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

  @media print {
    @page { size: A4; margin: 8mm; }
  }

  :root {
    --bg:         #0A0F1E;
    --surface:    rgba(26,32,53,0.82);
    --border:     rgba(99,102,241,0.18);
    --dim:        #5B6478;
    --muted:      #94A3B8;
    --text:       #C9D1D9;
    --text-bright:#F0EDE6;

    --blue:       #58A6FF;
    --blue-dim:   #1F3A5F;
    --green:      #3FB950;
    --green-dim:  #1A3A1A;
    --amber:      #E3B341;
    --amber-dim:  #3D2E0A;
    --purple:     #BC8CFF;
    --purple-dim: #2A1A4A;
    --cyan:       #39D4C4;
    --cyan-dim:   #0D2E2B;
    --red:        #F85149;
    --red-dim:    #3A0D0D;
    --accent:     #6366F1;
    --accent2:    #14B8A6;
  }

  html { scroll-behavior: smooth; }

  html, body {
    background: var(--bg);
    color: var(--text);
    font-family: 'JetBrains Mono', 'Courier New', monospace;
    font-size: 13.5px;
    line-height: 1.6;
    -webkit-print-color-adjust: exact;
    print-color-adjust: exact;
  }

  body {
    background:
      radial-gradient(circle at 85% 0%, rgba(99,102,241,0.10) 0%, transparent 45%),
      radial-gradient(circle at 0% 30%, rgba(20,184,166,0.06) 0%, transparent 40%),
      var(--bg);
    background-attachment: fixed;
  }

  ::selection { background: rgba(99,102,241,0.35); color: var(--text-bright); }
  ::-webkit-scrollbar { width: 10px; height: 10px; }
  ::-webkit-scrollbar-track { background: var(--bg); }
  ::-webkit-scrollbar-thumb { background: rgba(99,102,241,0.35); border-radius: 6px; }
  ::-webkit-scrollbar-thumb:hover { background: rgba(99,102,241,0.55); }

  .page { max-width: 1180px; margin: 0 auto; padding: 22px 20px 80px; }

  /* ── HEADER ──────────────────────────────────────────── */
  .header {
    border-bottom: 2px solid var(--border);
    padding-bottom: 14px;
    margin-bottom: 16px;
  }
  .header-top { display: flex; align-items: baseline; gap: 10px; }
  .prompt { color: var(--green); font-weight: 700; font-size: 20px; }
  .title { font-size: 24px; font-weight: 800; color: var(--text-bright); letter-spacing: -0.3px; }
  .subtitle { color: var(--muted); font-size: 12.5px; margin-top: 4px; padding-left: 18px; }

  .section-label {
    font-size: 11.4px;
    font-weight: 600;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--dim);
    margin-bottom: 5px;
    padding-left: 2px;
  }

  /* ── QUICK REF CARDS ─────────────────────────────────── */
  .cards-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 8px;
    margin-bottom: 14px;
  }
  .card {
    background: var(--surface);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 9px 11px;
    border-left-width: 3px;
    transition: transform .22s, border-color .22s, box-shadow .22s;
  }
  .card:hover {
    transform: translateY(-3px);
    box-shadow: 0 12px 26px rgba(0,0,0,0.28);
  }
  .card-name { font-weight: 700; font-size: 13.5px; margin-bottom: 3px; }
  .card-desc { font-size: 11.4px; color: var(--muted); line-height: 1.5; }

  .card-source  { border-left-color: var(--cyan);   }
  .card-source  .card-name { color: var(--cyan);   }
  .card-inter   { border-left-color: var(--blue);   }
  .card-inter   .card-name { color: var(--blue);   }
  .card-term    { border-left-color: var(--amber);  }
  .card-term    .card-name { color: var(--amber);  }
  .card-coll    { border-left-color: var(--purple); }
  .card-coll    .card-name { color: var(--purple); }

  /* ── LEGEND ──────────────────────────────────────────── */
  .legend {
    display: flex;
    flex-wrap: wrap;
    gap: 14px;
    align-items: center;
    background: var(--surface);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 9px 16px;
    margin-bottom: 16px;
  }
  .legend-label {
    font-size: 9.5px;
    font-weight: 600;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--dim);
    margin-right: 4px;
  }
  .legend-items { display: flex; flex-wrap: wrap; gap: 14px; }
  .legend-item { display: flex; align-items: center; gap: 6px; font-size: 12px; }
  .dot { width: 9px; height: 9px; border-radius: 50%; flex-shrink: 0; }
  .dot-source { background: var(--cyan); }
  .dot-inter  { background: var(--blue); }
  .dot-term   { background: var(--amber); }
  .dot-coll   { background: var(--purple); }
  .dot-lazy   { background: var(--red); }

  /* ── NAMING / KEY POINTS ─────────────────────────────── */
  .naming-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 8px;
    margin-bottom: 14px;
  }
  .naming-card {
    background: var(--surface);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 8px 10px;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: transform .2s, border-color .2s;
  }
  .naming-card:hover {
    transform: translateY(-2px);
    border-color: rgba(99,102,241,0.4);
  }
  .naming-prefix {
    font-weight: 700;
    font-size: 13px;
    color: var(--text-bright);
    background: rgba(99,102,241,0.16);
    border-radius: 5px;
    padding: 2px 7px;
    white-space: nowrap;
  }
  .naming-arrow { color: var(--dim); font-size: 12.5px; }
  .naming-meaning { font-size: 11.4px; color: var(--muted); }

  /* ── API TABLE PANELS ────────────────────────────────── */
  .tree-panel {
    background: var(--surface);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 12px 14px;
    margin-bottom: 10px;
    overflow: hidden;
    transition: border-color .22s;
  }
  .tree-panel:hover { border-color: rgba(99,102,241,0.4); }
  .tree-title {
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--dim);
    margin-bottom: 8px;
    padding-bottom: 6px;
    border-bottom: 1px solid var(--border);
  }

  .api-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 12.1px;
  }
  .api-table td {
    padding: 4px 6px;
    vertical-align: top;
    border-bottom: 1px solid var(--border);
  }
  .api-table tr:last-child td { border-bottom: none; }
  .api-code {
    font-weight: 700;
    white-space: nowrap;
    width: 150px;
  }
  .api-code.bl { color: var(--blue); }
  .api-code.am { color: var(--amber); }
  .api-code.pu { color: var(--purple); }
  .api-code.cy { color: var(--cyan); }
  .api-code.rd { color: var(--red); }
  .api-desc { color: var(--muted); }
  .api-desc code {
    color: var(--text);
    background: var(--bg);
    padding: 0 4px;
    border-radius: 4px;
  }

  .two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }

  /* ── FLOW DIAGRAM ─────────────────────────────────────── */
  .flow-panel {
    background: var(--surface);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 12px 14px;
  }
  .flow-row {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    flex-wrap: wrap;
    margin-top: 6px;
  }
  .flow-box {
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 5px 11px;
    font-size: 12px;
    color: var(--text-bright);
    text-align: center;
    font-weight: 500;
    white-space: nowrap;
  }
  .flow-box.source { border-color: var(--cyan);  color: var(--cyan); font-weight: 700; }
  .flow-box.inter  { border-color: var(--blue);  color: var(--blue); }
  .flow-box.term   { border-color: var(--amber); color: var(--amber); font-weight: 700; }
  .flow-box.warn   { border-color: var(--red); color: var(--red); font-weight: 700; }
  .flow-arrow { color: var(--dim); font-size: 15px; }

  .flow-sub-title {
    font-size: 10.6px;
    color: var(--muted);
    text-align: center;
    margin-top: 8px;
    margin-bottom: 3px;
    letter-spacing: 0.05em;
    text-transform: uppercase;
  }

  /* comparison panel */
  .cmp-panel {
    background: var(--surface);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 12px 14px;
    display: flex;
    flex-direction: column;
    gap: 8px;
  }
  .cmp-card {
    background: rgba(10,15,30,0.55);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 8px 10px;
  }
  .cmp-card.map     { border-left: 3px solid var(--blue); }
  .cmp-card.flatmap { border-left: 3px solid var(--purple); }
  .cmp-header { display: flex; align-items: center; gap: 8px; margin-bottom: 5px; }
  .cmp-name { font-weight: 700; font-size: 13.5px; }
  .cmp-name.bl { color: var(--blue); }
  .cmp-name.pu { color: var(--purple); }
  .cmp-rows { display: flex; flex-direction: column; gap: 3px; }
  .cmp-row { display: flex; gap: 6px; font-size: 11.4px; align-items: baseline; }
  .cmp-key { color: var(--dim); white-space: nowrap; min-width: 76px; }
  .cmp-val { color: var(--text); }
  .cmp-val.code { color: var(--amber); font-weight: 600; }
  .cmp-divider { height: 1px; background: var(--border); }

  /* compact vs table (two-column comparison inside a panel) */
  .vs-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 12px;
  }
  .vs-table th {
    text-align: left;
    color: var(--dim);
    font-size: 10.6px;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    padding: 4px 6px;
    border-bottom: 1px solid var(--border);
  }
  .vs-table td {
    padding: 4px 6px;
    border-bottom: 1px solid var(--border);
    color: var(--text);
  }
  .vs-table tr:last-child td { border-bottom: none; }
  .vs-table td:first-child { color: var(--blue); font-weight: 600; }
  .vs-table td:last-child { color: var(--purple); font-weight: 600; }

  /* ── INTERVIEW PROBLEMS / CODE SNIPPETS ──────────────── */
  .problem-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 8px;
  }
  .problem-card {
    background: var(--surface);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 8px 10px;
    border-left: 3px solid var(--green);
    transition: transform .2s;
  }
  .problem-card:hover { transform: translateY(-2px); }
  .problem-title {
    font-size: 12px;
    font-weight: 700;
    color: var(--green);
    margin-bottom: 4px;
  }
  .problem-code {
    font-size: 11.4px;
    color: var(--text);
    background: var(--bg);
    border-radius: 6px;
    padding: 6px 8px;
    white-space: pre;
    overflow: hidden;
    line-height: 1.5;
  }
  .problem-code .kw { color: var(--purple); }
  .problem-code .mt { color: var(--blue); }
  .problem-code .cl { color: var(--amber); }
  .problem-code .st { color: var(--green); }
  .problem-code .cm { color: var(--muted); }
  .problem-card { page-break-inside: avoid; }

  /* ── 30 SEC REVISION ─────────────────────────────────── */
  .revision-panel {
    background: var(--surface);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 12px 14px;
  }
  .revision-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 5px 20px;
  }
  .revision-item {
    font-size: 11.8px;
    color: var(--text);
    display: flex;
    gap: 6px;
  }
  .revision-item .chk { color: var(--green); font-weight: 700; }

  /* thread pool sizing panel */
  .sizing-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 8px;
  }
  .sizing-card {
    background: rgba(10,15,30,0.55);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 8px 10px;
  }
  .sizing-card .formula {
    color: var(--amber);
    font-weight: 700;
    font-size: 12.5px;
    margin: 4px 0;
  }
  .sizing-card .label { color: var(--muted); font-size: 11px; }

  @media (max-width: 900px) {
    .cards-grid { grid-template-columns: repeat(2, 1fr); }
    .naming-grid { grid-template-columns: 1fr; }
    .two-col, .problem-grid, .sizing-grid { grid-template-columns: 1fr; }
    .revision-grid { grid-template-columns: 1fr; }
  }

  @media print {
    html, body { width: 210mm; font-size: 9.5px; background: #0D1117; }
    .page { padding: 0; }
    .card:hover, .naming-card:hover, .tree-panel:hover, .problem-card:hover { transform: none; box-shadow: none; }
    .tree-panel { page-break-inside: avoid; }
    .flow-panel { page-break-inside: avoid; }
    .cmp-panel { page-break-inside: avoid; }
  }