:root{
  /* LIGHT (default) */
  --bg-base: #f4f7fb;
  --grad1: rgba(11,102,195,.14);
  --grad2: rgba(0,170,120,.10);

  --card: #ffffff;
  --text: #0b0f14;
  --muted: #42546a;
  --link: #0b66c3;

  --border: rgba(0,0,0,.10);
  --shadow: 0 10px 30px rgba(0,0,0,.12);

  --radius: 14px;
  --maxw: 980px;

  --note-border: rgba(11,102,195,.45);
  --note-bg: rgba(11,102,195,.06);

  --inline-code-bg: rgba(0,0,0,.05);
  --inline-code-border: rgba(0,0,0,.10);
}

body[data-theme="dark"]{
  /* DARK */
  --bg-base: #0b0f14;
  --grad1: rgba(124,196,255,.18);
  --grad2: rgba(88,255,192,.10);

  --card: #101826;
  --text: #e7eef7;
  --muted: #a9b6c7;
  --link: #7cc4ff;

  --border: rgba(255,255,255,.08);
  --shadow: 0 10px 30px rgba(0,0,0,.35);

  --note-border: rgba(124,196,255,.45);
  --note-bg: rgba(124,196,255,.06);

  --inline-code-bg: rgba(0,0,0,.22);
  --inline-code-border: rgba(255,255,255,.08);
}

*{ box-sizing:border-box; }

body{
  margin:0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji","Segoe UI Emoji";
  background:
    radial-gradient(1200px 600px at 20% -10%, var(--grad1), transparent 60%),
    radial-gradient(900px 500px at 100% 0%, var(--grad2), transparent 55%),
    var(--bg-base);
  color: var(--text);
  line-height: 1.55;
}

a{ color: var(--link); text-decoration:none; }
a:hover{ text-decoration:underline; }

.wrap{
  max-width: var(--maxw);
  margin: 36px auto;
  padding: 0 18px 56px;
}

.card{
  background: linear-gradient(180deg, rgba(255,255,255,.55), rgba(255,255,255,.35));
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 26px 22px;
}

body[data-theme="dark"] .card{
  background: linear-gradient(180deg, rgba(255,255,255,.04), rgba(255,255,255,.02));
}

header h1{
  margin: 0 0 6px;
  font-size: 28px;
  letter-spacing: .2px;
}

header p{
  margin: 6px 0 0;
  color: var(--muted);
  font-size: 14px;
}

.toc{
  margin: 18px 0 22px;
  padding: 14px 14px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: rgba(255,255,255,.45);
}

body[data-theme="dark"] .toc{
  background: rgba(0,0,0,.20);
}

.toc strong{ display:block; margin-bottom: 8px; }
.toc ul{ margin:0; padding-left: 18px; }
.toc li{ margin: 4px 0; }

h2{
  margin: 22px 0 10px;
  font-size: 18px;
  letter-spacing: .2px;
  padding-top: 8px;
  border-top: 1px solid var(--border);
}

h3{
  margin: 14px 0 6px;
  font-size: 15px;
  color: var(--text);
}

p{ margin: 8px 0; }
ul{ margin: 8px 0; padding-left: 20px; }
li{ margin: 4px 0; }

.note{
  color: var(--muted);
  font-size: 13px;
  border-left: 3px solid var(--note-border);
  padding: 8px 10px;
  background: var(--note-bg);
  border-radius: 10px;
  margin: 10px 0;
}

.pill{
  display:inline-block;
  font-size: 12px;
  color: var(--muted);
  border: 1px solid var(--border);
  background: rgba(255,255,255,.55);
  padding: 4px 10px;
  border-radius: 999px;
  margin-top: 10px;
}

body[data-theme="dark"] .pill{
  background: rgba(0,0,0,.18);
}

footer{
  margin-top: 18px;
  color: var(--muted);
  font-size: 12px;
  text-align: center;
}

code.inline{
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  font-size: 0.95em;
  padding: 1px 6px;
  border-radius: 8px;
  border: 1px solid var(--inline-code-border);
  background: var(--inline-code-bg);
  color: var(--text);
}