/* =====================================================================
 * 牛铮个人网站 · 基础样式（Claude 风格：象牙纸面 · 墨色文字 · 衬线标题 · 天蓝点缀）
 * ===================================================================== */
:root {
  /* 纸面与墨色 */
  --ivory: #FAF9F5;
  --paper: #F0EEE6;
  --paper-2: #E8E6DC;
  --card: #FFFFFF;
  --ink: #141413;
  --ink-2: #3D3D3A;
  --muted: #73726C;
  --faint: #A3A29C;
  --line: #E3E1D7;
  --line-2: #D5D3C8;
  --slate: #1F1E1D;
  --slate-2: #2A2927;
  --on-slate: #F0EEE6;
  /* 天蓝（替代 Claude 橙） */
  --sky: #3D9BE0;
  --sky-deep: #1F72B5;
  --sky-soft: #E4F1FB;
  --sky-tint: rgba(61, 155, 224, .12);
  --sky-rgb: 61, 155, 224;
  --heather: #CBCADB;
  /* 字体 */
  --serif: "Tiempos Headline", "Copernicus", "Source Serif 4", "Source Serif Pro", Georgia, "Noto Serif SC", "Source Han Serif SC", "Songti SC", "STSong", "SimSun", serif;
  --sans: "Styrene B", "Söhne", ui-sans-serif, system-ui, -apple-system, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  --mono: ui-monospace, "SFMono-Regular", "JetBrains Mono", Consolas, "Liberation Mono", monospace;
  --cn: var(--sans);
  /* 动效 */
  --ease-out: cubic-bezier(.16, 1, .3, 1);
  --ease-io: cubic-bezier(.65, 0, .35, 1);
  --radius: 1.25rem;
  --shadow-sm: 0 1px 2px rgba(20, 20, 19, .05), 0 2px 8px rgba(20, 20, 19, .04);
  --shadow: 0 1px 2px rgba(20, 20, 19, .04), 0 12px 32px rgba(20, 20, 19, .07);
  --shadow-lg: 0 2px 4px rgba(20, 20, 19, .04), 0 28px 64px rgba(20, 20, 19, .12);
  --pointer-x: 50vw;
  --pointer-y: 50vh;

  font-family: var(--sans);
  color: var(--ink);
  background: var(--ivory);
  font-synthesis: weight;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; background: var(--ivory); }
body { min-width: 320px; min-height: 100%; overflow-x: hidden; color: var(--ink); background: var(--ivory); line-height: 1.6; }
button, a { color: inherit; }
a { text-decoration: none; }
img { display: block; max-width: 100%; height: auto; }
picture { display: contents; }
::selection { color: var(--ink); background: rgba(var(--sky-rgb), .28); }
:focus-visible { outline: 2px solid var(--sky); outline-offset: 3px; border-radius: 6px; }
.site-shell { position: relative; overflow-x: clip; background: var(--ivory); }

/* ---------- 顶部进度条 / 指针柔光 / 动效开关 ---------- */
.scroll-progress {
  position: fixed; z-index: 1400; top: 0; left: 0; width: 100%; height: 2px;
  transform-origin: 0 50%; transform: scaleX(0);
  background: linear-gradient(90deg, var(--sky), var(--sky-deep));
}
.pointer-glow {
  position: fixed; z-index: 1; top: 0; left: 0; width: 520px; height: 520px; pointer-events: none; border-radius: 50%;
  opacity: .5;
  transform: translate(calc(var(--pointer-x) - 260px), calc(var(--pointer-y) - 260px));
  background: radial-gradient(circle, rgba(var(--sky-rgb), .10), transparent 65%);
}
body.niu-hero-active .pointer-glow { opacity: 0; }

.motion-toggle {
  position: fixed; z-index: 1300; right: 1rem; bottom: 1rem; display: inline-flex; align-items: center; gap: .55rem;
  min-height: 38px; padding: .55rem .85rem; border: 1px solid var(--line); border-radius: 999px;
  color: var(--ink-2); background: rgba(250, 249, 245, .88); backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px);
  box-shadow: var(--shadow-sm); font: 600 .72rem/1 var(--sans); letter-spacing: .02em; cursor: pointer;
  transition: border-color .3s ease, transform .4s var(--ease-out);
}
.motion-toggle:hover { transform: translateY(-2px); border-color: var(--sky); }
.motion-dot { width: .5rem; height: .5rem; border-radius: 50%; background: var(--sky); animation: motionDotPulse 2.4s ease-in-out infinite; }
@keyframes motionDotPulse { 0%, 100% { opacity: .45; transform: scale(.85); } 50% { opacity: 1; transform: scale(1.1); } }
body.motion-paused .motion-dot { animation: none !important; background: var(--faint); }
body.motion-paused *, body.motion-paused *::before, body.motion-paused *::after { animation-play-state: paused !important; }
body.motion-paused .reveal { opacity: 1 !important; transform: none !important; }
body.motion-paused .animated-copy .char { opacity: 1 !important; }
body.motion-paused .pointer-glow { display: none; }

/* ---------- 通用揭示 ---------- */
.reveal { opacity: 0; transform: translateY(18px); transition: opacity .9s var(--ease-out), transform 1s var(--ease-out); }
.reveal.visible { opacity: 1; transform: none; }
@keyframes gridDrift { from { background-position: 0 0, 0 0; } to { background-position: 56px 56px, 56px 56px; } }
@keyframes scanLine { from { transform: translateY(-100%); } to { transform: translateY(850%); } }

/* ---------- 标题 ---------- */
.section-heading {
  font-family: var(--serif); font-weight: 400; color: var(--ink); text-align: center;
  font-size: clamp(2.8rem, 7vw, 6rem); line-height: 1.08; letter-spacing: -.01em;
}
.section-heading-light { color: var(--ink); }

/* ---------- 主按钮 ---------- */
.primary-button {
  display: inline-flex; align-items: center; justify-content: center; gap: .6rem; padding: .9rem 1.4rem;
  border: 1px solid var(--ink); border-radius: 999px; color: var(--ivory); background: var(--ink);
  font: 600 .9rem/1 var(--sans); letter-spacing: .01em;
  transition: background .3s ease, border-color .3s ease, transform .4s var(--ease-out);
}
.primary-button:hover { background: var(--sky-deep); border-color: var(--sky-deep); transform: translateY(-2px); }

/* ---------- 首页：图像长卷 ---------- */
.marquee-section { position: relative; z-index: 3; overflow: hidden; padding: clamp(4rem, 7vw, 6rem) 0 3rem; background: var(--ivory); }
.marquee-section::before, .marquee-section::after { content: ''; position: absolute; z-index: 5; top: 0; bottom: 0; width: min(10vw, 160px); pointer-events: none; }
.marquee-section::before { left: 0; background: linear-gradient(90deg, var(--ivory), transparent); }
.marquee-section::after { right: 0; background: linear-gradient(-90deg, var(--ivory), transparent); }
.marquee-kicker { margin: 0 clamp(1.25rem, 4vw, 4rem) 1.4rem; color: var(--muted); font: 600 .8rem/1.5 var(--sans); letter-spacing: .04em; }
.marquee-kicker::before { content: '✳︎ '; color: var(--sky); }
.marquee-window { overflow: visible; }
.marquee-window + .marquee-window { margin-top: .9rem; }
.marquee-scroll-layer { width: max-content; will-change: transform; }
.marquee-row { display: flex; width: max-content; gap: .9rem; will-change: transform; }
.marquee-row-right { animation: marqueeDriftRight 40s linear infinite; }
.marquee-row-left { animation: marqueeDriftLeft 44s linear infinite; }
@keyframes marqueeDriftRight { from { transform: translateX(-6%); } to { transform: translateX(0); } }
@keyframes marqueeDriftLeft { from { transform: translateX(0); } to { transform: translateX(-6%); } }
.marquee-tile { position: relative; width: clamp(260px, 26vw, 400px); aspect-ratio: 1.5; overflow: hidden; border: 1px solid var(--line); border-radius: 1.1rem; background: var(--paper); box-shadow: var(--shadow-sm); }
.marquee-tile img { width: 100%; height: 100%; object-fit: cover; transition: transform .9s var(--ease-out); }
.marquee-tile figcaption { position: absolute; left: .7rem; bottom: .7rem; padding: .38rem .65rem; border-radius: 999px; color: var(--ink); background: rgba(250, 249, 245, .92); font-size: .74rem; font-weight: 600; opacity: 0; transform: translateY(6px); transition: opacity .35s ease, transform .5s var(--ease-out); }
.marquee-tile:hover img { transform: scale(1.04); }
.marquee-tile:hover figcaption { opacity: 1; transform: none; }

/* ---------- 首页：研究画像 ---------- */
.about-section { position: relative; display: grid; min-height: 92svh; place-items: center; overflow: hidden; padding: clamp(5rem, 9vw, 8rem) clamp(1.25rem, 4vw, 4rem); background: var(--ivory); }
.about-content { position: relative; z-index: 4; display: flex; width: min(100%, 920px); flex-direction: column; align-items: center; gap: clamp(2rem, 4vw, 3.4rem); text-align: center; }
.about-copy { max-width: 760px; color: var(--ink); font-family: var(--serif); font-size: clamp(1.25rem, 2.2vw, 1.7rem); font-weight: 400; line-height: 1.7; text-align: justify; text-justify: inter-ideograph; }
.animated-copy .char { opacity: .16; transition: opacity .12s linear; }
.about-evidence { position: absolute; z-index: 2; overflow: hidden; width: clamp(120px, 15vw, 220px); border: 1px solid var(--line); border-radius: 1rem; background: var(--card); box-shadow: var(--shadow); }
.about-evidence img { width: 100%; aspect-ratio: 1.25; object-fit: cover; }
.about-evidence figcaption { padding: .5rem .7rem; color: var(--muted); font-size: .72rem; font-weight: 600; }
.about-evidence-a { top: 8%; left: 4%; }
.about-evidence-b { top: 9%; right: 4%; }
.about-evidence-c { bottom: 8%; left: 7%; }
.about-evidence-d { right: 7%; bottom: 9%; }
.profile-facts { display: grid; grid-template-columns: repeat(4, 1fr); width: min(100%, 760px); border: 1px solid var(--line); border-radius: 1.2rem; background: var(--card); box-shadow: var(--shadow-sm); overflow: hidden; }
.profile-facts div { display: flex; flex-direction: column; gap: .35rem; padding: 1.15rem .8rem; border-right: 1px solid var(--line); }
.profile-facts div:last-child { border-right: 0; }
.profile-facts strong { color: var(--ink); font: 400 clamp(1.7rem, 3vw, 2.5rem)/1 var(--serif); }
.profile-facts span { color: var(--muted); font-size: .76rem; font-weight: 600; }

/* ---------- 首页：研究能力 ---------- */
.capabilities-section { position: relative; z-index: 5; overflow: hidden; padding: clamp(4.5rem, 8vw, 7rem) clamp(1.25rem, 4vw, 4rem); color: var(--ink); background: var(--paper); }
.capabilities-list { width: min(100%, 1120px); margin: clamp(2.5rem, 5vw, 4rem) auto 0; border-top: 1px solid var(--line-2); }
.capability-item { display: grid; grid-template-columns: minmax(120px, .3fr) minmax(0, 1fr); gap: clamp(1.2rem, 4vw, 3.5rem); padding: clamp(1.6rem, 3vw, 2.6rem) 1rem; border-bottom: 1px solid var(--line-2); border-radius: 1rem; transition: background .4s ease; }
.capability-item:hover { background: rgba(250, 249, 245, .7); }
.capability-number { color: var(--sky-deep); font: 400 clamp(3rem, 7vw, 5.4rem)/.9 var(--serif); }
.capability-main { display: flex; flex-direction: column; justify-content: center; }
.capability-title-row { display: flex; align-items: center; justify-content: space-between; gap: 1rem; }
.capability-title-row h3 { font: 400 clamp(1.5rem, 2.8vw, 2.3rem)/1.2 var(--serif); }
.capability-title-row span { display: grid; flex: 0 0 auto; width: 2.4rem; height: 2.4rem; place-items: center; border: 1px solid var(--line-2); border-radius: 50%; background: var(--ivory); }
.capability-main > p { max-width: 720px; margin-top: .8rem; color: var(--ink-2); font-size: clamp(.95rem, 1.3vw, 1.05rem); line-height: 1.8; }
.capability-main ul, .research-description-row ul { display: flex; flex-wrap: wrap; gap: .45rem; margin-top: 1.1rem; list-style: none; }
.capability-main li, .research-description-row li { padding: .38rem .75rem; border: 1px solid var(--line-2); border-radius: 999px; color: var(--ink-2); background: var(--ivory); font-size: .78rem; font-weight: 600; }

/* ---------- 首页：代表性研究（堆叠卡片） ---------- */
.research-section { position: relative; z-index: 8; padding: clamp(4.5rem, 8vw, 7rem) clamp(1rem, 2vw, 2rem) 5rem; background: var(--ivory); }
.research-intro { max-width: 720px; margin: 1.2rem auto 0; color: var(--muted); text-align: center; font-size: .95rem; }
.research-stack { width: min(100%, 1320px); margin: clamp(2.5rem, 5vw, 4rem) auto 0; }
.research-card-stage { height: 92vh; min-height: 760px; }
.research-card {
  position: sticky; overflow: hidden; padding: clamp(1rem, 2vw, 1.8rem); border: 1px solid var(--line); border-radius: clamp(1.4rem, 3vw, 2.4rem);
  color: var(--ink); background: var(--card); transform-origin: top center; box-shadow: var(--shadow-lg); will-change: transform, opacity;
}
.research-card-top { display: grid; grid-template-columns: auto minmax(0, 1fr) auto; align-items: start; gap: clamp(1rem, 3vw, 2.6rem); }
.research-number { color: var(--sky); font: 400 clamp(3.4rem, 8vw, 6.4rem)/.85 var(--serif); }
.research-meta { padding-top: .3rem; }
.research-meta p { color: var(--sky-deep); font-size: .8rem; font-weight: 700; letter-spacing: .02em; }
.research-meta h3 { margin-top: .35rem; font: 400 clamp(1.7rem, 3.4vw, 3rem)/1.15 var(--serif); }
.research-meta span { display: block; max-width: 720px; margin-top: .55rem; color: var(--muted); font-size: clamp(.9rem, 1.1vw, 1rem); line-height: 1.6; }
.research-link { display: inline-flex; align-items: center; gap: .5rem; padding: .7rem 1rem; border: 1px solid var(--line-2); border-radius: 999px; color: var(--ink); background: var(--card); font-size: .82rem; font-weight: 600; white-space: nowrap; transition: border-color .3s ease, transform .4s var(--ease-out), background .3s ease, color .3s ease; }
.research-link:hover { border-color: var(--ink); transform: translateY(-2px); }
.research-description-row { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 2rem; align-items: end; margin: 1rem 0 1.2rem; }
.research-description-row > p { max-width: 760px; color: var(--ink-2); font-size: clamp(.9rem, 1.1vw, 1rem); line-height: 1.75; }
.research-gallery { display: grid; grid-template-columns: minmax(0, .72fr) minmax(0, 1.25fr); gap: .7rem; height: min(48vh, 480px); }
.research-gallery-left { display: grid; grid-template-rows: .85fr 1.15fr; gap: .7rem; min-height: 0; }
.research-image-frame { position: relative; overflow: hidden; width: 100%; height: 100%; min-height: 0; border-radius: clamp(1rem, 2vw, 1.6rem); background: var(--paper); }
.research-image-frame img { width: 100%; height: 100%; object-fit: cover; transition: transform .9s var(--ease-out); }
.research-image-frame:hover img { transform: scale(1.03); }
.research-image-scan { display: none; }
[data-tilt] { transition: transform .4s var(--ease-out); }

/* ---------- 首页：联系 ---------- */
.contact-section { position: relative; z-index: 12; padding: clamp(5rem, 9vw, 8rem) clamp(1.25rem, 4vw, 4rem) 1.5rem; color: var(--on-slate); background: var(--slate); }
.contact-shell { display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(360px, .95fr); gap: clamp(2.5rem, 6vw, 6rem); align-items: start; width: min(100%, 1280px); margin: 0 auto; }
.contact-heading, .contact-card-grid, .contact-card, .contact-card > * { min-width: 0; }
.contact-kicker { margin-bottom: 1.6rem; color: var(--sky); font-size: .85rem; font-weight: 600; letter-spacing: .04em; }
.contact-heading h2 { display: flex; flex-direction: column; font: 400 clamp(3rem, 7vw, 6.4rem)/1.08 var(--serif); }
.contact-heading h2 span, .contact-heading h2 strong { display: block; font: inherit; }
.contact-heading h2 strong { color: var(--sky); }
.contact-summary { max-width: 620px; margin-top: 1.8rem; color: rgba(240, 238, 230, .72); font-size: clamp(.98rem, 1.3vw, 1.1rem); line-height: 1.85; }
.contact-card-grid { display: grid; gap: .9rem; }
.contact-card { position: relative; display: flex; min-height: 150px; flex-direction: column; justify-content: space-between; gap: 1.2rem; padding: clamp(1.2rem, 2.2vw, 1.8rem); border: 1px solid rgba(240, 238, 230, .14); border-radius: 1.3rem; background: var(--slate-2); transition: transform .5s var(--ease-out), border-color .3s ease; }
.contact-card:is(a):hover { transform: translateY(-4px); border-color: var(--sky); }
.contact-card-label { color: rgba(240, 238, 230, .55); font-size: .78rem; font-weight: 600; }
.contact-card strong { display: block; font: 400 clamp(1.3rem, 2.2vw, 2rem)/1.3 var(--serif); overflow-wrap: anywhere; }
.contact-card p { color: rgba(240, 238, 230, .65); font-size: .92rem; line-height: 1.65; }
.contact-card-arrow { position: absolute; top: 1.1rem; right: 1.2rem; display: grid; width: 2.3rem; height: 2.3rem; place-items: center; border-radius: 50%; color: var(--ink); background: var(--sky); }
.site-footer { display: grid; grid-template-columns: 1fr auto 1fr; gap: 1rem; width: min(100%, 1280px); margin: clamp(4rem, 8vw, 6rem) auto 0; padding-top: 1.1rem; border-top: 1px solid rgba(240, 238, 230, .14); color: rgba(240, 238, 230, .6); font-size: .8rem; }
.site-footer a { text-align: right; }
.site-footer a:hover { color: var(--sky); }
.site-footer .site-footer-icp { grid-column: 1 / -1; margin: 0; text-align: center; }
.site-footer .site-footer-icp a { text-align: center; }

/* ---------- 响应式 ---------- */
@media (max-width: 980px) {
  .about-evidence { opacity: .5; }
  .capability-item { grid-template-columns: 96px minmax(0, 1fr); }
  .research-card-stage { height: auto; min-height: auto; padding-bottom: 1.5rem; }
  .research-card { position: relative; top: auto !important; transform: none !important; opacity: 1 !important; }
  .research-card-top { grid-template-columns: auto minmax(0, 1fr); }
  .research-card-top > :last-child { grid-column: 2; justify-self: start; }
  .research-description-row { grid-template-columns: 1fr; }
  .research-gallery { height: 440px; }
  .contact-shell { grid-template-columns: 1fr; }
}
@media (max-width: 680px) {
  .pointer-glow { display: none; }
  .about-evidence { width: 96px; opacity: .3; }
  .about-evidence-a, .about-evidence-c { left: -1rem; }
  .about-evidence-b, .about-evidence-d { right: -1rem; }
  .profile-facts { grid-template-columns: repeat(2, 1fr); }
  .profile-facts div:nth-child(2) { border-right: 0; }
  .profile-facts div:nth-child(-n+2) { border-bottom: 1px solid var(--line); }
  .capability-item { grid-template-columns: 1fr; gap: .8rem; }
  .research-card { padding: .85rem; }
  .research-card-top { grid-template-columns: 1fr; }
  .research-card-top > :last-child { grid-column: 1; }
  .research-gallery { grid-template-columns: 1fr; height: auto; }
  .research-gallery-left { grid-template-columns: 1fr 1fr; grid-template-rows: none; height: 180px; }
  .research-gallery-main { height: 260px; }
  .site-footer { grid-template-columns: 1fr; }
  .site-footer a { text-align: left; }
  .motion-toggle { right: .65rem; bottom: .65rem; }
}
@media (prefers-reduced-motion: reduce) {
  .marquee-row { animation: none; }
}