:root {
  --bg: #f7f7f5;
  --surface: #ffffff;
  --surface-2: #f1f1ee;
  --text: #1c1d1f;
  --muted: #5f636b;
  --border: #e2e2dd;
  --accent: #0b7a75;
  --accent-soft: #e3f3f1;
  --c-base: #8a8f98;
  --c-recast: #0b7a75;
  --c-prepay: #c27a12;
  --c-refi: #6a55c9;
  --good: #1f7a3f;
  --bad: #b3261e;
  --radius: 12px;
  --shadow: 0 1px 2px rgba(0,0,0,.04), 0 4px 16px rgba(0,0,0,.04);
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #141517; --surface: #1c1d20; --surface-2: #232428; --text: #ececea; --muted: #a2a6ad;
    --border: #303238; --accent: #3fc2b9; --accent-soft: #173432;
    --c-base: #8f949c; --c-recast: #3fc2b9; --c-prepay: #e9a53d; --c-refi: #a595f0;
    --good: #5fcf86; --bad: #ff8a80; --shadow: none;
  }
}
:root[data-theme="dark"] {
  --bg: #141517; --surface: #1c1d20; --surface-2: #232428; --text: #ececea; --muted: #a2a6ad;
  --border: #303238; --accent: #3fc2b9; --accent-soft: #173432;
  --c-base: #8f949c; --c-recast: #3fc2b9; --c-prepay: #e9a53d; --c-refi: #a595f0;
  --good: #5fcf86; --bad: #ff8a80; --shadow: none;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--bg); color: var(--text);
  font: 16px/1.6 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}
a { color: var(--accent); }
.wrap { max-width: 1080px; margin: 0 auto; padding: 0 16px; }
header.site { border-bottom: 1px solid var(--border); background: var(--surface); }
header.site .wrap { display: flex; align-items: center; justify-content: space-between; height: 56px; }
.logo { font-weight: 700; letter-spacing: -.01em; text-decoration: none; color: var(--text); }
.logo span { color: var(--accent); }
nav a { color: var(--muted); text-decoration: none; margin-left: 18px; font-size: 14px; }
nav a:hover { color: var(--text); }
@media (max-width: 560px) { nav { display: none; } }

.crumbs { font-size: 13px; color: var(--muted); margin: 20px 0 6px; }
.crumbs a { color: var(--muted); text-decoration: none; }
h1 { font-size: clamp(28px, 4vw, 38px); line-height: 1.15; letter-spacing: -.02em; margin: 0 0 8px; }
.lede { color: var(--muted); font-size: 17px; margin: 0 0 24px; max-width: 720px; }

.calc { display: grid; grid-template-columns: 340px 1fr; gap: 20px; align-items: start; }
@media (max-width: 860px) { .calc { grid-template-columns: 1fr; } }
.card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); box-shadow: var(--shadow); }
.inputs { padding: 20px; }
.inputs h2, .results h2 { font-size: 15px; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); margin: 0 0 14px; font-weight: 600; }
.group + .group { margin-top: 18px; padding-top: 18px; border-top: 1px dashed var(--border); }
.group-title { font-size: 13px; font-weight: 600; margin-bottom: 10px; display: flex; align-items: center; gap: 8px; }
.dot { width: 10px; height: 10px; border-radius: 50%; display: inline-block; flex: none; }
.field { margin-bottom: 12px; }
.field label { display: block; font-size: 14px; margin-bottom: 4px; }
.hint { font-size: 12px; color: var(--muted); margin-top: 3px; }
.inp { position: relative; display: flex; align-items: center; }
.inp input {
  width: 100%; padding: 10px 12px; font: inherit; color: var(--text);
  background: var(--surface-2); border: 1px solid var(--border); border-radius: 8px; outline: none;
  -moz-appearance: textfield;
}
.inp input::-webkit-outer-spin-button, .inp input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
.inp input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
.inp.pre input { padding-left: 26px; }
.inp.suf input { padding-right: 44px; }
.inp .pfx, .inp .sfx { position: absolute; color: var(--muted); font-size: 14px; pointer-events: none; }
.inp .pfx { left: 12px; } .inp .sfx { right: 12px; }
.row2 { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.err { color: var(--bad); font-size: 13px; margin-top: 8px; min-height: 1em; }

.results { padding: 20px; }
.verdict { background: var(--accent-soft); border-radius: 10px; padding: 14px 16px; margin-bottom: 16px; font-size: 15px; }
.verdict strong { color: var(--text); }
.scen { display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px; }
@media (max-width: 1000px) { .scen { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 420px) { .scen { grid-template-columns: 1fr; } }
.sc { border: 1px solid var(--border); border-radius: 10px; padding: 12px; position: relative; background: var(--surface); }
.sc .name { font-size: 13px; font-weight: 600; display: flex; align-items: center; gap: 6px; margin-bottom: 8px; }
.sc .big { font-size: 24px; font-weight: 700; letter-spacing: -.02em; line-height: 1.1; font-variant-numeric: tabular-nums; }
.sc .big small { font-size: 13px; font-weight: 500; color: var(--muted); }
.sc dl { margin: 10px 0 0; font-size: 12px; display: grid; grid-template-columns: 1fr auto; gap: 4px 8px; }
.sc dt { color: var(--muted); white-space: nowrap; } .sc dd { white-space: nowrap; margin: 0; text-align: right; font-variant-numeric: tabular-nums; }
.sc .net { margin-top: 10px; padding-top: 8px; border-top: 1px solid var(--border); font-size: 13px; display: flex; justify-content: space-between; }
.sc .net b { font-variant-numeric: tabular-nums; }
.pos { color: var(--good); } .neg { color: var(--bad); }
.badges { display: flex; flex-wrap: wrap; gap: 4px; margin-top: 8px; min-height: 20px; }
.badge { font-size: 11px; font-weight: 600; padding: 2px 7px; border-radius: 99px; background: var(--accent-soft); color: var(--accent); }

.chart-card { margin-top: 16px; padding: 16px 16px 8px; }
.chart-head { display: flex; justify-content: space-between; align-items: baseline; flex-wrap: wrap; gap: 8px; }
.chart-head h3 { margin: 0; font-size: 15px; }
.legend { display: flex; flex-wrap: wrap; gap: 12px; font-size: 13px; color: var(--muted); }
.legend span { display: inline-flex; align-items: center; gap: 6px; }
.chart { position: relative; margin-top: 8px; }
.chart svg { width: 100%; height: auto; display: block; overflow: visible; }
.tip { position: absolute; pointer-events: none; background: var(--surface); border: 1px solid var(--border); border-radius: 8px;
       padding: 8px 10px; font-size: 12px; box-shadow: var(--shadow); opacity: 0; transition: opacity .1s; white-space: nowrap; }
.tip .t { font-weight: 600; margin-bottom: 4px; }
.tip div { display: flex; justify-content: space-between; gap: 12px; font-variant-numeric: tabular-nums; }

.ad-slot { margin: 28px 0; min-height: 100px; border: 1px dashed var(--border); border-radius: 10px;
           display: flex; align-items: center; justify-content: center; color: var(--muted); font-size: 12px; }

article { max-width: 720px; margin: 8px 0 0; }
article h2 { font-size: 24px; letter-spacing: -.01em; margin: 36px 0 10px; line-height: 1.25; }
article h3 { font-size: 18px; margin: 24px 0 6px; }
article p, article li { color: var(--text); }
.formula { background: var(--surface-2); border-radius: 8px; padding: 12px 14px; font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 14px; overflow-x: auto; }
.tbl-wrap { overflow-x: auto; border: 1px solid var(--border); border-radius: 10px; }
table { width: 100%; border-collapse: collapse; font-size: 14px; background: var(--surface); }
th, td { padding: 10px 12px; text-align: left; border-bottom: 1px solid var(--border); vertical-align: top; }
th { font-weight: 600; background: var(--surface-2); }
tr:last-child td { border-bottom: 0; }
details { border-bottom: 1px solid var(--border); padding: 12px 0; }
summary { cursor: pointer; font-weight: 600; }
details p { margin: 8px 0 0; }
.disclaimer { font-size: 13px; color: var(--muted); margin-top: 32px; }
footer.site { border-top: 1px solid var(--border); margin-top: 48px; padding: 24px 0 40px; font-size: 13px; color: var(--muted); }
footer.site a { color: var(--muted); margin-right: 16px; }

  /* ---- shared page styles (home, about, privacy, contact) ---- */
  .logo { display: inline-flex; align-items: center; gap: 8px; }
  .logo svg { width: 26px; height: 26px; flex: none; }
  .hero { padding: 40px 0 8px; }
  .hero h1 { max-width: 760px; text-wrap: balance; }
  .tools { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 14px; margin: 24px 0 8px; }
  a.tool { display: block; text-decoration: none; color: var(--text); padding: 18px; border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface); box-shadow: var(--shadow); transition: border-color .15s; }
  a.tool:hover, a.tool:focus-visible { border-color: var(--accent); outline: none; }
  a.tool .cat { font-size: 12px; letter-spacing: .06em; text-transform: uppercase; color: var(--accent); font-weight: 600; }
  a.tool h3 { margin: 6px 0 4px; font-size: 18px; }
  a.tool p { margin: 0; color: var(--muted); font-size: 14px; }
  .soon { color: var(--muted); font-size: 14px; }
  .soon ul { margin: 6px 0 0; padding-left: 18px; }
  .page { max-width: 720px; padding: 32px 0 0; }
  .page h1 { margin-bottom: 12px; }
  .page h2 { font-size: 20px; margin: 28px 0 8px; }
  .updated { color: var(--muted); font-size: 14px; }
  .email { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; background: var(--surface-2); padding: 3px 8px; border-radius: 6px; user-select: all; }
  @media (prefers-reduced-motion: reduce) { * { transition: none !important; } }