:root {
  --bg: #0f1729;
  --panel: #1f2b5e;
  --panel-2: #182447;
  --steel: #6a9bcc;
  --orange: #d97757;
  --teal: #00d4c8;
  --grey: #8b9dc3;
  --text: #e8ecf2;
  --muted: #8b9dc3;
  --line: rgba(232, 236, 242, 0.12);
  --radius: 10px;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
}

* { box-sizing: border-box; }

html, body {
  margin: 0; padding: 0;
  background: var(--bg); color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-size: 15px; line-height: 1.55; min-height: 100vh;
}

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

header.app-header {
  background: linear-gradient(135deg, #0f1729 0%, #1f2b5e 100%);
  padding: 22px 28px 18px; border-bottom: 1px solid var(--line);
}
header.app-header h1 { margin: 0 0 4px; font-size: 22px; letter-spacing: 0.01em; }
header.app-header .subtitle { color: var(--muted); font-size: 13px; }
header.app-header .post-link { margin-left: 10px; font-weight: 600; }

/* Tabs */
.tab-strip { display: flex; gap: 4px; padding: 0 20px; background: var(--panel-2); border-bottom: 1px solid var(--line); flex-wrap: wrap; }
.tab {
  background: none; border: none; color: var(--muted); cursor: pointer;
  padding: 12px 18px; font-size: 14px; font-weight: 600;
  border-bottom: 3px solid transparent; transition: color .15s, border-color .15s;
}
.tab:hover { color: var(--text); }
.tab.active { color: var(--teal); border-bottom-color: var(--teal); }

main { max-width: 1120px; margin: 0 auto; padding: 26px 22px 40px; }
.tab-pane { display: none; animation: fade .25s ease; }
.tab-pane.active { display: block; }
@keyframes fade { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }

h2 { font-size: 21px; margin: 4px 0 12px; }
.lede { color: #d4ddec; max-width: 760px; }
.caption { color: var(--muted); font-size: 13px; max-width: 760px; }
.credit { color: var(--muted); font-size: 13px; margin-top: 18px; border-top: 1px solid var(--line); padding-top: 12px; }

/* Intro placement cards */
.placement-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin: 22px 0; }
.placement-card { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 18px; box-shadow: var(--shadow); border-top: 4px solid var(--grey); }
.placement-card.corrected { border-top-color: var(--steel); }
.placement-card .pc-tag { font-size: 12px; letter-spacing: .08em; color: var(--muted); font-weight: 700; }
.placement-card .pc-formula { font-family: "SFMono-Regular", ui-monospace, Menlo, Consolas, monospace; font-size: 15px; color: var(--teal); margin: 6px 0 8px; }
.placement-card p { font-size: 13.5px; color: #d4ddec; margin: 0 0 10px; }
.placement-card .pc-num { font-size: 26px; font-weight: 800; color: var(--grey); }
.placement-card.corrected .pc-num { color: var(--steel); }

/* Explorer */
.explorer { display: grid; grid-template-columns: 340px 1fr; gap: 22px; margin-top: 18px; align-items: start; }
.explorer-left { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow); }
.readout { text-align: center; padding: 8px 0 14px; border-bottom: 1px solid var(--line); margin-bottom: 14px; }
.readout-label { font-size: 12px; letter-spacing: .1em; color: var(--muted); text-transform: uppercase; }
.readout-num { font-size: 46px; font-weight: 800; line-height: 1.1; margin: 4px 0 8px; color: var(--grey); transition: color .4s; font-variant-numeric: tabular-nums; }
.readout-badge { display: inline-block; font-size: 12px; padding: 4px 12px; border-radius: 999px; font-weight: 700; background: rgba(139,157,195,.18); color: var(--grey); }
.readout-badge.corrected { background: rgba(106,155,204,.2); color: var(--steel); }
.readout-badge.propensity { background: rgba(0,212,200,.16); color: var(--teal); }
.spec-name { font-weight: 700; font-size: 15px; margin-bottom: 6px; }
.spec-note { font-size: 13.5px; color: #d4ddec; min-height: 74px; }

.stepper-controls { display: flex; gap: 8px; margin: 6px 0 12px; }
.step-btn { flex: 1; background: var(--panel-2); color: var(--text); border: 1px solid var(--line); border-radius: 8px; padding: 9px 6px; font-size: 13px; font-weight: 600; cursor: pointer; transition: background .15s, border-color .15s; }
.step-btn:hover { border-color: var(--steel); }
.step-btn.primary { background: var(--steel); color: #0f1729; border-color: var(--steel); }
.step-btn.primary:hover { background: var(--teal); border-color: var(--teal); }
.step-btn:disabled { opacity: .4; cursor: default; }

.step-dots { display: flex; gap: 7px; justify-content: center; flex-wrap: wrap; }
.dot { width: 12px; height: 12px; border-radius: 50%; background: var(--grey); opacity: .35; cursor: pointer; transition: opacity .2s, transform .2s; }
.dot.corrected { background: var(--steel); }
.dot.propensity { background: var(--teal); }
.dot.active { opacity: 1; transform: scale(1.35); }

.explorer-right { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px 8px 8px 8px; box-shadow: var(--shadow); }
.chart { width: 100%; }
.chart.wide { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 14px; box-shadow: var(--shadow); margin: 14px 0; }

/* D3 chart styling */
.chart text { fill: var(--text); font-size: 12px; }
.chart .axis path, .chart .axis line { stroke: rgba(232,236,242,.25); }
.chart .grid line { stroke: rgba(232,236,242,.08); }
.chart .benchmark-line { stroke: var(--orange); stroke-width: 2; stroke-dasharray: 6 5; }
.chart .benchmark-label { fill: var(--orange); font-weight: 700; font-size: 12px; }
.est-row { transition: opacity .3s; }
.est-dim { opacity: .32; }

.app-footer { border-top: 1px solid var(--line); padding: 16px 28px; color: var(--muted); font-size: 12.5px; text-align: center; }
.app-footer code { background: var(--panel); padding: 2px 6px; border-radius: 5px; color: var(--steel); }

@media (max-width: 820px) {
  .placement-grid { grid-template-columns: 1fr; }
  .explorer { grid-template-columns: 1fr; }
}