/* ==========================================================================
   Jiawei Zhou — personal site
   Single stylesheet. Design tokens live in :root; change them there.
   Layout is mobile-first: base rules target phones, media queries add columns.
   ========================================================================== */

:root {
  --bg:            #ffffff;
  --bg-soft:       #f6f7f9;
  --bg-sunk:       #eef0f4;
  --text:          #23272f;
  --text-soft:     #5b6472;
  --text-faint:    #8b95a3;
  --border:        #e3e7ed;
  --accent:        #12667f;
  --accent-soft:   #e6f1f5;
  --accent-hover:  #0b485b;
  --award:         #9a5b12;
  --award-soft:    #fbf1e3;

  /* Public Sans (US Web Design System) with the platform stack behind it, so the
     page still renders correctly if the webfont is slow or blocked. Variable
     axis 400-700, which covers the 560-650 weights used below. */
  --font-sans: "Public Sans", ui-sans-serif, -apple-system, BlinkMacSystemFont,
               "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif,
               "Apple Color Emoji", "Segoe UI Emoji";
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas,
               "Liberation Mono", monospace;

  --maxw: 1160px;
  --side: 268px;
  --radius: 10px;
  --tap: 40px;               /* minimum comfortable touch target */
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg:           #14161a;
    --bg-soft:      #1c1f25;
    --bg-sunk:      #23272e;
    --text:         #e6e9ee;
    --text-soft:    #a8b1bd;
    --text-faint:   #78828f;
    --border:       #2c313a;
    --accent:       #5cc2dd;
    --accent-soft:  #17323b;
    --accent-hover: #8ad8ee;
    --award:        #e0a75c;
    --award-soft:   #33281a;
  }
}

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  overflow-x: hidden;          /* belt and braces against phone side-scroll */
}

body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: clamp(15.5px, 0.35vw + 15px, 16.5px);
  line-height: 1.62;
  -webkit-font-smoothing: antialiased;
  overflow-wrap: break-word;
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition: none !important; animation: none !important; }
}

a { color: var(--accent); text-decoration: none; transition: color .15s ease; }
a:hover { color: var(--accent-hover); text-decoration: underline; }

img { max-width: 100%; height: auto; display: block; }

h1, h2, h3 { color: var(--text); line-height: 1.25; margin: 0 0 .5em; font-weight: 640; }
h1 { font-size: clamp(1.5rem, 1.2rem + 1vw, 1.75rem); letter-spacing: -.01em; }
h2 { font-size: .95rem; letter-spacing: .08em; text-transform: uppercase; color: var(--text-soft); font-weight: 650; }
h3 { font-size: 1.02rem; }
p  { margin: 0 0 1.05em; }

::selection { background: var(--accent-soft); }

.skip {
  position: absolute; left: -9999px;
  background: var(--accent); color: #fff;
  padding: 10px 16px; border-radius: var(--radius); z-index: 100;
}
.skip:focus { left: 16px; top: 16px; }

:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; border-radius: 4px; }

/* ==========================================================================
   Layout — single column by default, sidebar added at 900px
   ========================================================================== */

.layout {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 28px 18px 56px;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 32px;
  align-items: start;
}

main { min-width: 0; }
.section { margin-bottom: 46px; scroll-margin-top: 24px; }

/* ==========================================================================
   Sidebar / header block
   ========================================================================== */

.sidebar { min-width: 0; }

.avatar {
  width: 120px; height: 120px;
  border-radius: 50%;
  object-fit: cover;
  border: 1px solid var(--border);
  margin-bottom: 14px;
}

.name { margin-bottom: 4px; }

.affil {
  color: var(--text-soft);
  font-size: .93rem;
  line-height: 1.5;
  margin: 0 0 14px;
}
.affil strong { color: var(--text); font-weight: 600; }

.email {
  margin: -6px 0 14px;
  font-size: .87rem;
  color: var(--text-soft);
  overflow-wrap: anywhere;
}

.social {
  display: flex; flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 4px;
}
.social a {
  display: inline-flex; align-items: center; justify-content: center;
  min-width: var(--tap); min-height: var(--tap);
  color: var(--text-soft);
  font-size: 1.16rem; line-height: 1;
  border-radius: 8px;
  transition: color .15s ease, background .15s ease;
}
.social a:hover { color: var(--accent); background: var(--accent-soft); text-decoration: none; }

.sidenav { display: none; }

/* ==========================================================================
   About
   ========================================================================== */

.about { font-size: .94rem; line-height: 1.65; }
.about .lede { font-size: inherit; color: var(--text); }
.about strong { font-weight: 640; color: var(--text); }

/* The three research directions. Tinted and underscored so they read as a set
   without breaking the paragraph into a list. */
.about strong.dir {
  color: var(--accent);
  font-weight: 620;
  box-shadow: inset 0 -0.42em 0 var(--accent-soft);
  padding: 0 .12em;
  border-radius: 2px;
}

/* ==========================================================================
   Research overview
   ========================================================================== */

.overview {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 18px;
}

.ov-card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-soft);
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

/* Square illustrations. White-background art, so the stage stays white in dark
   mode too rather than putting a bright square on a dark card. */
.ov-figure {
  background: #fff;
  border-bottom: 1px solid var(--border);
  padding: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent);
}
.ov-figure img {
  width: auto;
  max-width: 100%;
  max-height: 190px;
  object-fit: contain;
}
.ov-figure svg {           /* fallback if a card still points at inline art */
  width: 100%; max-width: 260px; height: auto; display: block;
}

.ov-body { padding: 16px 18px 18px; }
.ov-eyebrow {
  margin: 0 0 -1px;
  font-size: .6rem;
  font-weight: 700;
  letter-spacing: .05em;
  text-transform: uppercase;
  color: var(--accent);
}
.ov-body h3 { font-size: 1.05rem; margin-bottom: 8px; color: var(--text); line-height: 1.3; }
.ov-body p  { margin: 0 0 12px; font-size: .93rem; color: var(--text-soft); line-height: 1.55; }

.ov-papers { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--border); padding-top: 10px; }
.ov-papers li { margin-bottom: 5px; font-size: .79rem; line-height: 1.45; }
.ov-papers .venue.sm { font-size: .66rem; padding: 1px 5px; }
.ov-papers li:last-child { margin-bottom: 0; }
.ov-papers a { color: var(--text-soft); }
.ov-papers a:hover { color: var(--accent); }

/* ==========================================================================
   News — scrollable panel
   ========================================================================== */

.news-scroll {
  max-height: 248px;
  overflow-y: auto;
  overscroll-behavior: contain;
  -webkit-overflow-scrolling: touch;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 4px 14px;
  background: var(--bg-soft);
  scrollbar-width: thin;
  scrollbar-color: var(--text-faint) transparent;
}
.news-scroll::-webkit-scrollbar { width: 9px; }
.news-scroll::-webkit-scrollbar-track { background: transparent; }
.news-scroll::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 99px;
  border: 2px solid var(--bg-soft);
}
.news-scroll::-webkit-scrollbar-thumb:hover { background: var(--text-faint); }

.news { list-style: none; margin: 0; padding: 0; }
.news li {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  padding: 8px 0;
  border-bottom: 1px solid var(--border);
  font-size: .865rem;
}
.news li:last-child { border-bottom: 0; }
.news time {
  color: var(--text-faint);
  font-size: .765rem;
  font-variant-numeric: tabular-nums;
  letter-spacing: .02em;
}
.news .body { color: var(--text-soft); }
.news .ico { margin-right: 6px; }

/* ==========================================================================
   Buttons and filters
   ========================================================================== */

.btn {
  display: inline-flex; align-items: center;
  min-height: 34px;
  background: none;
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--text-soft);
  font: inherit;
  font-size: .84rem;
  padding: 4px 14px;
  cursor: pointer;
  white-space: nowrap;
  transition: all .15s ease;
}
.btn:hover { border-color: var(--accent); color: var(--accent); }
.btn[aria-pressed="true"] {
  background: var(--accent-soft);
  border-color: var(--accent);
  color: var(--accent);
  font-weight: 560;
}

/* ==========================================================================
   Publication entries
   ========================================================================== */

.pubs { display: grid; gap: 0; }

.pub { padding: 15px 0; border-bottom: 1px solid var(--border); }
.pub:last-child { border-bottom: 0; }
.pub[hidden] { display: none; }

/* Block, not flex: the chip sits inline so the title begins on the same line and
   wraps underneath it as ordinary text instead of being pushed to its own row. */
.pub-head {
  margin-bottom: 3px;
  line-height: 1.45;
}

.venue {
  display: inline-block;
  margin-right: 7px;
  position: relative;
  top: -1px;
  background: var(--accent-soft);
  color: var(--accent);
  border-radius: 5px;
  padding: 2px 8px;
  font-size: .75rem;
  font-weight: 650;
  letter-spacing: .02em;
  white-space: nowrap;
}
.venue.sm { padding: 1px 6px; font-size: .7rem; }

.pub-title {
  font-weight: 620;
  color: var(--text);
  font-size: 1rem;
  line-height: 1.4;
  overflow-wrap: anywhere;
}
a.pub-title:hover { color: var(--accent); }

.awards { margin: 3px 0 4px; display: flex; flex-wrap: wrap; gap: 6px; }
.award-tag {
  display: inline-block;
  background: var(--award-soft);
  color: var(--award);
  border-radius: 5px;
  padding: 1px 8px;
  font-size: .74rem;
  font-weight: 650;
  white-space: nowrap;
}

.authors { color: var(--text-soft); font-size: .91rem; margin: 2px 0 1px; }
.authors .me { color: var(--text); font-weight: 650; }

.venue-full { color: var(--text-faint); font-size: .84rem; font-style: italic; margin-bottom: 8px; }

.pub-links { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; }
.pub-links a, .pub-links button {
  display: inline-flex; align-items: center;
  min-height: 30px;
  font-size: .81rem;
  color: var(--text-soft);
  background: none;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 2px 10px;
  cursor: pointer;
  font-family: inherit;
  white-space: nowrap;
  transition: all .15s ease;
}
.pub-links a:hover, .pub-links button:hover {
  color: var(--accent); border-color: var(--accent); text-decoration: none;
}
.pub-links button[aria-expanded="true"] {
  color: var(--accent); border-color: var(--accent); background: var(--accent-soft);
}

.panel {
  position: relative;
  margin-top: 11px;
  background: var(--bg-sunk);
  border-radius: var(--radius);
  padding: 13px 15px;
  font-size: .89rem;
  color: var(--text-soft);
  line-height: 1.58;
}
.panel[hidden] { display: none; }

.panel-tools {
  position: absolute;
  top: 8px;
  left: 15px;
  z-index: 1;
}

.copy-btn {
  min-height: 26px;
  padding: 2px 11px;
  font: inherit;
  font-size: .76rem;
  color: var(--text-soft);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  cursor: pointer;
  transition: all .15s ease;
}
.copy-btn:hover { color: var(--accent); border-color: var(--accent); }
.copy-btn.copied { color: var(--accent); border-color: var(--accent); background: var(--accent-soft); }
.panel pre {
  margin: 0;
  padding-top: 30px;          /* clears the floating Copy button */
  font-family: var(--font-mono);
  font-size: .78rem;
  line-height: 1.55;
  white-space: pre;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  color: var(--text-soft);
}

.press { margin: 9px 0 0; padding: 0; list-style: none; }
.press li {
  font-size: .85rem;
  color: var(--text-soft);
  padding-left: 16px;
  position: relative;
  margin-bottom: 3px;
}
.press li::before {
  content: "›";
  position: absolute; left: 3px; top: -1px;
  color: var(--text-faint);
}

.pubs-note {
  margin: -6px 0 22px;
  font-size: .87rem;
  color: var(--text-faint);
  font-style: italic;
}
.pubs-note a { color: var(--accent); }

/* ==========================================================================
   Recent talks
   ========================================================================== */

.talks { list-style: none; margin: 0; padding: 0; }
.talks li {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  padding: 5px 0;
  font-size: .92rem;
}
.talks li[hidden] { display: none; }
.more-btn { margin-top: 14px; }
.talks .yr {
  color: var(--text-faint);
  font-size: .8rem;
  font-variant-numeric: tabular-nums;
  letter-spacing: .02em;
}
.talks .tv-host { font-weight: 600; color: var(--text); }
.talks .tv-host a { font-weight: 600; }
.talks .host { color: var(--text-soft); font-size: .88rem; }

/* ==========================================================================
   Kabi
   ========================================================================== */

.kabi p {
  margin: 0 0 12px;
  font-size: .93rem;
  color: var(--text-soft);
}
.kabi p .fa-paw { color: var(--accent); margin-left: 3px; }
.kabi img {
  width: 100%;
  max-width: 280px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

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

.site-footer {
  border-top: 1px solid var(--border);
  padding-top: 18px;
  color: var(--text-faint);
  font-size: .84rem;
}

.loading { color: var(--text-faint); font-size: .92rem; }

/* ==========================================================================
   Tablet — 640px and up
   ========================================================================== */

@media (min-width: 640px) {
  .layout { padding: 40px 28px 68px; }
  .section { margin-bottom: 54px; }

  .sidebar {
    display: grid;
    grid-template-columns: 128px minmax(0, 1fr);
    gap: 24px;
    align-items: center;
  }
  .avatar { width: 148px; height: 148px; margin-bottom: 0; }
  .social { margin-bottom: 0; }

  .news li, .talks li {
    grid-template-columns: 96px minmax(0, 1fr);
    gap: 14px;
  }
  .news li { grid-template-columns: 92px minmax(0, 1fr); }
  .news time, .talks .yr { padding-top: 2px; }
  .talks li { grid-template-columns: 92px minmax(0, 1fr); }

  .overview { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 20px; }
}

/* ==========================================================================
   Desktop — 900px and up: sidebar becomes a sticky rail
   ========================================================================== */

@media (min-width: 900px) {
  .layout {
    grid-template-columns: var(--side) minmax(0, 1fr);
    gap: 56px;
    padding: 56px 32px 80px;
  }

  .sidebar {
    position: sticky;
    top: 36px;
    display: block;
  }
  .avatar { width: 182px; height: 182px; margin-bottom: 18px; }
  .social { margin-bottom: 20px; margin-left: -8px; }

  .sidenav {
    display: block;
    border-top: 1px solid var(--border);
    padding-top: 14px;
  }
  .sidenav a {
    display: block;
    padding: 5px 0;
    font-size: .89rem;
    color: var(--text-soft);
    letter-spacing: .02em;
  }
  .sidenav a:hover { color: var(--accent); text-decoration: none; }

  .section { margin-bottom: 60px; }
  .news-scroll { max-height: 268px; }

  /* Three cards read better as a single column of wide rows than as an
     orphaned 2 + 1 grid. Art sits beside the text at this width. */
  .overview { grid-template-columns: minmax(0, 1fr); gap: 16px; }
  .ov-card { flex-direction: row; align-items: stretch; }
  .ov-figure {
    flex: 0 0 216px;
    border-bottom: 0;
    border-right: 1px solid var(--border);
  }
  .ov-figure img { max-height: 208px; }
  .ov-figure svg { max-width: 200px; }
  .ov-body { flex: 1 1 auto; padding: 18px 22px; }
}

/* ==========================================================================
   Small phones — 380px and below
   ========================================================================== */

@media (max-width: 380px) {
  .layout { padding: 22px 14px 44px; }
  .avatar { width: 100px; height: 100px; }
  .news-scroll { max-height: 216px; padding: 4px 11px; }
  .ov-figure { padding: 4px; }
  .ov-figure img { max-height: 160px; }
  .ov-figure svg { max-width: 210px; }
  .ov-body { padding: 14px 15px 15px; }
}

/* ==========================================================================
   Print
   ========================================================================== */

@media print {
  .sidenav, .pub-links button, .social { display: none; }
  body { font-size: 11pt; color: #000; background: #fff; }
  .layout { display: block; max-width: none; padding: 0; }
  .panel { display: none !important; }
  .news-scroll { max-height: none; overflow: visible; border: 0; padding: 0; background: none; }
  .overview { display: block; }
  a { color: #000; }
}