/* ===========================================================
   Yichong (Eric) Zhao — personal homepage
   Plain CSS, no build step. Edit the variables below to retheme.
   =========================================================== */

:root {
  --accent:        #2d5bd0;
  --accent-2:      #5b3bd0;
  --accent-soft:   rgba(45, 91, 208, 0.10);
  --bg:            #fcfcfd;
  --surface:       #ffffff;
  --text:          #1a1a1f;
  --text-muted:    #5b5b66;
  --text-faint:    #8a8a95;
  --border:        #e7e7ee;
  --shadow:        0 1px 2px rgba(20, 20, 40, .04), 0 8px 24px rgba(20, 20, 40, .05);

  --serif: "Source Serif 4", "Iowan Old Style", Georgia, "Times New Roman", "Hiragino Mincho ProN", "Yu Mincho", "Noto Serif JP", serif;
  --sans:  "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Yu Gothic", "Noto Sans JP", Meiryo, sans-serif;

  --maxw: 1080px;
  --radius: 14px;
}

/* dark palette — follows the OS unless the user forces light */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --accent:      #7aa0ff;
    --accent-2:    #b59bff;
    --accent-soft: rgba(122, 160, 255, 0.14);
    --bg:          #0e0f13;
    --surface:     #15171d;
    --text:        #e9e9ee;
    --text-muted:  #a6a7b2;
    --text-faint:  #71727d;
    --border:      #262833;
    --shadow:      0 1px 2px rgba(0,0,0,.3), 0 10px 30px rgba(0,0,0,.35);
  }
}
/* dark palette — manual override (always wins) */
:root[data-theme="dark"] {
  --accent:      #7aa0ff;
  --accent-2:    #b59bff;
  --accent-soft: rgba(122, 160, 255, 0.14);
  --bg:          #0e0f13;
  --surface:     #15171d;
  --text:        #e9e9ee;
  --text-muted:  #a6a7b2;
  --text-faint:  #71727d;
  --border:      #262833;
  --shadow:      0 1px 2px rgba(0,0,0,.3), 0 10px 30px rgba(0,0,0,.35);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 24px; }

body {
  margin: 0;
  font-family: var(--sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  font-size: 17px;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* subtle gradient wash at the very top */
body::before {
  content: "";
  position: fixed;
  inset: 0 0 auto 0;
  height: 320px;
  background: radial-gradient(60% 100% at 20% 0%, var(--accent-soft), transparent 70%);
  pointer-events: none;
  z-index: 0;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }

/* ---------- layout ---------- */
.page {
  position: relative;
  z-index: 1;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(28px, 5vw, 64px) clamp(20px, 5vw, 48px) 80px;
  display: grid;
  grid-template-columns: 290px 1fr;
  gap: clamp(32px, 5vw, 64px);
  align-items: start;
}

/* ---------- sidebar ---------- */
.sidebar {
  position: sticky;
  top: 40px;
  display: flex;
  flex-direction: column;
  gap: 22px;
}

.avatar {
  width: 150px;
  height: 150px;
  border-radius: 50%;
  object-fit: cover;
  box-shadow: var(--shadow);
  border: 3px solid var(--surface);
  outline: 1px solid var(--border);
}

.identity .name {
  font-family: var(--serif);
  font-size: 30px;
  line-height: 1.15;
  font-weight: 600;
  margin: 0;
  letter-spacing: -0.01em;
}
.identity .name-native {
  color: var(--text-faint);
  font-size: 15px;
  margin-top: 4px;
}
.identity .role {
  margin: 12px 0 0;
  font-weight: 600;
  color: var(--text);
}
.identity .affil,
.identity .loc {
  margin: 2px 0 0;
  color: var(--text-muted);
  font-size: 15px;
}
.identity .loc { display: flex; align-items: center; gap: 6px; }

/* contact icons */
.contacts {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}
.contacts a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 10px;
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text-muted);
  box-shadow: var(--shadow);
  transition: transform .15s ease, color .15s ease, border-color .15s ease;
}
.contacts a:hover {
  color: var(--accent);
  border-color: var(--accent);
  transform: translateY(-2px);
  text-decoration: none;
}
.contacts svg { width: 19px; height: 19px; }

/* in-page nav / table of contents */
.toc {
  display: flex;
  flex-direction: column;
  gap: 2px;
  border-left: 2px solid var(--border);
  padding-left: 14px;
  margin-top: 4px;
}
.toc a {
  color: var(--text-muted);
  font-size: 14.5px;
  padding: 3px 0;
  font-weight: 500;
}
.toc a:hover { color: var(--accent); text-decoration: none; }

/* ---------- main content ---------- */
.content { min-width: 0; }

section { margin-bottom: 44px; scroll-margin-top: 24px; }
section:last-child { margin-bottom: 0; }

.section-title {
  font-family: var(--serif);
  font-size: 13px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--accent);
  margin: 0 0 18px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}

.lead { font-size: 19px; line-height: 1.7; }
.content p { margin: 0 0 14px; max-width: 68ch; }
.content p:last-child { margin-bottom: 0; }
.muted { color: var(--text-muted); }

/* hero intro line */
.hero-hi {
  font-family: var(--serif);
  font-size: clamp(26px, 4vw, 34px);
  font-weight: 600;
  letter-spacing: -0.01em;
  margin: 0 0 18px;
}
.hero-hi .wave { display: inline-block; }

/* News list */
.news { list-style: none; margin: 0; padding: 0; }
.news li {
  display: grid;
  grid-template-columns: 92px 1fr;
  gap: 14px;
  padding: 9px 0;
  border-bottom: 1px dashed var(--border);
}
.news li:last-child { border-bottom: 0; }
.news .date {
  color: var(--text-faint);
  font-variant-numeric: tabular-nums;
  font-size: 14.5px;
  padding-top: 1px;
  white-space: nowrap;
}

/* Research interest cards */
.cards { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 18px;
  box-shadow: var(--shadow);
}
.card h3 { margin: 0 0 4px; font-size: 16px; }
.card p { margin: 0; font-size: 14.5px; color: var(--text-muted); }

/* Publications */
.pub {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 18px;
  padding: 16px 0;
  border-bottom: 1px solid var(--border);
}
.pub:last-child { border-bottom: 0; }
.pub .venue-tag {
  align-self: start;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .03em;
  color: var(--accent);
  background: var(--accent-soft);
  border-radius: 8px;
  padding: 5px 10px;
  white-space: nowrap;
  text-align: center;
  min-width: 84px;
}
.pub .pub-title { font-weight: 600; margin: 0 0 3px; }
.pub .authors { color: var(--text-muted); font-size: 15px; margin: 0 0 3px; }
.pub .authors .me { color: var(--text); font-weight: 600; }
.pub .pub-venue { color: var(--text-faint); font-size: 14.5px; font-style: italic; margin: 0 0 8px; }
.pub .note { font-size: 14.5px; color: var(--text-muted); margin: 0 0 8px; }
.pub-links { display: flex; gap: 8px; flex-wrap: wrap; }
.pub-links a {
  font-size: 13px;
  font-weight: 600;
  padding: 4px 12px;
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--text-muted);
  transition: all .15s ease;
}
.pub-links a:hover { color: var(--accent); border-color: var(--accent); text-decoration: none; }

/* timeline (experience / education) */
.timeline { display: flex; flex-direction: column; }
.entry {
  display: grid;
  grid-template-columns: 150px 1fr;
  gap: 20px;
  padding: 14px 0;
  border-bottom: 1px solid var(--border);
}
.entry:last-child { border-bottom: 0; }
.entry .when { color: var(--text-faint); font-size: 14.5px; font-variant-numeric: tabular-nums; padding-top: 2px; }
.entry .what h3 { margin: 0; font-size: 17px; }
.entry .what .org { color: var(--accent); font-weight: 600; }
.entry .what .sub { color: var(--text-muted); font-size: 15px; margin: 2px 0 0; }
.entry .what ul { margin: 8px 0 0; padding-left: 18px; color: var(--text-muted); font-size: 15px; }
.entry .what li { margin: 2px 0; }

/* awards / simple lists */
.simple { list-style: none; margin: 0; padding: 0; }
.simple li {
  padding: 11px 0;
  border-bottom: 1px solid var(--border);
  display: flex;
  gap: 12px;
  align-items: baseline;
}
.simple li:last-child { border-bottom: 0; }
.simple .yr { color: var(--text-faint); font-variant-numeric: tabular-nums; min-width: 44px; }
.badge {
  display: inline-block;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: .04em;
  color: var(--accent);
  background: var(--accent-soft);
  border-radius: 6px;
  padding: 2px 8px;
  margin-left: 6px;
  vertical-align: middle;
}

.tags { display: flex; flex-wrap: wrap; gap: 8px; }
.tag {
  font-size: 14px;
  color: var(--text-muted);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 5px 13px;
}

footer {
  margin-top: 56px;
  padding-top: 18px;
  border-top: 1px solid var(--border);
  color: var(--text-faint);
  font-size: 14px;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px;
}

/* ---------- responsive ---------- */
@media (max-width: 860px) {
  .page { grid-template-columns: 1fr; gap: 28px; }
  .sidebar {
    position: static;
    flex-direction: column;
    align-items: flex-start;
    text-align: left;
  }
  .sidebar-top {
    display: flex;
    gap: 20px;
    align-items: center;
    width: 100%;
  }
  .avatar { width: 96px; height: 96px; }
  .identity .name { font-size: 25px; }
  .toc { display: none; }
  .cards { grid-template-columns: 1fr; }
}

@media (max-width: 560px) {
  body { font-size: 16px; }
  .news li { grid-template-columns: 1fr; gap: 2px; }
  .news .date { padding-top: 0; }
  .pub { grid-template-columns: 1fr; gap: 8px; }
  .entry { grid-template-columns: 1fr; gap: 4px; }
}

@media print {
  body::before, .contacts, .toc, footer { display: none; }
  .page { display: block; max-width: none; }
  a { color: inherit; text-decoration: none; }
}

/* research-interest list (folded into About) */
.ri-label { font-weight: 600; margin: 22px 0 8px; color: var(--text); }
.ri-list { margin: 0; padding-left: 20px; color: var(--text-muted); }
.ri-list li { margin: 5px 0; }
.ri-list strong { color: var(--text); font-weight: 600; }

/* Hugging Face badge */
.hf-badge {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  margin-top: 10px;
  padding: 9px 15px 9px 11px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface);
  color: var(--text);
  font-size: 14.5px;
  font-weight: 600;
  box-shadow: var(--shadow);
  transition: transform .15s ease, border-color .15s ease, box-shadow .15s ease;
}
.hf-badge:hover {
  transform: translateY(-2px);
  border-color: #FFD21E;
  box-shadow: 0 8px 22px rgba(255, 190, 30, .22);
  text-decoration: none;
}
.hf-badge .hf-logo { width: 26px; height: 26px; flex: none; }
.hf-badge strong { font-weight: 700; }

/* language switch */
.lang-switch {
  display: flex;
  gap: 4px;
  font-size: 13px;
}
.lang-switch a {
  padding: 3px 11px;
  border-radius: 999px;
  border: 1px solid var(--border);
  color: var(--text-muted);
}
.lang-switch a:hover { border-color: var(--accent); color: var(--accent); text-decoration: none; }
.lang-switch a.active {
  background: var(--accent-soft);
  color: var(--accent);
  border-color: transparent;
  font-weight: 600;
}

/* Japanese typography */
html[lang="ja"] body { line-height: 1.85; }
html[lang="ja"] .lead { line-height: 1.95; }
html[lang="ja"] .section-title { letter-spacing: .08em; }

/* top controls: theme toggle + language switch */
.top-controls {
  align-self: flex-end;
  display: flex;
  align-items: center;
  gap: 8px;
}
.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 31px;
  height: 31px;
  padding: 0;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text-muted);
  cursor: pointer;
  transition: color .15s ease, border-color .15s ease, transform .15s ease;
}
.theme-toggle:hover { color: var(--accent); border-color: var(--accent); transform: translateY(-1px); }
.theme-toggle svg { width: 16px; height: 16px; }

/* project thumbnail */
.proj-img {
  display: block;
  margin-top: 12px;
  max-width: 213px;
  width: 100%;
  height: auto;
  border-radius: 10px;
  border: 1px solid var(--border);
}