/* InvestorMath — single stylesheet. Light theme is the default; [data-theme="dark"] overrides. */
:root {
  --bg: #f7f8fa; --surface: #ffffff; --surface-2: #f1f4f7; --text: #18202a; --muted: #5b6673;
  --border: #dde2e8; --accent: #0f766e; --accent-strong: #0b5c56; --accent-soft: #e3f4f1;
  --danger: #b42318; --danger-soft: #fdecea; --warn-soft: #fff6e0; --warn-border: #f0c86b;
  --s1: #0f766e; --s2: #2563eb; --s3: #d97706; --s4: #9333ea; --grid: #e7ebf0;
  --shadow: 0 1px 2px rgba(16,24,40,.05), 0 1px 3px rgba(16,24,40,.08);
  --radius: 12px; --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  color-scheme: light;
}
[data-theme="dark"] {
  --bg: #0f1419; --surface: #161d25; --surface-2: #1d2630; --text: #e6ebf0; --muted: #9aa6b2;
  --border: #2a3542; --accent: #2dd4bf; --accent-strong: #5eead4; --accent-soft: #11302d;
  --danger: #f87171; --danger-soft: #3a1d1d; --warn-soft: #2e2715; --warn-border: #8a6d2a;
  --s1: #2dd4bf; --s2: #60a5fa; --s3: #fbbf24; --s4: #c084fc; --grid: #26313c;
  --shadow: 0 1px 2px rgba(0,0,0,.4);
  color-scheme: dark;
}
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; font-family: var(--font); background: var(--bg); color: var(--text); line-height: 1.6; font-size: 16px; }
a { color: var(--accent); }
a:hover { color: var(--accent-strong); }
img, svg { max-width: 100%; }
.container { max-width: 1120px; margin: 0 auto; padding: 0 20px; }
.skip { position: absolute; left: -999px; } .skip:focus { left: 12px; top: 12px; background: var(--surface); padding: 8px; z-index: 10; }

/* Header */
.site-header { background: var(--surface); border-bottom: 1px solid var(--border); position: sticky; top: 0; z-index: 5; }
.site-header .container { display: flex; align-items: center; gap: 16px; height: 60px; }
.logo { font-weight: 800; font-size: 1.2rem; color: var(--text); text-decoration: none; letter-spacing: -.02em; display: flex; align-items: center; gap: 8px; }
.logo-mark { width: 30px; height: 30px; border-radius: 8px; background: var(--accent); color: var(--surface); display: grid; place-items: center; font-size: .9rem; font-weight: 800; }
.logo span.m { color: var(--accent); }
.nav { margin-left: auto; display: flex; align-items: center; gap: 4px; }
.nav a { color: var(--muted); text-decoration: none; padding: 6px 10px; border-radius: 8px; font-weight: 500; font-size: .95rem; }
.nav a:hover, .nav a[aria-current="page"] { color: var(--text); background: var(--surface-2); }
.theme-toggle { border: 1px solid var(--border); background: var(--surface); color: var(--text); width: 38px; height: 38px; border-radius: 10px; cursor: pointer; display: grid; place-items: center; margin-left: 4px; }
.theme-toggle:hover { background: var(--surface-2); }
.theme-toggle .sun { display: none; } [data-theme="dark"] .theme-toggle .sun { display: block; } [data-theme="dark"] .theme-toggle .moon { display: none; }
@media (max-width: 640px) { .nav a.hide-sm { display: none; } }

/* Typography */
h1 { font-size: clamp(1.7rem, 4vw, 2.4rem); line-height: 1.2; letter-spacing: -.02em; margin: .2em 0 .3em; }
h2 { font-size: 1.45rem; letter-spacing: -.01em; margin: 1.6em 0 .5em; }
h3 { font-size: 1.1rem; margin: 1.2em 0 .4em; }
.lede { color: var(--muted); font-size: 1.08rem; max-width: 760px; }
.breadcrumbs { font-size: .85rem; color: var(--muted); margin-top: 20px; }
.breadcrumbs a { color: var(--muted); }
code, .formula { font-family: var(--mono); }
.formula { display: block; background: var(--surface-2); border: 1px solid var(--border); border-radius: 8px; padding: 12px 14px; overflow-x: auto; font-size: .92rem; white-space: pre-wrap; margin: .6em 0; }

/* Cards & layout */
.card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); box-shadow: var(--shadow); padding: 20px; }
.calc { display: grid; grid-template-columns: minmax(280px, 360px) 1fr; gap: 20px; align-items: start; margin-top: 16px; }
@media (max-width: 860px) { .calc { grid-template-columns: 1fr; } }
.calc-inputs { position: sticky; top: 76px; }
@media (max-width: 860px) { .calc-inputs { position: static; } }
.calc-results { display: grid; gap: 20px; min-width: 0; }

/* Forms */
.field { margin-bottom: 14px; }
.field label, .field .label { display: block; font-weight: 600; font-size: .9rem; margin-bottom: 4px; }
.field .hint { color: var(--muted); font-size: .8rem; margin-top: 3px; }
.input-wrap { position: relative; display: flex; align-items: center; }
.input-wrap .pre, .input-wrap .post { position: absolute; color: var(--muted); font-size: .95rem; pointer-events: none; }
.input-wrap .pre { left: 11px; } .input-wrap .post { right: 11px; }
.input-wrap.has-pre input { padding-left: 24px; } .input-wrap.has-post input { padding-right: 30px; }
input[type="number"], input[type="email"], input[type="text"], select {
  width: 100%; font: inherit; color: var(--text); background: var(--surface); border: 1px solid var(--border);
  border-radius: 8px; padding: 9px 11px; min-height: 42px;
}
input:focus, select:focus, button:focus-visible, a:focus-visible { outline: 2px solid var(--accent); outline-offset: 1px; }
input[aria-invalid="true"] { border-color: var(--danger); background: var(--danger-soft); }
.field-error { color: var(--danger); font-size: .8rem; margin-top: 3px; }
.row-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.check { display: flex; gap: 8px; align-items: center; font-weight: 600; font-size: .9rem; }
.check input { width: 18px; height: 18px; accent-color: var(--accent); }
fieldset { border: 1px dashed var(--border); border-radius: 10px; padding: 10px 12px 2px; margin: 0 0 14px; }
legend { font-weight: 700; font-size: .85rem; color: var(--muted); padding: 0 4px; text-transform: uppercase; letter-spacing: .04em; }
.btn { display: inline-flex; align-items: center; gap: 6px; font: inherit; font-weight: 600; font-size: .9rem; padding: 8px 14px; border-radius: 8px; border: 1px solid var(--border); background: var(--surface); color: var(--text); cursor: pointer; text-decoration: none; }
.btn:hover { background: var(--surface-2); }
.btn-primary { background: var(--accent); color: #fff; border-color: var(--accent); }
[data-theme="dark"] .btn-primary { color: #0f1419; }
.btn-primary:hover { background: var(--accent-strong); color: #fff; }
.btn-small { padding: 4px 10px; font-size: .82rem; }
.actions { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 6px; }
.error-summary { background: var(--danger-soft); color: var(--danger); border-radius: 8px; padding: 10px 12px; font-size: .9rem; margin-bottom: 12px; }
.error-summary:empty { display: none; }

/* Results */
.stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(170px, 1fr)); gap: 12px; }
.stat { background: var(--surface-2); border-radius: 10px; padding: 12px 14px; }
.stat .k { color: var(--muted); font-size: .8rem; font-weight: 600; text-transform: uppercase; letter-spacing: .03em; }
.stat .v { font-size: 1.35rem; font-weight: 750; font-variant-numeric: tabular-nums; letter-spacing: -.01em; overflow-wrap: anywhere; }
.stat.primary { background: var(--accent-soft); } .stat.primary .v { color: var(--accent-strong); font-size: 1.6rem; }
.note { font-size: .88rem; color: var(--muted); margin: 10px 0 0; }
.callout { background: var(--warn-soft); border: 1px solid var(--warn-border); border-radius: 10px; padding: 10px 14px; font-size: .9rem; }
.callout.info { background: var(--accent-soft); border-color: transparent; }
.card-head { display: flex; align-items: center; justify-content: space-between; gap: 10px; flex-wrap: wrap; margin-bottom: 8px; }
.card-head h2 { margin: 0; font-size: 1.15rem; }

/* Chart */
.chart svg { width: 100%; height: auto; display: block; font-family: var(--font); }
.chart .gridline { stroke: var(--grid); stroke-width: 1; }
.chart .axis-label { fill: var(--muted); font-size: 11px; }
.chart .line { fill: none; stroke-width: 2.5; stroke-linejoin: round; stroke-linecap: round; }
.chart .area { opacity: .12; }
.chart .s1 { stroke: var(--s1); fill: var(--s1); } .chart .s2 { stroke: var(--s2); fill: var(--s2); } .chart .s3 { stroke: var(--s3); fill: var(--s3); } .chart .s4 { stroke: var(--s4); fill: var(--s4); }
.chart .line.s1, .chart .line.s2, .chart .line.s3, .chart .line.s4 { fill: none; }
.chart .dashed { stroke-dasharray: 6 5; }
.chart .hover-col { fill: transparent; } .chart .hover-col:hover { fill: var(--text); opacity: .06; }
.chart .dot { stroke: var(--surface); stroke-width: 2; }
.legend { display: flex; gap: 14px; flex-wrap: wrap; font-size: .85rem; color: var(--muted); margin-top: 6px; }
.legend i { display: inline-block; width: 14px; height: 4px; border-radius: 2px; vertical-align: middle; margin-right: 6px; }
.legend .s1 { background: var(--s1); } .legend .s2 { background: var(--s2); } .legend .s3 { background: var(--s3); } .legend .s4 { background: var(--s4); }

/* Table */
.table-wrap { overflow: auto; max-height: 460px; border: 1px solid var(--border); border-radius: 10px; }
table { border-collapse: collapse; width: 100%; font-size: .88rem; font-variant-numeric: tabular-nums; }
th, td { padding: 7px 10px; text-align: right; border-bottom: 1px solid var(--border); white-space: nowrap; }
th:first-child, td:first-child { text-align: left; }
thead th { position: sticky; top: 0; background: var(--surface-2); font-weight: 650; font-size: .8rem; color: var(--muted); z-index: 1; }
tbody tr:hover { background: var(--surface-2); }
tr.phase-change td { border-top: 2px solid var(--accent); }
.prose table { margin: .8em 0; border: 1px solid var(--border); border-radius: 8px; }

/* Content sections */
.prose { max-width: 820px; }
.prose li { margin: .25em 0; }
.example { border-left: 3px solid var(--accent); padding: 4px 0 4px 16px; margin: 1em 0; }
.example h3 { margin-top: .2em; }
details.faq { border-bottom: 1px solid var(--border); padding: 10px 0; }
details.faq summary { cursor: pointer; font-weight: 650; }
details.faq p { margin: .5em 0 0; }
.disclaimer { font-size: .88rem; color: var(--muted); border-top: 1px solid var(--border); padding-top: 14px; margin-top: 28px; }

/* Placeholders */
.sponsor-slot { border: 2px dashed var(--border); border-radius: var(--radius); padding: 16px; text-align: center; color: var(--muted); font-size: .85rem; background: repeating-linear-gradient(45deg, transparent, transparent 10px, var(--surface-2) 10px, var(--surface-2) 20px); }
.sponsor-slot strong { display: block; color: var(--text); font-size: .8rem; text-transform: uppercase; letter-spacing: .05em; }
/* To hide all sponsor placeholders before launch, uncomment: */
/* .sponsor-slot { display: none; } */
.newsletter { display: grid; grid-template-columns: 1fr auto; gap: 18px; align-items: center; background: var(--accent-soft); border: 1px solid transparent; }
.newsletter h2 { margin: 0 0 4px; font-size: 1.2rem; }
.newsletter p { margin: 0; color: var(--muted); font-size: .92rem; }
.newsletter form { display: flex; gap: 8px; flex-wrap: wrap; }
.newsletter input { min-width: 240px; }
.newsletter .nl-msg { grid-column: 1 / -1; font-size: .88rem; color: var(--accent-strong); margin: 0; }
@media (max-width: 760px) { .newsletter { grid-template-columns: 1fr; } .newsletter input { min-width: 0; flex: 1; } }

/* Home */
.hero { padding: 40px 0 10px; }
.hero h1 { font-size: clamp(2rem, 5vw, 3rem); max-width: 780px; }
.badges { display: flex; gap: 8px; flex-wrap: wrap; margin: 14px 0; }
.badge { background: var(--surface); border: 1px solid var(--border); border-radius: 999px; padding: 4px 12px; font-size: .82rem; color: var(--muted); }
.grid-cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 16px; margin: 20px 0; }
.calc-card { text-decoration: none; color: var(--text); display: flex; flex-direction: column; gap: 6px; transition: transform .12s, border-color .12s; }
.calc-card:hover { transform: translateY(-2px); border-color: var(--accent); color: var(--text); }
.calc-card .icon { width: 40px; height: 40px; border-radius: 10px; background: var(--accent-soft); color: var(--accent-strong); display: grid; place-items: center; font-weight: 800; }
.calc-card h2 { margin: 6px 0 0; font-size: 1.1rem; }
.calc-card p { margin: 0; color: var(--muted); font-size: .92rem; }
.calc-card .go { color: var(--accent); font-weight: 600; font-size: .9rem; margin-top: auto; }
.trust { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 16px; }
.trust h3 { margin-top: 0; }
.related { display: flex; gap: 8px; flex-wrap: wrap; }

/* Footer */
.site-footer { margin-top: 50px; border-top: 1px solid var(--border); background: var(--surface); padding: 26px 0; font-size: .88rem; color: var(--muted); }
.site-footer .cols { display: flex; gap: 30px; flex-wrap: wrap; justify-content: space-between; }
.site-footer a { color: var(--muted); }
.site-footer ul { list-style: none; padding: 0; margin: 0; } .site-footer li { margin: 4px 0; }
main { padding-bottom: 10px; }
@media print { .site-header, .site-footer, .newsletter, .sponsor-slot, .theme-toggle, .actions { display: none !important; } }
.row-3 { display: grid; grid-template-columns: 1fr 1fr 1fr auto; gap: 8px; align-items: end; }
.row-3 .remove { margin-bottom: 14px; min-height: 42px; }
.lot + .lot label { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }
.calc-results.stale { opacity: .45; transition: opacity .15s; }
.compare td, .compare th { white-space: normal; }
.ok { color: var(--accent-strong); font-weight: 700; }