/* ===== Reset & Variables ===== */
*, *::before, *::after {
  box-sizing: border-box;
}

:root {
  --blue: #1B5A8D;
  --snow: #F4F6F8;
  --red: #C84B31;
  --yellow: #E5A33B;
  --green: #2E8B57;
  --blue-dark: #143C5C;
  --gray: #6C7077;
  --moss: #5E7D5B;
  --terra: #A65D4A;
  --cream: #F3ECE0;
  --text-dark: #22262B;
  --line: #E2E8ED;
  --container-w: 1200px;
  --radius: 8px;
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

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

body {
  margin: 0;
  font-family: "Noto Sans SC", "HarmonyOS Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  font-size: 1rem;
  line-height: 1.8;
  color: var(--text-dark);
  background-color: var(--snow);
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4, h5, h6 {
  margin: 0 0 0.5em;
  font-weight: 900;
  line-height: 1.35;
  color: var(--blue);
}

p {
  margin: 0 0 1em;
}

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

a:hover {
  color: var(--blue-dark);
  text-decoration: underline;
}

ul, ol {
  margin: 0 0 1em;
  padding-left: 1.4em;
}

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

:focus-visible {
  outline: 3px solid rgba(229, 163, 59, 0.85);
  outline-offset: 2px;
  border-radius: 2px;
}

#main-content {
  scroll-margin-top: 64px;
}

/* ===== Utilities ===== */
.container {
  max-width: var(--container-w);
  margin-inline: auto;
  padding-inline: 24px;
}

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

/* ===== Skip Link ===== */
.skip-link {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 1000;
  background: var(--blue);
  color: var(--snow);
  padding: 12px 24px;
  border-radius: 0 0 8px 0;
  font-weight: 700;
  line-height: 1.2;
  transform: translateY(-120%);
  transition: transform 0.3s ease;
  box-shadow: 0 4px 20px rgba(20, 60, 92, 0.3);
}

.skip-link:focus {
  transform: translateY(0);
  color: var(--snow);
  text-decoration: none;
}

/* ===== Scroll Progress ===== */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  width: 0;
  background: linear-gradient(90deg, var(--blue) 0%, var(--red) 100%);
  z-index: 210;
  pointer-events: none;
}

/* ===== Shared Header ===== */
.site-header {
  position: relative;
  z-index: 100;
  background: var(--snow);
  border-bottom: 1px solid var(--line);
}

.header-top {
  background: var(--blue-dark);
  color: var(--snow);
}

.header-top-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  min-height: 36px;
}

.brand-mini {
  color: var(--snow);
  font-size: 0.8125rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  white-space: nowrap;
}

.brand-mini:hover {
  color: var(--yellow);
  text-decoration: none;
}

.header-util {
  display: flex;
  gap: 8px;
}

.util-btn {
  background: rgba(244, 246, 248, 0.1);
  border: 1px solid rgba(244, 246, 248, 0.32);
  color: var(--snow);
  font-size: 0.75rem;
  line-height: 1;
  padding: 5px 12px;
  border-radius: 999px;
  cursor: pointer;
  transition: background 0.2s, border-color 0.2s;
}

.util-btn:hover {
  background: rgba(244, 246, 248, 0.22);
  border-color: rgba(244, 246, 248, 0.5);
}

.header-hero {
  position: relative;
  overflow: hidden;
  padding: clamp(32px, 6vw, 72px) 0 clamp(36px, 6vw, 68px);
  background: linear-gradient(180deg, #E8F0F7 0%, var(--snow) 100%);
}

.header-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    repeating-linear-gradient(0deg, transparent 0px 30px, rgba(27, 90, 141, 0.05) 31px 32px),
    repeating-linear-gradient(90deg, transparent 0px 45px, rgba(27, 90, 141, 0.05) 46px 47px);
  pointer-events: none;
}

.header-hero::after {
  content: "";
  position: absolute;
  bottom: -1px;
  left: 0;
  right: 0;
  height: 64px;
  background: var(--snow);
  clip-path: polygon(0 100%, 0 70%, 9% 42%, 18% 55%, 30% 30%, 44% 58%, 58% 36%, 72% 62%, 88% 40%, 100% 60%, 100% 100%);
  pointer-events: none;
}

.header-hero-inner {
  position: relative;
  z-index: 1;
}

.hero-kicker {
  margin: 0 0 10px;
  font-family: "Noto Serif SC", "Songti SC", "SimSun", serif;
  font-size: clamp(0.75rem, 0.9vw, 0.875rem);
  font-weight: 700;
  letter-spacing: 0.22em;
  color: var(--terra);
  text-transform: uppercase;
}

.site-slogan {
  margin: 0 0 18px;
  font-size: clamp(1.5rem, 3.8vw, 3.375rem);
  font-weight: 900;
  line-height: 1.32;
  letter-spacing: -0.02em;
  color: var(--blue);
  max-width: 15em;
}

.slogan-seg {
  white-space: nowrap;
}

.slogan-sep {
  font-weight: 400;
  color: var(--gray);
  margin-inline: 0.06em;
}

.hero-note {
  margin: 0;
  max-width: 680px;
  font-family: "Noto Serif SC", "Songti SC", "SimSun", serif;
  font-size: clamp(0.875rem, 1.1vw, 1rem);
  line-height: 1.75;
  color: var(--gray);
}

.header-nav {
  position: sticky;
  top: 0;
  z-index: 200;
  background: var(--snow);
  border-top: 1px solid rgba(226, 232, 237, 0.8);
  border-bottom: 1px solid var(--line);
}

@supports (backdrop-filter: blur(8px)) {
  .header-nav {
    background: rgba(244, 246, 248, 0.88);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
  }
}

.header-nav-inner {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 16px;
  min-height: 58px;
}

.nav-brand {
  display: flex;
  align-items: baseline;
  gap: 10px;
  flex-shrink: 0;
  margin-right: auto;
  padding-right: 20px;
  border-right: 1px solid rgba(27, 90, 141, 0.15);
}

.nav-brand-name {
  font-size: 1rem;
  font-weight: 900;
  letter-spacing: 0.08em;
  color: var(--blue);
  white-space: nowrap;
}

.nav-brand-desc {
  font-family: "Noto Serif SC", "Songti SC", serif;
  font-size: 0.75rem;
  letter-spacing: 0.06em;
  color: var(--terra);
  white-space: nowrap;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 2px;
}

.nav-link {
  display: inline-block;
  padding: 8px 16px;
  font-size: 0.9375rem;
  font-weight: 500;
  color: #2A3038;
  border-radius: 999px;
  white-space: nowrap;
  transition: background-color 0.25s, color 0.25s;
}

.nav-link:hover {
  color: var(--blue);
  background: rgba(27, 90, 141, 0.07);
  text-decoration: none;
}

.nav-link[aria-current="page"] {
  color: var(--snow);
  background: var(--blue);
  font-weight: 700;
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  background: transparent;
  border: 1px solid var(--blue);
  color: var(--blue);
  font-size: 0.875rem;
  font-weight: 700;
  line-height: 1;
  padding: 8px 14px;
  border-radius: 999px;
  cursor: pointer;
  transition: background-color 0.2s, color 0.2s;
}

.nav-toggle:hover {
  background: rgba(27, 90, 141, 0.08);
}

.nav-toggle-box {
  display: inline-flex;
  flex-direction: column;
  gap: 3px;
}

.nav-toggle-line {
  display: block;
  width: 16px;
  height: 2px;
  background: currentColor;
  border-radius: 1px;
}

.nav-overlay {
  position: fixed;
  inset: 0;
  z-index: 180;
  background: rgba(20, 60, 92, 0.5);
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition: opacity 0.35s ease, visibility 0.35s ease;
}

.nav-overlay[data-open] {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
}

/* ===== Shared Footer ===== */
.site-footer {
  position: relative;
  background: var(--blue-dark);
  color: rgba(244, 246, 248, 0.82);
  font-size: 0.875rem;
  line-height: 1.7;
}

.site-footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 6px;
  background: linear-gradient(90deg,
    var(--blue) 0% 30%,
    var(--red) 30% 45%,
    var(--yellow) 45% 75%,
    var(--green) 75% 100%);
  pointer-events: none;
}

.site-footer::after {
  content: "";
  position: absolute;
  top: 24px;
  right: 24px;
  width: 180px;
  height: 120px;
  background: rgba(244, 246, 248, 0.03);
  clip-path: polygon(0 100%, 0 55%, 14% 30%, 26% 42%, 40% 12%, 58% 50%, 72% 22%, 84% 38%, 100% 10%, 100% 100%);
  pointer-events: none;
}

.footer-top {
  display: grid;
  grid-template-columns: 2.2fr 1.2fr 1.2fr 1.8fr;
  gap: 40px;
  padding-block: 56px 40px;
  position: relative;
  z-index: 1;
}

.footer-brand-name {
  margin: 0 0 6px;
  font-size: 1.125rem;
  font-weight: 900;
  letter-spacing: 0.12em;
  color: var(--snow);
}

.footer-brand-slogan {
  margin: 0 0 14px;
  font-size: 0.8125rem;
  letter-spacing: 0.04em;
  color: var(--yellow);
}

.footer-desc {
  margin: 0;
  max-width: 34em;
  font-size: 0.8125rem;
  line-height: 1.75;
  color: rgba(244, 246, 248, 0.6);
}

.footer-col-title {
  margin: 0 0 14px;
  font-size: 0.8125rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  color: var(--snow);
  text-transform: uppercase;
}

.footer-nav {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 8px;
}

.footer-link {
  color: rgba(244, 246, 248, 0.72);
  font-size: 0.875rem;
  transition: color 0.2s, padding-left 0.2s;
}

.footer-link:hover {
  color: var(--yellow);
  text-decoration: none;
  padding-left: 4px;
}

.footer-contact-line {
  margin: 0 0 6px;
  font-size: 0.875rem;
  color: rgba(244, 246, 248, 0.72);
}

.footer-note {
  margin: 14px 0 0;
  font-size: 0.75rem;
  line-height: 1.6;
  color: rgba(244, 246, 248, 0.45);
}

.footer-bottom {
  border-top: 1px solid rgba(244, 246, 248, 0.12);
  position: relative;
  z-index: 1;
}

.footer-bottom-inner {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 12px;
  min-height: 56px;
  padding-block: 20px;
  font-size: 0.75rem;
  color: rgba(244, 246, 248, 0.5);
  text-align: center;
}

.footer-bottom-inner p {
  margin: 0;
}

/* ===== Back to Top ===== */
.to-top {
  position: fixed;
  right: 20px;
  bottom: 20px;
  z-index: 300;
  width: 44px;
  height: 44px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: none;
  border-radius: 50%;
  background: var(--blue);
  color: var(--snow);
  font-size: 1.25rem;
  line-height: 1;
  cursor: pointer;
  box-shadow: 0 6px 24px rgba(20, 60, 92, 0.28);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: opacity 0.3s ease, transform 0.3s ease, visibility 0.3s ease, background 0.2s ease;
}

.to-top:hover {
  background: var(--red);
}

.to-top[data-visible] {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 28px;
  font-size: 0.9375rem;
  font-weight: 700;
  line-height: 1.2;
  border-radius: 999px;
  cursor: pointer;
  border: 2px solid transparent;
  white-space: nowrap;
  transition: background-color 0.25s, color 0.25s, border-color 0.25s, transform 0.2s ease;
}

.btn:active {
  transform: scale(0.97);
}

.btn--primary {
  background: var(--blue);
  color: var(--snow);
}

.btn--primary:hover {
  background: var(--blue-dark);
  color: var(--snow);
  text-decoration: none;
}

.btn--accent {
  background: var(--red);
  color: var(--snow);
}

.btn--accent:hover {
  background: #A93A22;
  color: var(--snow);
  text-decoration: none;
}

.btn--outline {
  background: transparent;
  border-color: var(--blue);
  color: var(--blue);
}

.btn--outline:hover {
  background: rgba(27, 90, 141, 0.08);
  color: var(--blue);
  text-decoration: none;
}

.btn--sm {
  padding: 8px 18px;
  font-size: 0.8125rem;
}

.btn--lg {
  padding: 16px 36px;
  font-size: 1rem;
}

/* ===== Section ===== */
.section {
  padding: clamp(48px, 8vw, 96px) 0;
}

.section--alt {
  background: var(--cream);
}

.section-head {
  max-width: 720px;
  margin-bottom: clamp(28px, 4vw, 48px);
}

.kicker {
  margin: 0 0 8px;
  font-family: "Noto Serif SC", "Songti SC", serif;
  font-size: 0.8125rem;
  font-weight: 700;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--terra);
}

.section-title {
  margin: 0 0 12px;
  font-size: clamp(1.375rem, 2.6vw, 2.25rem);
  font-weight: 900;
  line-height: 1.3;
  letter-spacing: -0.01em;
  color: var(--blue);
}

.section-desc {
  margin: 0;
  font-family: "Noto Serif SC", "Songti SC", serif;
  font-size: clamp(0.875rem, 1.2vw, 1rem);
  color: var(--gray);
}

/* ===== Breadcrumb ===== */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  margin: 0 0 24px;
  padding: 0;
  list-style: none;
  font-size: 0.8125rem;
  color: var(--gray);
}

.breadcrumb li {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.breadcrumb li + li::before {
  content: "›";
  color: var(--gray);
  opacity: 0.6;
}

.breadcrumb a {
  color: var(--gray);
}

.breadcrumb a:hover {
  color: var(--blue);
  text-decoration: underline;
}

.breadcrumb [aria-current="page"] {
  color: var(--blue-dark);
  font-weight: 700;
}

/* ===== Card ===== */
.card {
  background: var(--snow);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 28px;
  transition: box-shadow 0.3s ease, transform 0.3s ease;
}

.card:hover {
  box-shadow: 0 12px 32px rgba(20, 60, 92, 0.1);
  transform: translateY(-3px);
}

.card--cream {
  background: var(--cream);
}

.card--moss {
  background: var(--moss);
  color: var(--snow);
}

.card--moss .card-title,
.card--moss .card-desc {
  color: var(--snow);
}

.card-title {
  margin: 0 0 10px;
  font-size: 1.125rem;
  font-weight: 900;
  color: var(--blue);
}

.card-desc {
  margin: 0;
  font-size: 0.875rem;
  line-height: 1.7;
  color: var(--gray);
}

/* ===== Grid ===== */
.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.grid-12 {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 24px;
}

.col-span-4 {
  grid-column: span 4;
}

.col-span-6 {
  grid-column: span 6;
}

.col-span-8 {
  grid-column: span 8;
}

/* ===== Note ===== */
.note {
  margin: 24px 0;
  padding: 20px 24px;
  border-left: 4px solid var(--yellow);
  border-radius: 0 var(--radius) var(--radius) 0;
  background: var(--cream);
  font-size: 0.875rem;
  line-height: 1.7;
  color: #3A4046;
}

.note--terra {
  border-left-color: var(--terra);
  background: #F5EAE4;
}

.note--moss {
  border-left-color: var(--moss);
  background: #EAF0E6;
}

/* ===== Tag / Divider / Table ===== */
.tag {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 0.6875rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  background: rgba(27, 90, 141, 0.09);
  color: var(--blue);
  border: 1px solid rgba(27, 90, 141, 0.2);
}

.divider {
  height: 1px;
  border: none;
  margin: 0;
  background: var(--line);
}

.table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
  background: var(--snow);
}

.table th,
.table td {
  border: 1px solid var(--line);
  padding: 12px 16px;
  text-align: left;
}

.table thead th {
  background: var(--blue-dark);
  color: var(--snow);
  font-weight: 700;
  letter-spacing: 0.04em;
}

/* ===== Content Wrap & Link Arrow ===== */
.content-wrap {
  max-width: 720px;
  font-size: 1rem;
  line-height: 1.85;
}

.content-wrap h2 {
  margin-top: 2em;
  font-size: 1.5rem;
}

.content-wrap h3 {
  margin-top: 1.6em;
  font-size: 1.1875rem;
}

.content-wrap p {
  margin-bottom: 1.4em;
}

.link-arrow {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-weight: 700;
  color: var(--blue);
}

.link-arrow::after {
  content: "→";
  transition: transform 0.25s ease;
}

.link-arrow:hover {
  color: var(--red);
  text-decoration: none;
}

.link-arrow:hover::after {
  transform: translateX(4px);
}

/* ===== Image Frame ===== */
.img-frame {
  position: relative;
  display: block;
  overflow: hidden;
  background:
    linear-gradient(135deg, rgba(27, 90, 141, 0.08), rgba(229, 163, 59, 0.08)),
    var(--cream);
  aspect-ratio: 4 / 3;
  border-radius: var(--radius);
}

.img-frame::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    repeating-linear-gradient(0deg, transparent 0px 23px, rgba(27, 90, 141, 0.07) 24px),
    repeating-linear-gradient(90deg, transparent 0px 35px, rgba(27, 90, 141, 0.07) 36px);
  pointer-events: none;
  z-index: 1;
}

.img-frame::after {
  content: "图片";
  position: absolute;
  bottom: 12px;
  left: 12px;
  z-index: 2;
  font-size: 0.6875rem;
  letter-spacing: 0.12em;
  color: var(--gray);
  background: rgba(244, 246, 248, 0.88);
  padding: 2px 10px;
  border-radius: 999px;
}

.img-frame--wide {
  aspect-ratio: 16 / 9;
}

.img-frame--portrait {
  aspect-ratio: 3 / 4;
}

/* ===== Tabs ===== */
.tabs {
  margin: 0 0 24px;
}

.tab-list {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  list-style: none;
  margin: 0;
  padding: 0;
  border-bottom: 2px solid var(--line);
}

.tab-link {
  display: inline-block;
  padding: 10px 20px;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--gray);
  background: transparent;
  border: none;
  border-bottom: 3px solid transparent;
  margin-bottom: -2px;
  cursor: pointer;
  transition: color 0.25s, border-color 0.25s;
}

.tab-link:hover {
  color: var(--blue);
}

.tab-link[aria-selected="true"] {
  color: var(--blue);
  border-bottom-color: var(--blue);
  font-weight: 700;
}

.tab-panel {
  display: none;
  padding-top: 20px;
}

.tab-panel[aria-hidden="false"] {
  display: block;
}

/* ===== Mobile Responsive ===== */
@media (max-width: 991px) {
  .footer-top {
    grid-template-columns: 1fr 1fr;
    gap: 32px 24px;
    padding-block: 48px 32px;
  }

  .grid-3 {
    grid-template-columns: 1fr 1fr;
  }

  .col-span-4,
  .col-span-8 {
    grid-column: span 6;
  }
}

@media (max-width: 767px) {
  .header-top-inner {
    min-height: 32px;
  }

  .brand-mini {
    font-size: 0.75rem;
    letter-spacing: 0.06em;
  }

  .util-btn {
    font-size: 0.6875rem;
    padding: 4px 10px;
  }

  .header-hero {
    padding: 28px 0 32px;
  }

  .header-hero::after {
    height: 40px;
  }

  .header-nav-inner {
    min-height: 52px;
  }

  .nav-brand-desc {
    display: none;
  }

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

  .site-nav {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    width: min(84vw, 320px);
    z-index: 5;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 72px 24px 32px;
    background: var(--snow);
    box-shadow: -12px 0 48px rgba(20, 60, 92, 0.2);
    overflow-y: auto;
    transform: translateX(110%);
    opacity: 0;
    visibility: hidden;
    transition: transform 0.5s var(--ease), opacity 0.3s ease, visibility 0.3s ease;
  }

  .site-nav[data-open] {
    transform: translateX(0);
    opacity: 1;
    visibility: visible;
  }

  .nav-link {
    padding: 14px 12px;
    font-size: 1.0625rem;
    border-radius: 0;
    border-bottom: 1px solid var(--line);
  }

  .nav-link[aria-current="page"] {
    background: transparent;
    color: var(--blue);
    font-weight: 900;
    box-shadow: inset 3px 0 0 var(--blue);
  }

  .grid-2,
  .grid-3 {
    grid-template-columns: 1fr;
  }

  .grid-12 {
    grid-template-columns: 1fr;
  }

  .col-span-4,
  .col-span-6,
  .col-span-8 {
    grid-column: span 1;
  }

  .footer-top {
    grid-template-columns: 1fr;
    gap: 28px;
    padding-block: 40px 28px;
  }

  .to-top {
    right: 14px;
    bottom: 14px;
  }
}

/* ===== Reduced Motion ===== */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .site-nav,
  .nav-overlay,
  .to-top,
  .card,
  .btn,
  .link-arrow::after,
  .util-btn,
  .footer-link {
    transition: none;
  }

  .card:hover {
    transform: none;
  }

  .btn:active {
    transform: none;
  }

  .link-arrow:hover::after {
    transform: none;
  }
}