/* ===== 1. Design Tokens ===== */
:root {
  --deep-blue: #0B1F3A;
  --azure: #00A9CE;
  --orange: #FF7A00;
  --mist: #EEF2F7;
  --snow: #FFFFFF;
  --ink: #202A3A;
  --slate: #5A6B7B;
  --line: #D0D9E2;
  --success: #2EB39A;
  --error: #E4572E;

  --display-font: Impact, 'Noto Sans SC Black', 'PingFang SC Semibold', sans-serif;
  --body-font: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --number-font: 'DIN Alternate', Impact, sans-serif;

  --header-width: 320px;
  --content-max: 1120px;
  --grid-gap: 24px;

  --shadow-sm: 0 1px 3px rgba(11, 31, 58, 0.08);
  --shadow-md: 0 4px 16px rgba(11, 31, 58, 0.12);
  --shadow-lg: 0 12px 32px rgba(11, 31, 58, 0.16);
  --ease: cubic-bezier(0.33, 0, 0.2, 1);
  --transition: 220ms var(--ease);
}

/* ===== 2. Reset ===== */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: var(--body-font);
  font-size: 16px;
  line-height: 1.6;
  color: var(--ink);
  background: var(--snow);
  min-height: 100vh;
  overflow-x: hidden;
}

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

ul,
ol {
  list-style: none;
}

/* ===== 3. Typography & Accessibility ===== */
h1, h2, h3, h4 {
  font-family: var(--display-font);
  font-weight: 900;
  line-height: 1.2;
  color: var(--ink);
}

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

a:hover {
  color: var(--orange);
}

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

::selection {
  background: var(--deep-blue);
  color: var(--snow);
}

.skip-link {
  position: fixed;
  top: -100px;
  left: 16px;
  z-index: 3000;
  background: var(--orange);
  color: var(--snow);
  padding: 10px 16px;
  font-weight: 700;
  font-size: 14px;
  border-radius: 0 0 4px 4px;
  transition: top var(--transition);
}

.skip-link:focus-visible {
  top: 0;
}

/* ===== 4. Layout Helpers ===== */
.main-content {
  min-height: 70vh;
  padding-top: 24px;
}

.container {
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 0 32px;
}

.grid {
  display: grid;
  gap: var(--grid-gap);
}

.grid--2 { grid-template-columns: repeat(2, 1fr); }
.grid--3 { grid-template-columns: repeat(3, 1fr); }
.grid--4 { grid-template-columns: repeat(4, 1fr); }

/* ===== 5. Buttons & Tags ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px;
  padding: 12px 24px;
  font-family: var(--body-font);
  font-size: 15px;
  font-weight: 700;
  line-height: 1;
  text-decoration: none;
  color: var(--snow);
  background: var(--azure);
  border: 1px solid transparent;
  border-radius: 0;
  cursor: pointer;
  transition: background var(--transition), color var(--transition), border-color var(--transition), transform var(--transition), box-shadow var(--transition);
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  color: var(--snow);
}

.btn--solid {
  background: var(--orange);
  color: var(--snow);
}

.btn--solid:hover {
  background: #e06c00;
  color: var(--snow);
}

.btn--ghost {
  background: transparent;
  border-color: var(--azure);
  color: var(--azure);
}

.btn--ghost:hover {
  background: var(--azure);
  color: var(--snow);
}

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

.btn--dark:hover {
  background: #10294d;
  color: var(--snow);
}

.tag {
  display: inline-block;
  padding: 4px 12px;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.08em;
  border: 1px solid var(--azure);
  color: var(--azure);
  background: transparent;
}

.tag--orange {
  border-color: var(--orange);
  color: var(--orange);
}

.tag--dark {
  border-color: var(--deep-blue);
  color: var(--deep-blue);
  background: var(--mist);
}

/* ===== 6. Breadcrumb ===== */
.breadcrumb {
  padding: 16px 0;
  font-size: 13px;
  color: var(--slate);
}

.breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  list-style: none;
}

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

.breadcrumb li + li::before {
  content: '/';
  margin: 0 8px;
  color: var(--line);
}

.breadcrumb a {
  color: var(--azure);
  text-decoration: none;
}

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

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

/* ===== 7. Cards & Media Frames ===== */
.card {
  background: var(--snow);
  border: 1px solid var(--line);
  box-shadow: var(--shadow-sm);
  padding: 24px;
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--azure);
}

.media-frame {
  position: relative;
  overflow: hidden;
  background: var(--mist);
  border: 1px solid var(--line);
  aspect-ratio: 16 / 10;
}

.media-frame--tall { aspect-ratio: 3 / 4; }
.media-frame--wide { aspect-ratio: 21 / 9; }
.media-frame--square { aspect-ratio: 1 / 1; }

.media-frame--placeholder {
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--slate);
  background: linear-gradient(135deg, var(--mist) 0%, var(--line) 100%);
}

/* ===== 8. Editorial Section System ===== */
.section {
  padding: 64px 0;
  border-bottom: 1px solid var(--line);
}

.section:last-child {
  border-bottom: none;
}

.section-head {
  display: grid;
  grid-template-columns: 88px 1fr;
  align-items: end;
  gap: 8px 24px;
  margin-bottom: 40px;
}

.section-num {
  grid-row: span 2;
  font-family: var(--number-font);
  font-size: 72px;
  font-weight: 900;
  line-height: 0.85;
  color: var(--azure);
  letter-spacing: -0.02em;
}

.section-title {
  font-family: var(--display-font);
  font-size: clamp(28px, 4vw, 40px);
  line-height: 1.1;
  letter-spacing: 0.02em;
  color: var(--ink);
}

.section-note {
  grid-column: 2;
  font-family: var(--body-font);
  font-size: 13px;
  line-height: 1.6;
  color: var(--slate);
  max-width: 420px;
  border-left: 2px solid var(--orange);
  padding-left: 12px;
}

/* ===== 9. Shared Header & Sidebar ===== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  width: var(--header-width);
  height: 100vh;
  height: 100dvh;
  background: var(--deep-blue);
  color: var(--snow);
  z-index: 1000;
  display: flex;
  flex-direction: column;
  overflow-y: auto;
  transition: transform var(--transition);
}

.site-header__bar {
  flex: 0 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 24px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
  min-height: 40px;
}

.brand__name {
  font-family: var(--display-font);
  font-size: 26px;
  font-weight: 900;
  letter-spacing: 0.04em;
  line-height: 1.1;
  color: var(--snow);
  white-space: nowrap;
}

.brand__divider {
  width: 1px;
  height: 18px;
  background: rgba(255, 255, 255, 0.25);
}

.brand__region {
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--azure);
  border: 1px solid rgba(0, 169, 206, 0.4);
  padding: 2px 6px;
  white-space: nowrap;
}

.nav-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  padding: 0;
  border: 1px solid rgba(255, 255, 255, 0.2);
  background: transparent;
  color: var(--snow);
  cursor: pointer;
  transition: border-color var(--transition), background var(--transition);
}

.nav-toggle:hover {
  border-color: var(--azure);
}

.nav-toggle__icon {
  display: inline-flex;
  flex-direction: column;
  gap: 5px;
}

.nav-toggle__bar {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--snow);
  transition: transform var(--transition), opacity var(--transition);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(2) {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* Navigation sidebar */
.site-nav {
  flex: 1 1 auto;
  display: flex;
  flex-direction: column;
  padding: 24px;
}

.site-nav__label {
  font-size: 12px;
  letter-spacing: 0.18em;
  color: rgba(255, 255, 255, 0.4);
  text-transform: uppercase;
  margin-bottom: 16px;
  padding-left: 4px;
}

.site-nav__list {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.site-nav__list::before {
  content: '';
  position: absolute;
  left: 0;
  top: 8px;
  bottom: 8px;
  width: 1px;
  background: rgba(255, 255, 255, 0.12);
}

.site-nav__item {
  position: relative;
}

.site-nav__link {
  position: relative;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 12px 10px 20px;
  color: rgba(238, 242, 247, 0.72);
  text-decoration: none;
  transition: color var(--transition), background var(--transition);
}

.site-nav__link::before {
  content: '';
  position: absolute;
  left: 0;
  top: 8px;
  bottom: 8px;
  width: 3px;
  background: var(--azure);
  opacity: 0;
  transition: opacity var(--transition), transform var(--transition);
}

.site-nav__link:hover {
  color: var(--snow);
  background: rgba(0, 169, 206, 0.08);
}

.site-nav__link:hover::before,
.site-nav__link[aria-current="page"]::before {
  opacity: 1;
}

.site-nav__link[aria-current="page"] {
  color: var(--snow);
  background: rgba(0, 169, 206, 0.12);
}

.site-nav__link[aria-current="page"] .site-nav__index {
  color: var(--orange);
}

.site-nav__index {
  font-family: var(--number-font);
  font-size: 13px;
  font-weight: 700;
  color: rgba(255, 255, 255, 0.35);
  transition: color var(--transition);
  min-width: 22px;
}

.site-nav__title {
  font-family: var(--body-font);
  font-size: 15px;
  font-weight: 500;
  letter-spacing: 0.04em;
}

/* Nav CTA */
.nav-cta {
  margin-top: auto;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 14px 16px;
  background: var(--orange);
  color: var(--snow);
  font-family: var(--body-font);
  font-size: 15px;
  font-weight: 700;
  text-decoration: none;
  transition: background var(--transition), transform var(--transition), box-shadow var(--transition);
}

.nav-cta:hover {
  background: #e06c00;
  color: var(--snow);
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(255, 122, 0, 0.25);
}

.nav-cta__icon {
  font-size: 20px;
  font-weight: 900;
  line-height: 1;
}

/* Header meta */
.site-header__meta {
  flex: 0 0 auto;
  padding: 16px 24px 24px;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  position: relative;
}

.site-header__meta::before {
  content: '';
  position: absolute;
  top: -1px;
  left: 24px;
  width: 48px;
  height: 2px;
  background: var(--orange);
}

.site-header__status {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  color: rgba(238, 242, 247, 0.85);
  margin-bottom: 16px;
}

.site-header__pulse {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--success);
  box-shadow: 0 0 0 0 rgba(46, 179, 154, 0.5);
  animation: pulse 2s infinite;
  flex-shrink: 0;
}

.site-header__label {
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: rgba(255, 255, 255, 0.45);
  margin-top: 12px;
}

.site-header__link {
  display: inline-block;
  color: var(--snow);
  font-size: 15px;
  font-weight: 500;
  text-decoration: none;
  margin-top: 2px;
  transition: color var(--transition);
}

.site-header__link:hover {
  color: var(--azure);
}

.site-header__addr {
  margin-top: 12px;
  font-size: 12px;
  color: rgba(255, 255, 255, 0.4);
  line-height: 1.6;
}

/* ===== 10. Mobile Nav Overlay & Drawer ===== */
.nav-overlay {
  display: none;
}

/* ===== 11. Footer ===== */
.site-footer {
  background: var(--deep-blue);
  color: rgba(238, 242, 247, 0.72);
  position: relative;
  overflow: hidden;
}

.site-footer::after {
  content: '九博体育';
  position: absolute;
  right: -20px;
  bottom: -50px;
  font-family: var(--display-font);
  font-size: 140px;
  font-weight: 900;
  line-height: 1;
  color: transparent;
  -webkit-text-stroke: 1px rgba(255, 255, 255, 0.05);
  pointer-events: none;
}

.site-footer__inner {
  position: relative;
  z-index: 1;
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 72px 32px 48px;
  display: grid;
  grid-template-columns: 1.5fr 0.8fr 0.8fr 1.3fr;
  gap: 48px;
}

.site-footer__brand-name {
  font-family: var(--display-font);
  font-size: 40px;
  font-weight: 900;
  letter-spacing: 0.06em;
  line-height: 1.1;
  color: var(--snow);
}

.site-footer__brand-region {
  display: inline-block;
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--azure);
  border: 1px solid rgba(0, 169, 206, 0.35);
  padding: 3px 10px;
  margin-top: 8px;
}

.site-footer__about {
  margin-top: 16px;
  font-size: 14px;
  line-height: 1.7;
  color: rgba(238, 242, 247, 0.8);
  max-width: 320px;
}

.site-footer__trust {
  margin-top: 12px;
  font-size: 12px;
  line-height: 1.7;
  color: rgba(238, 242, 247, 0.45);
  max-width: 340px;
}

.site-footer__heading {
  font-family: var(--body-font);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: rgba(255, 255, 255, 0.5);
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.site-footer__list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.site-footer__list a {
  color: rgba(238, 242, 247, 0.72);
  font-size: 14px;
  text-decoration: none;
  transition: color var(--transition), padding-left var(--transition);
}

.site-footer__list a:hover {
  color: var(--azure);
  padding-left: 4px;
}

.site-footer__text {
  font-size: 13px;
  line-height: 1.7;
  color: rgba(238, 242, 247, 0.65);
  margin-bottom: 4px;
}

.site-footer__bottom {
  position: relative;
  z-index: 1;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}

.site-footer__bottom-inner {
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 24px 32px;
  display: flex;
  justify-content: space-between;
  gap: 12px;
  font-size: 12px;
  color: rgba(238, 242, 247, 0.5);
}

/* ===== 12. Scroll Progress & Back Top ===== */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: transparent;
  z-index: 2000;
  pointer-events: none;
}

.scroll-progress__bar {
  display: block;
  height: 100%;
  width: 0;
  background: linear-gradient(90deg, var(--azure), var(--orange));
}

.back-top {
  position: fixed;
  right: 32px;
  bottom: 32px;
  z-index: 1500;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  border: 1px solid rgba(255, 255, 255, 0.25);
  background: var(--deep-blue);
  color: var(--snow);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: opacity var(--transition), transform var(--transition), visibility var(--transition), background var(--transition);
}

.back-top:hover {
  background: var(--azure);
  border-color: var(--azure);
}

.back-top.is-visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-top__icon {
  font-size: 20px;
  font-weight: 900;
  line-height: 1;
}

/* ===== 13. Keyframes & Motion ===== */
@keyframes pulse {
  0% { box-shadow: 0 0 0 0 rgba(46, 179, 154, 0.5); }
  70% { box-shadow: 0 0 0 8px rgba(46, 179, 154, 0); }
  100% { box-shadow: 0 0 0 0 rgba(46, 179, 154, 0); }
}

@keyframes riseIn {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (prefers-reduced-motion: no-preference) {
  .main-content {
    animation: riseIn 500ms var(--ease) both;
  }
}

/* ===== 14. Responsive Adjustments ===== */
@media (min-width: 1024px) {
  body {
    padding-left: var(--header-width);
  }
}

@media (max-width: 1023px) {
  body {
    padding-left: 0;
  }

  .site-header {
    width: 100%;
    height: 64px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    overflow: visible;
  }

  .site-header__bar {
    height: 64px;
    padding: 0 16px;
    border-bottom: none;
  }

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

  .site-nav {
    position: fixed;
    top: 64px;
    left: 0;
    bottom: 0;
    width: 300px;
    max-width: 85vw;
    flex: none;
    background: var(--deep-blue);
    padding: 28px 20px;
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
    box-shadow: 16px 0 32px rgba(0, 0, 0, 0.24);
    transform: translateX(-100%);
    transition: transform 260ms var(--ease);
  }

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

  .site-header__meta {
    display: none;
  }

  .nav-overlay {
    display: block;
    position: fixed;
    inset: 0;
    background: rgba(11, 31, 58, 0.45);
    z-index: 999;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition), visibility var(--transition);
  }

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

  .site-footer__inner {
    grid-template-columns: 1fr 1fr;
    gap: 40px;
  }

  .back-top {
    right: 20px;
    bottom: 20px;
  }
}

@media (max-width: 767px) {
  .container {
    padding: 0 20px;
  }

  .grid--2,
  .grid--3,
  .grid--4 {
    grid-template-columns: 1fr;
  }

  .section {
    padding: 48px 0;
  }

  .section-head {
    grid-template-columns: 56px 1fr;
    gap: 6px 16px;
  }

  .section-num {
    font-size: 48px;
  }

  .section-title {
    font-size: 26px;
  }

  .site-footer__inner {
    grid-template-columns: 1fr;
    gap: 32px;
    padding: 48px 20px;
  }

  .site-footer__bottom-inner {
    flex-direction: column;
    gap: 6px;
    padding: 20px;
  }

  .brand__name {
    font-size: 22px;
  }
}

/* ===== 15. Reduced Motion ===== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }

  .main-content {
    animation: none;
  }

  .site-nav {
    transition: none;
  }

  .site-header__pulse {
    animation: none;
  }
}