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

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

body {
  font-family: 'PingFang SC', 'Microsoft YaHei', system-ui, sans-serif;
  font-weight: 400;
  font-size: 1rem;
  line-height: 1.6;
  color: #F5E6CC;
  background-color: #1A0D0D;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

ul, ol { list-style: none; }
a { color: inherit; text-decoration: none; }
button { font: inherit; cursor: pointer; border: none; background: none; color: inherit; }
img { max-width: 100%; height: auto; display: block; }

/* ===== CSS Variables ===== */
:root {
  --color-bg: #1A0D0D;
  --color-surface: #2D1B1B;
  --color-surface-light: #3D2525;
  --color-text: #F5E6CC;
  --color-text-muted: #C4A882;
  --color-gold: #D4A017;
  --color-gold-light: #F0C040;
  --color-gold-dark: #B8860B;
  --color-red: #C8302A;
  --color-red-light: #E86050;
  --color-red-dark: #8B1A1A;
  --color-border: #4A2828;
  --gradient-gold: linear-gradient(135deg, #D4A017, #F0C040);
  --gradient-red: linear-gradient(135deg, #C8302A, #E86050);
  --font-heading: 'STKaiti', 'KaiTi', 'PingFang SC', serif;
  --font-body: 'PingFang SC', 'Microsoft YaHei', system-ui, sans-serif;
  --side-track-width: 90px;
  --header-z: 1000;
  --drawer-z: 1100;
  --transition-speed: 0.25s;
  --shadow-gold: 0 4px 20px rgba(212, 160, 23, 0.25);
}

/* ===== Skip Link ===== */
.skip-link {
  position: fixed;
  top: -100%;
  left: 0;
  z-index: 9999;
  padding: 0.75rem 1.5rem;
  background: var(--gradient-gold);
  color: #1A0D0D;
  font-weight: 700;
  font-size: 0.875rem;
  border-radius: 0 0 4px 0;
  transition: top 0.2s;
}
.skip-link:focus {
  top: 0;
  outline: 2px solid #fff;
  outline-offset: 2px;
}

/* ===== Side Track Nav (Desktop) ===== */
.side-track {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--side-track-width);
  height: 100vh;
  background: var(--color-bg);
  border-right: 2px solid;
  border-image: var(--gradient-gold) 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 1.5rem 0;
  z-index: var(--header-z);
  overflow-y: auto;
}

.site-logo {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.25rem;
  margin-bottom: 2rem;
  color: var(--color-text);
}
.logo-icon {
  font-size: 1.75rem;
  line-height: 1;
}
.logo-text {
  font-family: var(--font-heading);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  background: var(--gradient-gold);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.site-logo:hover .logo-text,
.site-logo:focus-visible .logo-text {
  text-shadow: 0 0 12px rgba(212,160,23,0.5);
}

.nav-list {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  width: 100%;
  padding: 0 0.25rem;
  flex: 1;
}

.nav-item {
  width: 100%;
  text-align: center;
}

.nav-link {
  display: block;
  padding: 0.6rem 0.25rem;
  font-family: var(--font-heading);
  font-size: 0.72rem;
  font-weight: 500;
  color: var(--color-text-muted);
  letter-spacing: 0.03em;
  border-left: 3px solid transparent;
  transition: color var(--transition-speed), border-color var(--transition-speed), background var(--transition-speed);
  position: relative;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 60%;
  height: 1px;
  background: var(--gradient-gold);
  opacity: 0;
  transition: opacity var(--transition-speed);
}

.nav-link:hover,
.nav-link:focus-visible {
  color: var(--color-gold-light);
  border-left-color: var(--color-gold);
  background: rgba(212,160,23,0.08);
}
.nav-link:hover::after,
.nav-link:focus-visible::after {
  opacity: 0.3;
}

.nav-link[aria-current="page"] {
  color: var(--color-gold-light);
  border-left-color: var(--color-gold);
  background: rgba(212,160,23,0.12);
  font-weight: 700;
}
.nav-link[aria-current="page"]::after {
  opacity: 0.5;
}

.btn-download {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.55rem 1rem;
  font-family: var(--font-heading);
  font-size: 0.75rem;
  font-weight: 700;
  color: #1A0D0D;
  border-radius: 2px;
  clip-path: polygon(6px 0, 100% 0, 100% 100%, 0 100%, 0 6px);
  transition: transform var(--transition-speed), box-shadow var(--transition-speed);
  text-align: center;
  white-space: nowrap;
}

.gold-gradient {
  background: var(--gradient-gold);
}
.red-gradient {
  background: var(--gradient-red);
  color: #fff;
}

.btn-download:hover,
.btn-download:focus-visible {
  transform: translateY(-2px);
  box-shadow: var(--shadow-gold);
}

.side-track .btn-download {
  margin-top: 1.5rem;
  width: calc(100% - 1rem);
}

/* ===== Mobile Bar ===== */
.mobile-bar {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 56px;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  padding: 0 1rem;
  align-items: center;
  justify-content: space-between;
  z-index: var(--header-z);
}

.mobile-bar .site-logo {
  flex-direction: row;
  gap: 0.5rem;
  margin-bottom: 0;
}
.mobile-bar .logo-icon {
  font-size: 1.5rem;
}
.mobile-bar .logo-text {
  font-size: 1rem;
}

.nav-toggle {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 0.5rem;
  cursor: pointer;
}
.hamburger {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-gold);
  border-radius: 1px;
  transition: all var(--transition-speed);
}
.nav-toggle[aria-expanded="true"] .hamburger:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}
.nav-toggle[aria-expanded="true"] .hamburger:nth-child(2) {
  opacity: 0;
}
.nav-toggle[aria-expanded="true"] .hamburger:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

/* ===== Drawer (Mobile) ===== */
.drawer {
  position: fixed;
  top: 0;
  left: -100%;
  width: 85%;
  max-width: 320px;
  height: 100vh;
  background: var(--color-surface);
  border-right: 2px solid var(--color-gold-dark);
  z-index: var(--drawer-z);
  padding: 1.5rem 1.25rem;
  display: flex;
  flex-direction: column;
  transition: left 0.35s cubic-bezier(0.22, 1, 0.36, 1);
  overflow-y: auto;
}
.drawer[data-open] {
  left: 0;
}
.drawer[aria-hidden="true"]:not([data-open]) {
  visibility: visible;
}

.drawer-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--color-border);
}
.drawer-title {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
  background: var(--gradient-gold);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.drawer-close {
  font-size: 1.5rem;
  color: var(--color-text-muted);
  padding: 0.25rem;
  transition: color var(--transition-speed);
}
.drawer-close:hover,
.drawer-close:focus-visible {
  color: var(--color-gold-light);
}

.drawer-nav {
  flex: 1;
}
.drawer-list {
  display: flex;
  flex-direction: column;
  gap: 0.125rem;
}
.drawer-link {
  display: block;
  padding: 0.85rem 1rem;
  font-family: var(--font-heading);
  font-size: 1.1rem;
  font-weight: 500;
  color: var(--color-text-muted);
  border-left: 3px solid transparent;
  transition: all var(--transition-speed);
}
.drawer-link:hover,
.drawer-link:focus-visible {
  color: var(--color-gold-light);
  border-left-color: var(--color-gold);
  background: rgba(212,160,23,0.08);
}
.drawer-link[aria-current="page"] {
  color: var(--color-gold-light);
  border-left-color: var(--color-gold);
  background: rgba(212,160,23,0.12);
  font-weight: 700;
}

.drawer-download {
  margin-top: 2rem;
  width: 100%;
  padding: 0.85rem 1rem;
  font-size: 1rem;
}

.drawer-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.6);
  z-index: calc(var(--drawer-z) - 1);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-speed);
}
.drawer[data-open] ~ .drawer-overlay {
  opacity: 1;
  pointer-events: auto;
}
.drawer-overlay[aria-hidden="true"]:not([data-open]) {
  display: none;
}

/* ===== Footer ===== */
.site-footer {
  background: var(--color-bg);
  border-top: 2px solid;
  border-image: var(--gradient-gold) 1;
  padding: 3rem 1.5rem 1.5rem;
  margin-left: var(--side-track-width);
}

.footer-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 2rem 3rem;
}

.footer-brand {
  grid-column: 1 / 2;
}
.footer-logo {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.75rem;
}
.footer-logo .logo-icon {
  font-size: 1.5rem;
}
.footer-logo .logo-text {
  font-size: 1.1rem;
  font-family: var(--font-heading);
  font-weight: 700;
  background: var(--gradient-gold);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.footer-desc {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  line-height: 1.5;
}

.footer-links {
  grid-column: 2 / 3;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  padding-top: 0.25rem;
}
.footer-link {
  font-size: 0.92rem;
  color: var(--color-text-muted);
  transition: color var(--transition-speed);
  position: relative;
  width: fit-content;
}
.footer-link::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 1px;
  background: var(--gradient-gold);
  transition: width var(--transition-speed);
}
.footer-link:hover,
.footer-link:focus-visible {
  color: var(--color-gold-light);
}
.footer-link:hover::after,
.footer-link:focus-visible::after {
  width: 100%;
}

.footer-contact {
  grid-column: 3 / 4;
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
  font-size: 0.85rem;
  color: var(--color-text-muted);
}
.contact-item {
  display: flex;
  align-items: center;
  gap: 0.4rem;
}
.contact-note {
  margin-top: 0.35rem;
  font-size: 0.78rem;
  color: var(--color-gold-dark);
  font-style: italic;
}

.footer-bottom {
  grid-column: 1 / -1;
  padding-top: 1.5rem;
  margin-top: 1rem;
  border-top: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  font-size: 0.78rem;
  color: var(--color-text-muted);
  text-align: center;
}
.footer-icp {
  font-variant-numeric: tabular-nums;
}
.footer-trust {
  opacity: 0.7;
  max-width: 600px;
  margin: 0 auto;
}

/* ===== Utilities ===== */
.section-number {
  font-family: var(--font-heading);
  font-size: 4rem;
  font-weight: 700;
  line-height: 1;
  background: var(--gradient-gold);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  opacity: 0.3;
}

.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 2px;
  clip-path: polygon(12px 0, 100% 0, 100% 100%, 0 100%, 0 12px);
  padding: 1.5rem;
  transition: transform var(--transition-speed), box-shadow var(--transition-speed);
}
.card:hover,
.card:focus-within {
  transform: translateY(-3px);
  box-shadow: 0 6px 24px rgba(212,160,23,0.12);
  border-color: var(--color-gold-dark);
}

.tag {
  display: inline-flex;
  align-items: center;
  padding: 0.2rem 0.7rem;
  font-size: 0.72rem;
  font-weight: 600;
  border-radius: 1px;
  clip-path: polygon(4px 0, 100% 0, 100% 100%, 0 100%, 0 4px);
}

.gold-gradient { background: var(--gradient-gold); color: #1A0D0D; }
.red-gradient { background: var(--gradient-red); color: #fff; }

/* ===== Scroll Top Button ===== */
.scroll-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--gradient-gold);
  color: #1A0D0D;
  font-size: 1.25rem;
  border-radius: 2px;
  clip-path: polygon(6px 0, 100% 0, 100% 100%, 0 100%, 0 6px);
  z-index: 900;
  opacity: 0;
  transform: translateY(20px);
  pointer-events: none;
  transition: opacity var(--transition-speed), transform var(--transition-speed);
}
.scroll-top[data-visible] {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}
.scroll-top:hover,
.scroll-top:focus-visible {
  box-shadow: var(--shadow-gold);
  transform: translateY(-2px);
}
.scroll-top:focus-visible {
  outline: 2px solid #fff;
  outline-offset: 2px;
}

/* ===== Focus Visible ===== */
:focus-visible {
  outline: 2px solid var(--color-gold);
  outline-offset: 2px;
}

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

/* ===== Responsive ===== */
@media (max-width: 1024px) {
  .footer-inner {
    grid-template-columns: 1fr 1fr;
  }
  .footer-brand { grid-column: 1 / 2; }
  .footer-links { grid-column: 2 / 3; }
  .footer-contact { grid-column: 1 / -1; }
  .footer-bottom { grid-column: 1 / -1; }
}

@media (max-width: 767px) {
  .side-track { display: none; }

  .mobile-bar { display: flex; }

  .site-header {
    padding-top: 56px;
  }

  .site-footer {
    margin-left: 0;
    padding: 2rem 1rem 1rem;
  }

  .footer-inner {
    grid-template-columns: 1fr;
    gap: 1.5rem;
    text-align: center;
  }
  .footer-brand { grid-column: 1; }
  .footer-links { grid-column: 1; align-items: center; }
  .footer-link::after { left: 50%; transform: translateX(-50%); }
  .footer-contact { grid-column: 1; align-items: center; }
  .contact-item { justify-content: center; }

  .section-number {
    font-size: 3rem;
  }

  .scroll-top {
    bottom: 1.25rem;
    right: 1.25rem;
    width: 40px;
    height: 40px;
    font-size: 1.1rem;
  }
}

@media (min-width: 768px) {
  .mobile-bar { display: none; }
  .drawer, .drawer-overlay { display: none; }

  .site-footer {
    margin-left: var(--side-track-width);
  }
}

/* ===== Page Main Content Spacing ===== */
#main-content {
  margin-left: var(--side-track-width);
  min-height: calc(100vh - 200px);
}

@media (max-width: 767px) {
  #main-content {
    margin-left: 0;
    padding-top: 56px;
  }
}