:root {
      --bg: #0d0d0d;
      --bg2: #141414;
      --bg3: #1a1a1a;
      --border: #2a2a2a;
      --text: #d4d4d4;
      --muted: #666;
      --accent: #00ff88;
      --accent2: #ff6b35;
      --accent3: #4fc3f7;
      --heading: #f0f0f0;
      --code-bg: #111;
    }

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

    body {
      background: var(--bg);
      color: var(--text);
      font-family: 'IBM Plex Mono', monospace;
      font-size: 14px;
      line-height: 1.75;
    }

    /* HEADER */
    header {
      border-bottom: 1px solid var(--border);
      padding: 1.5rem 0;
      background: var(--bg);
      position: sticky;
      top: 0;
      z-index: 100;
    }
    .header-inner {
      max-width: 780px;
      margin: 0 auto;
      padding: 0 1.5rem;
      display: flex;
      align-items: center;
      justify-content: space-between;
    }
    .site-name {
      color: var(--accent);
      font-size: 1rem;
      font-weight: 600;
      text-decoration: none;
      letter-spacing: -0.03em;
    }
    .site-name span { color: var(--muted); }
    nav a {
      color: var(--muted);
      text-decoration: none;
      font-size: 0.8rem;
      margin-left: 1.5rem;
      transition: color 0.15s;
    }
    nav a:hover { color: var(--accent); }

    /* MAIN */
    main {
      max-width: 780px;
      margin: 0 auto;
      padding: 3rem 1.5rem 6rem;
    }

    /* META */
    .post-meta {
      color: var(--muted);
      font-size: 0.78rem;
      margin-bottom: 2.5rem;
      display: flex;
      gap: 1rem;
      align-items: center;
    }
    .tag {
      border: 1px solid var(--border);
      padding: 0.1rem 0.5rem;
      font-size: 0.72rem;
      color: var(--muted);
    }
    .tag.green { border-color: var(--accent); color: var(--accent); }

    /* TITLE */
    h1 {
      font-size: clamp(1.6rem, 4vw, 2.4rem);
      color: var(--heading);
      font-family: 'IBM Plex Mono', monospace;
      font-weight: 600;
      letter-spacing: -0.04em;
      line-height: 1.2;
      margin-bottom: 0.75rem;
    }
    h1 .dim { color: var(--muted); font-weight: 400; }

    .subtitle {
      color: var(--muted);
      font-size: 0.9rem;
      margin-bottom: 2rem;
      font-family: 'IBM Plex Sans', sans-serif;
    }

    /* DIVIDER */
    hr {
      border: none;
      border-top: 1px solid var(--border);
      margin: 2.5rem 0;
    }

    /* PROSE */
    p {
      font-family: 'IBM Plex Sans', sans-serif;
      font-size: 0.95rem;
      color: var(--text);
      margin-bottom: 1rem;
      line-height: 1.8;
    }

    h2 {
      font-family: 'IBM Plex Mono', monospace;
      font-size: 1rem;
      font-weight: 600;
      color: var(--accent);
      margin: 3rem 0 1rem;
      letter-spacing: -0.02em;
      display: flex;
      align-items: center;
      gap: 0.5rem;
    }
    h2::before {
      content: '##';
      color: var(--border);
    }

    h3 {
      font-family: 'IBM Plex Mono', monospace;
      font-size: 0.9rem;
      color: var(--heading);
      margin: 2rem 0 0.75rem;
      letter-spacing: -0.02em;
    }
    h3::before {
      content: '> ';
      color: var(--accent2);
    }

    /* CODE BLOCKS */
    .code-block {
      background: var(--code-bg);
      border: 1px solid var(--border);
      border-left: 3px solid var(--accent);
      padding: 1.25rem 1.5rem;
      margin: 1.25rem 0;
      overflow-x: auto;
      position: relative;
    }
    .code-block .label {
      position: absolute;
      top: 0.5rem;
      right: 0.75rem;
      font-size: 0.65rem;
      color: var(--muted);
      letter-spacing: 0.1em;
      text-transform: uppercase;
    }
    .code-block pre {
      font-family: 'IBM Plex Mono', monospace;
      font-size: 0.82rem;
      line-height: 1.7;
      color: var(--text);
    }
    .code-block .cmd { color: var(--accent3); }
    .code-block .cmt { color: var(--muted); font-style: italic; }
    .code-block .str { color: var(--accent); }
    .code-block .kw  { color: var(--accent2); }

    code {
      font-family: 'IBM Plex Mono', monospace;
      font-size: 0.82rem;
      background: var(--bg3);
      border: 1px solid var(--border);
      padding: 0.1rem 0.35rem;
      color: var(--accent3);
    }

    /* CALLOUT */
    .callout {
      background: var(--bg2);
      border: 1px solid var(--border);
      border-left: 3px solid var(--accent2);
      padding: 1rem 1.25rem;
      margin: 1.5rem 0;
      font-family: 'IBM Plex Sans', sans-serif;
      font-size: 0.88rem;
    }
    .callout .callout-title {
      font-family: 'IBM Plex Mono', monospace;
      color: var(--accent2);
      font-size: 0.75rem;
      margin-bottom: 0.4rem;
      letter-spacing: 0.08em;
      text-transform: uppercase;
    }

    /* CONCEPT TABLE */
    .concept-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 1px;
      background: var(--border);
      border: 1px solid var(--border);
      margin: 1.5rem 0;
    }
    .concept-cell {
      background: var(--bg2);
      padding: 1rem;
    }
    .concept-cell .term {
      font-family: 'IBM Plex Mono', monospace;
      color: var(--accent3);
      font-size: 0.82rem;
      font-weight: 600;
      margin-bottom: 0.3rem;
    }
    .concept-cell .def {
      font-family: 'IBM Plex Sans', sans-serif;
      font-size: 0.82rem;
      color: var(--muted);
      line-height: 1.5;
    }

    /* FLOW DIAGRAM */
    .flow {
      display: flex;
      align-items: center;
      gap: 0;
      margin: 1.5rem 0;
      overflow-x: auto;
      padding-bottom: 0.5rem;
    }
    .flow-step {
      background: var(--bg3);
      border: 1px solid var(--border);
      padding: 0.6rem 1rem;
      font-size: 0.78rem;
      white-space: nowrap;
      text-align: center;
    }
    .flow-step .step-label {
      color: var(--muted);
      font-size: 0.65rem;
      display: block;
      margin-bottom: 0.15rem;
      letter-spacing: 0.1em;
      text-transform: uppercase;
    }
    .flow-step .step-name {
      color: var(--accent);
      font-weight: 600;
    }
    .flow-arrow {
      color: var(--accent2);
      padding: 0 0.5rem;
      font-size: 1rem;
      flex-shrink: 0;
    }

    /* TOC */
    .toc {
      background: var(--bg2);
      border: 1px solid var(--border);
      padding: 1.25rem 1.5rem;
      margin: 2rem 0 2.5rem;
    }
    .toc-title {
      font-size: 0.72rem;
      color: var(--muted);
      letter-spacing: 0.1em;
      text-transform: uppercase;
      margin-bottom: 0.75rem;
    }
    .toc a {
      display: block;
      color: var(--text);
      text-decoration: none;
      font-size: 0.82rem;
      padding: 0.15rem 0;
      transition: color 0.15s;
    }
    .toc a:hover { color: var(--accent); }
    .toc a::before { content: '→ '; color: var(--muted); }

    /* FOOTER */
    footer {
      border-top: 1px solid var(--border);
      max-width: 780px;
      margin: 0 auto;
      padding: 2rem 1.5rem;
      color: var(--muted);
      font-size: 0.75rem;
      display: flex;
      justify-content: space-between;
    }

    /* TERMINAL INTRO */
    .terminal-intro {
      background: var(--code-bg);
      border: 1px solid var(--border);
      padding: 1.5rem;
      margin-bottom: 2.5rem;
      font-size: 0.82rem;
      line-height: 2;
    }
    .terminal-intro .prompt { color: var(--accent); }
    .terminal-intro .cmd-text { color: var(--text); }
    .terminal-intro .output { color: var(--muted); padding-left: 1rem; }

    @media (max-width: 540px) {
      .concept-grid { grid-template-columns: 1fr; }
      .flow { flex-direction: column; align-items: flex-start; }
      .flow-arrow { transform: rotate(90deg); }
    }