:root {
  color-scheme: dark;
  --bg: #0b0b0c;
  --bg-soft: #1a1a1d;
  --fg: #ffffff;
  --fg-dim: rgba(255, 255, 255, 0.65);
  --fg-subtle: rgba(255, 255, 255, 0.4);
  --accent: #4da3ff;
  --accent-soft: rgba(77, 163, 255, 0.16);
  --surface: rgba(30, 30, 32, 0.72);
  --surface-hover: rgba(50, 50, 54, 0.82);
  --border: rgba(255, 255, 255, 0.08);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
}

body {
  min-height: 100dvh;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, "Hiragino Sans",
    "Noto Sans JP", sans-serif;
  background: radial-gradient(ellipse at top, #1a1a1f 0%, var(--bg) 60%) fixed;
  color: var(--fg);
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent);
}

#app {
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  height: 56px;
  background: rgba(11, 11, 12, 0.7);
  backdrop-filter: blur(16px) saturate(140%);
  -webkit-backdrop-filter: blur(16px) saturate(140%);
  border-bottom: 1px solid var(--border);
}

.site-header__inner {
  max-width: 1200px;
  margin: 0 auto;
  height: 100%;
  padding: 0 16px;
  padding-left: max(16px, env(safe-area-inset-left));
  padding-right: max(16px, env(safe-area-inset-right));
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--fg);
  text-decoration: none;
  font-weight: 700;
  font-size: 17px;
  letter-spacing: 0.01em;
}

.brand__dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 10px rgba(77, 163, 255, 0.8);
}

.lang-switcher {
  appearance: none;
  border: 1px solid rgba(255, 255, 255, 0.18);
  background: transparent;
  color: var(--fg);
  padding: 6px 14px;
  border-radius: 999px;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.05em;
  cursor: pointer;
  transition: background-color 120ms ease, border-color 120ms ease;
}

.lang-switcher:hover {
  background: rgba(255, 255, 255, 0.06);
  border-color: rgba(255, 255, 255, 0.3);
}

.site-main {
  flex: 1;
}

.doc {
  max-width: 760px;
  margin: 0 auto;
  padding: 48px 20px 96px;
  user-select: text;
  -webkit-user-select: text;
}

.doc h1 {
  font-size: clamp(24px, 4vw, 32px);
  font-weight: 800;
  letter-spacing: -0.01em;
  margin: 0 0 8px;
}

.doc .doc__updated {
  color: var(--fg-subtle);
  font-size: 13px;
  margin: 0 0 32px;
}

.doc h2 {
  font-size: 18px;
  font-weight: 700;
  margin: 32px 0 8px;
}

.doc p,
.doc li {
  color: var(--fg-dim);
  font-size: 15px;
  line-height: 1.7;
}

.doc ul,
.doc ol {
  padding-left: 1.4em;
}

.doc a {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 2px;
}

.doc__back {
  display: inline-block;
  margin-top: 40px;
  font-size: 14px;
}

.doc--center {
  text-align: center;
}

.doc--center .doc__back {
  margin-top: 24px;
}

.site-footer {
  padding: 28px 16px calc(28px + env(safe-area-inset-bottom));
  border-top: 1px solid var(--border);
  color: var(--fg-subtle);
  font-size: 13px;
}

.site-footer__inner {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
}

.site-footer__nav {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
  justify-content: center;
}

.site-footer__nav a {
  color: var(--fg-dim);
  text-decoration: none;
  transition: color 120ms ease;
}

.site-footer__nav a:hover {
  color: var(--fg);
}