/* ===== 基础变量 ===== */
:root {
  --ink: #14202e;
  --ink-soft: #4a5a6b;
  --muted: #7d8b9a;
  --line: #e3e8ef;
  --bg: #f7f9fc;
  --card: #ffffff;
  --accent: #2f5bd7;
  --accent-soft: #eaf0ff;
  --accent-deep: #1d3f9e;
  --radius: 14px;
  --shadow: 0 1px 2px rgba(20, 32, 46, .04), 0 12px 32px -16px rgba(20, 32, 46, .18);
  --max: 1080px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.75;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-deep); }

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

.wrap {
  width: 100%;
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 24px;
}

/* ===== 顶部导航 ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255, 255, 255, .86);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--line);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 66px;
  gap: 20px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-weight: 700;
  letter-spacing: .01em;
}

.brand:hover { color: var(--ink); }

.brand-mark {
  width: 34px;
  height: 34px;
  border-radius: 9px;
  background: linear-gradient(145deg, #3f6ee8, #1f3d9e);
  color: #fff;
  display: grid;
  place-items: center;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  font-size: 15px;
  font-weight: 700;
  box-shadow: 0 6px 14px -6px rgba(47, 91, 215, .8);
}

.brand-text { font-size: 17px; }
.brand-text small {
  display: block;
  font-size: 11px;
  font-weight: 400;
  color: var(--muted);
  letter-spacing: .16em;
  line-height: 1.2;
  text-transform: uppercase;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 6px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-links a {
  display: block;
  padding: 8px 14px;
  border-radius: 8px;
  color: var(--ink-soft);
  font-size: 14.5px;
}

.nav-links a:hover { background: #eef2f9; color: var(--ink); }

.nav-links a.active { color: var(--accent); background: var(--accent-soft); font-weight: 600; }

/* ===== 首屏 ===== */
.hero {
  position: relative;
  overflow: hidden;
  border-bottom: 1px solid var(--line);
  background:
    radial-gradient(680px 320px at 88% -10%, #e6edff 0%, rgba(230, 237, 255, 0) 70%),
    linear-gradient(180deg, #ffffff 0%, #f7f9fc 100%);
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, rgba(20, 32, 46, .045) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(20, 32, 46, .045) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: radial-gradient(70% 80% at 20% 0%, #000 0%, transparent 75%);
  -webkit-mask-image: radial-gradient(70% 80% at 20% 0%, #000 0%, transparent 75%);
  pointer-events: none;
}

.hero-inner {
  position: relative;
  display: grid;
  grid-template-columns: 1.15fr .85fr;
  gap: 48px;
  align-items: center;
  padding: 74px 0 78px;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 5px 12px 5px 8px;
  border: 1px solid #d5e0ff;
  background: #f3f7ff;
  color: var(--accent-deep);
  border-radius: 999px;
  font-size: 12.5px;
  letter-spacing: .04em;
}

.eyebrow .dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: #2fbf71;
  box-shadow: 0 0 0 3px rgba(47, 191, 113, .16);
}

.hero h1 {
  margin: 20px 0 14px;
  font-size: clamp(30px, 4.2vw, 44px);
  line-height: 1.28;
  letter-spacing: -.015em;
  font-weight: 800;
}

.hero h1 em {
  font-style: normal;
  color: var(--accent);
  background: linear-gradient(180deg, transparent 66%, rgba(47, 91, 215, .16) 66%);
}

.hero-lead {
  margin: 0 0 30px;
  max-width: 30em;
  color: var(--ink-soft);
  font-size: 16.5px;
}

.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 20px;
  border-radius: 10px;
  font-size: 15px;
  font-weight: 600;
  border: 1px solid transparent;
  transition: transform .15s ease, box-shadow .15s ease, background .15s ease;
}

.btn-primary {
  background: linear-gradient(180deg, #3a67e0, #2a4fbe);
  color: #fff;
  box-shadow: 0 10px 22px -12px rgba(42, 79, 190, .9);
}

.btn-primary:hover { color: #fff; transform: translateY(-1px); box-shadow: 0 14px 26px -12px rgba(42, 79, 190, .95); }

.btn-ghost {
  background: #fff;
  border-color: #d8e0ec;
  color: var(--ink);
}

.btn-ghost:hover { border-color: #b9c8dd; color: var(--ink); }

/* 代码窗口装饰 */
.code-card {
  background: #101a2a;
  border-radius: 14px;
  box-shadow: 0 28px 60px -30px rgba(16, 26, 42, .75), 0 0 0 1px rgba(255, 255, 255, .06) inset;
  overflow: hidden;
  transform: rotate(.6deg);
}

.code-top {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 12px 14px;
  background: #16233a;
  border-bottom: 1px solid rgba(255, 255, 255, .06);
}

.code-top i {
  width: 10px; height: 10px; border-radius: 50%;
  background: #3b4a61;
}

.code-top i:nth-child(1) { background: #ff5f57; }
.code-top i:nth-child(2) { background: #febc2e; }
.code-top i:nth-child(3) { background: #28c840; }

.code-top span {
  margin-left: auto;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 11.5px;
  color: #7d8ea8;
}

.code-body {
  margin: 0;
  padding: 20px 20px 24px;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  font-size: 13px;
  line-height: 1.85;
  color: #c9d5e6;
  overflow-x: auto;
}

.c-key { color: #7aa2ff; }
.c-fn { color: #7ee2b8; }
.c-str { color: #ffd479; }
.c-com { color: #64778f; font-style: italic; }
.c-num { color: #ff9d8a; }

/* ===== 通用区块 ===== */
.section { padding: 66px 0; }
.section.alt { background: #fff; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.section-head { margin-bottom: 34px; max-width: 44em; }

.section-head h2 {
  margin: 0 0 8px;
  font-size: 25px;
  letter-spacing: -.01em;
  font-weight: 700;
}

.section-head p { margin: 0; color: var(--muted); font-size: 15px; }

.split-head {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 34px;
}

.split-head .section-head { margin-bottom: 0; }

.head-link { font-size: 14px; white-space: nowrap; }

/* ===== 研究方向卡片 ===== */
.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 24px 22px;
  box-shadow: var(--shadow);
  transition: transform .18s ease, box-shadow .18s ease, border-color .18s ease;
}

.card:hover {
  transform: translateY(-2px);
  border-color: #cfdaea;
  box-shadow: 0 2px 4px rgba(20, 32, 46, .04), 0 20px 40px -24px rgba(20, 32, 46, .3);
}

.card-icon {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  background: var(--accent-soft);
  color: var(--accent);
  display: grid;
  place-items: center;
  margin-bottom: 16px;
}

.card h3 { margin: 0 0 8px; font-size: 16.5px; font-weight: 700; }
.card p { margin: 0; color: var(--ink-soft); font-size: 14.5px; }

/* ===== 笔记列表 ===== */
.notes { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; }

.note {
  display: block;
  color: inherit;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px 24px;
  box-shadow: var(--shadow);
  transition: transform .18s ease, box-shadow .18s ease, border-color .18s ease;
}

.note:hover { color: inherit; transform: translateY(-2px); border-color: #cfdaea; box-shadow: 0 2px 4px rgba(20,32,46,.04), 0 20px 40px -24px rgba(20,32,46,.3); }

.note .meta {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 12.5px;
  color: var(--muted);
  margin-bottom: 10px;
}

.tag {
  display: inline-block;
  padding: 2px 9px;
  border-radius: 999px;
  background: #f0f4fb;
  color: #4a6b9e;
  font-size: 12px;
  letter-spacing: .02em;
}

.note h3 { margin: 0 0 8px; font-size: 17px; line-height: 1.5; font-weight: 700; }
.note p { margin: 0; color: var(--ink-soft); font-size: 14.5px; }

/* ===== 关于 / 声明 ===== */
.about-grid {
  display: grid;
  grid-template-columns: 1.1fr .9fr;
  gap: 40px;
  align-items: start;
}

.about-grid p { color: var(--ink-soft); margin: 0 0 14px; }
.about-grid p:last-child { margin-bottom: 0; }

.info-list {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 8px 24px;
  box-shadow: var(--shadow);
  margin: 0;
}

.info-list div {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  padding: 14px 0;
  border-bottom: 1px dashed var(--line);
  font-size: 14.5px;
}

.info-list div:last-child { border-bottom: 0; }
.info-list dt { color: var(--muted); }
.info-list dd { margin: 0; color: var(--ink); font-weight: 600; text-align: right; }

/* ===== 联系 ===== */
.contact-band {
  background: linear-gradient(135deg, #17253a 0%, #1e3a6e 55%, #2a4fbe 100%);
  color: #e9eefb;
  border-radius: 18px;
  padding: 40px 44px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
  flex-wrap: wrap;
  box-shadow: 0 30px 60px -34px rgba(20, 40, 90, .8);
}

.contact-band h2 { margin: 0 0 8px; font-size: 22px; color: #fff; }
.contact-band p { margin: 0; color: #b9c8e8; font-size: 14.5px; }

.mail {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 12px 20px;
  border-radius: 10px;
  background: rgba(255, 255, 255, .1);
  border: 1px solid rgba(255, 255, 255, .22);
  color: #fff;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 14px;
}

.mail:hover { background: rgba(255, 255, 255, .16); color: #fff; }

/* ===== 页脚 ===== */
.site-footer {
  background: #0f1926;
  color: #93a3b6;
  padding: 46px 0 34px;
  font-size: 13.5px;
}

.footer-top {
  display: flex;
  justify-content: space-between;
  gap: 30px;
  flex-wrap: wrap;
  padding-bottom: 26px;
  border-bottom: 1px solid rgba(255, 255, 255, .08);
}

.footer-brand { display: flex; align-items: center; gap: 10px; color: #fff; font-weight: 700; }
.footer-brand .brand-mark { width: 30px; height: 30px; font-size: 13px; }
.footer-desc { margin: 10px 0 0; max-width: 26em; color: #7f90a5; line-height: 1.7; }

.footer-links {
  display: flex;
  gap: 22px;
  flex-wrap: wrap;
  align-items: flex-start;
  padding-top: 4px;
}

.footer-links a { color: #a9b8ca; font-size: 13.5px; }
.footer-links a:hover { color: #fff; }

.footer-bottom {
  padding-top: 22px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px 26px;
  align-items: center;
  justify-content: space-between;
  color: #7f90a5;
}

.filing { display: flex; flex-wrap: wrap; gap: 8px 22px; align-items: center; }
.filing a { color: #a9b8ca; }
.filing a:hover { color: #fff; }

/* ===== 内页 ===== */
.page-hero {
  padding: 54px 0 40px;
  border-bottom: 1px solid var(--line);
  background: linear-gradient(180deg, #fff, #f7f9fc);
}

.page-hero h1 { margin: 0 0 10px; font-size: clamp(26px, 3.4vw, 34px); letter-spacing: -.01em; }
.page-hero p { margin: 0; color: var(--muted); max-width: 42em; }

.prose { max-width: 760px; }
.prose h2 { font-size: 21px; margin: 40px 0 12px; }
.prose h3 { font-size: 17px; margin: 26px 0 8px; }
.prose p { color: var(--ink-soft); }
.prose ul { color: var(--ink-soft); padding-left: 22px; }
.prose li { margin-bottom: 6px; }

.note-list { list-style: none; margin: 0; padding: 0; }

.note-list li {
  display: grid;
  grid-template-columns: 108px 1fr;
  gap: 20px;
  padding: 20px 0;
  border-bottom: 1px solid var(--line);
}

.note-list time {
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 13px;
  color: var(--muted);
  padding-top: 3px;
}

.note-list h3 { margin: 0 0 5px; font-size: 16.5px; }
.note-list h3 a { color: var(--ink); }
.note-list h3 a:hover { color: var(--accent); }
.note-list p { margin: 0; color: var(--muted); font-size: 14px; }

/* ===== 响应式 ===== */
@media (max-width: 900px) {
  .hero-inner { grid-template-columns: 1fr; padding: 52px 0 58px; gap: 36px; }
  .code-card { transform: none; }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .about-grid { grid-template-columns: 1fr; gap: 26px; }
}

@media (max-width: 680px) {
  .wrap { padding: 0 18px; }
  .nav { height: auto; padding: 12px 0; flex-wrap: wrap; }
  .nav-links { width: 100%; overflow-x: auto; }
  .nav-links a { padding: 7px 11px; font-size: 14px; white-space: nowrap; }
  .hero h1 { font-size: 28px; }
  .hero-lead { font-size: 15.5px; }
  .section { padding: 48px 0; }
  .grid-3, .notes { grid-template-columns: 1fr; }
  .contact-band { padding: 30px 24px; }
  .split-head { flex-direction: column; align-items: flex-start; gap: 10px; }
  .note-list li { grid-template-columns: 1fr; gap: 6px; }
}