:root,
:root[data-mode="light"] {
  --bg: #f5f6f9;
  --bg-2: #eceff4;
  --paper: #ffffff;
  --text: #121417;
  --muted: #5f6875;
  --stroke: rgba(25, 34, 48, 0.14);
  --accent: #2f5ea8;
  --shadow: 0 10px 26px rgba(28, 38, 54, 0.1);
}

:root[data-mode="dark"] {
  --bg: #121316;
  --bg-2: #1a1c21;
  --paper: #1f232b;
  --text: #edf2fb;
  --muted: #b8c0cd;
  --stroke: rgba(236, 242, 250, 0.16);
  --accent: #8bb2ff;
  --shadow: 0 14px 30px rgba(0, 0, 0, 0.45);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-mode]) {
    --bg: #121316;
    --bg-2: #1a1c21;
    --paper: #1f232b;
    --text: #edf2fb;
    --muted: #b8c0cd;
    --stroke: rgba(236, 242, 250, 0.16);
    --accent: #8bb2ff;
    --shadow: 0 14px 30px rgba(0, 0, 0, 0.45);
  }
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: linear-gradient(180deg, var(--bg) 0%, var(--bg-2) 60%, var(--bg) 100%);
  color: var(--text);
  line-height: 1.7;
}

.bg {
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background: linear-gradient(180deg, color-mix(in srgb, var(--bg) 88%, transparent) 0%, transparent 100%);
}

.wrap {
  max-width: 940px;
  margin: 0 auto;
  padding: 1rem 1rem 2.2rem;
}

.topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.8rem;
  border: 1px solid var(--stroke);
  border-radius: 14px;
  padding: 0.5rem 0.7rem;
  background: color-mix(in srgb, var(--paper) 88%, transparent);
  box-shadow: var(--shadow);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--text);
  text-decoration: none;
  font-weight: 700;
}

.brand-mark {
  width: 1.85rem;
  height: 1.85rem;
  border-radius: 0.45rem;
  display: grid;
  place-items: center;
  font-weight: 700;
  color: #fff;
  background: var(--accent);
}

.top-links {
  display: inline-flex;
  gap: 0.4rem;
  flex-wrap: wrap;
  align-items: center;
}

.top-links a,
.mode-toggle {
  text-decoration: none;
  color: var(--muted);
  border: 1px solid var(--stroke);
  border-radius: 999px;
  padding: 0.38rem 0.68rem;
  font-size: 0.82rem;
  font-weight: 600;
  background: color-mix(in srgb, var(--paper) 80%, transparent);
}

.top-links a.active {
  color: var(--text);
  background: var(--paper);
}

.mode-toggle {
  cursor: pointer;
}

.card {
  margin-top: 0.95rem;
  border: 1px solid var(--stroke);
  border-radius: 16px;
  padding: 1.2rem 1rem;
  background: var(--paper);
  box-shadow: var(--shadow);
}

h1,
h2 {
  margin: 0;
  line-height: 1.25;
  font-family: inherit;
}

h1 {
  font-size: 1.9rem;
  font-weight: 800;
}

h2 {
  margin-top: 1.2rem;
  font-size: 1.12rem;
  font-weight: 700;
}

.meta {
  color: var(--muted);
  margin: 0.5rem 0 0.95rem;
  font-size: 0.92rem;
}

p,
li {
  font-size: 0.98rem;
  color: var(--text);
}

ul {
  margin: 0.45rem 0 0.1rem 1.15rem;
}

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

.footer-note {
  margin-top: 1rem;
  color: var(--muted);
  font-size: 0.88rem;
}

@media (max-width: 640px) {
  .wrap { padding: 0.8rem 0.8rem 2rem; }
  .topbar { border-radius: 12px; }
  .card { padding: 1rem 0.85rem; border-radius: 14px; }
  h1 { font-size: 1.62rem; }
}

@media print {
  body {
    background: #fff;
    color: #000;
  }

  .bg,
  .topbar,
  .mode-toggle {
    display: none !important;
  }

  .wrap {
    max-width: 100%;
    padding: 0;
    margin: 0;
  }

  .card {
    box-shadow: none;
    border: 0;
    margin: 0;
    padding: 0;
  }

  a {
    color: #000;
    text-decoration: underline;
  }
}