:root {
  --bg: #f6f8f7;
  --surface: #ffffff;
  --text: #17201d;
  --muted: #56635e;
  --border: #dfe5e2;
  --accent: #0f766e;
  --accent-hover: #115e59;
  --accent-soft: #e3f4f1;
  --ok: #15803d;
  --ok-soft: #e8f6ed;
  --warn: #b45309;
  --warn-soft: #fdf3e2;
  --err: #b91c1c;
  --s0: #0f766e; --s1: #f59e0b; --s2: #6366f1; --s3: #ec4899; --s4: #0ea5e9; --s5: #84cc16;
  --radius: 12px;
  --shadow: 0 1px 2px rgba(16, 24, 40, .05), 0 1px 3px rgba(16, 24, 40, .06);
  color-scheme: light dark;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0e1211;
    --surface: #161c1a;
    --text: #e7ecea;
    --muted: #9aa8a3;
    --border: #28312e;
    --accent: #2dd4bf;
    --accent-hover: #5eead4;
    --accent-soft: #12302c;
    --ok: #4ade80;
    --ok-soft: #13291c;
    --warn: #fbbf24;
    --warn-soft: #2d2412;
    --err: #f87171;
    --s0: #2dd4bf; --s1: #fbbf24; --s2: #818cf8; --s3: #f472b6; --s4: #38bdf8; --s5: #a3e635;
    --shadow: none;
  }
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--text); font: 16px/1.6 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif; }
a { color: var(--accent); }
.wrap { max-width: 880px; margin: 0 auto; padding: 0 16px; }

/* Header / footer */
.site-header { background: var(--surface); border-bottom: 1px solid var(--border); }
.site-header .wrap { display: flex; align-items: center; justify-content: space-between; gap: 16px; height: 60px; }
.logo { display: flex; align-items: center; gap: 8px; font-weight: 700; color: var(--text); text-decoration: none; font-size: 1.1rem; }
.logo svg { width: 26px; height: 26px; }
.site-nav { display: flex; gap: 18px; font-size: .95rem; }
.site-nav a { color: var(--muted); text-decoration: none; }
.site-nav a:hover { color: var(--text); }
.site-footer { margin-top: 64px; padding: 32px 0; border-top: 1px solid var(--border); color: var(--muted); font-size: .9rem; }
.site-footer nav { display: flex; flex-wrap: wrap; gap: 8px 20px; margin-bottom: 12px; }
.site-footer a { color: var(--muted); }
.site-footer .footer-popular { font-size: .85rem; padding-bottom: 12px; margin-bottom: 14px; border-bottom: 1px solid var(--border); }
.site-footer .footer-popular a { text-decoration: none; }
.site-footer .footer-popular a:hover { color: var(--accent); text-decoration: underline; }
.site-footer .fine { font-size: .8rem; }

/* Page heading */
.crumbs { font-size: .85rem; color: var(--muted); margin: 20px 0 4px; }
.crumbs a { color: var(--muted); text-decoration: none; }
h1 { font-size: clamp(1.6rem, 4vw, 2.2rem); line-height: 1.2; margin: 8px 0 8px; letter-spacing: -.01em; }
.lead { color: var(--muted); margin: 0 0 16px; font-size: 1.05rem; }
.updated { font-size: .8rem; color: var(--muted); margin: -8px 0 16px; }

/* Calculator */
.tool { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); box-shadow: var(--shadow); padding: 20px; }
.form-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(190px, 1fr)); gap: 14px 16px; }
.field { display: flex; flex-direction: column; gap: 4px; }
.field.wide { grid-column: 1 / -1; }
.field-label { font-size: .85rem; font-weight: 600; color: var(--muted); }
.field-hint { font-size: .75rem; color: var(--muted); }
.check { display: flex; align-items: center; gap: 8px; font-size: .9rem; align-self: end; padding-bottom: 8px; }
.check input { width: 18px; height: 18px; accent-color: var(--accent); }
.input-wrap { position: relative; display: flex; }
.input-wrap input { width: 100%; }
.input-wrap.has-pre input { padding-left: 24px; }
.input-wrap.has-suf input { padding-right: 56px; }
.affix { position: absolute; top: 50%; transform: translateY(-50%); color: var(--muted); font-size: .9rem; pointer-events: none; }
.affix.pre { left: 10px; }
.affix.suf { right: 10px; }
input[type=text], input[type=date], input[type=time], select {
  font: inherit; font-size: 1rem; color: var(--text); background: var(--bg);
  border: 1px solid var(--border); border-radius: 8px; padding: 8px 10px; min-width: 0; width: 100%;
}
input:focus, select:focus { outline: 2px solid var(--accent); outline-offset: -1px; border-color: var(--accent); }

.calc-out { margin-top: 20px; }
.answer { background: var(--accent-soft); border-radius: 10px; padding: 16px 18px; margin-bottom: 14px; }
.answer-label { font-size: .9rem; color: var(--muted); font-weight: 600; }
.answer-value { font-size: clamp(1.7rem, 5vw, 2.3rem); font-weight: 750; color: var(--accent); line-height: 1.2; font-variant-numeric: tabular-nums; }
.answer-sub { font-size: .9rem; color: var(--muted); }
.working { font-family: ui-monospace, Consolas, monospace; font-size: .9rem; color: var(--muted); }
.stat-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(160px, 1fr)); gap: 10px; margin: 12px 0; }
.stat { border: 1px solid var(--border); border-radius: 10px; padding: 10px 12px; background: var(--bg); }
.stat-value { font-size: 1.15rem; font-weight: 700; font-variant-numeric: tabular-nums; }
.stat-label { font-size: .78rem; color: var(--muted); }
.status { color: var(--muted); }
.status.error { color: var(--err); }
.hint { font-size: .85rem; color: var(--muted); }
.callout { padding: 10px 14px; border-radius: 10px; font-size: .92rem; }
.callout.ok { background: var(--ok-soft); color: var(--ok); }
.callout.warn { background: var(--warn-soft); color: var(--warn); }

.btn { display: inline-flex; align-items: center; justify-content: center; gap: 6px; font: inherit; font-weight: 600; font-size: .95rem; text-decoration: none; cursor: pointer; background: var(--accent); color: #fff; border: 0; border-radius: 8px; padding: 9px 16px; }
.btn:hover { background: var(--accent-hover); color: #fff; }
.btn.secondary { background: var(--accent-soft); color: var(--accent); }
.btn.small { padding: 6px 12px; font-size: .85rem; }
.icon-btn { font: inherit; background: none; border: 1px solid var(--border); color: var(--text); border-radius: 6px; width: 34px; height: 34px; cursor: pointer; }
.actions { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-top: 16px; }

.breakdown { margin: 12px 0; }
.bar-stack { display: flex; height: 14px; border-radius: 7px; overflow: hidden; background: var(--border); }
.seg { display: block; height: 100%; }
.legend { list-style: none; padding: 0; margin: 8px 0 0; display: flex; flex-wrap: wrap; gap: 4px 16px; font-size: .85rem; color: var(--muted); }
.legend strong { color: var(--text); }
.sw { display: inline-block; width: 10px; height: 10px; border-radius: 3px; margin-right: 6px; vertical-align: middle; }
.s0 { background: var(--s0); fill: var(--s0); } .s1 { background: var(--s1); fill: var(--s1); } .s2 { background: var(--s2); fill: var(--s2); }
.s3 { background: var(--s3); fill: var(--s3); } .s4 { background: var(--s4); fill: var(--s4); } .s5 { background: var(--s5); fill: var(--s5); }
.chart { margin: 16px 0; }
.chart svg { width: 100%; height: 180px; display: block; }
.chart figcaption { display: flex; flex-wrap: wrap; gap: 4px 16px; font-size: .8rem; color: var(--muted); margin-top: 6px; }
.chart-axis { margin-left: auto; }
.scale { position: relative; height: 12px; border-radius: 6px; margin: 12px 0 4px; background: linear-gradient(90deg, #60a5fa 0 14%, #22c55e 14% 40%, #f59e0b 40% 60%, #ef4444 60%); }
.scale-mark { position: absolute; top: -5px; width: 4px; height: 22px; margin-left: -2px; background: var(--text); border-radius: 2px; }
.scale-labels { display: flex; justify-content: space-between; font-size: .75rem; color: var(--muted); }
.clock { display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px; margin: 12px 0; }
.clock-cell { text-align: center; border: 1px solid var(--border); border-radius: 10px; padding: 8px 4px; background: var(--bg); }
.clock-cell strong { display: block; font-size: 1.6rem; font-variant-numeric: tabular-nums; }
.clock-cell span { font-size: .75rem; color: var(--muted); }

.gpa-row, .tc-row { display: grid; gap: 8px; align-items: center; margin-bottom: 8px; }
.gpa-row { grid-template-columns: 2fr 1fr 1fr 1.2fr 34px; }
.tc-row { grid-template-columns: 48px 1fr 1fr 90px 80px; }
.gpa-head, .tc-head { font-size: .78rem; font-weight: 600; color: var(--muted); margin-bottom: 4px; }
.tc-total { font-variant-numeric: tabular-nums; font-size: .9rem; }

details.more { margin-top: 12px; border: 1px solid var(--border); border-radius: 10px; background: var(--bg); }
details.more summary { padding: 10px 14px; font-weight: 600; cursor: pointer; font-size: .9rem; }
details.more .table-wrap { padding: 0 12px 12px; max-height: 420px; overflow: auto; }

/* Tables */
.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; margin: 12px 0; font-size: .92rem; font-variant-numeric: tabular-nums; }
th, td { text-align: left; padding: 7px 10px; border-bottom: 1px solid var(--border); vertical-align: top; }
th { font-size: .82rem; color: var(--muted); font-weight: 600; }
tbody tr:last-child td { border-bottom: 0; }
caption { text-align: left; font-weight: 600; padding-bottom: 6px; }
tr.current td { background: var(--accent-soft); font-weight: 600; }

/* Question pages: pre-rendered answer */
.qa { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); box-shadow: var(--shadow); padding: 20px; margin-bottom: 20px; }
.qa .answer { margin-bottom: 8px; }
.qa p { margin: 8px 0 0; }
.steps { padding-left: 22px; }
.steps li { margin-bottom: 4px; }
.subhead { font-size: 1.1rem; margin: 28px 0 10px; }

/* Affiliate offers */
.offer { display: flex; gap: 16px; align-items: center; justify-content: space-between; flex-wrap: wrap; border: 1px solid var(--border); border-left: 4px solid var(--accent); border-radius: 10px; background: var(--surface); padding: 14px 16px; margin: 20px 0; }
.offer-text strong { display: block; }
.offer-text span { font-size: .88rem; color: var(--muted); }
.offer-tag { font-size: .7rem; letter-spacing: .05em; text-transform: uppercase; color: var(--muted); display: block; margin-bottom: 2px; }
.disclosure { font-size: .78rem; color: var(--muted); margin: -12px 0 20px; }

/* Ads */
.ad { margin: 24px 0; min-height: 100px; text-align: center; overflow: hidden; }
.ad::before { content: "Advertisement"; display: block; font-size: .7rem; letter-spacing: .05em; text-transform: uppercase; color: var(--muted); margin-bottom: 4px; }

/* Article */
.article { margin-top: 32px; }
.article h2 { font-size: 1.35rem; margin: 32px 0 10px; }
.article ol, .article ul { padding-left: 22px; }
.article li { margin-bottom: 6px; }
.formula { font-family: ui-monospace, Consolas, monospace; background: var(--surface); border: 1px solid var(--border); border-radius: 8px; padding: 10px 14px; overflow-x: auto; }
.faq details { border: 1px solid var(--border); border-radius: 10px; background: var(--surface); margin-bottom: 8px; }
.faq summary { cursor: pointer; padding: 12px 16px; font-weight: 600; }
.faq details p { margin: 0; padding: 0 16px 14px; color: var(--muted); }
.disclaimer { font-size: .82rem; color: var(--muted); border-top: 1px solid var(--border); padding-top: 12px; margin-top: 28px; }

/* Cards */
.cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); gap: 12px; }
.card { display: block; padding: 14px 16px; background: var(--surface); border: 1px solid var(--border); border-radius: 10px; text-decoration: none; color: var(--text); transition: border-color .15s, transform .15s; }
.card:hover { border-color: var(--accent); transform: translateY(-1px); }
.card strong { display: block; }
.card span { font-size: .85rem; color: var(--muted); }
.tool-card { display: flex; gap: 14px; align-items: flex-start; padding: 16px; }
.card-icon { flex: none; display: flex; align-items: center; justify-content: center; width: 40px; height: 40px; border-radius: 10px; background: var(--accent-soft); color: var(--accent); }
.card-icon svg { width: 20px; height: 20px; }
.card-text { display: flex; flex-direction: column; gap: 2px; min-width: 0; }

.chips-label { font-size: .9rem; color: var(--muted); margin: 28px 0 8px; }
.chips { display: flex; flex-wrap: wrap; gap: 6px 8px; }
.chip { font-size: .85rem; padding: 3px 10px; border: 1px solid var(--border); border-radius: 6px; background: var(--surface); color: var(--text); text-decoration: none; }
a.chip:hover { border-color: var(--accent); color: var(--accent); }
.chip.current { border-color: var(--accent); color: var(--accent); font-weight: 600; }

/* Home */
.hero { padding: 40px 0 16px; text-align: center; }
.hero h1 { font-size: clamp(1.8rem, 5vw, 2.6rem); }
.hero .lead { max-width: 580px; margin: 0 auto 16px; }
.search { max-width: 420px; font-size: 1rem; padding: 10px 14px; }
.category h2 { font-size: 1.1rem; margin: 32px 0 12px; color: var(--muted); }
.all-tools { margin-top: 56px; padding-top: 8px; border-top: 1px solid var(--border); }
.all-tools h2 { font-size: 1.1rem; margin: 24px 0 16px; color: var(--muted); }
.index { columns: 3 200px; column-gap: 32px; }
.index > div { break-inside: avoid; margin-bottom: 20px; }
.index h3 { font-size: .85rem; margin: 0 0 6px; }
.index ul { list-style: none; margin: 0; padding: 0; }
.index li { font-size: .85rem; line-height: 1.8; }
.index a { color: var(--muted); text-decoration: none; }
.index a:hover { color: var(--accent); text-decoration: underline; }
.link-grid { columns: 3 180px; column-gap: 24px; padding: 0; list-style: none; }
.link-grid li { font-size: .9rem; line-height: 1.9; break-inside: avoid; }

.prose { max-width: 680px; }
.prose h2 { font-size: 1.25rem; margin-top: 28px; }

@media (max-width: 560px) {
  .site-nav { display: none; }
  .tool, .qa { padding: 14px; }
  .gpa-row { grid-template-columns: 1fr 1fr 34px; }
  .gpa-row > :first-child { grid-column: 1 / -1; }
  .gpa-head { display: none; }
  .tc-row { grid-template-columns: 40px 1fr 1fr; }
  .tc-row > :nth-child(4), .tc-row > :nth-child(5) { grid-column: span 1; }
  .tc-head { display: none; }
  .clock-cell strong { font-size: 1.3rem; }
}