/* ── Design Tokens ── */
:root {
  --color-bg: #0A0E17;
  --color-surface: rgba(16, 23, 40, 0.85);
  --color-border: rgba(48, 105, 167, 0.25);
  --color-border-hover: rgba(61, 127, 192, 0.5);
  --color-text-primary: #E8EDF4;
  --color-text-secondary: #8A9BB5;
  --color-text-tertiary: #5A6E87;
  --color-primary: #3069A7;
  --color-primary-hover: #3D7FC0;
  --color-glow: rgba(48, 105, 167, 0.08);
  --color-glow-md: rgba(48, 105, 167, 0.2);
  --color-glow-strong: rgba(48, 105, 167, 0.4);
  --color-link-bg: rgba(48, 105, 167, 0.08);
  --color-link-bg-hover: rgba(48, 105, 167, 0.2);
  --color-link-border: rgba(48, 105, 167, 0.12);
  --color-tooltip-bg: rgba(48, 105, 167, 0.95);

  --font-sans: 'DM Sans', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-mono: 'JetBrains Mono', 'Menlo', monospace;

  --fs-name: 1.8rem;
  --fs-subtitle: 0.95rem;
  --fs-link: 0.8rem;
  --fs-footer: 0.75rem;
  --fs-tooltip: 0.7rem;

  --radius-card: 20px;
  --radius-link: 12px;
  --radius-tooltip: 6px;
  --radius-logo: 16px;

  --space-card-y: 48px;
  --space-card-x: 40px;
  --space-card-bottom: 32px;

  --card-shadow: 0 0 40px rgba(48, 105, 167, 0.08), 0 20px 60px rgba(0, 0, 0, 0.4);
  --logo-filter: drop-shadow(0 0 12px rgba(48, 105, 167, 0.4));
}

/* ── Light Theme ── */
[data-theme="light"] {
  --color-bg: #F7F8FA;
  --color-surface: #FFFFFF;
  --color-border: #E4E7EC;
  --color-border-hover: rgba(48, 105, 167, 0.4);
  --color-text-primary: #111827;
  --color-text-secondary: #6B7280;
  --color-text-tertiary: #9CA3AF;
  --color-link-bg: rgba(48, 105, 167, 0.06);
  --color-link-bg-hover: rgba(48, 105, 167, 0.12);
  --color-link-border: #E4E7EC;
  --color-tooltip-bg: #3069A7;
  --card-shadow: 0 4px 24px rgba(0, 0, 0, 0.08);
  --logo-filter: none;
}
[data-theme="light"] #card {
  -webkit-backdrop-filter: none;
  backdrop-filter: none;
}
[data-theme="light"] #particles {
  display: none;
}

/* ── Theme toggle ── */
.theme-toggle {
  position: absolute;
  top: 16px;
  right: 16px;
  background: none;
  border: none;
  color: var(--color-text-tertiary);
  font-size: 1.1rem;
  cursor: pointer;
  padding: 4px;
  line-height: 1;
  transition: color 0.3s ease;
}
.theme-toggle:hover {
  color: var(--color-primary-hover);
}
.theme-toggle:focus-visible {
  outline: 2px solid var(--color-primary-hover);
  outline-offset: 2px;
  border-radius: 4px;
}

/* ── Reset ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { height: 100%; }
body {
  min-height: 100%;
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text-primary);
  overflow-x: hidden;
}

/* ── Particle canvas ── */
#particles {
  position: fixed; inset: 0;
  z-index: 0;
  pointer-events: none;
}

/* ── Page layout ── */
#page {
  position: relative; z-index: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 20px;
}

/* ── Card ── */
#card {
  position: relative;
  width: 100%;
  max-width: 520px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-card);
  padding: var(--space-card-y) var(--space-card-x) var(--space-card-bottom);
  text-align: center;
  -webkit-backdrop-filter: blur(20px);
  backdrop-filter: blur(20px);
  box-shadow: var(--card-shadow);
}

/* ── Header ── */
#card header {
  margin-bottom: 32px;
}
#card header img {
  width: 80px; height: 80px;
  border-radius: var(--radius-logo);
  margin-bottom: 16px;
  filter: var(--logo-filter);
}
#card h1 {
  font-size: var(--fs-name);
  font-weight: 600;
  color: var(--color-text-primary);
  letter-spacing: 0.05em;
}
.subtitle {
  margin-top: 6px;
  font-size: var(--fs-subtitle);
  font-weight: 400;
  color: var(--color-text-secondary);
  letter-spacing: 0.1em;
}

/* ── Links grid ── */
.links {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(90px, 1fr));
  gap: 12px;
  margin-bottom: 32px;
}
.link-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  padding: 16px 8px;
  border-radius: var(--radius-link);
  background: var(--color-link-bg);
  border: 1px solid var(--color-link-border);
  color: var(--color-text-secondary);
  text-decoration: none;
  font-size: var(--fs-link);
  transition: all 0.3s ease;
  position: relative;
  cursor: pointer;
}
.link-item i {
  font-size: 1.4rem;
  transition: all 0.3s ease;
}
.link-item:hover {
  background: var(--color-link-bg-hover);
  border-color: var(--color-border-hover);
  color: var(--color-text-primary);
  transform: translateY(-2px);
  box-shadow: 0 4px 20px var(--color-glow-md);
}
.link-item:hover i {
  color: var(--color-primary-hover);
}
.link-item:active {
  transform: translateY(0);
}
.link-item:focus-visible {
  outline: 2px solid var(--color-primary-hover);
  outline-offset: 2px;
}

/* ── Tooltip ── */
.link-item[data-tooltip]:hover::after,
.link-item[data-tooltip]:focus::after {
  content: attr(data-tooltip);
  position: absolute;
  bottom: calc(100% + 8px);
  left: 50%;
  transform: translateX(-50%);
  padding: 4px 10px;
  background: var(--color-tooltip-bg);
  color: #fff;
  font-size: var(--fs-tooltip);
  font-family: var(--font-mono);
  border-radius: var(--radius-tooltip);
  white-space: nowrap;
  pointer-events: none;
  z-index: 10;
}

/* ── QRCode container ── */
#link-wechat .qrcode-container {
  display: none;
  position: absolute;
  top: calc(100% + 12px);
  left: 50%;
  transform: translateX(-50%);
  padding: 8px;
  background: #fff;
  border-radius: 8px;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.4);
  z-index: 20;
}
#link-wechat .qrcode-container.active {
  display: block;
}

/* ── Footer ── */
.footer {
  font-size: var(--fs-footer);
  color: var(--color-text-tertiary);
  line-height: 1.8;
}
.footer a {
  color: var(--color-text-secondary);
  text-decoration: none;
  transition: color 0.2s;
}
.footer a:hover {
  color: var(--color-primary-hover);
}
.footer a:focus-visible {
  outline: 2px solid var(--color-primary-hover);
  outline-offset: 2px;
}
#beian_logo {
  vertical-align: middle;
  margin: 0 2px;
  display: none;
}
.footer-br-hide {
  display: none;
}

/* ── Mobile: hide tooltips, WeChat direct link ── */
@media (hover: none) {
  .link-item[data-tooltip]:hover::after,
  .link-item[data-tooltip]:focus::after {
    display: none;
  }
}

/* ── Responsive ── */
@media (max-width: 560px) {
  :root {
    --space-card-y: 36px;
    --space-card-x: 24px;
    --space-card-bottom: 24px;
    --radius-card: 16px;
  }
  #card h1 { font-size: 1.5rem; }
  .links {
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
  }
  .link-item {
    padding: 12px 4px;
    font-size: 0.7rem;
    min-height: 44px;
  }
  .link-item i { font-size: 1.2rem; }
}
@media (max-width: 360px) {
  .links {
    grid-template-columns: repeat(3, 1fr);
  }
}