@import url('https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@700&display=swap');

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

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

body {
  margin: 0;
  background: #fff;
  color: #000;
  font-family: "Space Grotesk", system-ui, -apple-system, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  font-size: 17px;
  line-height: 1.75;
  font-weight: 400;
  overflow-x: hidden;
}

body.nav-open { overflow: hidden; }

img { max-width: 100%; }

a { color: inherit; }

/* 页头 */
.site-head {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1rem clamp(1rem, 4vw, 3rem);
  border-bottom: 2px solid #000;
  background: #fff;
  position: relative;
  z-index: 60;
}

.brand {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  flex: 0 0 48px;
  border: 2px solid #000;
  border-radius: 14px;
  overflow: hidden;
  background: #fff;
  text-decoration: none;
}

.brand img { width: 100%; height: 100%; object-fit: cover; display: block; }

.brand span {
  font-size: .72rem;
  font-weight: 900;
  line-height: 1.05;
  letter-spacing: -.04em;
  padding: 0 3px;
  text-align: center;
}

.burger {
  margin-left: auto;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: .4rem 1.1rem;
  border: 2px solid #000;
  border-radius: 999px;
  background: #fff;
  color: #000;
  font: inherit;
  font-weight: 700;
  font-size: .95rem;
  cursor: pointer;
}

.burger:hover { background: #000; color: #fff; }

body.nav-open .burger {
  position: fixed;
  top: 1rem;
  right: clamp(1rem, 4vw, 3rem);
  z-index: 70;
  background: #fff;
  color: #000;
}

/* 全屏遮罩菜单 */
.nav {
  position: fixed;
  inset: 0;
  z-index: 55;
  display: grid;
  place-items: center;
  padding: 5.5rem 1.25rem 2rem;
  background: #000;
  color: #fff;
  opacity: 0;
  visibility: hidden;
  overflow-y: auto;
  transition: opacity .25s ease, visibility .25s ease;
}

body.nav-open .nav { opacity: 1; visibility: visible; }

.nav p {
  margin: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: .1rem;
  text-align: center;
}

.nav a {
  display: block;
  padding: .32em .55em;
  min-height: 48px;
  font-size: clamp(1.45rem, 5vw, 2.6rem);
  font-weight: 900;
  line-height: 1.25;
  letter-spacing: -.045em;
  text-decoration: none;
  color: #fff;
  border-radius: 12px;
}

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

/* 二级粘性锚点条 */
.anchors {
  position: sticky;
  top: 0;
  z-index: 50;
  background: #fff;
  border-bottom: 2px solid #000;
  padding: .5rem clamp(1rem, 4vw, 3rem);
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.anchors p {
  margin: 0;
  display: flex;
  gap: .4rem;
  flex-wrap: nowrap;
  white-space: nowrap;
}

.anchors a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: .2rem .85rem;
  border: 2px solid #000;
  border-radius: 999px;
  font-size: .82rem;
  font-weight: 700;
  letter-spacing: -.01em;
  text-decoration: none;
  color: #000;
}

.anchors a:hover { background: #000; color: #fff; }

/* Hero */
.hero {
  position: relative;
  isolation: isolate;
  display: flex;
  align-items: flex-end;
  min-height: 70vh;
  padding: clamp(2rem, 6vw, 4.5rem) clamp(1rem, 4vw, 3rem);
  background: #000;
  color: #fff;
  overflow: hidden;
}

.hero-grid {
  position: absolute;
  inset: 0;
  z-index: -2;
  background-image:
    linear-gradient(#ffffff1f 1px, transparent 1px),
    linear-gradient(90deg, #ffffff1f 1px, transparent 1px);
  background-size: 48px 48px;
}

.hero-fig {
  position: absolute;
  inset: 0;
  margin: 0;
  z-index: -1;
  overflow: hidden;
}

.hero-fig img,
.hero-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  filter: grayscale(1) contrast(1.1);
  opacity: .4;
  transform: scale(1.06);
  will-change: transform;
}

.hero-inner { position: relative; width: 100%; max-width: 1180px; }

.hero h1 {
  margin: 0;
  font-size: clamp(3rem, 10vw, 8rem);
  line-height: .9;
  letter-spacing: -.055em;
  font-weight: 900;
  word-break: break-word;
}

.hero-desc {
  max-width: 46ch;
  margin: 1.3rem 0 0;
  font-size: clamp(1rem, 2.2vw, 1.2rem);
  line-height: 1.65;
  color: #fff;
  opacity: .92;
}

/* 正文区 */
.board {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 258px;
  gap: clamp(1.5rem, 4vw, 4rem);
  align-items: start;
  max-width: 1240px;
  margin: 0 auto;
  padding: clamp(3rem, 7vw, 6.5rem) clamp(1rem, 4vw, 3rem) 0;
}

main div[id] { scroll-margin-top: 4.5rem; }

.board-main div[id] {
  padding: clamp(2.2rem, 4.5vw, 3.6rem) 0;
  border-top: 2px solid #000;
}

.board-main div[id]:first-child { border-top: 0; padding-top: 0; }

.board-main h2 {
  margin: 0 0 .5rem;
  font-size: clamp(2rem, 5.5vw, 4rem);
  line-height: .98;
  letter-spacing: -.05em;
  font-weight: 900;
}

.board-main h3 {
  margin: 2rem 0 .5rem;
  font-size: clamp(1.25rem, 2.6vw, 1.75rem);
  line-height: 1.25;
  letter-spacing: -.03em;
  font-weight: 900;
}

.board-main p {
  max-width: 62ch;
  margin: 0 0 1.1rem;
}

.board-main .subtitle,
.board-main p.subtitle,
.subtitle {
  max-width: 60ch;
  margin: 0 0 1.4rem;
  font-size: .95rem;
  line-height: 1.6;
  color: #444;
}

.board-main ul,
.board-main ol {
  max-width: 62ch;
  margin: 0 0 1.2rem;
  padding-left: 1.25rem;
}

.board-main li { margin: .35rem 0; }

.board-main a {
  color: #000;
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-thickness: 2px;
}

.board-main a:hover { background: #000; color: #fff; text-decoration: none; }

.board-main figure { margin: 1.8rem 0; }

.board-main figure img {
  width: 100%;
  height: auto;
  display: block;
  border-radius: 18px;
  box-shadow: 0 24px 48px -32px #00000059;
}

.board-main blockquote {
  margin: 1.6rem 0;
  padding: .4rem 1.2rem;
  border-left: 4px solid #000;
  font-size: 1.05rem;
}

.board-main blockquote p { margin: .5rem 0; }

.board-main hr {
  border: 0;
  border-top: 2px solid #000;
  margin: 2.4rem 0;
}

.board-main table {
  width: 100%;
  border-collapse: collapse;
  font-size: .95rem;
  margin: 1.4rem 0;
}

.board-main th,
.board-main td {
  border: 1px solid #000;
  padding: .55rem .7rem;
  text-align: left;
}

/* 右侧栏 */
.rail {
  position: sticky;
  top: 4.6rem;
  align-self: start;
  padding: 1.35rem 1.25rem;
  border: 2px solid #000;
  border-radius: 18px;
  background: #fff;
  box-shadow: 0 26px 50px -34px #00000073;
}

.rail h2 {
  margin: 0;
  font-size: 1.35rem;
  line-height: 1.1;
  letter-spacing: -.045em;
  font-weight: 900;
}

.rail .subtitle {
  margin: .3rem 0 1rem;
  font-size: .8rem;
  color: #555;
}

.rail-links {
  display: flex;
  flex-direction: column;
  margin: 0;
}

.rail-links a {
  display: block;
  min-height: 40px;
  padding: .45rem .1rem;
  border-bottom: 1px solid #00000024;
  font-size: .93rem;
  text-decoration: none;
  color: #000;
  transition: padding-left .18s ease;
}

.rail-links a:last-child { border-bottom: 0; }

.rail-links a:hover { padding-left: .55rem; border-bottom-color: #000; }

/* 页脚 */
.site-foot {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 1.8rem clamp(1rem, 4vw, 3rem);
  margin-top: clamp(3rem, 7vw, 6rem);
  padding: clamp(2.5rem, 6vw, 4.5rem) clamp(1rem, 4vw, 3rem) 1.5rem;
  background: #000;
  color: #fff;
}

.site-foot dl { margin: 0; }

.site-foot dt {
  padding-bottom: .5rem;
  margin-bottom: .6rem;
  border-bottom: 1px solid #ffffff4d;
  font-size: .82rem;
  font-weight: 700;
  letter-spacing: .16em;
}

.site-foot dd {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  margin: 0;
  font-size: .94rem;
  line-height: 1.6;
  color: #fff;
}

.site-foot dd:first-of-type { color: #fff; }

.site-foot a {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  padding: .1rem 0;
  color: #fff;
  text-decoration: none;
}

.site-foot a:hover {
  text-decoration: underline;
  text-underline-offset: 4px;
  text-decoration-thickness: 2px;
}

.copyright {
  grid-column: 1 / -1;
  margin: 1.6rem 0 0;
  padding-top: 1.1rem;
  border-top: 1px solid #ffffff33;
  font-size: .82rem;
  color: #b9b9b9;
  letter-spacing: .04em;
}

/* 断点 */
@media (max-width: 860px) {
  .board {
    grid-template-columns: minmax(0, 1fr);
    padding-top: clamp(2.2rem, 5vw, 3.5rem);
  }

  .rail {
    position: static;
    order: 2;
    margin-top: 2rem;
  }

  .site-foot { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 560px) {
  body { font-size: 16px; }

  .hero { min-height: 62vh; padding-top: 4rem; }

  .hero h1 { font-size: clamp(2.6rem, 13vw, 4rem); }

  .board-main h2 { font-size: clamp(1.7rem, 8vw, 2.4rem); }

  .site-foot { grid-template-columns: 1fr; }

  .nav a { font-size: 1.35rem; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    transition: none !important;
    animation: none !important;
  }

  .hero-fig img,
  .hero-img { transform: none; }
}

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