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 1.5rem;
  text-align: center;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
}
.site-footer a {
  color: var(--text-muted);
}

/* Reveal on scroll */
.reveal {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}
.reveal.is-visible {
  opacity: 1;
  transform: none;
}