/* Tokens follow design.md: one Action Blue accent, near-black ink, white and parchment surfaces. */
:root {
  --primary: #0066cc;
  --primary-focus: #0071e3;
  --link: #0066cc;
  --ink: #1d1d1f;
  --ink-80: #333333;
  --ink-48: #7a7a7a;
  --canvas: #ffffff;
  --parchment: #f5f5f7;
  --hairline: #e0e0e0;
  --divider: #f0f0f0;
  --tile: #272729;
  --on-dark: #ffffff;
  --on-dark-muted: #cccccc;
  --nav: #000000;
  --product-shadow: rgba(0,0,0,.22) 3px 5px 30px 0;

  --display: 'SF Pro Display',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',Inter,'PingFang SC','Microsoft YaHei',sans-serif;
  --text: 'SF Pro Text',system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',Inter,'PingFang SC','Microsoft YaHei',sans-serif;

  --radius-sm: 8px;
  --radius-lg: 18px;
  --pill: 9999px;
  color-scheme: light;
}

/* Dark colors follow the visitor's system setting. */
@media (prefers-color-scheme: dark) {
  :root {
    --link: #2997ff;
    --ink: #f5f5f7;
    --ink-80: #d2d2d7;
    --ink-48: #86868b;
    --canvas: #000000;
    --parchment: #161617;
    --hairline: #333336;
    --divider: #242426;
    --product-shadow: none;
    color-scheme: dark;
  }
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 64px;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--canvas);
  color: var(--ink);
  font-family: var(--text);
  font-size: 17px;
  line-height: 1.47;
  letter-spacing: -.374px;
  -webkit-font-smoothing: antialiased;
}

/* Negative tracking suits Latin glyphs only. */
:lang(zh) body,
:lang(zh) body * {
  letter-spacing: 0 !important;
}

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

p {
  margin: 0;
}

strong {
  font-weight: 600;
}

a {
  color: inherit;
  text-decoration: none;
}

button {
  font: inherit;
  letter-spacing: inherit;
  color: inherit;
  cursor: pointer;
}

a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--primary-focus);
  outline-offset: 2px;
  border-radius: 4px;
}

/* Global nav: slim, true black. */

.global-nav {
  position: sticky;
  top: 0;
  z-index: 10;
  height: 44px;
  background: rgba(0,0,0,.86);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  color: var(--on-dark);
}

.bar {
  max-width: 1068px;
  height: 100%;
  margin: auto;
  padding: 0 22px;
  display: flex;
  align-items: center;
  gap: 32px;
  font-size: 12px;
  line-height: 1;
  letter-spacing: -.12px;
}

.brand {
  font-size: 14px;
  font-weight: 600;
  letter-spacing: -.224px;
  margin-right: auto;
}

nav {
  display: flex;
  gap: 24px;
}

nav a,
#language {
  color: rgba(255,255,255,.72);
  transition: color .2s;
}

nav a:hover,
nav a.active,
#language:hover,
#language[aria-expanded="true"] {
  color: var(--on-dark);
}

/* Icons are decorative; translated labels remain separate. */
.global-nav nav a {
  display: inline-flex;
  align-items: center;
  gap: 5px;
}

.global-nav .nav-icon {
  display: block;
  flex-shrink: 0;
  width: 16px;
  height: 16px;
}

.global-nav .language-icon {
  width: 18px;
  height: 18px;
  color: #40a9ed;
}

@media (min-width: 735px) and (max-width: 900px) {
  .global-nav .bar {
    gap: 24px;
  }

  .global-nav nav {
    gap: 16px;
  }
}

/* Language menu */

.language {
  position: relative;
}

#language {
  border: 0;
  background: none;
  height: 32px;
  padding: 0 2px;
  display: inline-flex;
  align-items: center;
  gap: 5px;
}

#language .language-chevron {
  transition: transform .2s;
}

#language[aria-expanded="true"] .language-chevron {
  transform: rotate(180deg);
}

.language-menu {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  min-width: 140px;
  margin: 0;
  padding: 6px;
  list-style: none;
  background: var(--canvas);
  border: 1px solid var(--hairline);
  border-radius: 11px;
}

.language-menu button {
  width: 100%;
  border: 0;
  background: none;
  color: var(--ink);
  padding: 9px 12px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  letter-spacing: -.224px;
  text-align: left;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.language-menu button:hover {
  background: var(--parchment);
}

.language-menu button[aria-current="true"] {
  font-weight: 600;
}

.language-menu button[aria-current="true"]::after {
  content: '✓';
  color: var(--link);
}

/* Buttons: the Apple pill grammar. */

.button-primary,
.button-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 11px 22px;
  border-radius: var(--pill);
  font-size: 17px;
  line-height: 1;
  transition: transform .15s;
}

.button-primary {
  background: var(--primary);
  color: #fff;
}

.button-secondary {
  color: var(--link);
  border: 1px solid var(--link);
}

.button-primary:active,
.button-secondary:active {
  transform: scale(.95);
}

.text-link {
  color: var(--link);
}

.text-link:hover {
  text-decoration: underline;
}

/* Layout: portrait sidebar on the left, content on the right. */

.layout {
  max-width: 1068px;
  margin: auto;
  padding: 80px 22px 0;
  display: grid;
  grid-template-columns: 260px minmax(0,1fr);
  gap: 80px;
}

.profile {
  position: sticky;
  top: 108px;
  align-self: start;
}

.portrait {
  display: block;
  width: 200px;
  height: auto;
  border-radius: var(--radius-lg);
  background: var(--parchment);
  box-shadow: var(--product-shadow);
  margin-bottom: 32px;
}

.profile h1 {
  font-size: 34px;
  line-height: 1.1;
  letter-spacing: -.374px;
}

.handle {
  margin: 6px 0 17px;
  font-size: 14px;
  letter-spacing: -.224px;
  color: var(--ink-48);
}

.role {
  font-weight: 600;
}

.school {
  color: var(--ink-80);
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 24px 0 32px;
}

.actions a {
  gap: 7px;
}

.actions .action-icon {
  display: block;
  width: 18px;
  height: 18px;
  flex-shrink: 0;
}

.interests h2 {
  font-family: var(--text);
  font-size: 14px;
  line-height: 1.29;
  letter-spacing: -.224px;
  margin-bottom: 8px;
}

.interests ul {
  list-style: none;
  margin: 0;
  padding: 0;
  font-size: 14px;
  line-height: 2;
  letter-spacing: -.224px;
  color: var(--ink-80);
}

.location {
  margin-top: 17px;
  font-size: 12px;
  letter-spacing: -.12px;
  color: var(--ink-48);
}

/* Content */

section {
  padding-bottom: 80px;
}

section > h2 {
  font-size: 34px;
  line-height: 1.2;
  letter-spacing: -.374px;
  margin-bottom: 24px;
}

.hero h2 {
  font-size: 56px;
  line-height: 1.07;
  letter-spacing: -.28px;
  margin-bottom: 32px;
}

.soft {
  color: var(--ink-48);
}

.hero .lead {
  font-size: 24px;
  font-weight: 300;
  line-height: 1.5;
  letter-spacing: 0;
  margin-bottom: 17px;
}

.hero p {
  color: var(--ink-80);
}

.hero .lead {
  color: var(--ink);
}

/* Highlights: the dark tile carries the emphasis instead of extra chrome. */

.highlights {
  margin-top: 48px;
  padding: 32px;
  border-radius: var(--radius-lg);
  background: var(--tile);
  color: var(--on-dark);
}

.highlights h3 {
  font-size: 21px;
  line-height: 1.19;
  letter-spacing: .231px;
  margin-bottom: 17px;
}

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

.highlights li {
  display: grid;
  grid-template-columns: 88px 1fr;
  gap: 16px;
  padding: 12px 0;
  border-top: 1px solid rgba(255,255,255,.1);
}

.highlights .when {
  font-size: 14px;
  letter-spacing: -.224px;
  color: var(--on-dark-muted);
  padding-top: 2px;
}

.highlights p {
  color: var(--on-dark-muted);
}

.highlights strong {
  color: var(--on-dark);
}

/* Utility cards */

.card {
  padding: 24px;
  border: 1px solid var(--hairline);
  border-radius: var(--radius-lg);
}

.card + .card {
  margin-top: 20px;
}

.card h3 {
  font-size: 21px;
  line-height: 1.19;
  letter-spacing: .231px;
  margin-bottom: 12px;
}

.card p,
.card ul {
  color: var(--ink-80);
}

.chips {
  margin-bottom: 12px;
}

.chip {
  display: inline-block;
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  background: var(--parchment);
  color: var(--ink-80);
  font-size: 12px;
  font-weight: 600;
  line-height: 1.3;
  letter-spacing: -.12px;
}

.chip.strong {
  background: var(--ink);
  color: var(--canvas);
}

.card .authors {
  font-size: 14px;
  letter-spacing: -.224px;
  margin-bottom: 12px;
}

.authors strong {
  color: var(--ink);
}

.card-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 4px 24px;
}

.card-head h3 {
  margin-bottom: 4px;
}

time {
  font-size: 14px;
  letter-spacing: -.224px;
  color: var(--ink-48);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

.card .sub {
  color: var(--ink-48);
  margin-bottom: 12px;
}

.card ul {
  margin: 12px 0 0;
  padding-left: 20px;
}

.card li + li {
  margin-top: 4px;
}

.card .stack {
  margin-top: 17px;
  font-size: 14px;
  letter-spacing: -.224px;
  color: var(--ink-48);
}

/* Education timeline */

.timeline article {
  display: grid;
  grid-template-columns: 160px 1fr;
  gap: 24px;
  padding: 20px 0;
  border-top: 1px solid var(--divider);
}

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

.timeline time {
  padding-top: 3px;
}

.timeline h3 {
  font-family: var(--text);
  font-size: 17px;
  line-height: 1.24;
  letter-spacing: -.374px;
  margin-bottom: 4px;
}

.timeline p {
  color: var(--ink-80);
}

.timeline strong {
  color: var(--ink);
}

.timeline .note {
  margin-top: 4px;
  font-size: 14px;
  letter-spacing: -.224px;
  color: var(--ink-48);
}

/* Footer: parchment band with contact. */

footer {
  background: var(--parchment);
  margin-top: 16px;
}

.footer-inner {
  max-width: 1068px;
  margin: auto;
  padding: 64px 22px 32px;
}

footer h2 {
  font-size: 40px;
  line-height: 1.1;
  margin-bottom: 12px;
}

footer p {
  color: var(--ink-80);
  margin-bottom: 8px;
}

footer .text-link {
  font-size: 21px;
  overflow-wrap: anywhere;
}

.legal {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 48px;
  padding-top: 17px;
  border-top: 1px solid var(--hairline);
  font-size: 12px;
  line-height: 1.3;
  letter-spacing: -.12px;
  color: var(--ink-48);
}

.legal a:hover {
  color: var(--ink);
}

[hidden] {
  display: none !important;
}

/* Responsive: breakpoints from design.md. */

@media (max-width: 1068px) {
  .layout {
    grid-template-columns: 220px minmax(0,1fr);
    gap: 56px;
  }

  .portrait {
    width: 180px;
  }

  .hero h2 {
    font-size: 40px;
    line-height: 1.1;
  }
}

@media (max-width: 833px) {
  .layout {
    display: block;
    padding-top: 48px;
  }

  /* Portrait stays on the left, beside the name. */
  .profile {
    position: static;
    display: grid;
    grid-template-columns: 112px 1fr;
    gap: 0 24px;
    align-items: center;
    margin-bottom: 56px;
  }

  .portrait {
    width: 112px;
    margin: 0;
  }

  .actions,
  .interests {
    grid-column: 1 / -1;
  }

  .actions {
    margin: 24px 0 0;
  }

  .interests {
    display: none;
  }
}

@media (max-width: 734px) {
  nav {
    display: none;
  }
}

@media (max-width: 640px) {
  .layout {
    padding: 40px 16px 0;
  }

  .bar {
    padding: 0 16px;
  }

  .profile {
    grid-template-columns: 88px 1fr;
    gap: 0 17px;
  }

  .portrait {
    width: 88px;
    border-radius: var(--radius-sm);
  }

  .profile h1 {
    font-size: 28px;
  }

  .handle {
    margin-bottom: 8px;
  }

  .actions a {
    flex: 1;
  }

  section {
    padding-bottom: 56px;
  }

  section > h2 {
    font-size: 28px;
  }

  .hero h2 {
    font-size: 34px;
  }

  .hero .lead {
    font-size: 21px;
  }

  .highlights {
    padding: 24px 20px;
  }

  .highlights li {
    grid-template-columns: 1fr;
    gap: 2px;
  }

  .card {
    padding: 20px;
  }

  .card h3 {
    font-size: 19px;
  }

  .timeline article {
    grid-template-columns: 1fr;
    gap: 4px;
  }

  .footer-inner {
    padding: 48px 16px 28px;
  }

  footer h2 {
    font-size: 28px;
  }

  footer .text-link {
    font-size: 17px;
  }
}

@media (max-width: 419px) {
  .hero h2 {
    font-size: 28px;
  }
}

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

  .button-primary,
  .button-secondary {
    transition: none;
  }
}