/* ==========================================================================
   Design tokens (mobile-first, content-first)
   ========================================================================== */

:root {
  color-scheme: light;

  /* Typography */
  --font-sans: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial,
    "Noto Sans", "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol",
    sans-serif;
  --font-display: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia,
    "Songti SC", "STSong", serif;
  --font-mono: ui-monospace, "Cascadia Code", "SF Mono", Menlo, Monaco, Consolas,
    "Liberation Mono", monospace;

  --leading-tight: 1.2;
  --leading-normal: 1.55;
  --leading-relaxed: 1.75;

  /* Fluid type (clamp) */
  --text-sm: clamp(0.9rem, 0.3vw + 0.85rem, 1rem);
  --text-base: clamp(1rem, 0.45vw + 0.92rem, 1.125rem);
  --text-lg: clamp(1.15rem, 0.8vw + 1rem, 1.35rem);
  --text-xl: clamp(1.35rem, 1.4vw + 1.05rem, 1.75rem);
  --text-2xl: clamp(1.7rem, 2.2vw + 1.2rem, 2.25rem);
  --text-3xl: clamp(2.1rem, 3.2vw + 1.25rem, 3rem);

  /* Spacing (4px base) */
  --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 */
  --container: 72rem;
  --radius-sm: 0.5rem;
  --radius-md: 0.75rem;
  --radius-lg: 1rem;

  /* Mondrian-ish palette (light) */
  --paper: #f8f5ef;
  --ink: #0b0b0b;
  --red: #d62828;
  --blue: #1d4ed8;
  --yellow: #f6c90e;

  --bg: var(--paper);
  --surface: #ffffff;
  --text: #111827; /* near-black for legibility */
  --muted: #374151;
  --border: var(--ink);

  --frame: 2px;
  --line: 6px;
  --shadow: 10px 10px 0 rgba(11, 11, 11, 0.12);

  --accent: var(--red);
  --accent-2: var(--blue);
  --on-accent: #ffffff;
  --focus: var(--blue);
}

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

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  color: var(--text);
  background-color: var(--bg);
  background-image:
    /* subtle paper grain */
    radial-gradient(circle at 1px 1px, rgba(11, 11, 11, 0.03) 1px, transparent 0);
  background-size: 6px 6px;
  text-rendering: optimizeLegibility;
}

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

:where(a) {
  color: inherit;
  text-decoration-thickness: 0.08em;
  text-underline-offset: 0.18em;
}

:where(a:hover) {
  color: var(--accent);
}

:where(a:focus-visible),
:where(button:focus-visible) {
  outline: 2px solid var(--focus);
  outline-offset: 3px;
}

/* 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-sm);
  background: var(--accent);
  color: var(--on-accent);
  text-decoration: none;
  transform: translateY(-150%);
  transition: transform 180ms ease;
  z-index: 1000;
}

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

.container {
  width: min(var(--container), calc(100% - (var(--space-4) * 2)));
  margin-inline: auto;
}

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

.dot {
  margin-inline: var(--space-2);
}

/* ==========================================================================
   Header / Nav
   ========================================================================== */

.site-header {
  position: sticky;
  top: 0;
  background: var(--paper);
  border-bottom: var(--frame) solid var(--border);
  z-index: 10;
}

.site-header::after {
  content: "";
  display: block;
  height: 8px;
  background: linear-gradient(
    90deg,
    var(--red) 0 36%,
    var(--blue) 36% 72%,
    var(--yellow) 72% 100%
  );
}

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

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

.lang-switch {
  display: inline-flex;
  border: var(--frame) solid var(--border);
  border-radius: 999px;
  overflow: hidden;
  background: #ffffff;
  box-shadow: 4px 4px 0 rgba(11, 11, 11, 0.12);
}

.lang-btn {
  appearance: none;
  border: 0;
  background: transparent;
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 700;
  padding: 0.35rem 0.7rem;
  min-height: 36px;
  cursor: pointer;
}

.lang-btn[aria-pressed="true"] {
  background: var(--ink);
  color: #ffffff;
}

.lang-btn:active {
  transform: translate(1px, 1px);
}

.brand {
  font-family: var(--font-display);
  font-weight: 700;
  letter-spacing: 0.02em;
  text-decoration: none;
}

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

.nav-list {
  display: flex;
  gap: var(--space-3);
  list-style: none;
  padding: 0;
  margin: 0;
  flex-wrap: wrap;
  justify-content: center;
}

.nav-list a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding-inline: var(--space-2);
  border-radius: var(--radius-sm);
  text-decoration: none;
  border: var(--frame) solid transparent;
}

.nav-list a:hover {
  background: #ffffff;
  border-color: var(--border);
}

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

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  min-height: 44px;
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-sm);
  border: var(--frame) solid var(--border);
  font-weight: 650;
  text-decoration: none;
  transition: transform 150ms ease, background-color 150ms ease,
    border-color 150ms ease, color 150ms ease, box-shadow 150ms ease;
}

.btn:active {
  transform: translate(1px, 1px);
}

.btn-primary {
  background: var(--accent);
  color: var(--on-accent);
  box-shadow: 6px 6px 0 rgba(11, 11, 11, 0.16);
}

.btn-primary:hover {
  color: var(--on-accent);
  transform: translate(-1px, -1px);
  box-shadow: 8px 8px 0 rgba(11, 11, 11, 0.18);
  filter: saturate(1.05);
}

.btn-secondary {
  background: #ffffff;
  color: var(--ink);
  box-shadow: 6px 6px 0 rgba(11, 11, 11, 0.12);
}

.btn-secondary:hover {
  transform: translate(-1px, -1px);
  box-shadow: 8px 8px 0 rgba(11, 11, 11, 0.14);
}

.btn-ghost {
  background: transparent;
  color: var(--ink);
}

.btn-ghost:hover {
  background: #ffffff;
  transform: translate(-1px, -1px);
}

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

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

.section {
  padding-block: var(--space-12);
  scroll-margin-top: 6rem;
  position: relative;
}

.section + .section {
  border-top: var(--frame) solid var(--border);
}

/* Keep section layout clean; decorative accents live on headings/cards. */
.section > .container {
  position: relative;
  z-index: 1;
}

/* Section layout: asymmetric grid on larger screens */
@media (min-width: 48rem) {
  .section > .container {
    display: grid;
    grid-template-columns: repeat(12, 1fr);
    column-gap: var(--space-6);
    align-items: start;
  }

  .section > .container > h2 {
    grid-column: 1 / span 3;
    margin-bottom: var(--space-8);
    width: fit-content;
  }

  .section > .container > :where(.prose, .grid, .timeline, .pubs, .contact-row) {
    grid-column: 4 / -1;
  }

  .section.section--flip > .container > h2 {
    grid-column: 10 / -1;
    justify-self: end;
    text-align: end;
    width: fit-content;
  }

  .section.section--flip > .container > :where(.prose, .grid, .timeline, .pubs, .contact-row) {
    grid-column: 1 / span 9;
  }
}

.hero {
  padding-block: var(--space-12);
}

.hero-grid {
  display: grid;
  gap: var(--space-8);
  align-items: start;
}

.hero-copy {
  background: #ffffff;
  border: var(--frame) solid var(--border);
  border-radius: 0.35rem;
  padding: var(--space-8);
  box-shadow: var(--shadow);
  position: relative;
  overflow: clip;
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

.hero-copy::before {
  content: "";
  position: absolute;
  inset-block-start: 0;
  inset-inline-start: 0;
  width: 22%;
  height: 10px;
  background: var(--yellow);
  border-bottom: var(--frame) solid var(--border);
  border-right: var(--frame) solid var(--border);
}

.hero-side {
  display: grid;
  gap: var(--space-4);
}

/* Unified right-side panel (composition + facts) */
.side-stack {
  border: var(--frame) solid var(--border);
  border-radius: 0.35rem;
  overflow: clip;
  background: #ffffff;
  box-shadow: var(--shadow);
}

.side-stack .composition {
  border: 0;
  border-radius: 0;
  box-shadow: none;
}

.facts-panel {
  padding: var(--space-6);
  border-top: var(--line) solid var(--border);
}

.facts-panel .card-title {
  margin: 0 0 var(--space-4);
}

.phones {
  margin: 0;
  display: grid;
  gap: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
}

.phones a {
  text-decoration: none;
  border-bottom: var(--frame) solid var(--border);
  width: fit-content;
}

.kicker {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin: 0 0 var(--space-3);
}

.hero h1 {
  font-family: var(--font-display);
  font-size: var(--text-3xl);
  line-height: var(--leading-tight);
  margin: 0 0 var(--space-3);
  letter-spacing: -0.02em;
}

.lead {
  font-size: var(--text-lg);
  line-height: var(--leading-relaxed);
  color: var(--muted);
  margin: 0 0 var(--space-6);
  max-width: 60ch;
}

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

.hero-foot {
  margin-top: auto;
  border-top: var(--line) solid var(--border);
  padding-top: var(--space-4);
  background: linear-gradient(0deg, rgba(246, 201, 14, 0.14), transparent 70%);
}

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

.foot-item {
  border: var(--frame) solid var(--border);
  border-radius: 0.35rem;
  padding: var(--space-3);
  background: var(--paper);
}

.foot-label {
  margin: 0 0 var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.foot-value {
  margin: 0;
  font-family: var(--font-display);
  line-height: var(--leading-tight);
}

/* Mondrian composition panel (decorative) */
.composition {
  aspect-ratio: 4 / 3;
  background: var(--border);
  border: var(--frame) solid var(--border);
  padding: var(--line);
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  grid-template-rows: repeat(6, 1fr);
  gap: var(--line);
  border-radius: 0.35rem;
  box-shadow: var(--shadow);
}

.composition .cell {
  background: var(--paper);
  border-radius: 0.15rem;
}

.cell-1 {
  grid-column: 1 / 4;
  grid-row: 1 / 3;
  background: #ffffff;
}

.cell-2 {
  grid-column: 4 / 7;
  grid-row: 1 / 2;
  background: var(--blue);
}

.cell-3 {
  grid-column: 4 / 7;
  grid-row: 2 / 4;
  background: #ffffff;
}

.cell-4 {
  grid-column: 1 / 3;
  grid-row: 3 / 7;
  background: var(--red);
}

.cell-5 {
  grid-column: 3 / 4;
  grid-row: 3 / 5;
  background: #ffffff;
}

.cell-6 {
  grid-column: 3 / 4;
  grid-row: 5 / 7;
  background: #ffffff;
}

.cell-7 {
  grid-column: 4 / 7;
  grid-row: 4 / 6;
  background: #ffffff;
}

.cell-8 {
  grid-column: 4 / 6;
  grid-row: 6 / 7;
  background: var(--yellow);
}

.cell-9 {
  grid-column: 6 / 7;
  grid-row: 6 / 7;
  background: #ffffff;
}

h2 {
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  line-height: var(--leading-tight);
  margin: 0 0 var(--space-6);
  letter-spacing: -0.015em;
  display: inline-block;
  padding-inline-start: 18px;
  padding-bottom: var(--space-2);
  border-bottom: var(--line) solid var(--border);
  position: relative;
  width: fit-content;
}

h2::after {
  content: "";
  position: absolute;
  inset-inline-start: 0;
  inset-block-start: 0.15em;
  width: 14px;
  height: 14px;
  background: var(--red);
  border: var(--frame) solid var(--border);
}

h3 {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  line-height: var(--leading-tight);
  margin: 0 0 var(--space-2);
}

.prose {
  max-width: 70ch;
}

.prose p {
  margin: 0;
}

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

/* Simple list styling (used in experience/skills) */
.bullets {
  margin: 0;
  padding-inline-start: 1.1rem;
}

.bullets li + li {
  margin-top: var(--space-2);
}

/* Cards / Grids */
.grid {
  display: grid;
  gap: var(--space-4);
}

.cards {
  grid-template-columns: repeat(auto-fit, minmax(16rem, 1fr));
}

@media (min-width: 48rem) {
  /* Turn cards into a deliberate asymmetric 12-col poster grid */
  .cards {
    grid-template-columns: repeat(12, 1fr);
    gap: var(--space-6);
  }

  .cards > .card {
    grid-column: span 6;
  }

  .cards > .card:nth-child(1) { grid-column: span 7; }
  .cards > .card:nth-child(2) { grid-column: span 5; }
  .cards > .card:nth-child(3) { grid-column: span 5; }
  .cards > .card:nth-child(4) { grid-column: span 7; }
}

.card {
  background: #ffffff;
  border: var(--frame) solid var(--border);
  border-radius: 0.35rem;
  padding: var(--space-6);
  box-shadow: var(--shadow);
}

.card-framed {
  box-shadow: 0 0 0 rgba(0, 0, 0, 0);
}

.card-title {
  margin: 0 0 var(--space-3);
}

.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: var(--frame) solid var(--border);
  border-radius: 999px;
  padding: 0.15rem 0.6rem;
  background: var(--paper);
}

/* Facts (dl) */
.fact-list {
  margin: 0;
}

.fact {
  display: grid;
  grid-template-columns: 6ch 1fr;
  gap: var(--space-3);
  padding-block: var(--space-3);
  border-top: var(--frame) solid var(--border);
}

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

.fact dt {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--muted);
}

.fact dd {
  margin: 0;
}

/* Timeline */
.timeline {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: var(--space-6);
  max-width: 80ch;
}

.timeline-item {
  border-inline-start: var(--line) solid var(--border);
  padding-inline-start: var(--space-4);
}

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

.timeline-title {
  margin: 0;
}

.timeline-time {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--muted);
}

.pubs {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: var(--space-4);
  max-width: 90ch;
}

@media (min-width: 48rem) {
  .pubs {
    grid-template-columns: repeat(12, 1fr);
    gap: var(--space-6);
    max-width: none;
  }

  .pubs > .pub {
    grid-column: span 7;
  }

  .pubs > .pub:nth-child(even) {
    grid-column: 8 / -1;
  }
}

.exp-aside {
  margin-top: var(--space-8);
}

@media (min-width: 48rem) {
  .exp-aside {
    grid-column: 9 / -1;
    align-self: start;
    margin-top: 0;
    position: sticky;
    top: 7.5rem;
  }

  .section.section--flip .exp-aside {
    grid-column: 9 / -1;
  }
}

.pub {
  background: #ffffff;
  border: var(--frame) solid var(--border);
  border-radius: 0.35rem;
  padding: var(--space-6);
  box-shadow: 6px 6px 0 rgba(11, 11, 11, 0.12);
}

.pub-title {
  margin: 0 0 var(--space-2);
  font-family: var(--font-display);
  font-size: var(--text-lg);
  line-height: var(--leading-tight);
}

.pub-meta {
  margin: 0;
}

.contact-row {
  display: flex;
  gap: var(--space-3);
  flex-wrap: wrap;
  margin-top: var(--space-4);
}

/* ==========================================================================
   Footer
   ========================================================================== */

.site-footer {
  border-top: var(--frame) solid var(--border);
  padding-block: var(--space-8);
}

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

.footer-copy {
  margin: 0;
}

.social {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  gap: var(--space-4);
}

.social a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding-inline: var(--space-2);
  border-radius: var(--radius-sm);
  text-decoration: none;
  border: var(--frame) solid transparent;
}

.social a:hover {
  background: #ffffff;
  border-color: var(--border);
}

/* ==========================================================================
   Responsive enhancements
   ========================================================================== */

@media (min-width: 48rem) {
  .header-inner {
    padding-block: var(--space-5);
  }

  .hero-grid {
    grid-template-columns: 1.5fr 1fr;
    gap: var(--space-10);
    align-items: stretch;
  }
}

@media (min-width: 64rem) {
  .site-main {
    padding-block: var(--space-12);
  }

  .section {
    padding-block: var(--space-16);
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }
}