/* ========================================================
   Version 3: Quiet Academic Theme
   Flat layout, hairline separators, no cards, no emojis.
   Tailored for Xijie Gong (龚熙杰)
   ======================================================== */

:root {
  --bg-page: #fcfcfa;
  --bg-nav: rgba(252, 252, 250, 0.9);
  --text-main: #1e2530;
  --text-muted: #57606f;
  --text-light: #8b95a5;
  --border: #e4e7ec;
  --primary: #2f4f9e;
  --primary-hover: #22397a;
  --code-bg: #141a26;
  --code-text: #e3e9f2;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  --font-serif: 'Newsreader', Georgia, 'Times New Roman', 'Songti SC', 'Noto Serif SC', serif;
  --font-mono: 'JetBrains Mono', 'SFMono-Regular', Consolas, monospace;
  --font-body: var(--font-sans);
  --font-heading: var(--font-serif);
  --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  background: var(--bg-page);
  color: var(--text-main);
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.65;
  letter-spacing: -0.003em;
  -webkit-font-smoothing: antialiased;
  min-width: 320px;
}

a {
  color: var(--primary);
  text-decoration: none;
  transition: var(--transition);
}

a:hover {
  color: var(--primary-hover);
  text-decoration: underline;
  text-underline-offset: 3px;
}

::selection {
  background: rgba(47, 79, 158, 0.14);
}

/* NAVBAR */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  background: var(--bg-nav);
  border-bottom: 1px solid var(--border);
}

.nav-container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 0.9rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-brand {
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 1.15rem;
  letter-spacing: -0.01em;
  color: var(--text-main);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  list-style: none;
}

.nav-link {
  font-size: 0.88rem;
  font-weight: 500;
  color: var(--text-muted);
}

.nav-link:hover {
  color: var(--primary);
  text-decoration: none;
}

/* MAIN CONTAINER */
.page-wrap {
  max-width: 1000px;
  margin: 0 auto;
  padding: 2.75rem 1.5rem 4.5rem;
}

/* SECTION COMMON */
.section {
  margin-bottom: 2.9rem;
  scroll-margin-top: 4.5rem;
}

.section-title {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--text-main);
  margin-bottom: 1.25rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.section-title::after {
  content: "";
  flex: 1;
  height: 1px;
  background: var(--border);
}

/* HERO SECTION */
.hero {
  display: flex;
  align-items: center;
  gap: 2.4rem;
  margin-bottom: 3rem;
}

.hero-avatar {
  flex-shrink: 0;
}

.avatar-img {
  width: 148px;
  height: 148px;
  border-radius: 18px;
  object-fit: cover;
  border: 1px solid var(--border);
}

.hero-info {
  flex: 1;
  min-width: 0;
}

.hero-title-row {
  display: flex;
  align-items: baseline;
  gap: 0.7rem;
  margin-bottom: 0.4rem;
}

.hero-name {
  font-family: var(--font-heading);
  font-size: 2.3rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  color: var(--text-main);
}

.hero-cn-name {
  font-size: 1.15rem;
  font-weight: 500;
  color: var(--text-muted);
  font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  letter-spacing: 0.02em;
}

.hero-affils {
  margin-bottom: 1.15rem;
}

.hero-affil {
  font-size: 0.95rem;
  color: var(--text-muted);
  line-height: 1.55;
}

.hero-affil strong {
  color: var(--text-main);
  font-weight: 600;
}

.hero-socials {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.hero-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.42rem 0.85rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 0.82rem;
  font-weight: 500;
  color: var(--text-main);
  background: transparent;
  transition: var(--transition);
}

.hero-btn svg {
  width: 15px;
  height: 15px;
  fill: currentColor;
}

.hero-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
  text-decoration: none;
}

/* ABOUT */
.about p {
  margin-bottom: 1rem;
  font-size: 1rem;
  max-width: 46rem;
  text-wrap: pretty;
}

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

.research-line {
  margin-top: 1.1rem;
  font-size: 0.95rem;
  color: var(--text-muted);
}

.research-line strong {
  color: var(--text-main);
}

/* NEWS */
.news-list {
  border-top: 1px solid var(--border);
}

.news-item {
  display: grid;
  grid-template-columns: 92px minmax(0, 1fr);
  gap: 1.25rem;
  padding: 0.7rem 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.94rem;
  line-height: 1.55;
  align-items: baseline;
  text-wrap: pretty;
}

.news-date {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-muted);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

/* PUBLICATIONS */
.pub-filter-row {
  display: flex;
  gap: 1.4rem;
  margin-bottom: 0.4rem;
}

.filter-btn {
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  padding: 0.15rem 0;
  cursor: pointer;
  font-family: var(--font-body);
  font-size: 0.86rem;
  font-weight: 500;
  color: var(--text-muted);
  transition: var(--transition);
}

.filter-btn:hover {
  color: var(--primary);
}

.filter-btn.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
}

.pub-entry {
  padding: 1.35rem 0;
  border-bottom: 1px solid var(--border);
}

.pub-entry:last-of-type {
  border-bottom: none;
  padding-bottom: 0;
}

.pub-meta {
  display: flex;
  align-items: baseline;
  gap: 0.75rem;
  flex-wrap: wrap;
  margin-bottom: 0.3rem;
}

.pub-venue {
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--primary);
  letter-spacing: 0.02em;
}

.pub-track {
  font-size: 0.8rem;
  color: var(--text-light);
}

.pub-title {
  font-family: var(--font-heading);
  font-size: 1.22rem;
  font-weight: 600;
  line-height: 1.4;
  letter-spacing: -0.01em;
  color: var(--text-main);
  margin-bottom: 0.4rem;
  text-wrap: pretty;
}

.pub-authors {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 0.6rem;
}

.pub-authors strong {
  color: var(--text-main);
  font-weight: 600;
}

.pub-abstract {
  font-size: 0.88rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 0.7rem;
  max-width: 46rem;
  text-wrap: pretty;
}

.pub-links {
  display: flex;
  flex-wrap: wrap;
  gap: 1.1rem;
}

.btn-link {
  background: none;
  border: none;
  padding: 0;
  cursor: pointer;
  font-family: var(--font-body);
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--primary);
  transition: var(--transition);
}

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

.bibtex-pane {
  display: none;
  margin-top: 0.75rem;
  padding: 0.9rem 1rem;
  background: var(--code-bg);
  color: var(--code-text);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  line-height: 1.55;
  border-radius: 8px;
  position: relative;
  white-space: pre-wrap;
}

.bibtex-pane.show {
  display: block;
}

.copy-btn {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  background: rgba(255, 255, 255, 0.12);
  color: #fff;
  border: none;
  font-size: 0.72rem;
  padding: 0.2rem 0.55rem;
  border-radius: 4px;
  cursor: pointer;
}

.copy-btn:hover {
  background: rgba(255, 255, 255, 0.28);
}

/* EXPERIENCE: left-hand date timeline */
.exp-list {
  border-top: 1px solid var(--border);
}

.exp-block {
  display: grid;
  grid-template-columns: 11rem minmax(0, 1fr);
  column-gap: 1.5rem;
  padding: 1.05rem 0;
  border-bottom: 1px solid var(--border);
  position: relative;
}

.exp-block:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.exp-time {
  grid-column: 1;
  grid-row: 1;
  position: relative;
  margin: 0;
  padding-right: 1.25rem;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  line-height: 1.4;
  color: var(--text-muted);
  font-variant-numeric: tabular-nums;
  text-align: right;
  white-space: nowrap;
}

.exp-time::after {
  content: "";
  position: absolute;
  right: 0;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--border);
}

.exp-block:first-child .exp-time::after {
  top: 50%;
}

.exp-block:last-child .exp-time::after {
  bottom: auto;
  height: 50%;
}

.exp-time::before {
  content: "";
  position: absolute;
  right: -4px;
  top: 50%;
  transform: translateY(-50%);
  z-index: 1;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--bg-page);
  border: 2px solid var(--primary);
  box-sizing: border-box;
}

.exp-main {
  grid-column: 2;
  grid-row: 1;
  min-width: 0;
}

.exp-title {
  font-family: var(--font-heading);
  font-size: 1.05rem;
  font-weight: 600;
  line-height: 1.45;
  color: var(--text-main);
  text-wrap: pretty;
}

.exp-sub {
  font-size: 0.87rem;
  font-weight: 600;
  color: var(--primary);
  margin: 0.15rem 0 0.25rem;
}

.exp-desc {
  font-size: 0.86rem;
  color: var(--text-muted);
  line-height: 1.6;
  text-wrap: pretty;
}

/* HONORS */
.award-list {
  border-top: 1px solid var(--border);
}

.award-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 1rem;
  padding: 0.7rem 0;
  border-bottom: 1px solid var(--border);
}

.award-row:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.award-title {
  font-size: 0.92rem;
  font-weight: 500;
  color: var(--text-main);
  min-width: 0;
  line-height: 1.5;
  text-wrap: pretty;
}

.award-date {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-muted);
  white-space: nowrap;
  font-variant-numeric: tabular-nums;
}

/* FOOTER */
.site-footer {
  margin-top: 3.5rem;
  padding-top: 1.4rem;
  border-top: 1px solid var(--border);
  font-size: 0.84rem;
  color: var(--text-light);
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.4rem;
}

/* RESPONSIVE */
@media (max-width: 760px) {
  .hero {
    flex-direction: column;
    text-align: center;
    gap: 1.4rem;
  }

  .hero-title-row,
  .hero-socials {
    justify-content: center;
  }

  .news-item {
    grid-template-columns: 1fr;
    gap: 0.15rem;
  }

  .exp-block {
    grid-template-columns: 1fr;
    row-gap: 0.3rem;
    padding: 0.95rem 0;
  }

  .exp-time,
  .exp-main {
    grid-column: 1;
  }

  .exp-time {
    grid-row: 1;
    display: block;
    padding: 0 0 0.1rem 1.05rem;
    text-align: left;
  }

  .exp-main {
    grid-row: 2;
    padding-left: 1.05rem;
  }

  .exp-time::before {
    left: -4px;
    right: auto;
    top: 0.3rem;
    transform: none;
  }

  .exp-time::after,
  .exp-block:first-child .exp-time::after {
    left: 0;
    right: auto;
    top: 0.6rem;
    bottom: -0.95rem;
    height: auto;
  }

  .exp-block:last-child .exp-time::after {
    display: none;
  }
}

@media (max-width: 620px) {
  .nav-link {
    display: none;
  }

  .page-wrap {
    padding: 1.9rem 1rem 3rem;
  }

  .hero-name {
    font-size: 1.95rem;
  }

  .section-title {
    font-size: 1.32rem;
  }
}