@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@300;400;500;600;700&display=swap');

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

html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }

:root {
  --paper: #ffffff;
  --haze: #f5f5f5;
  --ink: #1f1f1f;
  --ink-2: #4a4a4a;
  --ink-3: #6b6b6b;
  --line: rgba(31, 31, 31, .13);
  --glass: rgba(255, 255, 255, .68);
  --r: 18px;
  --e1: 0 1px 2px rgba(31, 31, 31, .07);
  --e2: 0 8px 22px -12px rgba(31, 31, 31, .22);
  --e3: 0 20px 44px -22px rgba(31, 31, 31, .3);
  --e4: 0 36px 76px -34px rgba(31, 31, 31, .38);
}

body {
  margin: 0;
  font-family: 'Plus Jakarta Sans', system-ui, -apple-system, 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  font-size: 17px;
  line-height: 1.8;
  color: var(--ink);
  background:
    radial-gradient(120% 55% at 50% -5%, #ffffff 0%, rgba(255, 255, 255, 0) 62%),
    var(--haze);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a { color: var(--ink); }
img { max-width: 100%; height: auto; }

.shell {
  width: 100%;
  max-width: 1220px;
  margin-inline: auto;
  padding-inline: clamp(16px, 4vw, 44px);
}

/* 页头：品牌居中，菜单分列两侧 */
.site-head {
  position: relative;
  z-index: 40;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 18px 0 12px;
}

.head-nav p {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 2px;
  margin: 0;
}

.head-nav a {
  display: inline-flex;
  align-items: center;
  min-height: 42px;
  padding: 0 10px;
  border-radius: 12px;
  font-size: 16px;
  color: var(--ink-2);
  text-decoration: none;
  white-space: nowrap;
  transition: background .2s ease, color .2s ease, box-shadow .2s ease;
}

.head-nav a:hover,
.head-nav a:focus-visible {
  color: var(--ink);
  background: rgba(255, 255, 255, .92);
  box-shadow: var(--e1);
}

.head-nav--r { margin-left: auto; }

.nav-cta {
  background: var(--ink);
  color: #fff !important;
  padding: 0 18px;
  box-shadow: var(--e3);
}

.nav-cta:hover,
.nav-cta:focus-visible {
  background: #000;
  color: #fff;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-inline: clamp(6px, 2vw, 22px);
  padding: 8px 18px;
  border-radius: 999px;
  background: var(--glass);
  backdrop-filter: blur(12px);
  box-shadow: var(--e2);
  font-weight: 700;
  font-size: 19px;
  letter-spacing: -.02em;
  text-decoration: none;
  color: var(--ink);
}

.brand-mark { width: 26px; height: 26px; border-radius: 8px; }

/* 二级粘性锚点条 */
.subbar {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(245, 245, 245, .86);
  backdrop-filter: blur(16px);
  border-block: 1px solid var(--line);
}

.subbar p {
  display: flex;
  gap: 4px;
  margin: 0;
  padding: 8px 0;
  overflow-x: auto;
  scrollbar-width: none;
}

.subbar p::-webkit-scrollbar { display: none; }

.subbar a {
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  padding: 0 12px;
  border-radius: 999px;
  font-size: 16px;
  color: var(--ink-2);
  text-decoration: none;
  white-space: nowrap;
}

.subbar a:hover,
.subbar a:focus-visible {
  background: #fff;
  color: var(--ink);
  box-shadow: var(--e1);
}

.subbar a:first-child { color: var(--ink); font-weight: 600; }

/* 版面 */
main {
  position: relative;
  z-index: 10;
  display: grid;
  grid-template-columns: minmax(0, 1fr) 296px;
  gap: clamp(18px, 2.6vw, 36px);
  align-items: start;
  padding: 22px 0 46px;
}

/* 首屏 */
.hero {
  position: relative;
  z-index: 1;
  display: grid;
  align-items: center;
  overflow: hidden;
  min-height: clamp(380px, 70vh, 600px);
  margin: 6px 0 34px;
  padding: clamp(26px, 5vw, 56px);
  border: 1px solid rgba(255, 255, 255, .9);
  border-radius: 26px;
  background: linear-gradient(155deg, #ffffff 0%, #f1f1f1 55%, #ffffff 100%);
  box-shadow: var(--e4);
}

.hero__dots {
  position: absolute;
  inset: -14% -6% auto auto;
  width: 74%;
  height: 128%;
  background-image: radial-gradient(rgba(31, 31, 31, .18) 1px, transparent 1.1px);
  background-size: 20px 20px;
  opacity: .55;
  transform: rotate(-4deg);
  -webkit-mask-image: radial-gradient(58% 58% at 58% 40%, #000 0%, transparent 76%);
  mask-image: radial-gradient(58% 58% at 58% 40%, #000 0%, transparent 76%);
  pointer-events: none;
}

.hero__grid {
  position: relative;
  z-index: 2;
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: center;
  gap: clamp(16px, 4vw, 46px);
}

h1 {
  margin: 0 0 16px;
  font-size: clamp(30px, 5vw, 52px);
  line-height: 1.16;
  letter-spacing: -.035em;
}

.hero__sub {
  max-width: 44ch;
  margin: 0;
  color: var(--ink-2);
  font-size: 17px;
}

.hero__art {
  width: clamp(150px, 24vw, 250px);
  will-change: transform;
}

.hero__art svg {
  display: block;
  width: 100%;
  height: auto;
  animation: bob 7s ease-in-out infinite;
}

@keyframes bob {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-14px); }
}

/* 正文层 */
div { position: relative; z-index: 2; min-width: 0; }

div section {
  position: relative;
  margin: 0 0 22px;
  padding: clamp(20px, 3.2vw, 34px);
  border: 1px solid rgba(255, 255, 255, .85);
  border-radius: var(--r);
  background: var(--glass);
  backdrop-filter: blur(10px);
  box-shadow: var(--e2);
  scroll-margin-top: 96px;
}

div section:nth-of-type(3n + 2) { box-shadow: var(--e3); }

div h2,
aside h2 {
  margin: 0 0 8px;
  font-size: clamp(21px, 2.4vw, 28px);
  line-height: 1.3;
  letter-spacing: -.02em;
}

div h3 {
  margin: 1.3em 0 .4em;
  font-size: 19px;
  letter-spacing: -.01em;
}

h2 + hr,
h3 + hr {
  width: 56px;
  height: 3px;
  margin: 0 0 18px;
  border: 0;
  border-radius: 3px;
  background: var(--ink);
}

div section p { margin: 0 0 1.05em; color: #292929; }
div section > :last-child { margin-bottom: 0; }

div section ul,
div section ol {
  margin: 0 0 1.1em;
  padding-left: 1.4em;
  color: #292929;
}

div section li { margin: .3em 0; }

div section blockquote {
  margin: 1.2em 0;
  padding: 14px 20px;
  border-left: 3px solid var(--ink);
  border-radius: 4px 14px 14px 4px;
  background: #fff;
  box-shadow: var(--e1);
}

div section blockquote p { margin: 0; }

div section a {
  text-underline-offset: 3px;
  text-decoration-color: rgba(31, 31, 31, .35);
}

div section a:hover { text-decoration-color: var(--ink); }

div section table {
  width: 100%;
  border-collapse: collapse;
  font-size: 16px;
}

div section th,
div section td {
  padding: 8px 10px;
  border-bottom: 1px solid var(--line);
  text-align: left;
}

div section code {
  padding: .1em .35em;
  border-radius: 6px;
  background: #fff;
  font-size: 15px;
}

/* 右侧栏 */
.rail {
  position: sticky;
  top: 84px;
  z-index: 3;
  padding: 20px;
  border: 1px solid #fff;
  border-radius: var(--r);
  background: rgba(255, 255, 255, .8);
  backdrop-filter: blur(14px);
  box-shadow: var(--e4);
}

.rail-nav p {
  display: flex;
  flex-direction: column;
  gap: 2px;
  margin: 0;
}

.rail-nav a {
  display: flex;
  align-items: center;
  min-height: 40px;
  padding: 6px 10px;
  border-radius: 10px;
  font-size: 16px;
  color: var(--ink-2);
  text-decoration: none;
}

.rail-nav a:hover,
.rail-nav a:focus-visible {
  background: #fff;
  color: var(--ink);
  box-shadow: var(--e1);
}

/* 页脚：仅 p 与 small */
footer {
  position: relative;
  z-index: 5;
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 22px 40px;
  margin: 0 0 44px;
  padding: clamp(24px, 3.5vw, 40px);
  border: 1px solid #fff;
  border-radius: 24px;
  background: linear-gradient(180deg, #ffffff, #eeeeee);
  box-shadow: var(--e3);
}

footer p { margin: 0; }

.f-about strong {
  display: block;
  font-size: 19px;
  font-weight: 700;
  letter-spacing: -.02em;
}

.f-about span {
  display: block;
  margin-top: 6px;
  color: var(--ink-2);
  font-size: 16px;
}

.f-links {
  display: flex;
  flex-wrap: wrap;
  gap: 2px 6px;
  align-content: start;
}

.f-links a {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  padding: 0 10px;
  border-radius: 10px;
  font-size: 16px;
  color: var(--ink-2);
  text-decoration: none;
}

.f-links a:hover,
.f-links a:focus-visible {
  background: #fff;
  color: var(--ink);
  box-shadow: var(--e1);
}

.f-form {
  grid-column: 1 / -1;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 10px;
  padding-top: 12px;
  border-top: 1px solid var(--line);
}

.f-form label { font-size: 16px; color: var(--ink-3); }

.f-form input {
  flex: 1 1 200px;
  min-height: 44px;
  padding: 0 14px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #fff;
  font: inherit;
  font-size: 16px;
  color: var(--ink);
}

.f-form input:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 1px;
}

.f-form button {
  min-height: 44px;
  padding: 0 22px;
  border: 0;
  border-radius: 12px;
  background: var(--ink);
  color: #fff;
  font: inherit;
  font-size: 16px;
  cursor: pointer;
  box-shadow: var(--e2);
}

.f-form button:hover { background: #000; }

.f-copy {
  grid-column: 1 / -1;
  display: block;
  text-align: center;
  font-size: 16px;
  color: var(--ink-3);
}

/* 滚动进入 */
.fx {
  opacity: 0;
  transform: translateY(18px);
}

.fx.in {
  opacity: 1;
  transform: none;
  transition:
    opacity .6s cubic-bezier(.2, .7, .2, 1) var(--d, 0ms),
    transform .6s cubic-bezier(.2, .7, .2, 1) var(--d, 0ms);
}

@media (min-width: 981px) {
  div section:nth-of-type(even) { margin-left: 14px; }
  div section:nth-of-type(odd) { margin-right: 14px; }
}

@media (max-width: 980px) {
  main { grid-template-columns: minmax(0, 1fr); }
  .rail { position: static; }
  .rail-nav p { flex-direction: row; flex-wrap: wrap; }
}

@media (max-width: 860px) {
  .site-head { flex-wrap: wrap; row-gap: 6px; padding-top: 12px; }
  .brand {
    order: -1;
    width: 100%;
    justify-content: center;
    margin: 0 0 4px;
    background: transparent;
    backdrop-filter: none;
    box-shadow: none;
  }
  .head-nav a { padding: 0 8px; min-height: 44px; }
  .hero { min-height: 0; padding: 28px 22px 34px; border-radius: 22px; }
  .hero__grid { grid-template-columns: minmax(0, 1fr); }
  .hero__art { width: 128px; margin-top: 8px; }
  footer { grid-template-columns: minmax(0, 1fr); }
  .f-about, .f-links { grid-column: 1 / -1; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .hero__art svg { animation: none; }
  .fx { opacity: 1; transform: none; transition: none; }
}

button[aria-expanded]{min-width:44px;min-height:44px}