@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:wght@300;400;600;700&family=Libre+Baskerville:ital,wght@0,400;0,700;1,400&display=swap');

  :root {
    --bg: #0e0b1a;
    --surface: #16122a;
    --surface2: #1e1a36;
    --border: #2e2850;
    --text: #dcd8f8;
    --text-dim: #7870a8;
    --purple: #a090e8;
    --purple-dim: #1e1a36;
    --blue: #7cb8f0;
    --blue-dim: #0e1828;
    --green: #98c870;
    --green-dim: #0e1a0e;
    --red: #f07878;
    --red-dim: #2a1020;
    --orange: #e8a060;
    --orange-dim: #251610;
    --cyan: #60c8c0;
    --cyan-dim: #0a1e1e;
    --yellow: #d8b860;
    --yellow-dim: #20180a;
    --magenta: #e060a8;
    --magenta-dim: #280e20;
  }

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

  body {
    background: var(--bg);
    color: var(--text);
    font-family: 'Libre Baskerville', Georgia, serif;
    line-height: 1.7;
    min-height: 100vh;
  }

  /* Purple nebula background */
  body::before {
    content: '';
    position: fixed; inset: 0; pointer-events: none; z-index: 0;
    background:
      radial-gradient(ellipse at 15% 20%, rgba(120,80,220,0.15) 0%, transparent 55%),
      radial-gradient(ellipse at 85% 75%, rgba(80,50,180,0.12) 0%, transparent 50%),
      radial-gradient(ellipse at 55% 5%,  rgba(160,100,240,0.08) 0%, transparent 40%);
  }

  .content { position: relative; z-index: 1; }

  /* Header — Emacs minibuffer aesthetic */
  header {
    background: #1c1636;
    color: white;
    padding: 0;
    border-bottom: 3px solid #3a3060;
  }

  .header-top {
    padding: 2.5rem 3rem 1.5rem;
    display: flex; align-items: flex-start; gap: 2rem;
    flex-wrap: wrap;
  }

  .logo {
    font-family: 'IBM Plex Mono', monospace;
    font-size: 3rem;
    font-weight: 700;
    letter-spacing: -3px;
    line-height: 1;
    color: var(--text);
    text-shadow: 0 0 30px rgba(160,144,232,0.5);
  }
  .logo em { color: var(--purple); font-style: normal; }

  .header-meta {
    border-left: 2px solid rgba(160,144,232,0.3);
    padding-left: 2rem;
  }
  .header-meta h1 { font-size: 1.3rem; font-weight: 700; font-style: italic; color: var(--text); }
  .header-meta p { font-size: 0.9rem; color: var(--text-dim); font-family: 'IBM Plex Mono', monospace; }

  /* Minibuffer bar */
  .minibuffer {
    background: #100e20;
    padding: 0.4rem 3rem;
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.8rem;
    color: var(--text-dim);
    display: flex; gap: 2rem; align-items: center;
    border-top: 1px solid #2a2448;
  }
  .minibuffer .mb-key { color: var(--purple); }
  .minibuffer .mb-sep { color: #2e2850; }

  .container { max-width: 1100px; margin: 0 auto; padding: 3rem 2rem; }

  /* Section */
  .section { margin-bottom: 3.5rem; }

  .section-title {
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.65rem;
    letter-spacing: 4px;
    text-transform: uppercase;
    color: var(--text-dim);
    margin-bottom: 0.75rem;
    display: flex; align-items: center; gap: 1rem;
  }
  .section-title::after { content: ''; flex: 1; height: 1px; background: var(--border); }

  .section-header {
    font-size: 1.6rem;
    font-weight: 700;
    font-style: italic;
    margin-bottom: 1.5rem;
    color: var(--purple);
    text-shadow: 0 0 20px rgba(160,144,232,0.3);
  }

  /* Notation explanation */
  .notation {
    background: var(--purple-dim);
    border: 1px solid #3a3060;
    border-left: 4px solid var(--purple);
    border-radius: 0 8px 8px 0;
    padding: 1.25rem 1.5rem;
    margin-bottom: 1.5rem;
    font-size: 0.9rem;
  }
  .notation strong { color: var(--purple); font-family: 'IBM Plex Mono', monospace; }
  .notation p { margin-top: 0.5rem; color: var(--text-dim); }

  /* Grid */
  .grid { display: grid; gap: 1rem; }
  .grid-2 { grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); }
  .grid-3 { grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }

  /* Card */
  .card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: 2px 3px 0 rgba(0,0,0,0.3);
    transition: transform 0.15s, box-shadow 0.15s, border-color 0.15s;
  }
  .card:hover { transform: translateY(-2px); box-shadow: 3px 6px 0 rgba(0,0,0,0.4); border-color: var(--purple); }

  .card-title {
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.75rem; font-weight: 700; letter-spacing: 1.5px;
    text-transform: uppercase; margin-bottom: 1rem;
    display: flex; align-items: center; gap: 0.5rem;
    padding-bottom: 0.75rem;
    border-bottom: 1px solid var(--border);
    color: var(--text);
  }

  .stripe { width: 12px; height: 4px; border-radius: 2px; flex-shrink: 0; }
  .stripe.purple { background: var(--purple); }
  .stripe.blue { background: var(--blue); }
  .stripe.green { background: var(--green); }
  .stripe.red { background: var(--red); }
  .stripe.orange { background: var(--orange); }
  .stripe.cyan { background: var(--cyan); }
  .stripe.yellow { background: var(--yellow); }
  .stripe.magenta { background: var(--magenta); }

  /* Key-value rows */
  .kv { display: flex; flex-direction: column; gap: 0.4rem; }
  .kv-row {
    display: flex; align-items: center; justify-content: space-between;
    padding: 0.45rem 0.6rem;
    border-radius: 4px;
    font-size: 0.88rem;
    gap: 1rem;
    transition: background 0.1s;
  }
  .kv-row:hover { background: var(--surface2); }

  kbd {
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.78rem;
    font-weight: 600;
    padding: 0.2rem 0.55rem;
    border-radius: 4px;
    white-space: nowrap;
    flex-shrink: 0;
    border: 1px solid;
  }
  kbd.purple { color: var(--purple); background: var(--purple-dim); border-color: #b8b4f0; }
  kbd.blue { color: var(--blue); background: var(--blue-dim); border-color: #aad0f0; }
  kbd.green { color: var(--green); background: var(--green-dim); border-color: #c4d488; }
  kbd.red { color: var(--red); background: var(--red-dim); border-color: #f0b0b0; }
  kbd.orange { color: var(--orange); background: var(--orange-dim); border-color: #e8b098; }
  kbd.cyan { color: var(--cyan); background: var(--cyan-dim); border-color: #88ccc8; }
  kbd.yellow { color: var(--yellow); background: var(--yellow-dim); border-color: #d8c070; }
  kbd.magenta { color: var(--magenta); background: var(--magenta-dim); border-color: #e8a0c4; }

  .desc { color: var(--text-dim); font-family: 'Libre Baskerville', serif; font-size: 0.85rem; flex: 1; }

  /* Terminal */
  .terminal {
    background: #080612;
    border: 1px solid #2a2448;
    border-radius: 8px;
    overflow: hidden;
    margin-bottom: 1rem;
    box-shadow: 4px 6px 0 rgba(0,0,0,0.4);
  }
  .term-bar {
    background: #100e20;
    padding: 0.6rem 1rem;
    display: flex; align-items: center; gap: 0.5rem;
    border-bottom: 1px solid #2a2448;
  }
  .term-dot { width: 11px; height: 11px; border-radius: 50%; }
  .term-dot:nth-child(1) { background: #ff5f57; }
  .term-dot:nth-child(2) { background: #febc2e; }
  .term-dot:nth-child(3) { background: #28c840; }
  .term-bar span { color: #5a5080; font-size: 0.78rem; margin-left: 0.5rem; font-family: 'IBM Plex Mono', monospace; }
  .term-body {
    padding: 1.5rem; font-family: 'IBM Plex Mono', monospace; font-size: 0.82rem;
    line-height: 1.9; color: #b0a8e0;
  }
  .term-cmd { color: var(--purple); }
  .term-out { color: #5a5080; }
  .term-comment { color: #302848; }
  .term-key { color: #c4b8ff; }
  .term-result { color: var(--green); }
  .cursor {
    display: inline-block; width: 8px; height: 1em;
    background: #6c71c4; opacity: 0.9;
    animation: blink 1s step-end infinite; vertical-align: text-bottom;
  }
  @keyframes blink { 50% { opacity: 0; } }

  /* Tip */
  .tip {
    background: #0e1a0e;
    border: 1px solid #1e3a1e;
    border-radius: 6px;
    padding: 0.9rem 1.25rem;
    font-size: 0.88rem;
    display: flex; gap: 0.75rem; align-items: flex-start;
    margin-top: 1rem;
    font-family: 'Libre Baskerville', serif;
  }
  .tip-icon { flex-shrink: 0; font-size: 1rem; }
  .tip p { color: var(--text-dim); }
  .tip p strong { color: var(--text); }
  .tip.warn { background: #200e08; border-color: #3a1e10; }
  .tip.info { background: #0a1220; border-color: #1a2840; }
  .tip.purple { background: var(--purple-dim); border-color: #3a3060; }

  /* Mode display */
  .modeline {
    background: #1c1636;
    color: var(--text);
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.8rem;
    padding: 0.4rem 1rem;
    border-radius: 6px;
    margin-bottom: 1.5rem;
    display: flex; gap: 1rem; flex-wrap: wrap;
    align-items: center;
    border: 1px solid #3a3060;
  }
  .modeline-item { opacity: 0.7; }
  .modeline-item strong { opacity: 1; color: var(--purple); }

  /* Big concept */
  .concept-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 0.75rem; margin-bottom: 1.5rem; }
  .concept-node {
    border-radius: 8px; padding: 1.2rem 1rem; text-align: center;
    border: 2px solid;
  }
  .concept-node .cn-key {
    font-family: 'IBM Plex Mono', monospace; font-size: 1.3rem; font-weight: 700;
    margin-bottom: 0.3rem;
  }
  .concept-node .cn-name { font-size: 0.85rem; font-weight: 700; margin-bottom: 0.2rem; }
  .concept-node .cn-desc { font-size: 0.75rem; color: var(--text-dim); font-family: 'IBM Plex Mono', monospace; }
  .concept-node.C { background: var(--blue-dim); border-color: #1a3858; color: var(--blue); }
  .concept-node.M { background: var(--purple-dim); border-color: #3a3060; color: var(--purple); }
  .concept-node.SPC { background: var(--green-dim); border-color: #1a3020; color: var(--green); }
  .concept-node.RET { background: var(--yellow-dim); border-color: #302010; color: var(--yellow); }

  footer {
    border-top: 2px solid #2a2448;
    background: #100e20;
    padding: 1.5rem 3rem;
    text-align: center;
    color: var(--text-dim);
    font-family: 'IBM Plex Mono', monospace;
    font-size: 0.8rem;
  }
  footer span { color: var(--purple); }