:root {
  --bg: #0c1117;
  --panel: #111821;
  --panel-2: #151f2b;
  --text: #e7edf5;
  --muted: #a9b4c2;
  --line: #263241;
  --accent: #88d1ff;
  --accent-2: #b7f0d1;
  --warning: #ffd08a;
  --max: 1180px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  color: var(--text);
  background: radial-gradient(circle at top left, #162233 0, var(--bg) 36rem);
  font: 16px/1.65 system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

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

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: .85rem max(1rem, calc((100vw - var(--max)) / 2));
  border-bottom: 1px solid rgba(255,255,255,.08);
  background: rgba(12,17,23,.88);
  backdrop-filter: blur(14px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: .6rem;
  color: var(--text);
  font-weight: 750;
  letter-spacing: .02em;
}

.brand:hover { text-decoration: none; }

.site-nav {
  display: flex;
  align-items: center;
  gap: .35rem;
}

.site-nav a {
  color: var(--muted);
  padding: .45rem .7rem;
  border-radius: .6rem;
}

.site-nav a:hover,
.site-nav a[aria-current="page"] {
  color: var(--text);
  background: rgba(255,255,255,.08);
  text-decoration: none;
}

.nav-toggle { display: none; }

.layout {
  display: grid;
  grid-template-columns: 15rem minmax(0, 1fr);
  gap: 2rem;
  width: min(var(--max), calc(100% - 2rem));
  margin: 0 auto;
  padding: 2rem 0 4rem;
  transition: grid-template-columns 180ms ease;
}

.toc {
  position: sticky;
  top: 5rem;
  align-self: start;
  display: flex;
  flex-direction: column;
  gap: .35rem;
  padding: 1rem;
  border: 1px solid var(--line);
  border-radius: 1rem;
  background: rgba(17,24,33,.72);
}

.toc strong { margin-bottom: .35rem; }
.toc a { color: var(--muted); font-size: .95rem; }

.toc-links {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.toc .toc-child {
    padding-left: 1.25rem;
    font-size: 0.92em;
    opacity: 0.85;
}

.toc-toggle {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.75rem;

  border: 0;
  background: transparent;
  color: inherit;
  font: inherit;
  font-weight: 700;

  cursor: pointer;
  padding: 0;
  margin-bottom: 0.75rem;
}

.toc-toggle:hover {
  opacity: 0.9;
}

.toc-toggle-icon {
  font-size: 1.2rem;
  line-height: 1;
  transition: transform 180ms ease;
}

/* collapsed state */
.layout.toc-collapsed {
  grid-template-columns: 2.75rem minmax(0, 1fr);
}

.layout.toc-collapsed .toc {
  padding: 0.8rem 0.4rem;
}

.layout.toc-collapsed .toc-links,
.layout.toc-collapsed .toc-toggle-label {
  display: none;
}

.layout.toc-collapsed .toc-toggle {
  justify-content: center;
  margin-bottom: 0;
}

.layout.toc-collapsed .toc-toggle-icon {
  transform: rotate(180deg);
}

.content {
  min-width: 0;
  padding: 0 0 2rem;
}

.hero,
.content > section,
.content > h1 + p.lead {
  margin-bottom: 2rem;
}

.hero {
  padding: clamp(2rem, 6vw, 5rem);
  border: 1px solid var(--line);
  border-radius: 1.4rem;
  background: linear-gradient(135deg, rgba(136,209,255,.15), rgba(183,240,209,.06)), var(--panel);
}

.eyebrow {
  margin: 0 0 .6rem;
  color: var(--accent-2);
  font-size: .85rem;
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
}

h1, h2, h3 { line-height: 1.18; }
h1 { margin: 0 0 1rem; font-size: clamp(2.2rem, 6vw, 4.8rem); }
h2 { margin: 2.5rem 0 .8rem; font-size: clamp(1.55rem, 3vw, 2.2rem); }
h3 { margin: 0 0 .55rem; font-size: 1.15rem; }

.lead { color: #d3dce7; font-size: clamp(1.1rem, 2vw, 1.35rem); }
p { margin: 0 0 1rem; }

.actions { display: flex; flex-wrap: wrap; gap: .8rem; margin-top: 1.4rem; }
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: .75rem 1rem;
  border-radius: .8rem;
  color: #061018;
  background: var(--accent);
  font-weight: 700;
}
.button:hover { text-decoration: none; filter: brightness(1.05); }
.button.secondary { color: var(--text); background: var(--panel-2); border: 1px solid var(--line); }
.disabled { opacity: .65; cursor: not-allowed; }

.card-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
  margin: 1.5rem 0;
}

.card,
.note,
.discussion-card {
  padding: 1rem;
  border: 1px solid var(--line);
  border-radius: 1rem;
  background: rgba(17,24,33,.82);
}

.note.warning { border-color: rgba(255,208,138,.45); }
.note strong { color: var(--warning); }

.figure-placeholder {
  margin: 1.5rem 0;
  padding: 1rem;
  border: 1px dashed #52657a;
  border-radius: 1rem;
  background: rgba(255,255,255,.035);
}

.placeholder-box {
  display: grid;
  place-items: center;
  min-height: 12rem;
  border-radius: .8rem;
  color: var(--muted);
  background: repeating-linear-gradient(45deg, rgba(255,255,255,.05), rgba(255,255,255,.05) 12px, rgba(255,255,255,.025) 12px, rgba(255,255,255,.025) 24px);
  font-weight: 700;
}

section {
    scroll-margin-top: 6rem;
}

figcaption { margin-top: .8rem; color: var(--muted); font-size: .95rem; }

.reading-list li { margin-bottom: .65rem; }
.muted, .meta { color: var(--muted); }
.discussion-list { display: grid; gap: 1rem; }

pre,
pre[class*="language-"] {
  overflow-x: auto;
  padding: 1rem;
  border: 1px solid var(--line);
  border-radius: 1rem;
  background: #080d13;
}

code,
code[class*="language-"] {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

.site-footer {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  padding: 1.4rem max(1rem, calc((100vw - var(--max)) / 2));
  border-top: 1px solid rgba(255,255,255,.08);
  color: var(--muted);
}

@media (max-width: 900px) {
  .nav-toggle {
    display: inline-flex;
    padding: .5rem .75rem;
    border: 1px solid var(--line);
    border-radius: .7rem;
    color: var(--text);
    background: var(--panel);
  }

  .site-nav {
    position: absolute;
    top: calc(100% + 1px);
    left: 0;
    right: 0;
    display: none;
    flex-direction: column;
    align-items: stretch;
    padding: .7rem 1rem 1rem;
    background: rgba(12,17,23,.98);
    border-bottom: 1px solid rgba(255,255,255,.08);
  }

  .site-nav.open { display: flex; }
  .site-nav a { padding: .8rem; }

  .layout,
  .layout.toc-collapsed {
    grid-template-columns: 1fr;
  }
  .toc { position: static; order: 2; }
  .content { order: 1; }
  .card-grid { grid-template-columns: 1fr; }
}

@media (max-width: 560px) {
  body { font-size: 15px; }
  .hero { padding: 1.2rem; }
  .site-footer { flex-direction: column; }
}

.spslr-svg-figure {
    margin: 2rem 0;
}

.spslr-svg-figure > figcaption {
    color: var(--muted);
    font-size: 0.95rem;
    margin-bottom: 1rem;
}

.spslr-diagram-wrap {
    overflow-x: auto;
    padding: 1rem;
    border: 1px solid var(--border);
    border-radius: 1.25rem;
    background:
        radial-gradient(circle at top left, rgba(107, 114, 255, 0.12), transparent 35%),
        rgba(255, 255, 255, 0.025);
}

.spslr-diagram {
    display: block;
    width: 100%;
    min-width: 1050px;
    height: auto;
}

.svg-node {
    cursor: pointer;
    outline: none;
}

.svg-node rect {
    fill: rgba(255, 255, 255, 0.045);
    stroke: var(--border);
    stroke-width: 1.5;
    transition: fill 140ms ease, stroke 140ms ease, filter 140ms ease;
}

.svg-node:hover rect,
.svg-node:focus rect,
.svg-node.is-hovered rect {
    stroke: var(--accent);
    fill: rgba(107, 114, 255, 0.11);
    filter: drop-shadow(0 0 8px rgba(107, 114, 255, 0.22));
}

.svg-node.is-active rect {
    stroke: var(--accent-2);
    fill: rgba(107, 114, 255, 0.2);
    filter: drop-shadow(0 0 12px rgba(107, 114, 255, 0.38));
}

.svg-node-title {
    fill: var(--text);
    font-size: 17px;
    font-weight: 700;
    pointer-events: none;
}

.svg-node.small .svg-node-title {
    font-size: 15px;
}

.svg-node-subtitle {
    fill: var(--muted);
    font-size: 13px;
    pointer-events: none;
}

.svg-lane-label {
    fill: var(--muted);
    font-size: 12px;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    pointer-events: none;
}

.svg-edge {
    fill: none;
    stroke: var(--muted);
    stroke-width: 2.4;
    opacity: 0.72;
    cursor: pointer;
    pointer-events: stroke;
    vector-effect: non-scaling-stroke;
    transition: stroke 140ms ease, opacity 140ms ease, filter 140ms ease;
}

.svg-edge-arrow {
    marker-end: url(#arrow-head);
}

.svg-edge.dashed {
    stroke-dasharray: 7 7;
}

.svg-edge:hover,
.svg-edge:focus,
.svg-edge.is-hovered {
    stroke: var(--accent);
    opacity: 1;
    filter: drop-shadow(0 0 8px rgba(107, 114, 255, 0.28));
}

.svg-edge.is-active {
    stroke: var(--accent-2);
    opacity: 1;
    filter: drop-shadow(0 0 10px rgba(183, 240, 209, 0.45));
}

.svg-arrow-head {
    fill: context-stroke;
}

.spslr-diagram-detail {
    position: sticky;
    bottom: 1rem;
    z-index: 2;
    margin-top: 1rem;
    padding: 1rem;
    border: 1px solid var(--border);
    border-radius: 1rem;
    background: rgba(8, 12, 24, 0.96);
    box-shadow: 0 16px 40px rgba(0, 0, 0, 0.35);
}

.spslr-diagram-detail h4 {
    margin: 0.2rem 0 0.5rem;
}

.spslr-diagram-detail p {
    margin-top: 0;
}

.spslr-diagram-detail pre {
    margin-bottom: 0;
    max-height: 14rem;
    overflow: auto;
}

.detail-kicker {
    color: var(--muted);
    display: block;
    font-size: 0.72rem;
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

@media (max-width: 760px) {
    .spslr-diagram {
        min-width: 1200px;
    }

    .spslr-diagram-detail {
        position: static;
    }
}