:root {
  --bg: #ffffff;
  --surface: #f5f6f8;
  --text: #16181d;
  --muted: #5c6270;
  --border: #e2e5ea;
  --accent: #2665eb;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1115;
    --surface: #171a20;
    --text: #e9ebef;
    --muted: #9aa1ae;
    --border: #262b33;
    --accent: #6f9bff;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  padding: 0 20px 72px;
  background: var(--bg);
  color: var(--text);
  font: 17px/1.65 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  -webkit-text-size-adjust: 100%;
}

.wrap { max-width: 680px; margin: 0 auto; }

header {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 40px 0 8px;
}

.mark {
  width: 44px;
  height: 44px;
  border-radius: 10px;
  background: linear-gradient(180deg, #4382ff, #1243cc);
  display: grid;
  place-items: center;
  flex: none;
}

.mark span {
  display: block;
  width: 24px;
  height: 16px;
  background:
    repeating-linear-gradient(90deg, #fff 0 3px, transparent 3px 5px),
    repeating-linear-gradient(90deg, #fff 0 1px, transparent 1px 4px);
  background-size: 100% 100%;
}

h1 { font-size: 1.6rem; margin: 0; letter-spacing: -0.02em; }
h2 { font-size: 1.15rem; margin: 2.2em 0 0.5em; letter-spacing: -0.01em; }
h3 { font-size: 1rem; margin: 1.6em 0 0.3em; }

p, li { color: var(--text); }
.muted { color: var(--muted); }
.small { font-size: 0.9rem; }

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

nav {
  display: flex;
  gap: 18px;
  padding: 14px 0 6px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 8px;
  font-size: 0.95rem;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 18px 20px;
  margin: 20px 0;
}

.card p:first-child { margin-top: 0; }
.card p:last-child { margin-bottom: 0; }

ul { padding-left: 1.2em; }
li { margin: 0.35em 0; }

footer {
  margin-top: 56px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.88rem;
}