/* ==========================================================================
   Academic homepage — styles
   配色都在 :root 变量里改；深色模式的配色在 html[data-theme="dark"] 一节。
   ========================================================================== */

:root {
  --header-h: 72px;
  --layout-w: 1180px;
  --font: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue",
          Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);

  /* Light theme */
  --bg: #ffffff;
  --surface: #f6f7f9;
  --text: #494e52;
  --heading: #33383c;
  --muted: #6b7075;
  --border: #eceef0;
  --primary: #1e3a8a;          /* navy: links, nav, buttons */
  --primary-hover: #172554;
  --on-primary: #ffffff;
  --header-bg: rgba(255, 255, 255, 0.88);
  --toggle-bg: rgba(255, 255, 255, 0.85);
  --toggle-border: rgba(0, 0, 0, 0.1);
  --footer-bg: #f5f6f7;
  --footer-text: #6b7278;
  --shadow: 0 12px 28px rgba(15, 23, 42, 0.12);
  color-scheme: light;
}

html[data-theme="dark"] {
  --bg: #0f1115;
  --surface: #151821;
  --text: #e5e7eb;
  --heading: #f3f4f6;
  --muted: #9ca3af;
  --border: #2a2f3a;
  --primary: #93c5fd;
  --primary-hover: #bfdbfe;
  --on-primary: #0f1115;
  --header-bg: rgba(15, 17, 21, 0.86);
  --toggle-bg: rgba(21, 24, 33, 0.85);
  --toggle-border: rgba(255, 255, 255, 0.15);
  --footer-bg: #151821;
  --footer-text: #9ca3af;
  --shadow: 0 12px 28px rgba(0, 0, 0, 0.5);
  color-scheme: dark;
}

/* ---------- Base ---------- */

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

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  scroll-padding-top: calc(var(--header-h) + 16px);
}
@media (min-width: 64em) { html { font-size: 18px; } }
@media (prefers-reduced-motion: no-preference) { html { scroll-behavior: smooth; } }

body {
  margin: 0;
  padding-top: var(--header-h);
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  transition: background-color 0.3s ease, color 0.3s ease;
}

img { max-width: 100%; }

a {
  color: var(--primary);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.18em;
  transition: color 0.2s ease;
}
a:hover { color: var(--primary-hover); }

:focus-visible { outline: 2px solid var(--primary); outline-offset: 3px; border-radius: 3px; }
main:focus { outline: none; }

h1, h2, h3 { color: var(--heading); line-height: 1.25; }

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0.75rem;
  z-index: 100;
  padding: 0.5rem 0.75rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
}
.skip-link:focus { left: 1rem; }

/* ---------- Header & navigation ---------- */

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 50;
  height: var(--header-h);
  background: var(--header-bg);
  -webkit-backdrop-filter: saturate(160%) blur(10px);
  backdrop-filter: saturate(160%) blur(10px);
  border-bottom: 1px solid var(--border);
  transition: background-color 0.3s ease, border-color 0.3s ease;
}

.nav {
  position: relative;
  display: flex;
  align-items: center;
  max-width: var(--layout-w);
  height: 100%;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.nav__brand {
  margin-right: 2.75rem;
  color: var(--primary);
  font-weight: 700;
  text-decoration: none;
  white-space: nowrap;
}
.nav__brand:hover { color: var(--primary-hover); }

.nav__links {
  display: flex;
  align-items: center;
  gap: 1.75rem;
  margin: 0;
  padding: 0;
  list-style: none;
}
.nav__links a {
  position: relative;
  display: block;
  padding: 0.4rem 0;
  color: var(--primary);
  font-weight: 500;
  text-decoration: none;
}
/* Underline that grows from the left on hover */
.nav__links a::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0.1rem;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 0.3s var(--ease);
}
.nav__links a:hover { color: var(--primary-hover); }
.nav__links a:hover::after { transform: scaleX(1); }

/* Round theme button */
.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  margin-left: auto;
  padding: 0;
  border: 1px solid var(--toggle-border);
  border-radius: 999px;
  background: var(--toggle-bg);
  color: var(--primary);
  cursor: pointer;
  transition: transform 0.15s ease, background-color 0.2s ease, color 0.2s ease;
}
.theme-toggle:hover { transform: scale(1.06); }
.theme-toggle svg { width: 17px; height: 17px; }
.theme-toggle .icon-sun { display: none; }
html[data-theme="dark"] .theme-toggle .icon-sun { display: block; }
html[data-theme="dark"] .theme-toggle .icon-moon { display: none; }

.nav__toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  margin-left: 0.5rem;
  padding: 0;
  border: 0;
  border-radius: 8px;
  background: transparent;
  color: var(--primary);
  cursor: pointer;
}
.nav__toggle svg { width: 20px; height: 20px; }
.nav__toggle .icon-close { display: none; }
.nav__toggle[aria-expanded="true"] .icon-menu { display: none; }
.nav__toggle[aria-expanded="true"] .icon-close { display: block; }

/* Phones & small tablets: links collapse into a drop-down menu */
@media (max-width: 55em) {
  .nav { padding: 0 1rem; }
  .nav__toggle { display: inline-flex; }
  .nav__brand { margin-right: 1rem; overflow: hidden; text-overflow: ellipsis; }
  .nav__links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 0.25rem 1.25rem 0.75rem;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow);
  }
  .nav__links.is-open { display: flex; animation: drop-in 0.25s var(--ease); }
  .nav__links a { padding: 0.75rem 0; border-bottom: 1px solid var(--border); }
  .nav__links a::after { display: none; }
  .nav__links li:last-child a { border-bottom: 0; }
}

/* ---------- Page layout: profile sidebar + content ---------- */

.layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 2.5rem;
  max-width: var(--layout-w);
  margin: 0 auto;
  padding: 2.5rem 1.25rem 4rem;
  animation: intro 0.5s ease both;
}
@media (min-width: 57.5em) {
  .layout {
    grid-template-columns: 250px minmax(0, 1fr);
    gap: 4.5rem;
    padding: 3.25rem 1.5rem 5rem;
  }
}

/* ---------- Profile ---------- */

.profile { text-align: center; }

.profile__photo {
  display: block;
  margin: 0 auto;
  padding: 0;
  border: 0;
  border-radius: 50%;
  background: none;
  cursor: zoom-in;
}

/* 头像大小：手机上约占屏幕宽度的 72%（最大 300px），电脑上 240px */
.profile__avatar {
  display: block;
  width: min(72vw, 300px);
  height: auto;
  aspect-ratio: 4 / 5;
  padding: 5px;
  border: 1px solid var(--border);
  border-radius: 50%;
  background: var(--bg);
  object-fit: cover;
  transition: transform 0.4s var(--ease), box-shadow 0.4s var(--ease);
}
.profile__photo:hover .profile__avatar { transform: scale(1.02); box-shadow: var(--shadow); }

.profile__name { margin: 1.1rem 0 0.25rem; color: var(--heading); font-size: 1.15rem; font-weight: 700; }
.profile__bio { margin: 0; color: var(--muted); font-size: 0.85rem; }

.profile__links {
  display: inline-flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0.4rem;
  margin: 1.25rem 0 0;
  padding: 0;
  list-style: none;
  font-size: 0.85rem;
}
.profile__links a {
  display: inline-flex;
  align-items: center;
  gap: 0.6em;
  color: var(--text);
  text-decoration: none;
}
.profile__links i { width: 1.1em; color: var(--primary); text-align: center; transition: transform 0.2s ease; }
.profile__links a:hover { color: var(--primary); }
.profile__links a:hover i { transform: translateX(2px); }

/* 学校 logo：浅色模式用深蓝版，深色模式用白色版 */
.profile__logo { max-width: 175px; margin: 1.6rem auto 0; }
.profile__logo img { display: block; width: 100%; height: auto; }
.profile__logo--dark { display: none; }
html[data-theme="dark"] .profile__logo--light { display: none; }
html[data-theme="dark"] .profile__logo--dark { display: block; }

@media (min-width: 57.5em) {
  .profile {
    position: sticky;
    top: calc(var(--header-h) + 2.25rem);
    align-self: start;
    text-align: left;
  }
  .profile__photo { margin: 0; }
  .profile__avatar { width: 240px; }
  .profile__logo { margin-left: 0; }
}

/* ---------- Content sections ---------- */

.content > section + section { margin-top: 3rem; }

.intro h1 {
  margin: 0 0 0.75em;
  font-size: 1.75rem;
  font-weight: 800;
  letter-spacing: -0.02em;
}
.intro p { margin: 0 0 1em; }
.intro .note { color: var(--heading); font-weight: 600; }

.content h2 {
  margin: 0 0 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border);
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.01em;
}
.content h3 { margin: 1.75rem 0 0.75rem; font-size: 1rem; font-weight: 700; }
.content h2 + h3 { margin-top: 0; }

.content ul,
.content ol { margin: 0; padding-left: 1.3rem; }
.content li { margin: 0.45rem 0; }
.content li::marker { color: var(--muted); }
.content ul ul { margin-top: 0.15rem; list-style: circle; }
.content strong { color: var(--heading); font-weight: 600; }

.content .empty { margin: 0; color: var(--muted); font-style: italic; }

/* ---------- Papers (for later) ---------- */

.papers > li { margin: 0 0 1.5rem; padding-left: 0.25rem; }
.papers > li::marker { color: var(--muted); font-weight: 600; }
.paper__title { color: var(--heading); }
.paper__authors { color: var(--muted); font-size: 0.9em; }
.paper__status { color: var(--muted); font-size: 0.9em; font-style: italic; }
.paper__actions { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-top: 0.5rem; }

.pill {
  display: inline-block;
  padding: 0.1rem 0.55rem;
  border: 1px solid var(--primary);
  border-radius: 3px;
  color: var(--primary);
  font-size: 0.8em;
  font-weight: 500;
  text-decoration: none;
  cursor: pointer;
  transition: color 0.2s ease, background-color 0.2s ease;
}
.pill:hover,
.paper__abstract[open] > summary.pill { background: var(--primary); color: var(--on-primary); }
.paper__abstract > summary { list-style: none; }
.paper__abstract > summary::-webkit-details-marker { display: none; }
.paper__abstract-body {
  margin-top: 0.6rem;
  padding: 0.75rem 1rem;
  border-left: 3px solid var(--primary);
  background: var(--surface);
  font-size: 0.9em;
}

/* ---------- Footer ---------- */

.site-footer {
  padding: 1.75rem 1.5rem 2.25rem;
  background: var(--footer-bg);
  border-top: 1px solid var(--border);
  color: var(--footer-text);
  font-size: 0.75rem;
}
.site-footer p { max-width: var(--layout-w); margin: 0 auto; }

/* ---------- Photo lightbox ---------- */

.lightbox {
  max-width: none;
  max-height: none;
  padding: 0;
  border: 0;
  background: transparent;
  overflow: visible;
}
.lightbox::backdrop {
  background: rgba(8, 10, 14, 0.78);
  -webkit-backdrop-filter: blur(4px);
  backdrop-filter: blur(4px);
}
.lightbox[open] { animation: zoom-in 0.3s var(--ease); }
.lightbox img {
  display: block;
  width: min(92vw, 640px);
  height: auto;
  max-height: 86vh;
  object-fit: contain;
  border-radius: 14px;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.5);
  cursor: zoom-out;
}
.lightbox__close {
  position: absolute;
  top: -14px;
  right: -14px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border: 0;
  border-radius: 999px;
  background: #fff;
  color: #111;
  cursor: pointer;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}
.lightbox__close svg { width: 18px; height: 18px; }

/* ---------- Motion ---------- */

@keyframes intro { from { opacity: 0; } to { opacity: 1; } }
@keyframes drop-in { from { opacity: 0; transform: translateY(-6px); } to { opacity: 1; transform: none; } }
@keyframes zoom-in { from { opacity: 0; transform: scale(0.94); } to { opacity: 1; transform: none; } }

/* Section headings fade, slide and gently scale in as they scroll into view.
   Only when JavaScript is on, so the text is never hidden without it. */
html.js .reveal {
  opacity: 0;
  transform: translate3d(0, 24px, 0) scale(0.985);
  transform-origin: left center;
  transition: opacity 0.75s var(--ease), transform 0.75s var(--ease);
}
html.js .reveal.is-visible { opacity: 1; transform: none; }
@media (max-width: 37.5em) {
  html.js .reveal {
    transform: translate3d(0, 12px, 0) scale(0.99);
    transition-duration: 0.55s;
  }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
  html.js .reveal { opacity: 1; transform: none; }
}

/* ---------- Print ---------- */

@media print {
  .site-header, .skip-link, .lightbox { display: none !important; }
  body { padding-top: 0; }
  .layout { display: block; padding: 0; }
  .profile { position: static; }
}