:root {
  --bg: #f7f9fc;
  --surface: #ffffff;
  --surface-soft: #f8faff;
  --text: #0f172a;
  --muted: #5b667a;
  --muted-2: #7b8495;
  --border: #dde3ed;
  --border-strong: #cad3e2;
  --primary: #155eef;
  --primary-2: #0b4ed7;
  --primary-soft: #edf4ff;
  --success: #087443;
  --success-soft: #edf9f2;
  --danger: #b42318;
  --danger-soft: #fff2f0;
  --warning: #9a6700;
  --warning-soft: #fff8e6;
  --shadow: 0 12px 35px rgba(15, 23, 42, .07);
  --radius: 18px;
  --radius-sm: 11px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--text);
  background: radial-gradient(circle at 50% -30%, #eef5ff 0, transparent 34rem), var(--bg);
  line-height: 1.55;
}
button, input, select { font: inherit; }
button, select { cursor: pointer; }
a { color: inherit; }
.shell { width: min(1480px, calc(100% - 40px)); margin-inline: auto; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255, 255, 255, .88);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid rgba(221, 227, 237, .9);
}
.header-inner { min-height: 68px; display: flex; align-items: center; justify-content: space-between; gap: 20px; }
.brand { display: inline-flex; align-items: center; gap: 10px; text-decoration: none; font-weight: 800; font-size: 18px; letter-spacing: -.02em; }
.brand-accent { color: var(--primary); margin-left: 3px; }
.brand-mark { width: 30px; height: 30px; display: grid; place-items: center; border-radius: 8px; background: var(--primary-soft); }
.brand-mark svg { width: 20px; fill: var(--primary); }
.github-button { display: inline-flex; align-items: center; gap: 8px; text-decoration: none; padding: 9px 13px; border: 1px solid var(--border); border-radius: 10px; background: #fff; font-size: 14px; font-weight: 650; transition: border-color .18s, box-shadow .18s, transform .18s; }
.github-button:hover { border-color: #b8c3d5; box-shadow: 0 5px 15px rgba(15,23,42,.08); transform: translateY(-1px); }
.github-button svg { width: 18px; height: 18px; fill: currentColor; }

.hero { padding: 46px 0 26px; }
.hero-copy { max-width: 900px; margin: 0 auto 28px; text-align: center; }
h1 { margin: 0; font-size: clamp(34px, 4vw, 54px); line-height: 1.06; letter-spacing: -.045em; }
.hero-copy p { margin: 14px auto 0; max-width: 820px; color: var(--muted); font-size: clamp(16px, 1.7vw, 19px); }

.calculator-layout { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1.08fr); gap: 20px; align-items: stretch; }
.panel, .content-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); box-shadow: var(--shadow); }
.panel { padding: 24px; }
.panel-heading { display: flex; align-items: center; justify-content: space-between; gap: 18px; margin-bottom: 18px; }
.panel-heading h2, .options-heading h2, .content-card h2 { margin: 2px 0 0; font-size: 19px; letter-spacing: -.02em; }
.step-kicker, .mini-label { display: inline-block; color: var(--primary); font-weight: 750; font-size: 12px; text-transform: uppercase; letter-spacing: .08em; }
.mini-label { color: var(--muted-2); }
.toolbar { display: flex; flex-wrap: wrap; gap: 8px; }
.button { border: 0; border-radius: 10px; padding: 10px 14px; font-weight: 700; font-size: 14px; transition: transform .16s, box-shadow .16s, background .16s, border-color .16s; }
.button:focus-visible, input:focus-visible, select:focus-visible { outline: 3px solid rgba(21, 94, 239, .2); outline-offset: 2px; }
.button:hover { transform: translateY(-1px); }
.button-primary { color: #fff; background: linear-gradient(135deg, var(--primary), #3274f6); box-shadow: 0 9px 20px rgba(21, 94, 239, .22); }
.button-primary:hover { background: linear-gradient(135deg, var(--primary-2), var(--primary)); }
.button-secondary { color: #27364d; background: #fff; border: 1px solid var(--border); }
.button-quiet { color: #364152; background: var(--surface-soft); border: 1px solid var(--border); }

.data-note { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 8px 14px; margin-bottom: 12px; padding: 10px 12px; border-radius: 10px; background: var(--primary-soft); color: #405273; font-size: 12px; }
.data-note strong { color: #173f8f; }
.table-wrap { overflow-x: auto; }
.input-table-wrap { max-height: 345px; border: 1px solid var(--border); border-radius: 12px; overflow: auto; }
.data-table { width: 100%; border-collapse: collapse; font-size: 13px; }
.data-table th { position: sticky; top: 0; z-index: 1; padding: 10px 9px; background: #f7f9fc; border-bottom: 1px solid var(--border); color: #4c5668; text-align: left; font-size: 11px; letter-spacing: .03em; text-transform: uppercase; }
.data-table td { padding: 6px; border-bottom: 1px solid #edf0f5; }
.data-table tbody tr:last-child td { border-bottom: 0; }
.pair-col { width: 52px; text-align: center !important; }
.remove-col { width: 38px; }
.pair-number { text-align: center; color: var(--muted-2); font-variant-numeric: tabular-nums; }
.data-input { width: 100%; min-width: 100px; border: 1px solid var(--border); border-radius: 8px; padding: 8px 9px; color: var(--text); background: #fff; font-variant-numeric: tabular-nums; }
.data-input:hover { border-color: var(--border-strong); }
.row-difference { min-width: 86px; font-weight: 750; font-variant-numeric: tabular-nums; color: #32435f; }
.row-difference.empty { color: #a1a9b7; font-weight: 500; }
.remove-row { border: 0; width: 28px; height: 28px; border-radius: 7px; background: transparent; color: #98a2b3; font-size: 18px; line-height: 1; }
.remove-row:hover { color: var(--danger); background: var(--danger-soft); }
.row-incomplete td { background: #fffdfa; }
.row-invalid td { background: #fff8f7; }
.row-invalid .data-input { border-color: #e3a6a1; }
.table-actions { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-top: 12px; }
.pair-count { color: var(--muted); font-size: 12px; }
.divider { height: 1px; background: var(--border); margin: 22px 0 18px; }
.options-heading { margin-bottom: 12px; }
.options-grid { display: grid; grid-template-columns: minmax(0, 1.35fr) minmax(130px, .65fr); gap: 12px; }
.field { display: grid; gap: 6px; }
.field > span { font-size: 12px; font-weight: 750; color: #465166; }
.field select { width: 100%; border: 1px solid var(--border); border-radius: 10px; background: #fff; color: var(--text); padding: 10px 11px; }
.inline-message { min-height: 21px; margin: 12px 0 4px; font-size: 12px; color: var(--muted); }
.inline-message.error { color: var(--danger); }
.inline-message.warning { color: var(--warning); }
.calculate-button { width: 100%; margin-top: 4px; padding-block: 12px; font-size: 15px; }

.results-panel { display: flex; flex-direction: column; }
.result-cards { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 10px; }
.metric-card { border: 1px solid var(--border); border-radius: 12px; background: linear-gradient(180deg, #fff, #fbfcff); padding: 15px 13px; text-align: center; min-width: 0; }
.metric-label { display: block; color: var(--muted); font-size: 11px; font-weight: 750; text-transform: uppercase; letter-spacing: .05em; }
.metric-card strong { display: block; margin-top: 7px; font-size: clamp(21px, 2vw, 28px); line-height: 1; color: var(--primary); font-variant-numeric: tabular-nums; overflow-wrap: anywhere; }
.metric-card strong.decision-neutral { color: #58657a; font-size: 20px; }
.metric-card strong.decision-success { color: var(--success); font-size: 20px; }
.metric-card strong.decision-muted { color: #475467; font-size: 18px; }
.result-block { margin-top: 14px; border: 1px solid var(--border); border-radius: 13px; overflow: hidden; }
.block-title-row { display: flex; align-items: center; justify-content: space-between; gap: 14px; }
.result-block .block-title-row { padding: 13px 15px; border-bottom: 1px solid var(--border); background: #fbfcfe; }
.block-title-row h3, .interpretation-card h3, .apa-card h3 { margin: 0; font-size: 14px; letter-spacing: -.01em; }
.summary-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); }
.summary-grid > div { display: flex; align-items: center; justify-content: space-between; gap: 14px; padding: 10px 14px; border-bottom: 1px solid #edf0f5; }
.summary-grid > div:nth-last-child(-n+2) { border-bottom: 0; }
.summary-grid > div:nth-child(odd) { border-right: 1px solid #edf0f5; }
.summary-grid span { color: var(--muted); font-size: 12px; }
.summary-grid strong { font-size: 13px; font-variant-numeric: tabular-nums; text-align: right; }
.interpretation-card { display: grid; grid-template-columns: 32px 1fr; gap: 10px; margin-top: 14px; padding: 15px; border-radius: 13px; background: var(--primary-soft); border: 1px solid #d9e8ff; }
.interpretation-card.success { background: var(--success-soft); border-color: #cfeadb; }
.interpretation-card.neutral { background: #f8fafc; border-color: var(--border); }
.interpretation-card.warning { background: var(--warning-soft); border-color: #efdfae; }
.interpretation-icon { width: 28px; height: 28px; display: grid; place-items: center; border-radius: 50%; background: #fff; color: var(--primary); font-weight: 900; border: 1px solid currentColor; }
.interpretation-card.success .interpretation-icon { color: var(--success); }
.interpretation-card.warning .interpretation-icon { color: var(--warning); }
.interpretation-card p { margin: 5px 0 0; color: #465166; font-size: 13px; }
.apa-card { margin-top: 14px; padding: 15px; border: 1px solid var(--border); border-radius: 13px; background: #fff; }
.apa-card p { margin: 11px 0 0; padding: 12px; border-radius: 10px; background: #f8fafc; color: #3b4659; font-size: 13px; }

.details { padding: 0 0 48px; }
.details-grid, .learning-grid { display: grid; grid-template-columns: minmax(0, 1.1fr) minmax(0, .9fr); gap: 20px; margin-top: 20px; }
.learning-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.content-card { padding: 22px; box-shadow: 0 8px 24px rgba(15, 23, 42, .045); }
.content-card p { margin: 10px 0 0; color: var(--muted); font-size: 14px; }
.chart-empty { min-height: 260px; display: grid; place-items: center; color: var(--muted-2); text-align: center; }
.paired-svg { width: 100%; height: auto; min-height: 250px; display: block; }
.chart-axis { stroke: #d8dfeb; stroke-width: 1; }
.chart-label { fill: #667085; font-size: 12px; font-weight: 700; }
.chart-value-label { fill: #7b8495; font-size: 10px; }
.chart-line { stroke: #9db5e5; stroke-width: 1.4; opacity: .72; }
.chart-point-before { fill: #527bc7; }
.chart-point-after { fill: #155eef; }
.detail-table-wrap { margin-top: 13px; max-height: 300px; border: 1px solid var(--border); border-radius: 11px; overflow: auto; }
.detail-table td { font-variant-numeric: tabular-nums; }
.empty-cell { padding: 28px !important; text-align: center; color: var(--muted-2); }
.formula { margin-top: 14px; padding: 18px; border: 1px solid #dbe7fb; background: #f4f8ff; border-radius: 12px; font-family: Georgia, "Times New Roman", serif; font-size: 24px; text-align: center; color: #23395f; }

.toast { position: fixed; left: 50%; bottom: 24px; z-index: 50; transform: translate(-50%, 20px); opacity: 0; pointer-events: none; background: #101828; color: #fff; padding: 10px 14px; border-radius: 10px; font-size: 13px; box-shadow: 0 12px 30px rgba(15,23,42,.2); transition: opacity .2s, transform .2s; }
.toast.show { opacity: 1; transform: translate(-50%, 0); }
.site-footer { border-top: 1px solid var(--border); color: var(--muted); font-size: 13px; background: #fff; }
.site-footer .shell { padding-block: 24px; text-align: center; }

@media (max-width: 1080px) {
  .calculator-layout { grid-template-columns: 1fr; }
  .results-panel { min-height: auto; }
}

@media (max-width: 720px) {
  .shell { width: min(100% - 24px, 1480px); }
  .site-header { position: static; }
  .header-inner { min-height: 60px; }
  .brand { font-size: 16px; }
  .github-button { padding: 8px 10px; }
  .github-button { font-size: 0; gap: 0; }
  .github-button svg { width: 19px; height: 19px; }
  .hero { padding-top: 28px; }
  .hero-copy { margin-bottom: 20px; }
  h1 { font-size: 34px; }
  .hero-copy p { font-size: 15px; }
  .panel { padding: 16px; border-radius: 14px; }
  .panel-heading { align-items: flex-start; }
  .panel-heading h2, .options-heading h2, .content-card h2 { font-size: 17px; }
  .data-note { display: grid; }
  .options-grid, .details-grid, .learning-grid { grid-template-columns: 1fr; }
  .result-cards { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .summary-grid { grid-template-columns: 1fr; }
  .summary-grid > div, .summary-grid > div:nth-last-child(-n+2) { border-bottom: 1px solid #edf0f5; border-right: 0 !important; }
  .summary-grid > div:last-child { border-bottom: 0; }
  .result-actions { width: 100%; }
  .results-heading-row { flex-direction: column; }
  .result-actions .button { flex: 1; }
  .content-card { padding: 16px; border-radius: 14px; }
  .details { padding-bottom: 28px; }
  .table-actions { align-items: flex-start; flex-direction: column; }
}

@media (max-width: 430px) {
  .hero-copy { text-align: left; }
  h1 { font-size: 31px; }
  .panel-heading { flex-direction: column; }
  .toolbar { width: 100%; }
  .toolbar .button { flex: 1; }
  .metric-card { padding: 13px 8px; }
  .metric-card strong { font-size: 21px; }
}