/* ============================================================
   正版蓝 · blue-u.com.cn 共享样式表 /assets/site.css
   深海蓝加速通道：reset · 变量 · 中文排版 · 页头 · 页脚 · 通用组件
   ============================================================ */

:root {
  --ink: #0B1E3A;
  --ink-deep: #071529;
  --blue: #2D7DFF;
  --blue-dark: #1E6BE6;
  --mist: #9DB8D9;
  --cyan: #33E0D0;
  --cyan-deep: #12776F;
  --orange: #FF8A3D;
  --snow: #F2F6FC;
  --slate: #1B2A44;
  --fog: #C9D6E8;
  --ink-soft: #33486B;

  --line: rgba(157, 184, 217, 0.24);
  --line-soft: rgba(157, 184, 217, 0.13);
  --line-strong: rgba(45, 125, 255, 0.55);

  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);

  --font-head: 'Noto Sans SC', 'Source Han Sans SC', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  --font-body: 'Noto Sans SC', 'Source Han Sans SC', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', ui-monospace, 'Cascadia Mono', Consolas, monospace;

  --shell: 1280px;
  --gutter: clamp(18px, 4vw, 48px);
  --radius: 18px;
  --radius-sm: 12px;
  --nav-break: 899px;
}

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 112px;
}

body {
  margin: 0;
  background: var(--ink);
  color: var(--fog);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.85;
  font-weight: 400;
  letter-spacing: 0.01em;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background:
    radial-gradient(1200px 620px at 14% -12%, rgba(45, 125, 255, 0.18), transparent 62%),
    radial-gradient(900px 520px at 92% 4%, rgba(51, 224, 208, 0.08), transparent 64%);
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-head);
  color: var(--snow);
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin: 0 0 0.6em;
  font-weight: 700;
}

p { margin: 0 0 1.1em; }
p:last-child { margin-bottom: 0; }

a { color: var(--blue); text-decoration: none; }

img, svg, video { max-width: 100%; height: auto; display: block; }

ul, ol { margin: 0 0 1.1em; padding-left: 1.3em; }

button { font: inherit; color: inherit; }

code, kbd, samp, .mono { font-family: var(--font-mono); }

hr {
  border: 0;
  border-top: 1px solid var(--line-soft);
  margin: clamp(32px, 5vw, 64px) 0;
}

::selection { background: rgba(45, 125, 255, 0.4); color: var(--snow); }

:where(a, button, [tabindex], summary):focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 3px;
}

/* ---------- 布局容器 ---------- */
.shell {
  width: min(calc(100% - 2 * var(--gutter)), var(--shell));
  margin-inline: auto;
  position: relative;
  z-index: 1;
}

.visually-hidden {
  position: absolute !important;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  left: 14px;
  top: -72px;
  z-index: 900;
  padding: 11px 18px;
  border-radius: 10px;
  background: var(--snow);
  color: var(--ink-deep);
  font-weight: 700;
  font-size: 14px;
  transition: top 0.18s var(--ease);
}
.skip-link:focus { top: 14px; }

/* ---------- 页头 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--ink-deep);
  border-bottom: 1px solid var(--line-soft);
  color: var(--fog);
}

.header-beam {
  position: absolute;
  inset: 0;
  display: block;
  overflow: hidden;
  pointer-events: none;
}

.header-beam::before {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  left: -35%;
  width: 35%;
  background: linear-gradient(90deg, transparent, rgba(45, 125, 255, 0.22), rgba(51, 224, 208, 0.07), transparent);
  animation: beam-slide 7.5s linear infinite;
}

@keyframes beam-slide {
  from { transform: translateX(0); }
  to { transform: translateX(390%); }
}

.masthead {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
  grid-template-areas: "meta brand act";
  align-items: center;
  gap: 18px;
  padding: 22px 0 14px;
}

.brand {
  grid-area: brand;
  display: inline-flex;
  align-items: center;
  gap: 12px;
  justify-self: center;
  text-decoration: none;
  color: inherit;
}

.brand__mark {
  width: 14px;
  height: 14px;
  border-radius: 4px;
  flex: none;
  background: linear-gradient(140deg, var(--blue), var(--cyan));
  box-shadow: 0 0 0 4px rgba(45, 125, 255, 0.14);
}

.brand__name {
  font-family: var(--font-head);
  font-weight: 900;
  font-size: clamp(26px, 3.2vw, 38px);
  letter-spacing: -0.02em;
  line-height: 1;
  color: var(--snow);
  transition: font-size 0.22s var(--ease);
}

.brand__meta {
  grid-area: meta;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 2px;
  font-size: 12px;
  line-height: 1.55;
  letter-spacing: 0.1em;
  color: var(--mist);
  transition: opacity 0.2s var(--ease);
}

.brand__domain {
  font-family: var(--font-mono);
  font-weight: 600;
  color: var(--blue);
}

.brand__line { color: var(--mist); }

.masthead__act {
  grid-area: act;
  justify-self: end;
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.nav-toggle {
  grid-area: toggle;
  display: none;
  width: 46px;
  height: 42px;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: transparent;
  cursor: pointer;
  transition: border-color 0.18s var(--ease);
}
.nav-toggle:hover { border-color: var(--blue); }

.nav-toggle__bar {
  display: block;
  width: 18px;
  height: 2px;
  border-radius: 2px;
  background: var(--fog);
  transition: transform 0.22s var(--ease), opacity 0.22s var(--ease), background-color 0.22s var(--ease);
}

.site-header[data-open="true"] .nav-toggle__bar:nth-child(1) { transform: translateY(7px) rotate(45deg); background: var(--cyan); }
.site-header[data-open="true"] .nav-toggle__bar:nth-child(2) { opacity: 0; }
.site-header[data-open="true"] .nav-toggle__bar:nth-child(3) { transform: translateY(-7px) rotate(-45deg); background: var(--cyan); }

.nav {
  display: block;
  border-top: 1px solid var(--line-soft);
}

.nav__list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: clamp(6px, 2.4vw, 30px);
  margin: 0;
  padding: 11px 0 0;
  list-style: none;
}

.nav__item { display: block; }

.nav__link {
  display: inline-block;
  padding: 6px 2px 10px;
  font-family: var(--font-head);
  font-size: 15px;
  font-weight: 500;
  letter-spacing: 0.02em;
  color: var(--fog);
  text-decoration: none;
  border-bottom: 2px solid transparent;
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease);
}

.nav__link:hover { color: var(--snow); border-bottom-color: var(--blue); }

.nav__link[aria-current="page"] {
  color: var(--snow);
  border-bottom-color: var(--cyan);
}

.header-ruler {
  display: block;
  height: 2px;
  background: var(--line-soft);
}

.header-ruler__fill {
  display: block;
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--blue), var(--cyan));
  transition: width 0.08s linear;
}

.site-header.is-condensed .masthead { padding: 10px 0 8px; }
.site-header.is-condensed .brand__name { font-size: clamp(20px, 2.4vw, 26px); }
.site-header.is-condensed .brand__meta { opacity: 0; }

/* ---------- 返回顶部刻度按钮 ---------- */
.back-top {
  position: fixed;
  right: clamp(14px, 3vw, 30px);
  bottom: clamp(14px, 3vw, 26px);
  z-index: 60;
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 10px 15px 10px 12px;
  border-radius: 999px;
  border: 1px solid var(--line-strong);
  background: rgba(7, 21, 41, 0.94);
  color: var(--fog);
  cursor: pointer;
  opacity: 0;
  transform: translateY(12px);
  pointer-events: none;
  transition: opacity 0.2s var(--ease), transform 0.2s var(--ease),
              border-color 0.18s var(--ease), color 0.18s var(--ease);
}

.back-top[data-visible="true"] {
  opacity: 1;
  transform: none;
  pointer-events: auto;
}

.back-top:hover { border-color: var(--cyan); color: var(--snow); }

.back-top__tick {
  width: 9px;
  height: 9px;
  border-radius: 2px;
  background: var(--cyan);
  box-shadow: 0 0 0 3px rgba(51, 224, 208, 0.16);
  flex: none;
}

.back-top__text {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.12em;
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 20px;
  border-radius: 999px;
  border: 1px solid transparent;
  font-family: var(--font-head);
  font-size: 14px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: 0.01em;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 0.18s var(--ease), border-color 0.18s var(--ease),
              color 0.18s var(--ease), transform 0.18s var(--ease);
}

.btn--primary {
  background: var(--blue);
  color: #ffffff;
  box-shadow: 0 12px 26px -14px rgba(45, 125, 255, 0.9);
}
.btn--primary:hover { background: var(--blue-dark); transform: translateY(-1px); }

.btn--ghost {
  background: transparent;
  border-color: var(--line);
  color: var(--fog);
}
.btn--ghost:hover { border-color: var(--blue); color: var(--snow); }

.btn--line {
  background: transparent;
  border-color: var(--blue);
  color: var(--blue);
}
.btn--line:hover { background: rgba(45, 125, 255, 0.12); color: var(--snow); }

/* ---------- 区块 ---------- */
.section {
  padding: clamp(56px, 8vw, 104px) 0;
  position: relative;
}

.section--light {
  background: var(--snow);
  color: var(--ink-soft);
}
.section--light h1, .section--light h2, .section--light h3, .section--light h4 { color: var(--ink-deep); }

.section--slate {
  background: var(--slate);
}

.section__head {
  max-width: 64ch;
  margin-bottom: clamp(24px, 3vw, 42px);
}

.eyebrow {
  display: inline-block;
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--blue);
}
.section--light .eyebrow { color: var(--blue-dark); }

.section__title {
  font-size: clamp(28px, 4.4vw, 48px);
  font-weight: 900;
  margin: 0 0 0.42em;
  color: var(--snow);
}

.section__lede {
  margin: 0;
  max-width: 66ch;
  font-size: 17px;
  line-height: 1.85;
  color: var(--fog);
}
.section--light .section__lede { color: var(--ink-soft); }

.lede {
  font-size: clamp(17px, 2vw, 19px);
  line-height: 1.85;
  color: var(--snow);
  max-width: 66ch;
}
.section--light .lede { color: var(--ink-soft); }

/* ---------- 面包屑 ---------- */
.breadcrumb { padding: clamp(14px, 2vw, 22px) 0; }

.breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: 13px;
}

.breadcrumb__item { color: var(--mist); }

.breadcrumb__link {
  color: var(--mist);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease);
}
.breadcrumb__link:hover { color: var(--snow); border-bottom-color: var(--blue); }

.breadcrumb__sep {
  font-family: var(--font-mono);
  color: rgba(157, 184, 217, 0.5);
}

/* ---------- 网格 ---------- */
.grid {
  display: grid;
  gap: clamp(20px, 3vw, 34px);
  grid-template-columns: minmax(0, 1fr);
}

.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid--aside { grid-template-columns: minmax(0, 7fr) minmax(0, 4fr); }
.grid--aside-left { grid-template-columns: minmax(0, 4fr) minmax(0, 7fr); }

/* ---------- 卡片 ---------- */
.card {
  position: relative;
  background: var(--slate);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: clamp(20px, 2.6vw, 30px);
  box-shadow: inset 0 1px 0 rgba(242, 246, 252, 0.05);
  transition: border-color 0.18s var(--ease), transform 0.18s var(--ease);
}

.card:hover { border-color: var(--blue); }

.card--accent { border-color: rgba(255, 138, 61, 0.45); }
.card--accent:hover { border-color: var(--orange); }

.card__head { margin-bottom: 12px; }

.card__title {
  font-size: clamp(19px, 2.2vw, 24px);
  font-weight: 700;
  letter-spacing: -0.01em;
  margin: 0 0 10px;
  color: var(--snow);
}

.card__text {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.85;
  color: var(--fog);
}

.card__foot {
  margin-top: 16px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
}

.section--light .card {
  background: #ffffff;
  border-color: rgba(11, 30, 58, 0.12);
  box-shadow: 0 20px 44px -36px rgba(11, 30, 58, 0.55);
}
.section--light .card__title { color: var(--ink-deep); }
.section--light .card__text { color: var(--ink-soft); }

/* ---------- 标签 ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  line-height: 1;
  letter-spacing: 0.08em;
  color: var(--mist);
  white-space: nowrap;
}

.tag--go { color: var(--cyan); border-color: rgba(51, 224, 208, 0.4); }
.tag--hot { color: var(--orange); border-color: rgba(255, 138, 61, 0.45); }

/* ---------- 数据 ---------- */
.stat { display: grid; gap: 5px; }

.stat__num {
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: clamp(24px, 3vw, 32px);
  line-height: 1.1;
  letter-spacing: -0.01em;
  color: var(--cyan);
}

.stat__label {
  font-size: 13px;
  letter-spacing: 0.06em;
  color: var(--mist);
}
.section--light .stat__label { color: #55688a; }

/* ---------- 要点列表 ---------- */
.tick-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.tick-list__item {
  position: relative;
  padding-left: 24px;
  font-size: 15.5px;
  line-height: 1.8;
  color: var(--fog);
}

.tick-list__item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.72em;
  width: 10px;
  height: 2px;
  border-radius: 2px;
  background: var(--blue);
}

.section--light .tick-list__item { color: var(--ink-soft); }

/* ---------- 图片容器 ---------- */
.media { margin: 0; }

.media__frame {
  position: relative;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--line);
  background:
    linear-gradient(160deg, rgba(45, 125, 255, 0.2), rgba(7, 21, 41, 0.92)),
    repeating-linear-gradient(135deg, rgba(157, 184, 217, 0.06) 0 1px, transparent 1px 14px);
  aspect-ratio: 16 / 9;
}

.media__frame--tall { aspect-ratio: 4 / 5; }
.media__frame--wide { aspect-ratio: 21 / 9; }

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

.media__caption {
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.7;
  color: var(--mist);
}

/* ---------- 显现动画 ---------- */
[data-reveal] {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.5s var(--ease), transform 0.5s var(--ease);
}
[data-reveal].is-shown { opacity: 1; transform: none; }

/* ---------- 页脚 ---------- */
.site-footer {
  position: relative;
  overflow: hidden;
  margin-top: clamp(72px, 10vw, 120px);
  background: var(--ink-deep);
  border-top: 1px solid var(--line-soft);
  color: var(--fog);
}

.site-footer::before {
  content: "";
  position: absolute;
  left: -12%;
  top: -180px;
  width: 52%;
  height: 340px;
  pointer-events: none;
  background: radial-gradient(closest-side, rgba(45, 125, 255, 0.22), transparent 72%);
}

.footer__top {
  display: grid;
  grid-template-columns: minmax(0, 1.5fr) minmax(0, 1fr);
  gap: clamp(24px, 4vw, 56px);
  padding: clamp(40px, 6vw, 72px) 0 clamp(24px, 3vw, 38px);
  border-bottom: 1px solid var(--line-soft);
}

.footer__mark {
  margin: 0 0 12px;
  font-family: var(--font-head);
  font-size: clamp(24px, 3vw, 34px);
  font-weight: 900;
  letter-spacing: -0.02em;
  line-height: 1.1;
  color: var(--snow);
}

.footer__tagline {
  margin: 0;
  max-width: 44ch;
  font-size: 15px;
  line-height: 1.85;
  color: var(--fog);
}

.footer__index {
  border-left: 1px solid var(--line);
  padding-left: clamp(18px, 3vw, 34px);
}

.footer__index-title {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.18em;
  color: var(--mist);
}

.footer__index-list {
  display: flex;
  flex-wrap: wrap;
  gap: 9px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.footer__index-list .footer__link {
  display: inline-block;
  padding: 7px 14px;
  border: 1px solid var(--line);
  border-radius: 999px;
  font-size: 13px;
  color: var(--fog);
  transition: border-color 0.18s var(--ease), color 0.18s var(--ease), background-color 0.18s var(--ease);
}
.footer__index-list .footer__link:hover {
  border-color: var(--blue);
  color: var(--snow);
  background: rgba(45, 125, 255, 0.1);
}

.footer__grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(20px, 4vw, 48px);
  padding: clamp(28px, 4vw, 46px) 0;
  border-bottom: 1px solid var(--line-soft);
}

.footer__heading {
  margin: 0 0 15px;
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.16em;
  color: var(--snow);
}

.footer__links {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 11px;
}

.footer__link {
  color: var(--fog);
  font-size: 14.5px;
  text-decoration: none;
  transition: color 0.18s var(--ease);
}
.footer__link:hover { color: var(--blue); }

.footer__contact {
  display: grid;
  gap: 10px;
  padding: clamp(22px, 3vw, 32px) 0;
  border-bottom: 1px solid var(--line-soft);
}

.footer__contact-line {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 6px 16px;
  margin: 0;
  font-size: 14px;
  color: var(--mist);
}

.footer__contact-line > span:first-child {
  min-width: 4.6em;
  letter-spacing: 0.06em;
}

.footer__contact-value {
  font-family: var(--font-mono);
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--snow);
}

.footer__bottom {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 10px 24px;
  padding: 18px 0 34px;
}

.footer__legal {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: 0.04em;
  color: var(--mist);
}

/* ---------- 响应式 ---------- */
@media (max-width: 1100px) {
  .grid--aside { grid-template-columns: minmax(0, 6fr) minmax(0, 4fr); }
}

@media (max-width: 900px) {
  html { scroll-padding-top: 96px; }

  .grid--2,
  .grid--3,
  .grid--aside,
  .grid--aside-left { grid-template-columns: minmax(0, 1fr); }

  .footer__top { grid-template-columns: minmax(0, 1fr); gap: 26px; }
  .footer__index {
    border-left: 0;
    padding-left: 0;
    padding-top: 22px;
    border-top: 1px solid var(--line-soft);
  }
  .footer__grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 899px) {
  .site-header { position: sticky; }

  .masthead {
    grid-template-columns: minmax(0, 1fr) auto;
    grid-template-areas:
      "brand toggle"
      "meta act";
    gap: 10px 14px;
    padding: 14px 0 10px;
  }

  .brand { justify-self: start; }
  .brand__name { font-size: clamp(22px, 6vw, 30px); }
  .brand__meta { justify-self: start; }

  .masthead__act { justify-self: end; }
  .masthead__act .btn { padding: 9px 15px; font-size: 13px; }

  .nav-toggle { display: inline-flex; }

  .nav {
    max-height: 0;
    overflow: hidden;
    opacity: 0;
    border-top-color: transparent;
    transition: max-height 0.3s var(--ease), opacity 0.22s var(--ease), border-color 0.22s var(--ease);
  }

  .site-header[data-open="true"] .nav {
    max-height: 620px;
    opacity: 1;
    border-top-color: var(--line-soft);
  }

  .nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 6px 0 16px;
  }

  .nav__link {
    display: block;
    padding: 13px 2px;
    border-bottom: 1px solid var(--line-soft);
    border-radius: 0;
  }
  .nav__link:hover { border-bottom-color: var(--blue); }
  .nav__link[aria-current="page"] { border-bottom-color: var(--cyan); }

  .site-header.is-condensed .brand__meta { opacity: 0.6; }
}

@media (max-width: 640px) {
  .footer__grid { grid-template-columns: minmax(0, 1fr); }
  .footer__bottom { flex-direction: column; align-items: flex-start; }
  .back-top__text { display: none; }
  .back-top { padding: 12px; }
}

@media (max-width: 560px) {
  .brand__meta { display: none; }
  .masthead__act .btn--ghost { display: none; }
}

/* ---------- 动效降级 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }

  .header-beam::before { display: none; }

  [data-reveal] { opacity: 1; transform: none; }
}