/* ==========================================================================
   Apple-style theme (clean, modern, content-first)
   ========================================================================== */

:root {
  color-scheme: light;

  /* Typography (system) */
  --font-sans: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, Helvetica,
    Arial, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", sans-serif;
  --font-mono: ui-monospace, "SF Mono", "Cascadia Code", Menlo, Monaco, Consolas,
    "Liberation Mono", monospace;

  --leading-tight: 1.15;
  --leading-normal: 1.55;

  /* Fluid type */
  --text-sm: clamp(0.9rem, 0.25vw + 0.86rem, 1rem);
  --text-base: clamp(1rem, 0.35vw + 0.92rem, 1.125rem);
  --text-lg: clamp(1.125rem, 0.7vw + 1rem, 1.35rem);
  --text-xl: clamp(1.35rem, 1.3vw + 1.05rem, 1.8rem);
  --text-2xl: clamp(1.6rem, 2.1vw + 1.15rem, 2.3rem);
  --text-3xl: clamp(2rem, 3.2vw + 1.2rem, 3.25rem);

  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;

  /* Layout (wider, closer to Apple product pages) */
  --container: 92rem;
  --radius-sm: 0.75rem;
  --radius-md: 1rem;
  --radius-lg: 1.25rem;
  --radius-pill: 999px;

  /* Colors (Apple-like) */
  --bg: #f5f5f7;
  --surface: #ffffff;
  --text: #1d1d1f;
  --muted: #6e6e73;
  --border: rgba(0, 0, 0, 0.12);
  --hairline: rgba(0, 0, 0, 0.08);

  --blue: #0071e3;
  --blue-hover: #0077ed;
  --blue-pressed: #0066cc;
  --focus: rgba(0, 113, 227, 0.35);

  --shadow-sm: 0 1px 1px rgba(0, 0, 0, 0.04), 0 6px 20px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 2px 2px rgba(0, 0, 0, 0.04), 0 14px 40px rgba(0, 0, 0, 0.10);
}

/* ==========================================================================
   Base
   ========================================================================== */

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

html {
  scroll-behavior: smooth;
  overflow-x: clip;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: clip;
}

/* Better line-breaking: reduce awkward near-wraps */
h1, h2, h3, .lead {
  text-wrap: balance;
}

:lang(en) {
  hyphens: auto;
}

:lang(zh-CN) {
  line-break: strict;
}

/* Utility */
.nowrap {
  white-space: normal;
}

@media (min-width: 52rem) {
  .nowrap { white-space: nowrap; }
}

img,
svg {
  max-width: 100%;
  height: auto;
}

a {
  color: inherit;
  text-decoration-thickness: 0.06em;
  text-underline-offset: 0.18em;
}

a:hover {
  color: var(--blue);
}

:where(a:focus-visible, button:focus-visible) {
  outline: 0;
  box-shadow: 0 0 0 4px var(--focus);
  border-radius: 10px;
}

.muted {
  color: var(--muted);
}

/* Much tighter gutters (use nearly full width) */
:root { --gutter: clamp(6px, 1.6vw, 14px); }

.container {
  width: min(var(--container), calc(100% - (var(--gutter) * 2)));
  margin-inline: auto;
}

/* On very wide screens, allow even wider content (Apple-like) */
@media (min-width: 90rem) {
  :root {
    --container: 104rem;
    --gutter: clamp(10px, 1.2vw, 16px);
  }
}

/* Language toggle */
html[data-lang="zh"] [lang="en"] { display: none !important; }
html[data-lang="en"] [lang="zh-CN"] { display: none !important; }

/* Skip link */
.skip-link {
  position: absolute;
  inset-inline-start: var(--space-4);
  inset-block-start: var(--space-4);
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-pill);
  background: var(--blue);
  color: #fff;
  text-decoration: none;
  transform: translateY(-140%);
  transition: transform 180ms ease;
  z-index: 1000;
}

.skip-link:focus {
  transform: translateY(0);
}

/* ==========================================================================
   Header / Nav (frosted)
   ========================================================================== */

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(245, 245, 247, 0.82);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--hairline);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  padding-block: var(--space-4);
  flex-wrap: wrap;
}

.brand {
  font-weight: 700;
  letter-spacing: -0.02em;
  text-decoration: none;
}

.site-nav {
  flex: 1 1 auto;
}

.nav-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  gap: var(--space-2);
  justify-content: center;
  flex-wrap: wrap;
}

.nav-list a {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  padding: 0 var(--space-3);
  border-radius: var(--radius-pill);
  text-decoration: none;
  border: 1px solid transparent;
  color: var(--muted);
}

.nav-list a:hover {
  color: var(--text);
  background: rgba(255, 255, 255, 0.6);
  border-color: var(--hairline);
}

.header-actions {
  display: inline-flex;
  align-items: center;
  gap: var(--space-3);
  flex-wrap: wrap;
}

/* Mobile nav toggle (only visible on small screens) */
.nav-toggle {
  appearance: none;
  border: 1px solid var(--hairline);
  background: rgba(255, 255, 255, 0.7);
  color: var(--text);
  border-radius: var(--radius-pill);
  cursor: pointer;
  min-height: 40px;
  min-width: 40px;
  padding: 0.45rem 0.75rem;
  display: none;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  font-family: var(--font-sans);
  font-weight: 750;
  letter-spacing: -0.01em;
  transition: background-color 120ms ease, border-color 120ms ease, transform 120ms ease,
    box-shadow 120ms ease;
}

.nav-toggle:hover {
  border-color: var(--border);
  background: rgba(255, 255, 255, 0.85);
}

.nav-toggle:active {
  transform: scale(0.98);
}

.nav-toggle .nav-toggle-icon {
  width: 18px;
  height: 14px;
  display: grid;
  gap: 3px;
}

.nav-toggle .nav-toggle-icon span {
  display: block;
  height: 2px;
  border-radius: 999px;
  background: currentColor;
  opacity: 0.9;
}

.header-drawer {
  display: contents;
}

/* Segmented language control */
.lang-switch {
  display: inline-flex;
  padding: 3px;
  border-radius: var(--radius-pill);
  background: rgba(255, 255, 255, 0.7);
  border: 1px solid var(--hairline);
}

.lang-btn {
  appearance: none;
  border: 0;
  background: transparent;
  color: var(--muted);
  font-family: var(--font-sans);
  font-weight: 700;
  padding: 0.35rem 0.7rem;
  border-radius: var(--radius-pill);
  cursor: pointer;
  min-height: 32px;
}

.lang-btn[aria-pressed="true"] {
  background: #fff;
  color: var(--text);
  box-shadow: 0 1px 1px rgba(0, 0, 0, 0.06);
}

/* ==========================================================================
   Buttons
   ========================================================================== */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  min-height: 40px;
  padding: 0.55rem 0.95rem;
  border-radius: var(--radius-pill);
  border: 1px solid transparent;
  text-decoration: none;
  font-weight: 700;
  letter-spacing: -0.01em;
  transition: transform 120ms ease, background-color 120ms ease,
    border-color 120ms ease, color 120ms ease, box-shadow 120ms ease;
  user-select: none;
}

.btn:active {
  transform: scale(0.98);
}

.btn-primary {
  background: var(--blue);
  color: #fff;
  box-shadow: 0 10px 24px rgba(0, 113, 227, 0.20);
}

.btn-primary:hover {
  background: var(--blue-hover);
  color: #fff;
}

.btn-secondary {
  background: #fff;
  color: var(--text);
  border-color: var(--hairline);
  box-shadow: var(--shadow-sm);
}

.btn-secondary:hover {
  border-color: var(--border);
}

.btn-ghost {
  background: transparent;
  color: var(--text);
  border-color: var(--hairline);
}

.btn-ghost:hover {
  background: rgba(255, 255, 255, 0.7);
}

/* ==========================================================================
   Main / Sections
   ========================================================================== */

.site-main {
  padding-block: var(--space-10);
}

.tile {
  scroll-margin-top: 6rem;
  margin-block: var(--space-8);
}

.tile > .container,
.tile > .side-stack {
  width: min(var(--container), calc(100% - (var(--gutter) * 2)));
  margin-inline: auto;
}

.tile .container {
  background: var(--surface);
  border: 1px solid var(--hairline);
  border-radius: var(--radius-lg);
  padding: var(--space-8);
  box-shadow: var(--shadow-sm);
  min-width: 0;
  max-width: 100%;
}

.tile--hero .container {
  border: 1px solid rgba(0, 0, 0, 0.06);
  background:
    radial-gradient(900px 380px at 20% -10%, rgba(0, 113, 227, 0.14), transparent 60%),
    radial-gradient(700px 320px at 85% 0%, rgba(0, 0, 0, 0.06), transparent 55%),
    #ffffff;
  box-shadow: var(--shadow-md);
}

.hero-layout {
  display: grid;
  gap: var(--space-10);
  align-items: center;
}

.hero-layout > * {
  min-width: 0;
}

.hero-media {
  margin: 0;
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid rgba(0, 0, 0, 0.06);
  background: #fff;
  box-shadow: var(--shadow-md);
}

.hero-media img {
  display: block;
  width: 100%;
  height: auto;
}

.kicker {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin: 0 0 var(--space-4);
}

h1 {
  font-size: var(--text-3xl);
  line-height: var(--leading-tight);
  letter-spacing: -0.03em;
  margin: 0 0 var(--space-4);
}

.lead {
  font-size: var(--text-lg);
  color: var(--muted);
  margin: 0 0 var(--space-6);
  max-width: none;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
}

.hero-foot {
  margin-top: var(--space-8);
  padding-top: var(--space-6);
  border-top: 1px solid var(--hairline);
}

.foot-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--space-4);
}

.foot-item {
  border: 1px solid var(--hairline);
  border-radius: var(--radius-md);
  padding: var(--space-4);
  background: rgba(255, 255, 255, 0.7);
}

.foot-label {
  margin: 0 0 var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--muted);
}

.foot-value {
  margin: 0;
  font-weight: 700;
  letter-spacing: -0.01em;
}

h2 {
  font-size: var(--text-2xl);
  line-height: var(--leading-tight);
  letter-spacing: -0.02em;
  margin: 0 0 var(--space-6);
}

h3 {
  font-size: var(--text-xl);
  line-height: var(--leading-tight);
  letter-spacing: -0.02em;
  margin: 0 0 var(--space-3);
}

/* Card titles: slightly tighter to avoid awkward wraps */
.card .card-title {
  font-size: clamp(1.2rem, 1.2vw + 1rem, 1.6rem);
  line-height: 1.15;
  text-wrap: balance;
  overflow-wrap: anywhere;
}

.prose {
  max-width: 76ch;
}

.tile--about .prose {
  max-width: none;
}

.prose p { margin: 0; }
.prose p + p { margin-top: var(--space-4); }

/* Snapshot */
.side-stack {
  background: var(--surface);
  border: 1px solid var(--hairline);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}

.facts-panel {
  padding: var(--space-10);
}

.fact-list { margin: 0; }

.fact {
  display: grid;
  /* Make the label column adaptive for longer English words (e.g., "Availability") */
  grid-template-columns: clamp(8ch, 16vw, 14ch) 1fr;
  gap: var(--space-4);
  padding-block: var(--space-4);
  border-top: 1px solid var(--hairline);
}

.fact:first-child {
  border-top: 0;
  padding-top: 0;
}

.fact dt {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--muted);
  overflow-wrap: anywhere;
  word-break: break-word;
}

.fact dd { margin: 0; }

.fact dd a,
.phones a {
  overflow-wrap: anywhere;
  word-break: break-word;
}

.phones {
  display: grid;
  gap: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
}

/* Cards */
.grid { 
  display: grid; 
  gap: var(--space-4);
  min-width: 0;
  max-width: 100%;
}

.cards {
  /*
    Fixed, responsive column counts.
    This avoids the "almost fits 4 columns but gap pushes it over" overflow case.
  */
  grid-template-columns: repeat(4, minmax(0, 1fr));
  min-width: 0;
  max-width: 100%;
  width: 100%;
}

@media (max-width: 78rem) {
  .cards { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

@media (max-width: 56rem) {
  .cards { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 34rem) {
  .cards { grid-template-columns: 1fr; }
}

.card {
  border: 1px solid var(--hairline);
  border-radius: var(--radius-lg);
  padding: var(--space-4);
  background: rgba(255, 255, 255, 0.8);
  min-width: 0;
  max-width: 100%;
}

.card-media {
  border-radius: var(--radius-md);
  overflow: hidden;
  border: 1px solid rgba(0, 0, 0, 0.08);
  background: #fff;
  margin-bottom: var(--space-5);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.08);
  /* Taller cover like Apple cards */
  aspect-ratio: 16 / 11;
  min-height: clamp(140px, 14vw, 210px);
}

/* Projects grid: slightly tighter so 4-up doesn't overflow */
.tile--projects .grid { gap: var(--space-3); }
.tile--projects .card-media { margin-bottom: var(--space-4); }

.card-media img {
  display: block;
  width: 100%;
  height: 100%;
  max-width: 100%;
  object-fit: cover;
}

.meta {
  list-style: none;
  padding: 0;
  margin: var(--space-4) 0 0;
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--muted);
}

.meta li {
  border: 1px solid var(--hairline);
  border-radius: var(--radius-pill);
  padding: 0.12rem 0.6rem;
  background: rgba(0, 0, 0, 0.02);
}

/* Lists */
.bullets { margin: 0; padding-inline-start: 1.1rem; }
.bullets li + li { margin-top: var(--space-2); }

/* Timeline */
.timeline {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: var(--space-6);
  max-width: none;
}

.timeline-item {
  border: 1px solid var(--hairline);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  background: rgba(255, 255, 255, 0.8);
}

.timeline-head {
  display: flex;
  align-items: baseline;
  gap: var(--space-4);
  flex-wrap: wrap;
  margin-bottom: var(--space-2);
}

.timeline-title {
  flex: 1 1 auto;
  min-width: 0;
}

.timeline-time {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--muted);
  margin-left: auto;
  text-align: right;
  white-space: nowrap;
}

/* Publications */
.pubs {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: var(--space-4);
}

.pub {
  border: 1px solid var(--hairline);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  background: rgba(255, 255, 255, 0.8);
}

.pub-title {
  margin: 0 0 var(--space-2);
  font-weight: 750;
  letter-spacing: -0.02em;
}

.pub-meta { margin: 0; }

/* Footer */
.site-footer {
  border-top: 1px solid var(--hairline);
  padding-block: var(--space-8);
}

.footer-grid {
  background: transparent;
  border: 0;
  border-radius: 0;
  padding: 0;
  box-shadow: none;
}

.footer-contact {
  max-width: 76ch;
}

.footer-title {
  margin: 0 0 var(--space-4);
}

.footer-lead {
  margin: 0 0 var(--space-6);
  color: var(--muted);
  max-width: 80ch;
}

.contact-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
}

.footer-inner {
  margin-top: var(--space-8);
  padding-top: var(--space-6);
  border-top: 1px solid var(--hairline);
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  flex-wrap: wrap;
}

.footer-copy { margin: 0; color: var(--muted); }

.social {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  gap: var(--space-2);
  flex-wrap: wrap;
}

.social a {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  padding: 0 var(--space-3);
  border-radius: var(--radius-pill);
  border: 1px solid transparent;
  text-decoration: none;
  color: var(--muted);
}

.social a:hover {
  color: var(--text);
  border-color: var(--hairline);
  background: rgba(255, 255, 255, 0.7);
}

/* Clickable blocks (cards/timeline/publications) */
.card-link,
.timeline-link,
.pub-link {
  display: block;
  color: inherit;
  text-decoration: none;
}

.card-link:hover,
.timeline-link:hover,
.pub-link:hover {
  color: inherit;
  border-color: var(--border);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.card-link:active,
.timeline-link:active,
.pub-link:active {
  transform: translateY(0);
}

.card-link:focus-visible,
.timeline-link:focus-visible,
.pub-link:focus-visible {
  border-color: rgba(0, 113, 227, 0.35);
}

/* ==========================================================================
   Responsive + motion
   ========================================================================== */

@media (max-width: 40rem) {
  .tile .container {
    padding: var(--space-6);
  }

  .facts-panel { padding: var(--space-8); }

  .foot-grid {
    grid-template-columns: 1fr;
  }

  /* Mobile CTA layout: clearer, thumb-friendly */
  .hero-actions {
    flex-direction: column;
    align-items: stretch;
  }

  .hero-actions .btn {
    width: 100%;
    justify-content: center;
  }

  .contact-row {
    flex-direction: column;
    align-items: stretch;
  }

  .contact-row .btn {
    width: 100%;
    justify-content: center;
  }
}

@media (max-width: 40rem) {
  .footer-grid {
    padding: 0;
  }
}

/* Mobile-first nav / header layout */
@media (max-width: 48rem) {
  .header-inner {
    flex-wrap: nowrap;
    padding-block: var(--space-3);
  }

  .site-nav {
    width: 100%;
    flex: 0 0 100%;
  }

  html.js .nav-toggle {
    display: inline-flex;
  }

  /* Progressive enhancement: collapse drawer only when JS is available */
  html.js .header-drawer {
    display: none;
    width: 100%;
    flex: 0 0 100%;
    margin-top: var(--space-3);
    padding-top: var(--space-3);
    border-top: 1px solid var(--hairline);
  }

  html.js[data-nav-open="true"] .header-drawer {
    display: block;
  }

  html.js .site-nav {
    margin-bottom: var(--space-3);
  }

  .nav-list {
    justify-content: flex-start;
    gap: var(--space-2);
  }

  /* Make mobile nav feel like a soft “panel” under the frosted header */
  html.js .header-drawer {
    background: rgba(245, 245, 247, 0.55);
    border-radius: var(--radius-lg);
    padding: var(--space-4);
  }

  html.js .nav-list a {
    min-height: 44px;
    padding-inline: 0.9rem;
    background: rgba(255, 255, 255, 0.7);
    border-color: var(--hairline);
  }

  html.js .header-actions {
    width: 100%;
    justify-content: flex-start;
    gap: var(--space-3);
  }

  /* Better touch targets on small screens */
  .btn {
    min-height: 44px;
  }
  .lang-btn {
    min-height: 36px;
  }
}

@media (min-width: 56rem) {
  .hero-layout {
    grid-template-columns: 1.6fr 1fr;
    gap: var(--space-10);
  }
}

/* Very small screens (e.g., 320px): reduce density without losing hierarchy */
@media (max-width: 26rem) {
  .tile .container {
    padding: var(--space-5);
  }

  .facts-panel {
    padding: var(--space-6);
  }

  .card {
    padding: var(--space-4);
  }

  .timeline-item,
  .pub {
    padding: var(--space-5);
  }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; }
}