/* ==========================================================================
   Yuening Li — Personal Research Homepage
   Editorial minimalist design inspired by OpenAI / Anthropic research pages
   ========================================================================== */

:root {
  --bg: #faf9f5;
  --bg-subtle: #f2f0e8;
  --bg-hover: #efede4;
  --ink: #141413;
  --ink-secondary: #3d3d3a;
  --ink-muted: #6e6d68;
  --border: #e5e3db;
  --border-strong: #cfccc2;
  --link-underline: #b8b5aa;
  --link-underline-hover: #141413;
  --award-bg: #f3e9e2;
  --award-ink: #8c3d20;
  --award-border: #e4cfc2;
  --tag-bg: #efefea;
  --tag-ink: #4a4945;
  --avatar-ring: rgba(20, 20, 19, 0.1);

  --font-serif: "Newsreader", Georgia, Cambria, "Times New Roman", Times, serif;
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    Helvetica, Arial, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Monaco,
    Consolas, monospace;
}

html[data-theme="dark"] {
  --bg: #121211;
  --bg-subtle: #1b1b19;
  --bg-hover: #22221f;
  --ink: #ededeb;
  --ink-secondary: #c2c0b8;
  --ink-muted: #8b8981;
  --border: #262522;
  --border-strong: #3a3934;
  --link-underline: #57554e;
  --link-underline-hover: #ededeb;
  --award-bg: #2b1d17;
  --award-ink: #e89b7e;
  --award-border: #4a2f24;
  --tag-bg: #1e1e1c;
  --tag-ink: #b5b3ab;
  --avatar-ring: rgba(255, 255, 255, 0.14);
}

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  padding: 0;
  background-color: var(--bg);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 15.5px;
  line-height: 1.68;
  letter-spacing: -0.008em;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background-color 0.2s ease, color 0.2s ease;
}

/* Layout Shell */
.page {
  max-width: 760px;
  margin: 0 auto;
  padding: 2.25rem 1.5rem 5rem;
}

/* Minimal Top Bar */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 2.75rem;
  font-size: 13.5px;
}

.topbar__nav {
  display: flex;
  align-items: center;
  gap: 1.35rem;
}

.topbar__nav a {
  color: var(--ink-muted);
  text-decoration: none;
  transition: color 0.15s ease;
}

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

.theme-toggle {
  appearance: none;
  background: transparent;
  border: 1px solid var(--border);
  color: var(--ink-muted);
  border-radius: 999px;
  padding: 0.3rem 0.65rem;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.2;
  cursor: pointer;
  transition: color 0.15s ease, border-color 0.15s ease,
    background-color 0.15s ease;
}

.theme-toggle:hover {
  color: var(--ink);
  border-color: var(--border-strong);
  background-color: var(--bg-subtle);
}

/* Hero / Bio Header */
.hero {
  display: grid;
  grid-template-columns: 1fr 148px;
  gap: 2.5rem;
  align-items: start;
  margin-bottom: 2.75rem;
}

.hero__title {
  font-family: var(--font-serif);
  font-size: 2.35rem;
  font-weight: 500;
  line-height: 1.12;
  letter-spacing: -0.022em;
  margin: 0 0 0.4rem;
  color: var(--ink);
}

.hero__role {
  margin: 0 0 1.15rem;
  font-size: 15px;
  color: var(--ink-muted);
  font-weight: 450;
}

.hero__role strong {
  color: var(--ink-secondary);
  font-weight: 550;
}

/* Circular Avatar — Guaranteed 1:1 Circle (Never Oval) */
.hero__avatar-wrap {
  width: 148px;
  height: 148px;
  aspect-ratio: 1 / 1;
  border-radius: 50%;
  overflow: hidden;
  border: 1px solid var(--avatar-ring);
  background-color: var(--bg-subtle);
  flex-shrink: 0;
  margin-top: 0.25rem;
}

.hero__avatar {
  display: block;
  width: 100%;
  height: 100%;
  aspect-ratio: 1 / 1;
  border-radius: 50%;
  object-fit: cover;
  object-position: 50% 25%;
}

/* Inline Social / Contact Links */
.hero__links {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.4rem 0.95rem;
  margin-bottom: 1.45rem;
  font-family: var(--font-mono);
  font-size: 12.5px;
}

.hero__links a,
.email-copy-btn {
  color: var(--ink-secondary);
  text-decoration: underline;
  text-decoration-color: var(--link-underline);
  text-underline-offset: 3px;
  text-decoration-thickness: 1px;
  transition: color 0.15s ease, text-decoration-color 0.15s ease;
}

.hero__links a:hover,
.email-copy-btn:hover {
  color: var(--ink);
  text-decoration-color: var(--link-underline-hover);
}

.email-copy-btn {
  appearance: none;
  background: none;
  border: none;
  padding: 0;
  font: inherit;
  cursor: pointer;
}

.link-sep {
  color: var(--border-strong);
  user-select: none;
}

/* Narrative Bio Prose */
.bio p {
  margin: 0 0 1rem;
  color: var(--ink-secondary);
}

.bio p:last-child {
  margin-bottom: 0;
}

.bio strong {
  color: var(--ink);
  font-weight: 560;
}

.bio a,
.prose-link {
  color: var(--ink);
  text-decoration: underline;
  text-decoration-color: var(--link-underline);
  text-underline-offset: 3px;
  text-decoration-thickness: 1px;
  transition: text-decoration-color 0.15s ease;
}

.bio a:hover,
.prose-link:hover {
  text-decoration-color: var(--link-underline-hover);
}

/* Sections */
.section {
  padding-top: 2.35rem;
  margin-top: 2.35rem;
  border-top: 1px solid var(--border);
}

.section__header {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.75rem 1rem;
  margin-bottom: 1.35rem;
}

.section__title {
  font-family: var(--font-serif);
  font-size: 1.35rem;
  font-weight: 500;
  letter-spacing: -0.015em;
  margin: 0;
  color: var(--ink);
}

.section__subtitle {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-muted);
}

.section__lead {
  margin: -0.25rem 0 1.2rem;
  font-size: 14.5px;
  line-height: 1.62;
  color: var(--ink-secondary);
}

/* Frontier Model Releases (OpenAI / GDM Lab Style) */
.model-list {
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}

.model-item {
  display: grid;
  grid-template-columns: 96px 1fr;
  gap: 1.15rem;
  align-items: baseline;
}

.model-item__meta {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-muted);
  font-variant-numeric: tabular-nums;
}

.model-item__head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.45rem 0.7rem;
  margin-bottom: 0;
}

.model-item__name {
  font-size: 15.5px;
  font-weight: 600;
  color: var(--ink);
  margin: 0;
}

.model-item__name a {
  color: inherit;
  text-decoration: none;
}

.model-item__name a:hover {
  text-decoration: underline;
  text-decoration-color: var(--link-underline-hover);
  text-underline-offset: 3px;
}

.model-item__desc {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.6;
  color: var(--ink-secondary);
}

/* Micro Links ([blog], [paper], [arxiv]) */
.chip-link {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-muted);
  text-decoration: none;
  transition: color 0.15s ease;
}

.chip-link:hover {
  color: var(--ink);
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* Filter Tabs for Publications */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
}

.filter-btn {
  appearance: none;
  background: transparent;
  border: 1px solid transparent;
  border-radius: 999px;
  padding: 0.24rem 0.68rem;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-muted);
  cursor: pointer;
  transition: all 0.15s ease;
}

.filter-btn:hover {
  color: var(--ink);
  background-color: var(--bg-subtle);
}

.filter-btn.is-active {
  color: var(--ink);
  background-color: var(--bg-subtle);
  border-color: var(--border-strong);
  font-weight: 500;
}

/* Publications List */
.pub-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 1.15rem;
}

.pub-item {
  display: grid;
  grid-template-columns: 96px 1fr;
  gap: 1.15rem;
  align-items: baseline;
}

.pub-item[hidden] {
  display: none;
}

.pub-item__venue {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-muted);
  font-variant-numeric: tabular-nums;
  line-height: 1.5;
}

.pub-item__title {
  font-size: 15px;
  font-weight: 560;
  line-height: 1.45;
  color: var(--ink);
  margin: 0 0 0.18rem;
}

.pub-item__title a {
  color: inherit;
  text-decoration: none;
}

.pub-item__title a:hover {
  text-decoration: underline;
  text-decoration-color: var(--link-underline-hover);
  text-underline-offset: 3px;
  text-decoration-thickness: 1px;
}

.pub-item__authors {
  margin: 0;
  font-size: 13.75px;
  line-height: 1.52;
  color: var(--ink-muted);
}

.pub-item__authors strong {
  color: var(--ink-secondary);
  font-weight: 560;
}

.pub-item__meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.45rem 0.65rem;
  margin-top: 0.25rem;
}

.badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.3;
  padding: 0.1rem 0.45rem;
  border-radius: 4px;
  background-color: var(--tag-bg);
  color: var(--tag-ink);
}

.badge--award {
  background-color: var(--award-bg);
  color: var(--award-ink);
  border: 1px solid var(--award-border);
  font-weight: 500;
}

.pub-more-wrap {
  margin-top: 1.35rem;
  padding-left: calc(96px + 1.15rem);
}

.pub-more-wrap[hidden] {
  display: none;
}

.pub-more-btn {
  appearance: none;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.42rem 0.85rem;
  font-family: var(--font-mono);
  font-size: 12.5px;
  color: var(--ink-secondary);
  cursor: pointer;
  transition: background-color 0.15s ease, border-color 0.15s ease,
    color 0.15s ease;
}

.pub-more-btn:hover {
  background-color: var(--bg-subtle);
  border-color: var(--border-strong);
  color: var(--ink);
}

/* Experience & Education Timeline */
.timeline {
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
}

.timeline-item {
  display: grid;
  grid-template-columns: 112px 1fr;
  gap: 1rem;
  align-items: baseline;
}

.timeline-item__period {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-muted);
  font-variant-numeric: tabular-nums;
}

.timeline-item__head {
  font-size: 15px;
  color: var(--ink);
  margin: 0 0 0.18rem;
}

.timeline-item__head strong {
  font-weight: 580;
}

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

.timeline-item__desc {
  margin: 0;
  font-size: 14px;
  line-height: 1.58;
  color: var(--ink-muted);
}

/* Academic Service & Footer */
.service-note {
  margin: 0;
  font-size: 14px;
  color: var(--ink-secondary);
  line-height: 1.62;
}

.service-note strong {
  color: var(--ink);
  font-weight: 560;
}

.footer {
  margin-top: 3.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 0.5rem 1rem;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-muted);
}

/* Responsive Breakpoints */
@media (max-width: 640px) {
  .page {
    padding: 1.5rem 1.2rem 3.5rem;
  }

  .topbar {
    padding-bottom: 2rem;
  }

  .hero {
    grid-template-columns: 1fr;
    gap: 1.25rem;
  }

  .hero__avatar-wrap {
    order: -1;
    width: 116px;
    height: 116px;
    margin-top: 0;
  }

  .hero__title {
    font-size: 2rem;
  }

  .model-item,
  .pub-item,
  .timeline-item {
    grid-template-columns: 1fr;
    gap: 0.2rem;
  }

  .pub-more-wrap {
    padding-left: 0;
  }
}