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

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

body {
  margin: 0;
  font-family: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--c-blue-deep);
  background: var(--c-white);
  -webkit-font-smoothing: antialiased;
}

:root {
  --c-blue: #1E90FF;
  --c-blue-deep: #0A3D62;
  --c-green: #2E8B57;
  --c-orange: #FF4500;
  --c-yellow: #FFD700;
  --c-white: #FFFFFF;
  --c-gray: #D3D3D3;
  --c-night: #0B1020;
  --font-head: "Arial Black", "Source Han Sans CN", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
  --font-mono: "JetBrains Mono", "SF Mono", "Cascadia Code", Consolas, "Courier New", monospace;
  --w-page: 1240px;
  --radius: 14px;
  --radius-pill: 999px;
  --shadow: 0 10px 30px rgba(11, 16, 32, 0.12);
  --shadow-sm: 0 4px 14px rgba(11, 16, 32, 0.08);
  --t-fast: 150ms ease;
}

h1, h2, h3, h4, h5, h6 {
  margin: 0 0 0.5em;
  font-family: var(--font-head);
  font-weight: 900;
  line-height: 1.15;
  color: var(--c-blue-deep);
}

h1 { font-size: clamp(34px, 4.4vw, 48px); }
h2 { font-size: clamp(26px, 3vw, 36px); }
h3 { font-size: 24px; }
h4 { font-size: 20px; }

p { margin: 0 0 1em; }

a { color: var(--c-blue); text-decoration-thickness: 1px; }

ul, ol { margin: 0 0 1em; padding-left: 1.3em; }

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

button {
  font: inherit;
  color: inherit;
}

::selection {
  background: rgba(30, 144, 255, 0.22);
}

#main-content {
  scroll-margin-top: 108px;
}

#main-content:focus,
#main-content:focus-visible {
  outline: none;
}

/* ============ Focus & Accessibility ============ */
:focus-visible {
  outline: 3px solid var(--c-orange);
  outline-offset: 2px;
}

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

/* ============ Header ============ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  padding: 14px 20px 6px;
  pointer-events: none;
}

.site-header__progress {
  position: absolute;
  top: 0;
  left: 0;
  width: 0;
  height: 3px;
  z-index: 6;
  border-radius: 0 3px 3px 0;
  background: linear-gradient(90deg, var(--c-blue) 0%, var(--c-orange) 100%);
  pointer-events: none;
}

.site-header__inner {
  position: relative;
  pointer-events: auto;
  display: flex;
  align-items: center;
  gap: 18px;
  max-width: var(--w-page);
  margin: 0 auto;
  padding: 8px 10px 8px 18px;
  background: rgba(255, 255, 255, 0.88);
  border: 1px solid rgba(30, 144, 255, 0.16);
  border-radius: var(--radius-pill);
  box-shadow: var(--shadow-sm);
  -webkit-backdrop-filter: blur(14px) saturate(1.3);
  backdrop-filter: blur(14px) saturate(1.3);
}

.site-header__inner:has(.nav-toggle[aria-expanded="true"]) {
  border-radius: 20px;
}

.site-brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
  text-decoration: none;
}

.site-brand__mark {
  position: relative;
  width: 40px;
  height: 40px;
  flex-shrink: 0;
  border-radius: 50%;
  background: var(--c-night);
}

.site-brand__mark::before {
  content: "";
  position: absolute;
  inset: 4px;
  border-radius: 50%;
  background: conic-gradient(var(--c-blue) 0 130deg, var(--c-green) 130deg 200deg, var(--c-orange) 200deg 360deg);
}

.site-brand__mark::after {
  content: "";
  position: absolute;
  left: 50%;
  top: 50%;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--c-white);
  transform: translate(-50%, -50%);
  box-shadow: 0 0 0 3px rgba(11, 16, 32, 0.35);
}

.site-brand__text {
  display: flex;
  flex-direction: column;
  line-height: 1.25;
}

.site-brand__name {
  font-family: var(--font-head);
  font-size: 20px;
  font-weight: 900;
  letter-spacing: 0.02em;
  color: var(--c-night);
}

.site-brand__tagline {
  font-size: 11.5px;
  letter-spacing: 0.06em;
  color: var(--c-blue-deep);
  opacity: 0.6;
  white-space: nowrap;
}

.site-nav {
  display: flex;
  align-items: center;
  margin-inline: auto;
}

.site-nav__list {
  display: flex;
  align-items: center;
  gap: 2px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.site-nav__link {
  display: block;
  padding: 9px 14px;
  border-radius: var(--radius-pill);
  font-size: 14.5px;
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--c-blue-deep);
  text-decoration: none;
  transition: background-color var(--t-fast), color var(--t-fast);
}

.site-nav__link:hover {
  background-color: rgba(30, 144, 255, 0.12);
  color: var(--c-blue);
}

.site-nav__link[aria-current="page"] {
  background-color: var(--c-blue);
  color: var(--c-white);
}

.site-header__cta {
  margin-left: auto;
  padding: 9px 20px;
  border-radius: var(--radius-pill);
  background: var(--c-orange);
  color: var(--c-white);
  font-size: 14px;
  font-weight: 700;
  text-decoration: none;
  white-space: nowrap;
  box-shadow: 0 4px 12px rgba(255, 69, 0, 0.26);
  transition: transform var(--t-fast), box-shadow var(--t-fast);
}

.site-header__cta:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(255, 69, 0, 0.34);
}

.nav-toggle {
  display: none;
  width: 42px;
  height: 42px;
  margin-left: auto;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
  padding: 0;
  border: 1px solid rgba(30, 144, 255, 0.24);
  border-radius: 50%;
  background: rgba(30, 144, 255, 0.1);
  cursor: pointer;
  transition: background-color var(--t-fast);
}

.nav-toggle:hover {
  background: rgba(30, 144, 255, 0.18);
}

.nav-toggle__bar {
  display: block;
  width: 18px;
  height: 2px;
  border-radius: 2px;
  background: var(--c-blue-deep);
  transition: transform var(--t-fast), opacity var(--t-fast);
}

.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);
}

.site-nav__mobile-cta {
  display: none;
}

.skip-link {
  position: fixed;
  top: 12px;
  left: 12px;
  z-index: 300;
  display: inline-flex;
  align-items: center;
  padding: 10px 18px;
  border-radius: var(--radius-pill);
  background: var(--c-orange);
  color: var(--c-white);
  font-size: 14px;
  font-weight: 700;
  text-decoration: none;
  box-shadow: var(--shadow);
  transform: translateY(-180%);
  transition: transform var(--t-fast);
}

.skip-link:focus {
  transform: translateY(0);
}

/* ============ Footer ============ */
.site-footer {
  position: relative;
  margin-top: 72px;
  overflow: hidden;
  color: rgba(255, 255, 255, 0.72);
  background:
    radial-gradient(1100px 480px at 85% -10%, rgba(30, 144, 255, 0.16) 0%, transparent 60%),
    linear-gradient(180deg, var(--c-night) 0%, #0A1628 100%);
}

.site-footer__decor {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    repeating-linear-gradient(115deg, rgba(30, 144, 255, 0.05) 0 1px, transparent 1px 36px),
    repeating-linear-gradient(25deg, rgba(255, 255, 255, 0.03) 0 1px, transparent 1px 52px);
}

.site-footer__inner {
  position: relative;
  display: grid;
  grid-template-columns: 1.6fr 1fr 1fr;
  gap: 48px 56px;
  max-width: var(--w-page);
  margin: 0 auto;
  padding: 64px 24px 44px;
}

.site-footer__block {
  position: relative;
}

.site-footer__block--brand {
  max-width: 460px;
}

.site-footer__title {
  margin: 0 0 16px;
  font-size: 14px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--c-white);
}

.site-brand--footer .site-brand__mark {
  width: 46px;
  height: 46px;
}

.site-brand--footer .site-brand__name {
  color: var(--c-white);
  font-size: 24px;
}

.site-brand--footer .site-brand__tagline {
  color: rgba(255, 255, 255, 0.55);
}

.site-footer__trust {
  margin: 18px 0 12px;
  padding-left: 14px;
  border-left: 3px solid var(--c-blue);
  font-size: 13.5px;
  line-height: 1.7;
  color: rgba(255, 255, 255, 0.52);
}

.site-footer__note {
  margin: 0;
  font-size: 13px;
  color: rgba(255, 255, 255, 0.62);
}

.site-footer .data-num {
  color: var(--c-yellow);
  font-size: 1.15em;
}

.site-footer__contact {
  margin: 0 0 14px;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 10px;
  font-size: 14px;
  line-height: 1.5;
  color: rgba(255, 255, 255, 0.8);
}

.site-footer__contact li {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 12px;
}

.site-footer__contact-label {
  min-width: 44px;
  padding-top: 2px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--c-blue);
}

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

.site-footer__link-list a {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 14.5px;
  color: rgba(255, 255, 255, 0.74);
  text-decoration: none;
  transition: color var(--t-fast), padding-left var(--t-fast);
}

.site-footer__link-list a::before {
  content: "";
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--c-blue);
  opacity: 0.6;
  transition: background-color var(--t-fast), opacity var(--t-fast);
}

.site-footer__link-list a:hover {
  padding-left: 4px;
  color: var(--c-orange);
}

.site-footer__link-list a:hover::before {
  background: var(--c-orange);
  opacity: 1;
}

.site-footer__bottom {
  position: relative;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 8px 24px;
  max-width: var(--w-page);
  margin: 0 auto;
  padding: 18px 24px 24px;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  font-family: var(--font-mono);
  font-size: 13px;
  color: rgba(255, 255, 255, 0.48);
}

.site-footer__copyright {
  display: inline-flex;
  align-items: baseline;
  gap: 6px;
}

.site-footer__icp {
  letter-spacing: 0.04em;
}

/* ============ Layout ============ */
.container {
  width: min(var(--w-page), 100% - 40px);
  margin-inline: auto;
}

.container--narrow {
  max-width: 880px;
}

.section {
  padding: 56px 0;
}

.section--tint {
  background: linear-gradient(180deg, rgba(30, 144, 255, 0.06) 0%, rgba(255, 255, 255, 0) 55%);
}

.section-head {
  margin: 0 0 28px;
  max-width: 720px;
}

.section-kicker {
  margin: 0 0 6px;
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--c-orange);
}

.section-title {
  margin: 0 0 10px;
}

.section-sub {
  margin: 0;
  font-size: 15px;
  color: var(--c-blue-deep);
  opacity: 0.72;
}

/* ============ Hero Index & Page Head ============ */
.hero-index {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  padding: clamp(56px, 8vw, 88px) 0 clamp(40px, 6vw, 64px);
  border-radius: 0 0 32px 32px;
  color: var(--c-white);
  background: linear-gradient(118deg, var(--c-night) 0%, var(--c-blue-deep) 44%, var(--c-blue) 100%);
}

.hero-index::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background-image:
    repeating-linear-gradient(112deg, rgba(255, 255, 255, 0.05) 0 1px, transparent 1px 44px),
    repeating-linear-gradient(28deg, rgba(255, 255, 255, 0.03) 0 1px, transparent 1px 58px);
}

.hero-index::after {
  content: "";
  position: absolute;
  z-index: -1;
  top: -96px;
  right: -96px;
  width: 320px;
  height: 320px;
  border-radius: 28px;
  background: rgba(255, 69, 0, 0.16);
  transform: rotate(18deg);
}

.hero-index__inner {
  position: relative;
  z-index: 1;
  width: min(var(--w-page), 100% - 40px);
  margin-inline: auto;
}

.hero-index__kicker {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 22px;
  padding: 6px 16px;
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: var(--radius-pill);
  background: rgba(255, 255, 255, 0.08);
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: 0.1em;
  color: var(--c-yellow);
}

.hero-index__title {
  max-width: 760px;
  margin: 0 0 14px;
  font-family: var(--font-head);
  font-size: clamp(34px, 5vw, 72px);
  font-weight: 900;
  line-height: 1.08;
  color: var(--c-white);
}

.hero-index__sub {
  max-width: 620px;
  margin: 0 0 26px;
  font-size: 17px;
  line-height: 1.7;
  color: rgba(255, 255, 255, 0.82);
}

.hero-index__actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px 16px;
}

.hero-index__chapters {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
  margin-top: clamp(36px, 5vw, 52px);
}

.page-head {
  margin-bottom: 40px;
  padding: 48px 0 28px;
  border-bottom: 1px solid var(--c-gray);
  background: linear-gradient(180deg, rgba(30, 144, 255, 0.07) 0%, rgba(255, 255, 255, 0) 70%);
}

.page-head__kicker {
  margin: 0 0 6px;
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--c-orange);
}

.page-head__title {
  margin: 0 0 8px;
}

.page-head__sub {
  max-width: 680px;
  margin: 0;
  font-size: 15px;
  color: var(--c-blue-deep);
  opacity: 0.72;
}

/* ============ Breadcrumbs ============ */
.crumb {
  margin: 0 0 18px;
  font-size: 14px;
}

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

.crumb__item {
  display: inline-flex;
  align-items: center;
  min-height: 24px;
}

.crumb__item[aria-current="page"] {
  font-weight: 600;
  color: var(--c-blue-deep);
}

.crumb__sep {
  color: var(--c-gray);
}

.crumb__link {
  color: var(--c-blue);
  text-decoration: none;
}

.crumb__link:hover {
  text-decoration: underline;
}

/* ============ Buttons ============ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 22px;
  border: 2px solid transparent;
  border-radius: var(--radius-pill);
  font-size: 14.5px;
  font-weight: 700;
  line-height: 1;
  text-decoration: none;
  cursor: pointer;
  transition: background-color var(--t-fast), color var(--t-fast), border-color var(--t-fast), transform var(--t-fast), box-shadow var(--t-fast);
}

.btn--primary {
  background: var(--c-blue);
  color: var(--c-white);
  box-shadow: 0 4px 14px rgba(30, 144, 255, 0.24);
}

.btn--primary:hover {
  background: var(--c-blue-deep);
  box-shadow: 0 6px 18px rgba(10, 61, 98, 0.3);
}

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

.btn--ghost:hover {
  background: rgba(30, 144, 255, 0.08);
}

.btn--accent {
  background: var(--c-orange);
  color: var(--c-white);
  box-shadow: 0 4px 14px rgba(255, 69, 0, 0.26);
}

.btn--accent:hover {
  background: #E13D00;
  box-shadow: 0 6px 18px rgba(255, 69, 0, 0.32);
}

.btn--light {
  background: rgba(255, 255, 255, 0.14);
  border-color: rgba(255, 255, 255, 0.75);
  color: var(--c-white);
}

.btn--light:hover {
  background: rgba(255, 255, 255, 0.24);
  border-color: var(--c-white);
}

.btn--block {
  width: 100%;
}

/* ============ Grid ============ */
.grid {
  display: grid;
  gap: 24px;
}

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

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

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

/* ============ Cards ============ */
.card {
  display: block;
  margin: 0;
  padding: 22px;
  border: 1px solid var(--c-gray);
  border-radius: var(--radius);
  background: var(--c-white);
  color: var(--c-blue-deep);
  text-decoration: none;
  transition: border-color var(--t-fast), box-shadow var(--t-fast), transform var(--t-fast);
}

.card--hover:hover {
  transform: translateY(-3px);
  border-color: transparent;
  box-shadow: var(--shadow);
}

.card__num {
  display: block;
  margin-bottom: 8px;
  font-family: var(--font-mono);
  font-size: 30px;
  font-weight: 700;
  line-height: 1.1;
  color: var(--c-blue);
}

.card__title {
  margin: 0 0 6px;
  font-family: var(--font-head);
  font-size: 19px;
  font-weight: 900;
  color: var(--c-blue-deep);
}

.card__text {
  margin: 0 0 10px;
  font-size: 14px;
  line-height: 1.65;
  color: var(--c-blue-deep);
  opacity: 0.72;
}

.card__meta {
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: 0.04em;
  color: var(--c-blue);
}

.card--index {
  border: 1px solid rgba(255, 255, 255, 0.38);
  border-left: 4px solid var(--c-blue);
  border-radius: 8px var(--radius) var(--radius) 8px;
  background: rgba(255, 255, 255, 0.92);
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
}

.card--index:hover {
  transform: translateY(-3px);
  border-left-color: var(--c-orange);
  box-shadow: var(--shadow);
}

/* ============ Badges ============ */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 11px;
  border-radius: var(--radius-pill);
  font-size: 12.5px;
  font-weight: 700;
  letter-spacing: 0.03em;
  line-height: 1.5;
}

.badge--blue {
  background: rgba(30, 144, 255, 0.14);
  color: var(--c-blue);
}

.badge--green {
  background: rgba(46, 139, 87, 0.14);
  color: var(--c-green);
}

.badge--orange {
  background: rgba(255, 69, 0, 0.13);
  color: var(--c-orange);
}

.badge--yellow {
  background: rgba(255, 215, 0, 0.2);
  color: #9A7B00;
}

/* ============ Data ============ */
.data-num {
  font-family: var(--font-mono);
  font-weight: 700;
  color: var(--c-blue-deep);
}

.data-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--c-blue-deep);
  opacity: 0.62;
}

/* ============ Legend ============ */
.legend {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 20px;
  margin: 0 0 20px;
  padding: 12px 18px;
  list-style: none;
  border: 1px solid rgba(30, 144, 255, 0.18);
  border-radius: var(--radius-pill);
  background: rgba(255, 255, 255, 0.8);
  font-size: 13.5px;
}

.legend__item {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.legend__dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--c-blue);
  box-shadow: 0 0 0 3px rgba(30, 144, 255, 0.14);
}

.legend__dot--green {
  background: var(--c-green);
  box-shadow: 0 0 0 3px rgba(46, 139, 87, 0.14);
}

.legend__dot--orange {
  background: var(--c-orange);
  box-shadow: 0 0 0 3px rgba(255, 69, 0, 0.14);
}

.legend__dot--yellow {
  background: var(--c-yellow);
  box-shadow: 0 0 0 3px rgba(255, 215, 0, 0.16);
}

/* ============ Fold ============ */
.fold {
  overflow: hidden;
  border: 1px solid var(--c-gray);
  border-radius: 12px;
  background: var(--c-white);
}

.fold + .fold {
  margin-top: 10px;
}

.fold__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  width: 100%;
  padding: 16px 18px;
  border: 0;
  background: transparent;
  font-family: var(--font-body);
  font-size: 15.5px;
  font-weight: 600;
  text-align: left;
  color: var(--c-blue-deep);
  cursor: pointer;
  transition: background-color var(--t-fast);
}

.fold__head:hover {
  background: rgba(30, 144, 255, 0.06);
}

.fold__icon {
  position: relative;
  width: 22px;
  height: 22px;
  flex-shrink: 0;
}

.fold__icon::before,
.fold__icon::after {
  content: "";
  position: absolute;
  border-radius: 2px;
  background: var(--c-blue);
  transition: transform var(--t-fast), opacity var(--t-fast);
}

.fold__icon::before {
  left: 4px;
  right: 4px;
  top: 50%;
  height: 2px;
  transform: translateY(-50%);
}

.fold__icon::after {
  left: 50%;
  top: 4px;
  bottom: 4px;
  width: 2px;
  transform: translateX(-50%);
}

.fold__body {
  display: none;
  padding: 0 18px 18px;
  font-size: 14.5px;
  color: var(--c-blue-deep);
  opacity: 0.82;
}

.fold[data-open="true"] .fold__icon::after {
  opacity: 0;
  transform: translateX(-50%) rotate(90deg);
}

.fold[data-open="true"] .fold__body {
  display: block;
}

/* ============ Tabs ============ */
.tabs {
  position: relative;
}

.tabs__list {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  width: max-content;
  max-width: 100%;
  margin: 0 0 20px;
  padding: 6px;
  list-style: none;
  border: 1px solid rgba(30, 144, 255, 0.14);
  border-radius: var(--radius-pill);
  background: rgba(30, 144, 255, 0.08);
}

.tabs__btn {
  padding: 8px 18px;
  border: 0;
  border-radius: var(--radius-pill);
  background: transparent;
  font-size: 14px;
  font-weight: 600;
  color: var(--c-blue-deep);
  cursor: pointer;
  transition: background-color var(--t-fast), color var(--t-fast), box-shadow var(--t-fast);
}

.tabs__btn:hover {
  color: var(--c-blue);
}

.tabs__btn[aria-selected="true"] {
  background: var(--c-white);
  color: var(--c-blue);
  box-shadow: 0 2px 8px rgba(11, 16, 32, 0.1);
}

/* ============ Table ============ */
.table-wrap {
  overflow-x: auto;
  border: 1px solid var(--c-gray);
  border-radius: var(--radius);
  background: var(--c-white);
}

.table-wrap table {
  width: 100%;
  min-width: 640px;
  border-collapse: collapse;
}

.table-wrap caption {
  padding: 12px 16px;
  border-bottom: 1px solid var(--c-gray);
  background: rgba(30, 144, 255, 0.05);
  font-weight: 700;
  text-align: left;
  color: var(--c-blue-deep);
}

.table-wrap th,
.table-wrap td {
  padding: 12px 14px;
  border-bottom: 1px solid var(--c-gray);
  font-size: 14px;
  text-align: left;
  vertical-align: middle;
}

.table-wrap th {
  font-family: var(--font-head);
  font-size: 12.5px;
  letter-spacing: 0.05em;
  white-space: nowrap;
  color: var(--c-blue-deep);
  background: rgba(30, 144, 255, 0.08);
}

.table-wrap td {
  color: var(--c-blue-deep);
}

.table-wrap tr:last-child td {
  border-bottom: 0;
}

.table-wrap .data-num {
  color: var(--c-blue);
}

/* ============ Image Frame ============ */
.img-frame {
  position: relative;
  display: block;
  overflow: hidden;
  border: 1px solid var(--c-gray);
  border-radius: var(--radius);
  background:
    linear-gradient(135deg, rgba(30, 144, 255, 0.09), rgba(46, 139, 87, 0.09)),
    repeating-linear-gradient(45deg, rgba(255, 255, 255, 0.6) 0 10px, rgba(30, 144, 255, 0.06) 10px 12px);
}

.img-frame::after {
  content: "IMG";
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.24em;
  color: var(--c-blue-deep);
  opacity: 0.42;
}

.img-frame--16x9 {
  aspect-ratio: 16 / 9;
}

.img-frame--4x3 {
  aspect-ratio: 4 / 3;
}

.img-frame--1x1 {
  aspect-ratio: 1 / 1;
}

/* ============ Track Lines Decoration ============ */
.track-lines {
  position: absolute;
  inset: 0;
  overflow: hidden;
  pointer-events: none;
  background-image:
    repeating-linear-gradient(112deg, rgba(30, 144, 255, 0.08) 0 1px, transparent 1px 42px),
    repeating-linear-gradient(28deg, rgba(255, 255, 255, 0.05) 0 1px, transparent 1px 60px);
}

/* ============ Responsive ============ */
@media (max-width: 1200px) {
  .site-brand__tagline {
    display: none;
  }
}

@media (max-width: 1024px) {
  .site-header {
    padding: 12px 12px 6px;
  }

  .site-header__inner {
    gap: 10px;
    padding: 8px 10px 8px 14px;
    border-radius: 20px;
  }

  .site-brand__name {
    font-size: 19px;
  }

  .site-header__cta {
    display: none;
  }

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

  .site-nav {
    position: absolute;
    top: calc(100% + 10px);
    left: 0;
    right: 0;
    display: none;
    flex-direction: column;
    align-items: stretch;
    margin: 0;
    padding: 10px;
    border: 1px solid rgba(30, 144, 255, 0.18);
    border-radius: 18px;
    background: rgba(255, 255, 255, 0.96);
    box-shadow: var(--shadow);
    -webkit-backdrop-filter: blur(14px);
    backdrop-filter: blur(14px);
  }

  .site-nav[data-open="true"] {
    display: flex;
  }

  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
  }

  .site-nav__link {
    padding: 12px 16px;
    border-radius: 12px;
  }

  .site-nav__mobile-cta {
    display: inline-flex;
    width: 100%;
    margin: 10px 0 4px;
    border-radius: 12px;
  }

  .hero-index__chapters {
    grid-template-columns: 1fr 1fr;
  }

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

  .site-footer__inner {
    grid-template-columns: 1fr 1fr;
    gap: 36px;
    padding-top: 48px;
  }
}

@media (max-width: 620px) {
  .container {
    width: min(100% - 28px, var(--w-page));
  }

  .hero-index__inner {
    width: min(100% - 28px, var(--w-page));
  }

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

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

  .site-footer__bottom {
    justify-content: center;
    text-align: center;
  }
}