/* ============================================================
   Ruyue (Selina) Xiao — Portfolio
   macOS Vitreous Glass · Light + Dark · Serif headings
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=JetBrains+Mono:wght@400;500&display=swap');

html { scroll-behavior: smooth; }

/* ── LIGHT MODE ── */
:root {
  --depth-0:             #f2f2f7;
  --depth-1:             #ffffff;
  --depth-2:             #e5e5ea;
  --depth-3:             #d1d1d6;
  --glass-bg:            rgba(255,255,255,0.72);
  --glass-border:        rgba(0,0,0,0.08);
  --glass-border-strong: rgba(0,0,0,0.12);
  --text-primary:        #1c1c1e;
  --text-secondary:      #3a3a3c;
  --text-tertiary:       #8e8e93;
  --accent:              #0a84ff;
  --accent-subtle:       rgba(10,132,255,0.08);
  --accent-border:       rgba(10,132,255,0.22);
  --tag-text:            #0a84ff;
  --nav-active:          rgba(0,0,0,0.07);
  --shadow:              0 1px 2px rgba(0,0,0,0.06);
  --mono: 'JetBrains Mono', ui-monospace, 'SF Mono', monospace;
  --sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  --serif: Georgia, 'Times New Roman', serif;
}

/* ── DARK MODE ── */
@media (prefers-color-scheme: dark) {
  :root {
    --depth-0:             #1c1c1e;
    --depth-1:             #2c2c2e;
    --depth-2:             #3a3a3c;
    --depth-3:             #48484a;
    --glass-bg:            rgba(28,28,30,0.80);
    --glass-border:        rgba(255,255,255,0.08);
    --glass-border-strong: rgba(255,255,255,0.12);
    --text-primary:        #f2f2f7;
    --text-secondary:      rgba(235,235,245,0.80);
    --text-tertiary:       #8e8e93;
    --accent:              #0a84ff;
    --accent-subtle:       rgba(10,132,255,0.12);
    --accent-border:       rgba(10,132,255,0.28);
    --tag-text:            #409cff;
    --nav-active:          rgba(255,255,255,0.09);
    --shadow:              0 1px 3px rgba(0,0,0,0.35);
  }
}

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

body {
  font-family: var(--sans);
  background-color: var(--depth-0);
  color: var(--text-primary);
  margin: 0;
  line-height: 1.65;
  font-size: 15px;
  -webkit-font-smoothing: antialiased;
  transition: background-color 0.2s ease-out, color 0.2s ease-out;
  /* Prevent subpixel repaints during scroll */
  -webkit-overflow-scrolling: touch;
}

/* ══ HEADER ══ */
header {
  padding: 68px 24px 52px;
  text-align: center;
  border-bottom: 1px solid var(--glass-border);
  background: var(--glass-bg);
  backdrop-filter: blur(16px) saturate(1.4);
  -webkit-backdrop-filter: blur(16px) saturate(1.4);
  /* GPU layer — prevents repaint bleeding into scroll */
  transform: translateZ(0);
  will-change: transform;
}

header h1 {
  font-family: var(--serif);
  font-size: clamp(2rem,5vw,3.2rem);
  font-weight: normal;
  letter-spacing: -0.01em;
  color: var(--text-primary);
  margin: 0 0 8px;
}

header > p {
  font-size: 14px;
  color: var(--text-tertiary);
  margin: 0;
}

.header-mono {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--text-tertiary);
  margin-top: 8px;
}
.header-mono .kw  { color: var(--accent); }
.header-mono .str { color: #30d158; }

.status-badge {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-family: var(--mono);
  font-size: 11px;
  color: var(--text-tertiary);
  border: 1px solid var(--glass-border-strong);
  background: var(--glass-bg);
  padding: 4px 12px;
  border-radius: 6px;
  margin-bottom: 18px;
  letter-spacing: 0.04em;
}

.status-dot {
  width: 6px; height: 6px;
  border-radius: 50%;
  background: #30d158;
}

.cta-container {
  display: flex;
  gap: 10px;
  justify-content: center;
  flex-wrap: wrap;
  margin-top: 24px;
}

/* ══ LAYOUT ══ */
.Menue {
  display: flex;
  max-width: 1140px;
  margin: -22px auto 60px;
  padding: 0 24px;
  gap: 20px;
  position: relative;
  z-index: 10;
}

/* ══ NAV ══ */
nav {
  width: 205px;
  flex-shrink: 0;
  background: var(--glass-bg);
  backdrop-filter: blur(16px) saturate(1.4);
  -webkit-backdrop-filter: blur(16px) saturate(1.4);
  border: 1px solid var(--glass-border);
  border-radius: 18px;
  padding: 16px 10px;
  height: fit-content;
  position: sticky;
  top: 20px;
  box-shadow: var(--shadow);
  /* Critical: isolate into its own compositing layer */
  transform: translateZ(0);
  will-change: transform;
  /* Contain repaints to this element only */
  contain: layout style;
}

.nav-label {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.1em;
  color: var(--text-tertiary);
  padding: 0 10px;
  margin-bottom: 8px;
}

nav ul { list-style: none; padding: 0; margin: 0; }

nav ul li a {
  display: flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
  color: var(--text-secondary);
  font-family: var(--sans);
  font-size: 13px;
  padding: 8px 10px;
  border-radius: 10px;
  margin-bottom: 2px;
  border: 1px solid transparent;
  transition: background-color 0.2s ease-out, color 0.2s ease-out, border-color 0.2s ease-out;
}

nav ul li a:hover { background: var(--nav-active); color: var(--text-primary); }
nav ul li a.active {
  background: var(--nav-active);
  border-color: var(--glass-border-strong);
  color: var(--accent);
}

.nav-icon {
  font-family: var(--mono);
  font-size: 12px;
  width: 15px;
  text-align: center;
  color: var(--text-tertiary);
  flex-shrink: 0;
}

.nav-divider { height: 1px; background: var(--glass-border); margin: 10px 0; }

/* ══ MAIN ══ */
main { flex: 1; min-width: 0; display: flex; flex-direction: column; gap: 16px; }

/* ══ CARD ══ */
.card {
  background: var(--depth-1);
  border: 1px solid var(--glass-border);
  border-radius: 18px;
  padding: 30px 34px;
  box-shadow: var(--shadow);
  /* Limit repaint scope to card bounds */
  contain: layout style;
}

.card-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 22px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--glass-border);
}

.card-tag {
  font-family: var(--mono);
  font-size: 10px;
  color: var(--accent);
  border: 1px solid var(--accent-border);
  background: var(--accent-subtle);
  padding: 2px 8px;
  border-radius: 6px;
  letter-spacing: 0.08em;
}

.card-header h2 {
  font-family: var(--serif);
  font-size: 1.2rem;
  font-weight: normal;
  color: var(--text-primary);
  margin: 0;
}

/* ══ TERMINAL ══ */
.terminal {
  border: 1px solid var(--glass-border);
  border-radius: 18px;
  overflow: hidden;
  box-shadow: var(--shadow);
  contain: layout style;
}

.terminal-bar {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 11px 16px;
  border-bottom: 1px solid var(--glass-border);
  background: var(--depth-2);
}

@media (prefers-color-scheme: dark) {
  .terminal { background: #1c1c1e; }
  .terminal-bar { background: #2c2c2e; }
}

@media (prefers-color-scheme: light) {
  .terminal { background: #ffffff; }
}

.dot   { width: 11px; height: 11px; border-radius: 50%; flex-shrink: 0; }
.dot-r { background: #ff5f57; }
.dot-y { background: #febc2e; }
.dot-g { background: #28c840; }

.terminal-title {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--text-tertiary);
  margin-left: 6px;
}

.terminal-body {
  padding: 18px 22px;
  font-family: var(--mono);
  font-size: 12.5px;
  line-height: 1.9;
}

.t-prompt::before { content: '% '; color: var(--accent); opacity: 0.55; }
.t-cmd   { color: var(--accent); }
.t-dim   { color: var(--text-tertiary); }
.t-str   { color: #30d158; }
.t-ok    { color: #30d158; }
.t-out   { color: var(--text-tertiary); padding-left: 16px; }

.cursor {
  display: inline-block;
  width: 7px; height: 12px;
  background: var(--accent);
  vertical-align: text-bottom;
  border-radius: 1px;
  margin-left: 2px;
  animation: blink 1.1s step-end infinite;
}

@keyframes blink { 0%,100%{opacity:1} 50%{opacity:0} }

/* ══ BUTTONS ══ */
.btn {
  font-family: var(--sans);
  font-size: 13px;
  font-weight: 500;
  padding: 9px 20px;
  border-radius: 10px;
  cursor: pointer;
  text-decoration: none;
  display: inline-block;
  border: 1px solid transparent;
  transition: background-color 0.2s ease-out, border-color 0.2s ease-out;
}

.btn-primary { background: var(--accent); color: #fff; border-color: var(--accent); }
.btn-primary:hover { background: #0070e0; border-color: #0070e0; }

.btn-ghost { background: var(--accent-subtle); color: var(--accent); border-color: var(--accent-border); }
.btn-ghost:hover { background: rgba(10,132,255,0.15); }

/* Legacy link fallback */
main > p > a, main > a {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--accent);
  text-decoration: none;
  padding: 5px 12px;
  border: 1px solid var(--accent-border);
  border-radius: 6px;
  background: var(--accent-subtle);
  display: inline-block;
  margin-top: 6px;
  transition: background-color 0.2s ease-out;
}
main > p > a:hover, main > a:hover { background: rgba(10,132,255,0.15); }

/* ══ INDEX STATS ══ */
.hero-intro {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.75;
  margin-bottom: 8px;
}

.stat-row {
  display: grid;
  grid-template-columns: repeat(3,1fr);
  gap: 10px;
  margin: 18px 0 22px;
}

.stat-box {
  background: var(--depth-0);
  border: 1px solid var(--glass-border);
  border-radius: 14px;
  padding: 14px 12px;
  text-align: center;
}

.stat-box .num {
  display: block;
  font-family: var(--mono);
  font-size: 22px;
  font-weight: 500;
  color: var(--accent);
}

.stat-box .lbl {
  font-size: 11px;
  color: var(--text-tertiary);
  font-family: var(--mono);
}

/* ══ EDUCATION TIMELINE ══ */
.edu-entry {
  display: grid;
  grid-template-columns: 22px 1fr;
  gap: 0 18px;
  padding-bottom: 28px;
}

.edu-entry:last-child { padding-bottom: 0; }

.edu-line { display: flex; flex-direction: column; align-items: center; }

.edu-dot {
  width: 10px; height: 10px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--depth-1);
  flex-shrink: 0;
  margin-top: 5px;
}

.edu-track {
  width: 1px;
  flex: 1;
  background: var(--glass-border-strong);
  margin-top: 5px;
}

.edu-entry:last-child .edu-track { display: none; }

.edu-school {
  font-family: var(--serif);
  font-size: 1.05rem;
  font-weight: normal;
  color: var(--text-primary);
  margin: 0 0 3px;
}

.edu-degree {
  font-size: 13px;
  font-weight: 500;
  color: var(--accent);
  margin: 0 0 2px;
}

.edu-date {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--text-tertiary);
  margin: 0 0 5px;
}

.edu-desc {
  font-size: 13px;
  color: var(--text-tertiary);
  margin: 0;
}

/* ══ EXPERIENCE ══ */
.exp-entry {
  padding-bottom: 26px;
  border-bottom: 1px solid var(--glass-border);
  margin-bottom: 22px;
}
.exp-entry:last-child { border-bottom: none; padding-bottom: 0; margin-bottom: 0; }

.exp-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 6px;
}

.exp-title {
  font-family: var(--serif);
  font-size: 1.05rem;
  font-weight: normal;
  color: var(--text-primary);
  margin: 0 0 2px;
}

.exp-role {
  font-size: 13px;
  color: var(--accent);
  font-weight: 500;
  margin: 0;
}

.exp-meta {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--text-tertiary);
  text-align: right;
  flex-shrink: 0;
  line-height: 1.6;
}

.exp-tag {
  display: inline-block;
  font-family: var(--mono);
  font-size: 10px;
  padding: 2px 8px;
  border-radius: 6px;
  border: 1px solid var(--accent-border);
  background: var(--accent-subtle);
  color: var(--tag-text);
  margin-bottom: 8px;
}

.exp-entry ul {
  margin: 8px 0 0;
  padding-left: 18px;
}

.exp-entry ul li {
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 5px;
  line-height: 1.6;
}

/* ══ PROJECTS ══ */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(268px,1fr));
  gap: 13px;
}

.project-card {
  background: var(--depth-0);
  border: 1px solid var(--glass-border);
  border-radius: 14px;
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 9px;
  position: relative;
  overflow: hidden;
  transition: border-color 0.2s ease-out, background-color 0.2s ease-out;
}

.project-card:hover {
  border-color: var(--glass-border-strong);
  background: var(--depth-1);
}

.project-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 1px;
  background: var(--accent);
  opacity: 0;
  transition: opacity 0.2s ease-out;
}

.project-card:hover::before { opacity: 0.45; }

.project-category {
  font-family: var(--mono);
  font-size: 10px;
  color: var(--text-tertiary);
  letter-spacing: 0.05em;
}

.project-card h3 {
  font-family: var(--serif);
  font-size: 13.5px;
  font-weight: normal;
  color: var(--text-primary);
  margin: 0;
  line-height: 1.4;
}

.project-card p {
  font-size: 12.5px;
  color: var(--text-secondary);
  line-height: 1.65;
  margin: 0;
  flex: 1;
}

.project-tags { display: flex; flex-wrap: wrap; gap: 5px; }

.tag {
  font-family: var(--mono);
  font-size: 10px;
  padding: 2px 7px;
  background: var(--accent-subtle);
  color: var(--tag-text);
  border: 1px solid var(--accent-border);
  border-radius: 6px;
}

.project-links {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  padding-top: 10px;
  border-top: 1px solid var(--glass-border);
  margin-top: auto;
}

.proj-link {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--accent);
  text-decoration: none;
  padding: 3px 10px;
  border: 1px solid var(--accent-border);
  border-radius: 6px;
  background: var(--accent-subtle);
  white-space: nowrap;
  transition: background-color 0.2s ease-out, border-color 0.2s ease-out;
}

.proj-link:hover { background: rgba(10,132,255,0.15); border-color: var(--accent); }

/* ══ SKILLS ══ */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(195px,1fr));
  gap: 20px;
}

.skill-group h4 {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.1em;
  color: var(--text-tertiary);
  margin: 0 0 9px;
}

.skill-pills { display: flex; flex-wrap: wrap; gap: 6px; }

.skill-pill {
  font-family: var(--mono);
  font-size: 11px;
  padding: 4px 10px;
  border: 1px solid var(--glass-border-strong);
  border-radius: 10px;
  color: var(--text-secondary);
  background: var(--depth-0);
  transition: color 0.2s ease-out, border-color 0.2s ease-out, background-color 0.2s ease-out;
  cursor: default;
}

.skill-pill:hover {
  color: var(--accent);
  border-color: var(--accent-border);
  background: var(--accent-subtle);
}

/* ══ CONTACT ══ */
.contact-block { display: flex; flex-direction: column; gap: 12px; }

.contact-row-item {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 13px 16px;
  background: var(--depth-0);
  border: 1px solid var(--glass-border);
  border-radius: 14px;
  transition: border-color 0.2s ease-out;
}

.contact-row-item:hover { border-color: var(--glass-border-strong); }

.contact-label {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--text-tertiary);
  min-width: 52px;
  letter-spacing: 0.04em;
}

.contact-value { font-size: 13px; color: var(--text-primary); }

.contact-value a {
  color: var(--accent);
  text-decoration: none;
  font-size: 13px;
  font-family: var(--sans);
  border: none; background: none; padding: 0; margin: 0; display: inline;
}

.contact-value a:hover { text-decoration: underline; }

.contact-note {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.7;
  padding: 14px 16px;
  background: var(--depth-0);
  border: 1px solid var(--glass-border);
  border-radius: 14px;
}

/* ══ FOOTER ══ */
footer {
  padding: 34px 20px;
  text-align: center;
  font-family: var(--mono);
  font-size: 11px;
  color: var(--text-tertiary);
  border-top: 1px solid var(--glass-border);
  letter-spacing: 0.04em;
}

footer a {
  color: var(--accent);
  text-decoration: none;
  border: none !important; padding: 0 !important;
  background: none !important; display: inline; margin: 0 !important;
}

footer a:hover { text-decoration: underline; }

/* ══ RESPONSIVE ══ */
@media (max-width: 820px) {
  .Menue { flex-direction: column; margin-top: 14px; padding: 0 14px; }
  nav { width: 100%; position: relative; top: 0; }
  nav ul { display: grid; grid-template-columns: repeat(auto-fit, minmax(90px,1fr)); gap: 4px; }
  nav ul li a { justify-content: center; font-size: 12px; }
  .nav-icon { display: none; }
  .nav-label { display: none; }
  .card { padding: 20px 16px; }
  .stat-row { grid-template-columns: repeat(3,1fr); }
  .projects-grid { grid-template-columns: 1fr; }
  .skills-grid { grid-template-columns: repeat(2,1fr); }
  .exp-header { flex-direction: column; }
  .exp-meta { text-align: left; }
}