:root {
    --blue: #1a73e8;
    --blue-dark: #185abc;
    --green: #0f766e;
    --ink: #202124;
    --text: #3c4043;
    --muted: #5f6368;
    --line: #e1e5ea;
    --panel: #f8f9fa;
    --canvas: #fbfcff;
    --canvas-grid: #eef2f8;
    --shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 30px rgba(16, 32, 64, 0.16);
}

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

html, body { height: 100%; }

body {
    display: flex;
    flex-direction: column;
    height: 100vh;
    overflow: hidden;
    background: #fff;
    color: var(--text);
    font-family: 'Google Sans', Arial, sans-serif;
    line-height: 1.5;
}

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

/* ---------- header ---------- */
header.bar {
    display: flex;
    align-items: center;
    gap: 18px;
    padding: 14px 24px;
    border-bottom: 1px solid var(--line);
    background: #fff;
    z-index: 5;
}
header .brand { display: flex; flex-direction: column; min-width: 0; }
header .brand .eyebrow {
    color: var(--green); font-size: 0.7rem; font-weight: 700;
    letter-spacing: 0.06em; text-transform: uppercase;
}
header .brand h1 {
    color: var(--ink); font-size: 1.18rem; font-weight: 500; line-height: 1.2;
    white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}
header .brand h1 .sub { color: var(--muted); font-weight: 400; }

.stats { display: flex; gap: 8px; margin-left: 4px; }
.stat {
    display: flex; flex-direction: column; align-items: center;
    padding: 4px 12px; border: 1px solid var(--line); border-radius: 9px;
    background: var(--panel);
}
.stat b { color: var(--blue); font-size: 1.05rem; line-height: 1; }
.stat span { color: var(--muted); font-size: 0.66rem; text-transform: uppercase; letter-spacing: 0.04em; margin-top: 3px; }

.header-links { margin-left: auto; display: flex; gap: 10px; flex: 0 0 auto; }
.header-links a {
    display: inline-flex; align-items: center; gap: 7px;
    height: 38px; padding: 0 14px; border-radius: 8px;
    background: var(--blue); color: #fff; font-size: 0.86rem; font-weight: 500;
    box-shadow: var(--shadow); transition: background-color .2s, transform .2s;
}
.header-links a:hover { background: var(--blue-dark); text-decoration: none; transform: translateY(-1px); }
.header-links a.ghost { background: #fff; color: var(--text); border: 1px solid var(--line); }
.header-links a.ghost:hover { background: var(--panel); }

/* ---------- toolbar ---------- */
.toolbar {
    display: flex; align-items: center; gap: 14px; flex-wrap: wrap;
    padding: 10px 24px; border-bottom: 1px solid var(--line); background: #fff; z-index: 4;
}
.seg {
    display: inline-flex; border: 1px solid var(--line); border-radius: 9px; overflow: hidden; background: var(--panel);
}
.seg button {
    border: 0; background: transparent; color: var(--muted);
    padding: 7px 16px; font: inherit; font-size: 0.86rem; font-weight: 500; cursor: pointer;
}
.seg button.active { background: var(--blue); color: #fff; }

.search {
    position: relative; flex: 0 1 280px;
}
.search input {
    width: 100%; height: 38px; padding: 0 14px 0 34px;
    border: 1px solid var(--line); border-radius: 9px; background: var(--panel);
    font: inherit; font-size: 0.88rem; color: var(--ink);
}
.search input:focus { outline: none; border-color: var(--blue); background: #fff; }
.search svg { position: absolute; left: 11px; top: 11px; color: var(--muted); }

.legend { display: flex; flex-wrap: wrap; gap: 6px; margin-left: auto; }
.legend .chip {
    display: inline-flex; align-items: center; gap: 6px;
    padding: 4px 10px; border: 1px solid var(--line); border-radius: 20px;
    background: #fff; font-size: 0.76rem; color: var(--text); cursor: pointer;
    user-select: none; transition: background .15s, opacity .15s;
}
.legend .chip .dot { width: 10px; height: 10px; border-radius: 50%; flex: 0 0 auto; }
.legend .chip.dim { opacity: 0.32; }
.legend .chip:hover { background: var(--panel); }

.tool-btn {
    height: 38px; padding: 0 12px; border: 1px solid var(--line); border-radius: 9px;
    background: #fff; color: var(--text); font: inherit; font-size: 0.82rem; cursor: pointer;
}
.tool-btn:hover { background: var(--panel); text-decoration: none; }
a.tool-btn { display: inline-flex; align-items: center; color: var(--text); line-height: 38px; }

/* ---------- stage ---------- */
.stage { position: relative; flex: 1 1 auto; min-height: 0; overflow: hidden; }
#viz {
    width: 100%; height: 100%; display: block;
    background-color: var(--canvas);
    background-image: radial-gradient(var(--canvas-grid) 1px, transparent 1px);
    background-size: 26px 26px;
    cursor: grab;
}
#viz:active { cursor: grabbing; }

.hint {
    position: absolute; left: 18px; bottom: 14px; z-index: 2;
    color: var(--muted); font-size: 0.76rem; background: rgba(255,255,255,0.82);
    padding: 5px 10px; border-radius: 8px; border: 1px solid var(--line);
    pointer-events: none;
}

/* graph elements */
.link { stroke: #c4ccd8; stroke-opacity: 0.55; }
.link.cite { stroke: #d3dae5; }
.link.tree { stroke: #b6c0cf; stroke-opacity: 0.7; }
.link.hl { stroke: #1a73e8; stroke-opacity: 0.9; }
.node circle { stroke: #fff; stroke-width: 1.5px; cursor: pointer; transition: stroke-width .12s; }
.node.section circle, .node.root circle { stroke-width: 2.5px; }
.node.faded { opacity: 0.12; }
.node.sel circle { stroke: #202124; stroke-width: 3px; }
.label {
    font-family: 'Google Sans', Arial, sans-serif; fill: var(--ink);
    pointer-events: none; paint-order: stroke;
    stroke: #fbfcff; stroke-width: 3px; stroke-linejoin: round;
}
.label.faded { opacity: 0.08; }
.label.root { font-size: 15px; font-weight: 700; }
.label.section { font-size: 12.5px; font-weight: 600; }
.label.subsection { font-size: 10.5px; font-weight: 500; fill: var(--muted); }
.label.reference { font-size: 9.5px; fill: var(--text); }

/* indented outline tree */
.tguide { fill: none; stroke: #c8d2e0; stroke-width: 1.3px; }
.trow { cursor: pointer; }
.trow-hit { fill: transparent; }
.trow:hover .trow-hit { fill: rgba(26, 115, 232, 0.07); }
.trow circle { stroke: #fff; stroke-width: 1.2px; }
.caret { fill: var(--muted); font-size: 10px; }
.tlabel { fill: var(--ink); font-size: 12.5px; font-family: 'Google Sans', Arial, sans-serif; }
.trow:hover .tlabel { fill: var(--blue); }
.t-root .tlabel { font-size: 14px; }
.t-reference .tlabel { fill: var(--text); font-size: 11.5px; }
.t-reference:hover .tlabel { fill: var(--blue); }

/* ---------- detail panel ---------- */
#panel {
    position: absolute; top: 0; right: 0; height: 100%; width: 380px; max-width: 86vw;
    transform: translateX(105%); transition: transform .26s cubic-bezier(.4,0,.2,1);
    background: #fff; border-left: 1px solid var(--line); box-shadow: var(--shadow-lg);
    display: flex; flex-direction: column; z-index: 6;
}
#panel.open { transform: translateX(0); }
#panel .phead {
    display: flex; align-items: flex-start; gap: 10px;
    padding: 18px 18px 14px; border-bottom: 1px solid var(--line);
}
#panel .ptag {
    display: inline-block; padding: 3px 10px; border-radius: 20px;
    font-size: 0.7rem; font-weight: 700; color: #fff; text-transform: uppercase; letter-spacing: 0.04em;
}
#panel .pclose {
    margin-left: auto; border: 0; background: var(--panel); color: var(--muted);
    width: 30px; height: 30px; border-radius: 8px; font-size: 1.1rem; cursor: pointer; flex: 0 0 auto;
}
#panel .pclose:hover { background: #e8eaed; color: var(--ink); }
#panel .pbody { padding: 16px 18px 28px; overflow-y: auto; }
#panel h2.ptitle { color: var(--ink); font-size: 1.12rem; font-weight: 600; line-height: 1.3; margin-bottom: 10px; }
#panel .meta-row { font-size: 0.86rem; color: var(--text); margin-bottom: 5px; }
#panel .meta-row .k { color: var(--muted); }
#panel .authors-full { font-size: 0.82rem; color: var(--muted); margin: 8px 0 14px; line-height: 1.5; }
#panel h3 { font-size: 0.74rem; text-transform: uppercase; letter-spacing: 0.05em; color: var(--muted); margin: 16px 0 8px; }
#panel .cited-list { display: flex; flex-direction: column; gap: 6px; }
#panel .cited-list a {
    display: flex; align-items: center; gap: 8px; font-size: 0.84rem;
    padding: 7px 10px; border: 1px solid var(--line); border-radius: 8px; background: var(--panel); color: var(--text);
}
#panel .cited-list a:hover { background: #eef3f8; text-decoration: none; }
#panel .cited-list .swatch { width: 9px; height: 9px; border-radius: 50%; flex: 0 0 auto; }
#panel pre {
    position: relative; margin-top: 8px; padding: 14px; border: 1px solid #d9e1ea; border-radius: 10px;
    background: #f4f7fb; color: #263238; font-family: 'SFMono-Regular', Consolas, monospace;
    font-size: 0.78rem; line-height: 1.45; white-space: pre-wrap; word-break: break-word;
}
#panel .copy {
    margin-top: 10px; height: 34px; padding: 0 14px; border: 0; border-radius: 8px;
    background: var(--green); color: #fff; font: inherit; font-size: 0.82rem; font-weight: 500; cursor: pointer;
}
#panel .copy:hover { background: #0b5f59; }
#panel .sublist { display: flex; flex-direction: column; gap: 5px; }
#panel .sublist div { font-size: 0.85rem; padding: 6px 10px; border-left: 3px solid var(--line); color: var(--text); }

.loading {
    position: absolute; inset: 0; display: flex; align-items: center; justify-content: center;
    color: var(--muted); font-size: 0.95rem; z-index: 3;
}

@media (max-width: 760px) {
    header.bar { flex-wrap: wrap; gap: 10px; padding: 12px 16px; }
    .stats { order: 3; width: 100%; }
    .header-links { order: 2; }
    .legend { width: 100%; margin-left: 0; }
    .toolbar { padding: 10px 16px; }
}