:root {
  color-scheme: light dark;
  --bg: #f5f7fb;
  --surface: #ffffff;
  --text: #0f1621;
  --muted: #55607a;
  --border: #d7dce6;
  --brand: #0b3d91;
  --accent: #d62828;
  --accent-hover: #b81f1f;
  --on-accent: #fff;
  --good: #12813f;
  --hero-bg: #0b3d91;
  --link: #0b3d91;
  --link-hover: #0a2f6f;
  --ring: #0b3d91;
  --result-bg: #eef3ff;
  --result-border: #b6c7f5;
  --track: #dfe5f3;
  --shadow: 0 1px 2px rgba(20, 30, 60, .06), 0 4px 16px rgba(20, 30, 60, .06);
  --todo-bg: #fff3b0;
  --todo-text: #3d3200;
  --code-bg: #eef0f5;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f141c;
    --surface: #182030;
    --text: #e8ecf4;
    --muted: #a3adc0;
    --border: #2d384d;
    --brand: #7ba3ff;
    --accent: #ff6b6b;
    --accent-hover: #ff8f8f;
    --on-accent: #0f1621;
    --good: #4fd486;
    --hero-bg: #0a2f6f;
    --link: #7ba3ff;
    --link-hover: #a3bfff;
    --ring: #9db9ff;
    --result-bg: #16264a;
    --result-border: #34508f;
    --track: #25365e;
    --shadow: 0 1px 2px rgba(0, 0, 0, .4), 0 4px 16px rgba(0, 0, 0, .3);
    --todo-bg: #4a3f08;
    --todo-text: #fff3b0;
    --code-bg: #0c1118;
  }
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 1rem/1.6 -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  overflow-wrap: break-word;
}
.wrap { max-width: 72ch; margin: 0 auto; padding-left: 1rem; padding-right: 1rem; }
main.wrap { padding-top: 1.5rem; padding-bottom: 2.5rem; }
main.wrap:has(.hero) { max-width: none; padding: 0 0 2.5rem; }
.inner { max-width: 66rem; margin: 0 auto; padding-left: 1rem; padding-right: 1rem; }

/* header */
.site-header { background: var(--surface); border-bottom: 1px solid var(--border); box-shadow: var(--shadow); }
.site-header .wrap { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: .25rem 1.5rem; padding-top: .75rem; padding-bottom: .75rem; }
.brand { font-size: 1.2rem; font-weight: 800; letter-spacing: -.01em; color: var(--brand); text-decoration: none; }
.flag-rule { height: 3px; background: linear-gradient(90deg, #0b3d91, #d62828); }
nav { display: flex; flex-wrap: wrap; gap: .25rem; }
nav a { padding: .25rem .65rem; border-radius: 999px; color: var(--muted); text-decoration: none; font-weight: 500; transition: background-color .15s, color .15s; }
nav a:hover { background: var(--result-bg); color: var(--link); }

/* typography */
h1 { font-size: clamp(1.6rem, 4vw + .5rem, 2.1rem); line-height: 1.2; letter-spacing: -.02em; margin: 0 0 .75rem; }
h2 { font-size: 1.25rem; line-height: 1.3; margin: 2rem 0 .5rem; }
p, ul, ol, pre { margin: 0 0 1rem; }
ul, ol { padding-left: 1.4rem; }
a { color: var(--link); text-underline-offset: .15em; transition: color .15s; }
a:hover { color: var(--link-hover); }
code { background: var(--code-bg); padding: .1em .35em; border-radius: 4px; font-size: .92em; }
pre { background: var(--code-bg); border: 1px solid var(--border); border-radius: 8px; padding: .85rem 1rem; overflow-x: auto; font-size: .88rem; line-height: 1.5; }
.note { font-size: .9rem; color: var(--muted); }
.todo { background: var(--todo-bg); color: var(--todo-text); padding: 0 .25rem; border-radius: 3px; }
:focus-visible { outline: 3px solid var(--ring); outline-offset: 2px; border-radius: 4px; }

/* cards + calculator layout */
.card { background: var(--surface); border: 1px solid var(--border); border-radius: 12px; box-shadow: var(--shadow); padding: 1rem 1.25rem; }
.calc { display: grid; gap: 1.25rem; margin: 1.5rem 0; grid-template-columns: minmax(0, 1fr); }
.calc > * { min-width: 0; margin: 0; }
@media (min-width: 62rem) {
  main.wrap:has(.calc):not(:has(.hero)) { max-width: 66rem; }
  .calc { grid-template-columns: minmax(0, 1.1fr) minmax(0, 1fr); align-items: start; }
  #calc-form { grid-column: 1; grid-row: 1 / span 2; }
  #result { grid-column: 2; grid-row: 1; position: sticky; top: 1rem; }
  #state-info { grid-column: 2; grid-row: 2; }
}
#state-info h2 { margin-top: 0; font-size: 1.1rem; }
#state-info p:last-child { margin-bottom: 0; }

/* form */
label { display: block; margin: 1rem 0 .3rem; font-weight: 600; font-size: .95rem; }
#calc-form label:first-child { margin-top: 0; }
input[type=number], select {
  display: block; width: 100%; padding: .55rem .7rem; font: inherit; color: var(--text);
  background: var(--bg); border: 1px solid var(--border); border-radius: 8px;
  transition: border-color .15s;
}
input[type=number]:hover, select:hover { border-color: var(--muted); }
input[type=number]:focus-visible, select:focus-visible { outline: 3px solid var(--ring); outline-offset: 1px; border-color: var(--ring); }
input[type=number] { -moz-appearance: textfield; appearance: textfield; }
input[type=number]::-webkit-inner-spin-button, input[type=number]::-webkit-outer-spin-button { -webkit-appearance: none; margin: 0; }
label.inline { display: flex; gap: .6rem; align-items: flex-start; font-weight: 400; cursor: pointer; }
label.inline input { flex: none; width: 1.15rem; height: 1.15rem; margin: .25rem 0 0; accent-color: var(--brand); }

/* result */
#result { background: var(--result-bg); border-color: var(--result-border); border-width: 2px; }
#result-range { color: var(--good); font-size: clamp(2rem, 8vw, 2.6rem); font-weight: 800; line-height: 1.1; letter-spacing: -.02em; margin: 0 0 .75rem; font-variant-numeric: tabular-nums; }
#result-parts { margin: 0 0 1rem; padding: .75rem 0 0; border-top: 4px solid var(--track); color: var(--text); line-height: 1.7; }
.disclaimer { margin: 0; padding: .6rem .8rem; font-size: .88rem; color: var(--muted); background: var(--surface); border: 1px dashed var(--result-border); border-radius: 8px; }
.disclaimer strong { color: var(--text); }

/* landing */
.hero { background: var(--hero-bg); color: #fff; padding: 2.5rem 0 2rem; }
.hero h1 { font-size: clamp(2rem, 6vw + .5rem, 3rem); line-height: 1.1; margin: 0 0 .75rem; max-width: 22ch; }
.hero-sub { font-size: clamp(1.05rem, 2vw + .6rem, 1.3rem); margin: 0 0 1.5rem; max-width: 40rem; color: #dbe5fa; }
.cta { display: inline-block; background: var(--accent); color: var(--on-accent); font-weight: 700; padding: .75rem 1.5rem; border-radius: 999px; text-decoration: none; transition: background-color .15s; }
.cta:hover { background: var(--accent-hover); color: var(--on-accent); }
.hero :focus-visible { outline-color: #fff; }
.badges { list-style: none; padding: 0; margin: 1.5rem 0 0; display: flex; flex-wrap: wrap; gap: .5rem; }
.badges li { background: rgba(255, 255, 255, .16); border: 1px solid rgba(255, 255, 255, .28); border-radius: 999px; padding: .2rem .8rem; font-size: .88rem; font-weight: 600; }
.calc-section { margin-top: 1.5rem; }
.section h2 { font-size: 1.6rem; margin: 2.5rem 0 1rem; letter-spacing: -.01em; }
.section h3 { font-size: 1.05rem; line-height: 1.3; margin: 0 0 .35rem; }
.section p { margin: 0; }
.steps { list-style: none; padding: 0; margin: 0; display: grid; gap: 1rem; grid-template-columns: minmax(0, 1fr); }
.steps li { display: flex; gap: .85rem; align-items: flex-start; }
.step-num { flex: none; width: 2.25rem; height: 2.25rem; border-radius: 50%; background: var(--brand); color: var(--surface); display: grid; place-items: center; font-weight: 800; }
.grid-4 { display: grid; gap: 1rem; grid-template-columns: minmax(0, 1fr); }
.grid-4 .card { border-top: 4px solid var(--brand); }
details { background: var(--surface); border: 1px solid var(--border); border-radius: 10px; margin-bottom: .6rem; }
summary { cursor: pointer; padding: .8rem 1rem; font-weight: 600; }
details[open] summary { color: var(--link); }
details p { padding: 0 1rem 1rem; }
@media (min-width: 40rem) {
  .steps { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .grid-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (min-width: 62rem) {
  .grid-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}

/* footer */
.site-footer { background: var(--hero-bg); color: #dbe5fa; padding-top: 1.5rem; padding-bottom: 1.5rem; }
.site-footer a { color: #fff; }
.footer-disclaimer { font-size: .9rem; margin: 0 0 1rem; }
.footer-links { gap: .25rem 1.25rem; margin-bottom: 1rem; }
.footer-links a { padding: 0; font-weight: 600; }
.copyright { margin: 0; font-size: .85rem; opacity: .85; }

@media (max-width: 30rem) {
  .card { padding: .9rem 1rem; }
}
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; }
}
@media print {
  nav, .hero, .site-footer { display: none; }
  body { background: #fff; color: #000; }
  .card { box-shadow: none; }
}