/* ============================================================
   Lingjun Liu — portfolio
   Paper Violet: warm cream base, deep violet accent
   ============================================================ */

:root {
  --bg:             #FAF7F3;
  --bg-alt:         #F2ECE4;
  --surface:        #FFFFFF;
  --accent:         #6A4C93;
  --accent-deep:    #553579;
  --accent-soft:    #EDE4F5;
  --text:           #221F26;
  --text-secondary: #5C5560;
  --text-muted:     #6B6472;
  --border:         rgba(106, 76, 147, 0.14);
  --border-strong:  rgba(106, 76, 147, 0.30);

  --font-sans:    "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-display: "Space Grotesk", var(--font-sans);
  --font-mono:    "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;

  --wrap: 1120px;
  --gutter: 64px;
  --radius: 10px;
}

:root[data-theme="dark"] {
  --bg:             #16141A;
  --bg-alt:         #1E1A24;
  --surface:        #241F2B;
  --accent:         #B69AE0;
  --accent-deep:    #D9C8F5;
  --accent-soft:    rgba(182, 154, 224, 0.14);
  --text:           #EDE9F0;
  --text-secondary: #A9A2B3;
  --text-muted:     #968EA2;
  --border:         rgba(182, 154, 224, 0.16);
  --border-strong:  rgba(182, 154, 224, 0.34);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg:             #16141A;
    --bg-alt:         #1E1A24;
    --surface:        #241F2B;
    --accent:         #B69AE0;
    --accent-deep:    #D9C8F5;
    --accent-soft:    rgba(182, 154, 224, 0.14);
    --text:           #EDE9F0;
    --text-secondary: #A9A2B3;
    --text-muted:     #968EA2;
    --border:         rgba(182, 154, 224, 0.16);
    --border-strong:  rgba(182, 154, 224, 0.34);
  }
}

/* ---------- base ---------- */

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

html { scroll-behavior: smooth; scroll-padding-top: 76px; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

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

img { max-width: 100%; display: block; }

h1, h2, h3 { font-family: var(--font-display); font-weight: 600; line-height: 1.2; margin: 0; }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 3px;
}

.skip-link {
  position: absolute; left: -9999px;
  background: var(--accent); color: #fff;
  padding: 10px 18px; border-radius: 0 0 var(--radius) 0; z-index: 200;
}
.skip-link:focus { left: 0; top: 0; }

.wrap { max-width: var(--wrap); margin: 0 auto; padding: 0 var(--gutter); }

/* ---------- nav ---------- */

.nav {
  position: sticky; top: 0; z-index: 100;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.nav-inner {
  max-width: var(--wrap); margin: 0 auto; padding: 0 var(--gutter);
  height: 60px; display: flex; align-items: center; justify-content: space-between; gap: 16px;
}

.nav-brand {
  font-family: var(--font-mono); font-size: 14px; color: var(--accent);
  letter-spacing: 0.02em; text-decoration: none; white-space: nowrap;
}
.nav-brand:hover { text-decoration: none; }

.nav-links { display: flex; align-items: center; gap: 22px; }

.nav-links a {
  font-size: 14px; color: var(--text-secondary); text-decoration: none;
  transition: color .16s ease;
}
.nav-links a:hover, .nav-links a.active { color: var(--accent); text-decoration: none; }

.theme-toggle, .nav-toggle {
  background: none; border: 1px solid var(--border-strong); color: var(--text-secondary);
  width: 34px; height: 34px; border-radius: 8px; cursor: pointer;
  display: inline-flex; align-items: center; justify-content: center;
  font-size: 14px; transition: color .16s ease, border-color .16s ease;
  flex-shrink: 0;
}
.theme-toggle:hover, .nav-toggle:hover { color: var(--accent); border-color: var(--accent); }

.nav-toggle { display: none; }

/* ---------- sections ---------- */

.section { padding: 88px 0; }
.section--alt { background: var(--bg-alt); }

.section-label {
  font-family: var(--font-mono); font-size: 11px; letter-spacing: 0.14em;
  color: var(--accent); text-transform: uppercase; margin-bottom: 10px;
  text-align: center;
}

.section-title {
  font-size: 27px; margin-bottom: 34px; letter-spacing: -0.01em;
  text-align: center;
}

/* ---------- hero ---------- */

.hero { padding: 112px 0 76px; }

/* photo is a fixed portrait block; the text column is wider, as in the reference */
.hero-grid {
  display: flex; justify-content: center; align-items: center;
  gap: 56px; text-align: left;
  max-width: 960px; margin: 0 auto;
}

.hero-photo {
  width: 340px; height: 420px; flex-shrink: 0;
  object-fit: cover; object-position: center;
  border-radius: 24px;
  box-shadow: 0 20px 50px rgba(106, 76, 147, 0.22);
}
:root[data-theme="dark"] .hero-photo { box-shadow: 0 20px 50px rgba(0, 0, 0, 0.5); }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .hero-photo { box-shadow: 0 20px 50px rgba(0, 0, 0, 0.5); }
}

.hero-content { max-width: 550px; }

.badge {
  display: inline-block; font-family: var(--font-mono); font-size: 11px;
  letter-spacing: 0.06em; text-transform: uppercase;
  color: #fff; background: var(--accent);
  padding: 5px 12px; border-radius: 6px;
}
:root[data-theme="dark"] .badge { color: #16141A; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .badge { color: #16141A; }
}

.hero h1 { font-size: 42px; margin: 16px 0 0; letter-spacing: -0.025em; }

.hero-tagline {
  font-family: var(--font-display); font-size: 20px; font-weight: 500;
  color: var(--accent); margin: 10px 0 0; line-height: 1.35;
}

.hero-bio { color: var(--text-secondary); margin: 12px 0 0; }

.hero-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 22px; }

.btn {
  display: inline-flex; align-items: center; gap: 8px;
  font-size: 14px; font-weight: 500; padding: 9px 18px;
  border-radius: 8px; text-decoration: none; cursor: pointer;
  border: 1px solid transparent; transition: all .16s ease;
}
.btn:hover { text-decoration: none; transform: translateY(-1px); }

.btn--primary { background: var(--accent); color: #fff; }
.btn--primary:hover { background: var(--accent-deep); }
:root[data-theme="dark"] .btn--primary { color: #16141A; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .btn--primary { color: #16141A; }
}

.btn--ghost { color: var(--accent); border-color: var(--border-strong); }
.btn--ghost:hover { border-color: var(--accent); background: var(--accent-soft); }

.socials { display: flex; gap: 8px; margin-top: 20px; }

.socials a {
  width: 36px; height: 36px; border-radius: 8px;
  display: inline-flex; align-items: center; justify-content: center;
  color: var(--text-secondary); border: 1px solid var(--border);
  font-size: 15px; transition: all .16s ease; text-decoration: none;
}
.socials a:hover {
  color: var(--accent); border-color: var(--accent);
  background: var(--accent-soft); text-decoration: none;
}

/* ---------- highlights ---------- */

.metrics {
  display: grid; grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px; max-width: 960px; margin: 48px auto 0;
}

.metric { background: var(--bg-alt); border-radius: var(--radius); padding: 15px 16px; }
.section--alt .metric { background: var(--surface); }

.metric-value {
  font-family: var(--font-mono); font-size: 25px; font-weight: 500;
  color: var(--accent); line-height: 1.1;
}
.metric-label { font-size: 12px; color: var(--text-muted); margin-top: 5px; line-height: 1.4; }

/* ---------- cards ---------- */

.cards { display: grid; gap: 20px; max-width: 960px; margin: 0 auto; }

.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 12px; padding: 26px 30px;
  transition: border-color .18s ease, transform .18s ease;
}
.card:hover { border-color: var(--border-strong); transform: translateY(-2px); }

.card-head {
  display: flex; justify-content: space-between; align-items: baseline;
  gap: 14px; flex-wrap: wrap;
}

.card-title { font-size: 18px; }

.card-meta {
  font-family: var(--font-mono); font-size: 11px; color: var(--text-muted);
  white-space: nowrap;
}

.card-body { color: var(--text-secondary); font-size: 15px; margin: 9px 0 0; }

.tags { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 14px; }

.tag {
  font-family: var(--font-mono); font-size: 11px;
  color: var(--accent-deep); background: var(--accent-soft);
  padding: 4px 9px; border-radius: 5px;
}
:root[data-theme="dark"] .tag { color: var(--accent-deep); }

.card-links { display: flex; flex-wrap: wrap; gap: 16px; margin-top: 14px; }

.card-links a { font-size: 13px; font-weight: 500; display: inline-flex; align-items: center; gap: 6px; }

/* ---------- experience timeline ---------- */

.timeline { display: grid; gap: 40px; max-width: 960px; margin: 0 auto; }

.job { border-left: 2px solid var(--accent); padding-left: 20px; }

.job-head {
  display: flex; justify-content: space-between; align-items: baseline;
  gap: 14px; flex-wrap: wrap;
}

.job-org { font-family: var(--font-display); font-size: 17px; font-weight: 600; }
.job-dates { font-family: var(--font-mono); font-size: 11px; color: var(--text-muted); white-space: nowrap; }
.job-role { color: var(--accent); font-size: 14px; font-weight: 500; margin-top: 2px; }
.job-place { font-size: 13px; color: var(--text-muted); }

.job ul { margin: 11px 0 0; padding-left: 18px; color: var(--text-secondary); font-size: 15px; }
.job li { margin-bottom: 7px; }
.job li::marker { color: var(--accent); }

/* ---------- skills ---------- */

.skill-group { margin-bottom: 20px; max-width: 960px; margin-left: auto; margin-right: auto; }
.skill-group:last-child { margin-bottom: 0; }

/* skills are centred; tags elsewhere (project cards) stay left-aligned */
#skills .skill-group h3 { text-align: center; }
#skills .tags { justify-content: center; }

.skill-group h3 {
  font-family: var(--font-mono); font-size: 11px; letter-spacing: 0.1em;
  text-transform: uppercase; color: var(--text-muted); font-weight: 500; margin-bottom: 9px;
}

/* ---------- publications ---------- */

.pub {
  padding: 11px 0; border-bottom: 1px solid var(--border);
  max-width: 900px; margin-left: auto; margin-right: auto;
}
.pub:last-child { border-bottom: none; }

.pub-title { font-size: 14.5px; font-weight: 500; line-height: 1.35; }
.pub-authors { font-size: 13px; color: var(--text-secondary); margin-top: 2px; line-height: 1.5; }
.pub-authors strong { color: var(--text); font-weight: 600; }

/* venue and links share one line to keep each entry compact */
.pub-venue {
  display: inline-block; vertical-align: middle; margin: 3px 14px 0 0;
  font-family: var(--font-mono); font-size: 11px; color: var(--text-muted);
}

.pub-award {
  display: inline-block; font-family: var(--font-mono); font-size: 10px;
  color: var(--accent-deep); background: var(--accent-soft);
  padding: 2px 7px; border-radius: 4px; margin-left: 6px;
}

.pub-links { display: inline-flex; vertical-align: middle; gap: 14px; margin-top: 3px; }
.pub-links a { font-size: 12.5px; }

#pubs-more { display: none; }
#pubs-more.open { display: block; }

.pubs-toggle {
  display: block; margin: 22px auto 0;
  background: none; border: 1px solid var(--border-strong);
  color: var(--accent); font-family: var(--font-sans); font-size: 13px; font-weight: 500;
  padding: 8px 16px; border-radius: 8px; cursor: pointer; transition: all .16s ease;
}
.pubs-toggle:hover { background: var(--accent-soft); border-color: var(--accent); }

/* ---------- education & awards ---------- */

.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; }

.edu { margin-bottom: 20px; }
.edu:last-child { margin-bottom: 0; }
.edu-school { font-family: var(--font-display); font-size: 16px; font-weight: 600; }
.edu-degree { font-size: 14px; color: var(--accent); margin-top: 1px; }
.edu-meta { font-family: var(--font-mono); font-size: 11px; color: var(--text-muted); margin-top: 3px; }
.edu-note { font-size: 13px; color: var(--text-secondary); margin-top: 4px; }

.awards { list-style: none; margin: 0; padding: 0; }
.awards li {
  font-size: 14px; color: var(--text-secondary);
  padding-left: 22px; position: relative; margin-bottom: 11px; line-height: 1.55;
}
.awards li::before {
  content: "\f091"; font-family: "Font Awesome 6 Free"; font-weight: 900;
  position: absolute; left: 0; top: 1px; color: var(--accent); font-size: 12px;
}

/* ---------- contact ---------- */

.contact { text-align: center; }
.contact .section-label, .contact .section-title { text-align: center; }
.contact-blurb { color: var(--text-secondary); max-width: 46ch; margin: 0 auto 24px; }
.contact .socials { justify-content: center; }

.footer {
  border-top: 1px solid var(--border); padding: 22px 0;
  text-align: center; font-family: var(--font-mono);
  font-size: 11px; color: var(--text-muted);
}

/* ---------- reveal on scroll ---------- */

.reveal { opacity: 0; transform: translateY(14px); transition: opacity .5s ease, transform .5s ease; }
.reveal.visible { opacity: 1; transform: none; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; transition: none; }
  .card:hover, .btn:hover { transform: none; }
}

/* ---------- responsive ---------- */

/* gutter steps down 64 → 40 → 24 so the shell never crowds the viewport edge */
@media (max-width: 1040px) {
  :root { --gutter: 40px; }
  .hero { padding: 88px 0 60px; }
  .section { padding: 76px 0; }
}

/* once the two hero columns no longer fit side by side, stack and centre them */
@media (max-width: 900px) {
  .hero-grid {
    flex-direction: column; align-items: center;
    gap: 32px; text-align: center;
  }
  .hero-content { max-width: 620px; }
  .hero-actions, .socials { justify-content: center; }
  .hero-photo { width: 300px; height: 370px; }
}

@media (max-width: 780px) {
  :root { --gutter: 24px; }
  .hero { padding: 64px 0 48px; }
  .nav-toggle { display: inline-flex; }

  .nav-links {
    position: absolute; top: 60px; left: 0; right: 0;
    flex-direction: column; align-items: stretch; gap: 0;
    background: var(--bg); border-bottom: 1px solid var(--border);
    padding: 6px 24px 14px; display: none;
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 10px 0; border-bottom: 1px solid var(--border); }
  .nav-links a:last-child { border-bottom: none; }

  .hero-photo { width: 260px; height: 320px; border-radius: 20px; }
  .hero h1 { font-size: 33px; }
  .hero-tagline { font-size: 17px; }

  .metrics { grid-template-columns: repeat(2, minmax(0, 1fr)); }

  .two-col { grid-template-columns: 1fr; gap: 34px; }

  .section { padding: 60px 0; }
  .section-title { font-size: 23px; }
  .card { padding: 20px 22px; }
}

@media (max-width: 420px) {
  :root { --gutter: 18px; }
  .hero h1 { font-size: 29px; }
  .card { padding: 17px 18px; }
}