@charset "utf-8";
/* ==========================================================================
   清岚纯净 — 设计系统
   配色：深石墨 (graphite) + 青绿 (verdant)
   ========================================================================== */

:root {
  /* 石墨色阶 — 主文字与深色区块 */
  --ink-900: #1F1F1E;
  --ink-800: #2C2C2A;
  --ink-700: #444441;
  --ink-600: #5F5E5A;
  --ink-400: #888780;
  --ink-200: #B4B2A9;

  /* 纸面色阶 — 背景与浅色区块 */
  --paper: #FFFFFF;
  --paper-2: #F5F9FC;
  --paper-3: #E9F1F7;

  /* 品牌蓝 — 沿用 Filtermist 官方色系 */
  --brand: #0055A8;
  --brand-strong: #00447F;
  --brand-mid: #00ADEF;
  --brand-soft: #E8F4FB;
  --brand-line: #9FD8F2;

  /* 语义色 */
  --success: #0F6E56;
  --warning: #854F0B;
  --warning-soft: #FAEEDA;

  /* 线条 */
  --line: rgba(31, 31, 30, 0.12);
  --line-strong: rgba(31, 31, 30, 0.24);

  /* 排版尺度 */
  --fs-hero: clamp(2.25rem, 5.5vw, 4rem);
  --fs-h1: clamp(1.75rem, 3.5vw, 2.75rem);
  --fs-h2: clamp(1.375rem, 2.4vw, 1.875rem);
  --fs-h3: 1.1875rem;
  --fs-body: 1rem;
  --fs-sm: 0.9375rem;
  --fs-xs: 0.8125rem;
  --lh-tight: 1.15;
  --lh-body: 1.75;

  /* 间距 */
  --sp-section: clamp(3.5rem, 8vw, 7rem);
  --gutter: 1.5rem;
  --maxw: 1200px;
  --maxw-narrow: 760px;

  /* 其他 */
  --radius: 4px;
  --radius-lg: 8px;
  --nav-h: 72px;
  --ease: cubic-bezier(0.4, 0, 0.2, 1);

  --font-sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei",
    "Source Han Sans SC", "Noto Sans CJK SC", system-ui, -apple-system, sans-serif;
}

/* --------------------------------------------------------- 基础重置 */
*, *::before, *::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-h) + 1.5rem);
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: var(--fs-body);
  line-height: var(--lh-body);
  color: var(--ink-700);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

h1, h2, h3, h4 {
  margin: 0 0 1rem;
  color: var(--ink-900);
  font-weight: 600;
  line-height: var(--lh-tight);
  letter-spacing: -0.02em;
}

h1 { font-size: var(--fs-h1); }
h2 { font-size: var(--fs-h2); }
h3 { font-size: var(--fs-h3); }

p { margin: 0 0 1.25rem; }
p:last-child { margin-bottom: 0; }

a { color: var(--brand); text-decoration: none; transition: color 0.2s var(--ease); }
a:hover { color: var(--brand-strong); }

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

ul { margin: 0 0 1.25rem; padding-left: 1.25rem; }
li { margin-bottom: 0.5rem; }

button, input, select, textarea { font-family: inherit; font-size: inherit; }

:focus-visible {
  outline: 2px solid var(--brand);
  outline-offset: 3px;
}

/* --------------------------------------------------------- 布局 */
.container {
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

.container--narrow { max-width: var(--maxw-narrow); }

.section { padding: var(--sp-section) 0; }
.section--tight { padding: calc(var(--sp-section) * 0.6) 0; }
.section--paper { background: var(--paper-2); }
.section--ink { background: var(--ink-900); color: var(--paper-3); }
.section--ink h1, .section--ink h2, .section--ink h3 { color: var(--paper); }
.section--ink p { color: rgba(241, 239, 232, 0.78); }

.grid {
  display: grid;
  gap: var(--gutter);
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
}

.grid--2 { grid-template-columns: repeat(auto-fit, minmax(340px, 1fr)); }
.grid--4 { grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); }

.split {
  display: grid;
  gap: clamp(2rem, 5vw, 4rem);
  grid-template-columns: 1fr;
  align-items: center;
}

@media (min-width: 900px) {
  .split { grid-template-columns: 1fr 1fr; }
  .split--wide-left { grid-template-columns: 1.25fr 1fr; }
}

/* --------------------------------------------------------- 章节标题 */
.eyebrow {
  display: inline-block;
  margin-bottom: 0.875rem;
  font-size: var(--fs-xs);
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--brand);
}

.section--ink .eyebrow { color: var(--brand-line); }

.section-head {
  max-width: 680px;
  margin-bottom: clamp(2rem, 4vw, 3.5rem);
}

.section-head p {
  margin-top: 1rem;
  font-size: 1.0625rem;
  color: var(--ink-600);
}

/* --------------------------------------------------------- 导航 */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--line);
}

.nav__bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--nav-h);
  gap: 1rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.625rem;
  flex-shrink: 0;
  color: var(--ink-900);
}

.brand:hover { color: var(--ink-900); }

.brand__mark {
  width: 34px;
  height: 34px;
  flex-shrink: 0;
}

.brand__text { display: flex; flex-direction: column; line-height: 1.1; }

.brand__cn {
  font-size: 1.0625rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--ink-900);
}

.brand__en {
  font-size: 0.625rem;
  font-weight: 500;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--brand);
}

.nav__menu {
  display: none;
  list-style: none;
  margin: 0;
  padding: 0;
  align-items: center;
  gap: 0.25rem;
}

.nav__menu li { margin: 0; position: relative; }

.nav__link {
  display: block;
  padding: 0.5rem 0.75rem;
  font-size: var(--fs-sm);
  font-weight: 500;
  color: var(--ink-700);
  white-space: nowrap;
}

.nav__link:hover, .nav__link.is-active { color: var(--brand); }

.nav__item--has-sub:hover .nav__sub {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.nav__sub {
  position: absolute;
  top: 100%;
  left: 0;
  min-width: 210px;
  padding: 0.5rem 0;
  margin: 0;
  list-style: none;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: 0 12px 32px rgba(31, 31, 30, 0.1);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-6px);
  transition: all 0.2s var(--ease);
}

.nav__sub li { margin: 0; }

.nav__sub a {
  display: block;
  padding: 0.5rem 1.125rem;
  font-size: var(--fs-sm);
  color: var(--ink-700);
}

.nav__sub a:hover { background: var(--brand-soft); color: var(--brand-strong); }

.nav__actions { display: flex; align-items: center; gap: 0.75rem; flex-shrink: 0; }

.nav__toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  padding: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--paper);
  cursor: pointer;
}

.nav__toggle span {
  display: block;
  position: relative;
  width: 18px;
  height: 1.5px;
  background: var(--ink-800);
  transition: background 0.2s var(--ease);
}

.nav__toggle span::before,
.nav__toggle span::after {
  content: "";
  position: absolute;
  left: 0;
  width: 18px;
  height: 1.5px;
  background: var(--ink-800);
  transition: transform 0.25s var(--ease);
}

.nav__toggle span::before { top: -6px; }
.nav__toggle span::after { top: 6px; }

.nav.is-open .nav__toggle span { background: transparent; }
.nav.is-open .nav__toggle span::before { transform: translateY(6px) rotate(45deg); }
.nav.is-open .nav__toggle span::after { transform: translateY(-6px) rotate(-45deg); }

@media (min-width: 1024px) {
  .nav__menu { display: flex; }
  .nav__toggle { display: none; }
}

/* 移动端抽屉 */
.nav__drawer {
  display: none;
  border-top: 1px solid var(--line);
  background: var(--paper);
  max-height: calc(100dvh - var(--nav-h));
  overflow-y: auto;
}

.nav.is-open .nav__drawer { display: block; }

.nav__drawer ul { list-style: none; margin: 0; padding: 0.5rem 0; }

.nav__drawer a {
  display: block;
  padding: 0.75rem var(--gutter);
  font-size: var(--fs-sm);
  font-weight: 500;
  color: var(--ink-800);
  border-bottom: 1px solid var(--line);
}

.nav__drawer a:hover { background: var(--brand-soft); }

.nav__drawer .nav__drawer-sub a {
  padding-left: calc(var(--gutter) + 1rem);
  font-weight: 400;
  color: var(--ink-600);
  font-size: var(--fs-xs);
}

/* --------------------------------------------------------- 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border: 1px solid transparent;
  border-radius: var(--radius);
  font-size: var(--fs-sm);
  font-weight: 600;
  letter-spacing: 0.01em;
  cursor: pointer;
  transition: all 0.2s var(--ease);
  white-space: nowrap;
}

.btn--primary { background: var(--brand); color: var(--paper); }
.btn--primary:hover { background: var(--brand-strong); color: var(--paper); }

.btn--ghost { background: transparent; border-color: var(--line-strong); color: var(--ink-800); }
.btn--ghost:hover { border-color: var(--brand); color: var(--brand); background: var(--brand-soft); }

.btn--light { background: var(--paper); color: var(--ink-900); }
.btn--light:hover { background: var(--brand-soft); color: var(--brand-strong); }

.btn--sm { padding: 0.5rem 1rem; font-size: var(--fs-xs); }

.btn-row { display: flex; flex-wrap: wrap; gap: 0.75rem; margin-top: 2rem; }

/* --------------------------------------------------------- 卡片 */
.card {
  display: flex;
  flex-direction: column;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: all 0.25s var(--ease);
}

.card:hover {
  border-color: var(--brand-line);
  box-shadow: 0 8px 28px rgba(31, 31, 30, 0.08);
  transform: translateY(-2px);
}

.card__media {
  background: var(--paper-3);
  aspect-ratio: 4 / 3;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.card__media img { width: 100%; height: 100%; object-fit: cover; }

.card__body { padding: 1.5rem; flex: 1; display: flex; flex-direction: column; }

.card__title { margin-bottom: 0.5rem; font-size: 1.0625rem; font-weight: 600; color: var(--ink-900); }
.card__text { font-size: var(--fs-sm); color: var(--ink-600); margin-bottom: 1.25rem; }
.card__meta { margin-top: auto; font-size: var(--fs-xs); font-weight: 600; color: var(--brand); }

/* --------------------------------------------------------- Hero */
.hero {
  position: relative;
  padding: clamp(4rem, 10vw, 8rem) 0;
  background: var(--brand);
  color: var(--paper-3);
  overflow: hidden;
}

.hero::after {
  content: "";
  position: absolute;
  right: -10%;
  top: -20%;
  width: 55%;
  height: 150%;
  background: var(--brand-mid);
  opacity: 0.18;
  transform: rotate(12deg);
  pointer-events: none;
}

.hero__inner { position: relative; z-index: 1; max-width: 780px; }

.hero__title {
  margin-bottom: 1.5rem;
  font-size: var(--fs-hero);
  font-weight: 700;
  line-height: 1.08;
  letter-spacing: -0.03em;
  color: var(--paper);
}

.hero__title em {
  font-style: normal;
  color: var(--brand-line);
}

.hero__lead {
  max-width: 620px;
  margin-bottom: 2.5rem;
  font-size: clamp(1rem, 1.6vw, 1.1875rem);
  color: rgba(241, 239, 232, 0.8);
}

.hero--page { padding: clamp(3rem, 7vw, 5.5rem) 0; }
.hero--page .hero__title { font-size: var(--fs-h1); }
.hero--page .hero__lead { margin-bottom: 0; }

/* --------------------------------------------------------- 数据统计 */
.stats {
  display: grid;
  gap: var(--gutter);
  grid-template-columns: repeat(2, 1fr);
}

@media (min-width: 768px) { .stats { grid-template-columns: repeat(4, 1fr); } }

.stat {
  padding: 1.75rem 1.5rem;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
}

.stat__num {
  display: block;
  margin-bottom: 0.375rem;
  font-size: clamp(1.75rem, 3.5vw, 2.5rem);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--brand);
}

.stat__label { font-size: var(--fs-xs); color: var(--ink-600); line-height: 1.5; }

/* --------------------------------------------------------- 列表特性 */
.features { list-style: none; margin: 0; padding: 0; }
.features li { position: relative; margin-bottom: 0.875rem; padding-left: 1.875rem; }
.features li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.6em;
  width: 9px;
  height: 9px;
  background: var(--brand-mid);
  border-radius: 50%;
}

/* --------------------------------------------------------- 表格 */
.table-wrap { overflow-x: auto; margin-top: 2rem; border: 1px solid var(--line); border-radius: var(--radius-lg); }

table { width: 100%; border-collapse: collapse; font-size: var(--fs-sm); min-width: 620px; }

th, td { padding: 0.9375rem 1.125rem; text-align: left; border-bottom: 1px solid var(--line); }

thead th { background: var(--ink-900); color: var(--paper); font-weight: 600; white-space: nowrap; }

tbody tr:last-child td { border-bottom: 0; }
tbody tr:hover { background: var(--brand-soft); }

/* --------------------------------------------------------- CTA 区块 */
.cta-band {
  padding: clamp(3rem, 6vw, 4.5rem) 0;
  background: var(--brand-strong);
  color: var(--paper);
  text-align: center;
}

.cta-band h2 { color: var(--paper); }

.cta-band p {
  max-width: 620px;
  margin: 0 auto 0;
  color: rgba(255, 255, 255, 0.85);
}

.cta-band .btn-row { justify-content: center; }

/* --------------------------------------------------------- 页脚 */
.footer {
  background: var(--ink-900);
  color: rgba(241, 239, 232, 0.7);
  padding: clamp(3rem, 6vw, 4.5rem) 0 1.5rem;
  font-size: var(--fs-sm);
}

.footer__grid {
  display: grid;
  gap: 2.5rem;
  grid-template-columns: 1fr;
}

@media (min-width: 640px) { .footer__grid { grid-template-columns: repeat(2, 1fr); } }
@media (min-width: 960px) { .footer__grid { grid-template-columns: 1.6fr 1fr 1fr 1fr; } }

.footer h4 {
  margin-bottom: 1.125rem;
  font-size: var(--fs-xs);
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--paper);
}

.footer ul { list-style: none; margin: 0; padding: 0; }
.footer li { margin-bottom: 0.625rem; }
.footer a { color: rgba(241, 239, 232, 0.7); }
.footer a:hover { color: var(--brand-line); }

.footer__brand-desc { margin-top: 1.125rem; max-width: 320px; line-height: 1.7; }

.footer__contact {
  margin-top: 1.5rem;
  font-style: normal;
  line-height: 1.9;
  color: rgba(241, 239, 232, 0.7);
}

.footer__contact strong { color: var(--paper); font-weight: 600; }
.footer__contact a { color: var(--brand-line); text-decoration: underline; }
.footer__contact a:hover { color: var(--paper); }

.footer__bottom {
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid rgba(241, 239, 232, 0.14);
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: space-between;
  font-size: var(--fs-xs);
  color: rgba(241, 239, 232, 0.55);
}

.footer .brand__cn { color: var(--paper); }
.footer .brand__en { color: var(--brand-line); }

/* --------------------------------------------------------- 表单 */
.form-grid { display: grid; gap: 1.25rem; grid-template-columns: 1fr; }
@media (min-width: 768px) { .form-grid { grid-template-columns: 1fr 1fr; } }
.form-full { grid-column: 1 / -1; }

.field { display: flex; flex-direction: column; gap: 0.5rem; }

.field label { font-size: var(--fs-xs); font-weight: 600; color: var(--ink-800); }

.field input, .field select, .field textarea {
  padding: 0.75rem 0.875rem;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  background: var(--paper);
  color: var(--ink-900);
  transition: border-color 0.2s var(--ease);
}

.field input:focus, .field select:focus, .field textarea:focus {
  outline: none;
  border-color: var(--brand);
  box-shadow: 0 0 0 3px rgba(15, 110, 86, 0.1);
}

.field textarea { min-height: 140px; resize: vertical; }

.form-note { margin-top: 1rem; font-size: var(--fs-xs); color: var(--ink-600); }

/* --------------------------------------------------------- 面包屑 */
.breadcrumb {
  padding: 1.125rem 0;
  border-bottom: 1px solid var(--line);
  font-size: var(--fs-xs);
  color: var(--ink-600);
}

.breadcrumb ol { list-style: none; margin: 0; padding: 0; display: flex; flex-wrap: wrap; gap: 0.5rem; }
.breadcrumb li { margin: 0; }
.breadcrumb li + li::before { content: "/"; margin-right: 0.5rem; color: var(--ink-200); }
.breadcrumb a { color: var(--ink-600); }
.breadcrumb a:hover { color: var(--brand); }
.breadcrumb [aria-current] { color: var(--ink-800); font-weight: 500; }

/* --------------------------------------------------------- 其他 */
.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  z-index: 200;
  padding: 0.75rem 1.25rem;
  background: var(--brand);
  color: var(--paper);
  font-weight: 600;
}

.skip-link:focus { left: 0; }

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

.lead { font-size: 1.0625rem; color: var(--ink-600); }

.text-center { text-align: center; }

.mt-lg { margin-top: 2.5rem; }