/* Shared styles of the three scenario pages. One reading column; the stage stacks on phones. */
:root {
  --bg: #F1F4F3;
  --surface: #FFFFFF;
  --sunken: #E6ECEA;
  --ink: #14201E;
  --muted: #566865;
  --line: #CFD8D6;
  --flow: #0A7566;
  --flow-soft: #D9EEEA;
  --bad: #AD2A22;
  --bad-soft: #F6DDDA;
  --warn: #96500A;
  --font-body: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", system-ui, sans-serif;
  --font-data: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0D1413;
    --surface: #151F1E;
    --sunken: #1D2A29;
    --ink: #E2EBE9;
    --muted: #92A4A0;
    --line: #2C3B39;
    --flow: #49C6B2;
    --flow-soft: #143431;
    --bad: #F07A70;
    --bad-soft: #3E1D1B;
    --warn: #ECA552;
    color-scheme: dark;
  }
}
* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.7;
}
.page {
  max-width: 1040px;
  margin: 0 auto;
  padding-inline: 20px;
  padding-block: 28px 56px;
  display: flex;
  flex-direction: column;
  gap: 28px;
}
h1, h2, h3 { margin: 0; line-height: 1.3; font-weight: 600; }
h1 { font-size: 28px; }
h2 { font-size: 19px; }
h3 { font-size: 15px; }
p { margin: 0; }
a { color: var(--flow); }
.eyebrow { font-size: 12px; letter-spacing: 0.08em; color: var(--muted); margin-bottom: 6px; }
.lede { margin-top: 8px; max-width: 36em; color: var(--muted); }
.num { font-family: var(--font-data); font-variant-numeric: tabular-nums; }

/* the two needs */
.need { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; }
.need .card { padding: 14px 16px; border: 1px solid var(--line); border-radius: 10px; background: var(--surface); min-width: 0; }
.need .card h3 { color: var(--flow); font-size: 13px; letter-spacing: 0.04em; margin-bottom: 4px; }

/* segmented control */
.seg { display: inline-flex; flex-wrap: wrap; gap: 6px; }
.seg button {
  font: inherit; font-size: 14px; padding: 6px 14px;
  border: 1px solid var(--line); border-radius: 999px; background: transparent; color: var(--ink); cursor: pointer;
}
.seg button[aria-pressed="true"] { background: var(--ink); border-color: var(--ink); color: var(--bg); }
button:focus-visible, input:focus-visible { outline: 2px solid var(--flow); outline-offset: 2px; }

/* the stage: diagram and narration */
.stage { display: grid; grid-template-columns: minmax(0, 3fr) minmax(0, 2fr); gap: 24px; align-items: start; }
.visual { min-width: 0; padding: 16px; background: var(--surface); border: 1px solid var(--line); border-radius: 10px; }
.diagram-scroll { overflow-x: auto; }
.diagram-scroll svg { display: block; width: 100%; min-width: 540px; height: auto; }
.narration { min-width: 0; display: flex; flex-direction: column; gap: 12px; }
.step-count { font-family: var(--font-data); font-size: 12px; color: var(--muted); }
.narration p { max-width: 34em; }
.controls { display: flex; gap: 8px; margin-top: 4px; }
.btn {
  font: inherit; font-size: 14px; padding: 8px 18px; border-radius: 8px;
  border: 1px solid var(--ink); background: var(--ink); color: var(--bg); cursor: pointer;
}
.btn.secondary { background: transparent; border-color: var(--line); color: var(--ink); }
.btn.small { padding: 4px 10px; font-size: 13px; }
.btn:disabled { opacity: 0.4; cursor: default; }
.hint { font-size: 12px; color: var(--muted); }
.note { margin-top: 8px; font-size: 12px; color: var(--muted); }

/* diagram */
svg text { font-family: var(--font-body); fill: var(--ink); }
.node rect { fill: var(--surface); stroke: var(--ink); stroke-width: 1.25; }
.node .t { font-size: 14px; font-weight: 600; }
.node .s { font-size: 12px; fill: var(--muted); }
.edge { fill: none; stroke: var(--flow); stroke-width: 2; }
.edge.bad { stroke: var(--bad); stroke-dasharray: 6 5; }
.edge.muted { stroke: var(--muted); stroke-width: 1.5; stroke-dasharray: 3 4; }
.mk-flow { fill: var(--flow); }
.mk-bad { fill: var(--bad); }
.mk-muted { fill: var(--muted); }
.lbl { font-size: 12px; }
.lbl.flow { fill: var(--flow); }
.lbl.bad { fill: var(--bad); }
.lbl.muted { fill: var(--muted); }
.fade { transition: opacity 0.35s ease; }
.off { opacity: 0; }

/* inputs and numbers */
.inputs { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 14px 24px; }
.field { display: flex; flex-direction: column; gap: 4px; min-width: 0; }
.field label { font-size: 14px; }
.field input[type="range"] { width: 100%; accent-color: var(--flow); }
.field input[type="number"] { font: inherit; width: 100%; padding: 4px 8px; border: 1px solid var(--line); border-radius: 6px; background: var(--surface); color: var(--ink); }
.numbers { display: grid; grid-template-columns: repeat(auto-fit, minmax(170px, 1fr)); gap: 12px; }
.stat { padding: 10px 12px; border: 1px solid var(--line); border-radius: 8px; background: var(--surface); min-width: 0; }
.stat .k { font-size: 12px; color: var(--muted); }
.stat .v { font-size: 22px; line-height: 1.2; }
.stat .v small { font-size: 12px; color: var(--muted); margin-left: 4px; }
.stat.bad .v { color: var(--bad); }
.stat.good .v { color: var(--flow); }

/* tables */
.tbl { width: 100%; border-collapse: collapse; font-size: 13px; }
.tbl th, .tbl td { padding: 6px 8px; border-bottom: 1px solid var(--line); text-align: left; font-weight: 400; vertical-align: top; }
.tbl thead th { font-size: 12px; color: var(--muted); }
.tbl .r { text-align: right; }
.tbl .yes { color: var(--flow); }
.tbl .no { color: var(--bad); }
.tbl-scroll { overflow-x: auto; }
.records { margin: 0; padding: 0; list-style: none; font-size: 13px; }
.records li { padding: 4px 0; border-bottom: 1px solid var(--line); }
.records li.bad { color: var(--bad); }

footer.nav { display: flex; flex-wrap: wrap; gap: 8px 20px; padding-top: 16px; border-top: 1px solid var(--line); font-size: 14px; }

@media (max-width: 820px) {
  .stage { grid-template-columns: minmax(0, 1fr); }
}
@media (max-width: 640px) {
  h1 { font-size: 24px; }
  .need { grid-template-columns: minmax(0, 1fr); }
}
@media (prefers-reduced-motion: reduce) {
  .fade { transition: none; }
}