/* =============================================================================
   Debt calculator — built on the shared design system (design/DESIGN_SYSTEM.md).
   Reference brand: GOV.UK Design System, as a system (type scale, spacing,
   colour-by-role, flat components) — never its wordmark, crest, or copy.
   No ad-hoc colours, fonts, radii, or shadows outside the token set below.
   ========================================================================== */

@font-face {
  font-family: "Public Sans";
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url("fonts/PublicSans-Regular.woff2") format("woff2");
}
@font-face {
  font-family: "Public Sans";
  font-style: normal;
  font-weight: 500;
  font-display: swap;
  src: url("fonts/PublicSans-Medium.woff2") format("woff2");
}
@font-face {
  font-family: "Public Sans";
  font-style: normal;
  font-weight: 700;
  font-display: swap;
  src: url("fonts/PublicSans-Bold.woff2") format("woff2");
}
@font-face {
  font-family: "IBM Plex Mono";
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url("fonts/IBMPlexMono-Regular.woff2") format("woff2");
}
@font-face {
  font-family: "IBM Plex Mono";
  font-style: normal;
  font-weight: 600;
  font-display: swap;
  src: url("fonts/IBMPlexMono-SemiBold.woff2") format("woff2");
}

:root {
  --color-ink: #0b0c0c;
  --color-ink-secondary: #505a5f;
  --color-paper: #ffffff;
  --color-surface: #f3f2f1;
  --color-border: #b1b4b6;
  --color-border-strong: #0b0c0c;

  --color-brand: #1d70b8;
  --color-brand-dark: #003078;
  --color-focus: #f5a623;
  --color-focus-ink: #0b0c0c;

  --color-error: #d4351c;
  --color-error-bg: #fdf2f0;
  --color-success: #00703c;
  --color-success-bg: #eaf5ef;
  --color-warning: #f47738;
  --color-warning-bg: #fdf1e8;

  --space-0: 0;
  --space-1: 5px;
  --space-2: 10px;
  --space-3: 15px;
  --space-4: 20px;
  --space-5: 25px;
  --space-6: 30px;
  --space-7: 40px;
  --space-8: 50px;
  --space-9: 60px;

  --radius-sm: 2px;
  --radius-md: 4px;

  --border-thin: 1px solid var(--color-border);
  --border-input: 2px solid var(--color-ink);
  --border-focus: 3px solid var(--color-focus);

  --shadow-popover: 0 2px 6px rgba(11, 12, 12, 0.25);

  --font-ui: "Public Sans", "Segoe UI", Arial, sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, "SFMono-Regular", monospace;

  --motion-fast: 100ms;
  --motion-base: 150ms;
  --motion-ease: cubic-bezier(0.4, 0, 0.2, 1);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --color-ink: #f3f2f1;
    --color-ink-secondary: #b1b4b6;
    --color-paper: #0b0c0c;
    --color-surface: #1a1b1b;
    --color-border: #4c4f50;
    --color-border-strong: #f3f2f1;
    --color-brand: #5694ca;
    --color-brand-dark: #85b6e0;
    --color-error: #ff6f59;
    --color-error-bg: #2a1512;
    --color-success: #4fbd82;
    --color-success-bg: #0f241a;
    --color-warning: #f9a26c;
    --color-warning-bg: #2a1c10;
    --shadow-popover: 0 2px 8px rgba(0, 0, 0, 0.6);
  }
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--color-paper);
  color: var(--color-ink);
  font-family: var(--font-ui);
  font-size: 16px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

.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;
}

a { color: var(--color-brand); text-decoration: underline; text-underline-offset: 2px; }
a:hover { color: var(--color-brand-dark); }
a:focus-visible { outline: var(--border-focus); outline-offset: 2px; }

/* ---------------------------------- page shell ---------------------------- */

.page {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 var(--space-4);
}

/* ---------------------------------- page header ---------------------------- */

.page-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  flex-wrap: wrap;
  gap: var(--space-2);
  padding: var(--space-4) 0;
  border-bottom: var(--border-thin);
  margin-bottom: var(--space-6);
}
.page-header__brand {
  font: 700 19px/28px var(--font-ui);
  color: var(--color-ink);
  text-decoration: none;
}
.page-header__tag {
  font: 400 14px/20px var(--font-ui);
  color: var(--color-ink-secondary);
}

.intro {
  padding-bottom: var(--space-6);
}
.intro h1 {
  font: 700 36px/40px var(--font-ui);
  margin: 0 0 var(--space-4);
}
.intro p {
  font: 400 16px/24px var(--font-ui);
  max-width: 68ch;
  margin: 0 0 var(--space-3);
  color: var(--color-ink);
}

.disclosure {
  border-left: 4px solid var(--color-border);
  background: var(--color-surface);
  padding: var(--space-3) var(--space-4);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  font: 400 14px/20px var(--font-ui);
  color: var(--color-ink-secondary);
  max-width: 68ch;
}
.disclosure strong { color: var(--color-ink); }

/* ---------------------------------- sections ------------------------------ */

.page-section {
  padding-top: var(--space-7);
}
.page-section h2 {
  font: 700 27px/32px var(--font-ui);
  margin: 0 0 var(--space-4);
  padding-bottom: var(--space-2);
  border-bottom: var(--border-thin);
}

/* ---------------------------------- debts table ---------------------------- */

.table-scroll { overflow-x: auto; margin-bottom: var(--space-3); contain: layout; max-width: 100%; }

table.debts {
  width: 100%;
  border-collapse: collapse;
  min-width: 560px;
  font: 400 14px/20px var(--font-ui);
}
table.debts th {
  font: 500 14px/20px var(--font-ui);
  letter-spacing: 0.01em;
  color: var(--color-ink-secondary);
  text-align: left;
  padding: var(--space-2) var(--space-2);
  border-bottom: 2px solid var(--color-ink);
}
table.debts th.col-num, table.debts td.col-num { text-align: right; width: 22%; }
table.debts th.col-action, table.debts td.col-action { width: 40px; }
table.debts td {
  padding: var(--space-2) var(--space-2);
  border-bottom: var(--border-thin);
  vertical-align: middle;
}

input[type="text"], input[type="number"] {
  width: 100%;
  border: 2px solid transparent;
  background: transparent;
  font: 400 16px/24px var(--font-ui);
  color: var(--color-ink);
  padding: 6px 4px;
  border-radius: var(--radius-sm);
}
.debts .debt-name { font-family: var(--font-ui); }
.debts .debt-balance,
.debts .debt-apr,
.debts .debt-min {
  font-family: var(--font-mono);
  text-align: right;
  font-variant-numeric: tabular-nums;
}

input:hover { border-color: var(--color-border); }
input:focus-visible, select:focus-visible, button:focus-visible, [tabindex="-1"]:focus-visible {
  outline: var(--border-focus);
  outline-offset: 1px;
  border-color: var(--color-ink);
}

.money-input {
  display: flex;
  align-items: center;
  border-bottom: var(--border-thin);
}
.money-input span { color: var(--color-ink-secondary); font-family: var(--font-mono); padding-left: 4px; }
.money-input input { text-align: right; }
.money-input--cell { border-bottom: none; }

.row-remove {
  width: 28px; height: 28px;
  border: 2px solid var(--color-ink);
  background: var(--color-paper);
  color: var(--color-error);
  border-radius: var(--radius-sm);
  font-size: 16px;
  line-height: 1;
  cursor: pointer;
}
.row-remove:hover { background: var(--color-error); color: #fff; border-color: var(--color-error); }
.row-remove:focus-visible { outline: var(--border-focus); outline-offset: 2px; }

/* ---------------------------------- buttons -------------------------------- */

.btn {
  font: 500 16px/24px var(--font-ui);
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  border: 2px solid transparent;
  cursor: pointer;
  transition: background var(--motion-fast) var(--motion-ease);
}
.btn--primary { background: var(--color-brand); color: #fff; }
.btn--primary:hover { background: var(--color-brand-dark); }
.btn--ghost { background: transparent; color: var(--color-ink); border-color: var(--color-ink); }
.btn--ghost:hover { background: var(--color-surface); }
.btn--text {
  background: none;
  border-color: transparent;
  padding: 10px 4px;
  color: var(--color-ink-secondary);
  text-decoration: underline;
  text-underline-offset: 2px;
}
.btn--text:hover { color: var(--color-brand-dark); }
.btn:focus-visible { outline: var(--border-focus); outline-offset: 2px; }
.btn:disabled { background: var(--color-border); color: var(--color-ink-secondary); cursor: not-allowed; }

.action-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  align-items: center;
  margin-top: var(--space-4);
  padding-top: var(--space-4);
  border-top: var(--border-thin);
}

/* ---------------------------------- budget field --------------------------- */

.field-row--budget {
  max-width: 340px;
  margin-top: var(--space-5);
}
.field-row--budget label {
  display: block;
  font: 500 14px/20px var(--font-ui);
  margin-bottom: 4px;
}
.field-row--budget .money-input {
  border: var(--border-input);
  border-radius: var(--radius-sm);
  padding: 4px 8px;
}
.field-row--budget input { font-family: var(--font-mono); font-size: 19px; text-align: left; }
.field-hint {
  display: block;
  font: 400 14px/20px var(--font-ui);
  color: var(--color-ink-secondary);
  margin: var(--space-2) 0 0;
}

.alert {
  border-left: 4px solid var(--color-border);
  background: var(--color-surface);
  padding: var(--space-3) var(--space-4);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
}
.alert-error {
  border-left-color: var(--color-error);
  background: var(--color-error-bg);
  color: var(--color-error);
  margin-top: var(--space-4);
  font: 400 16px/24px var(--font-ui);
}

/* ---------------------------------- results -------------------------------- */

.results { padding-top: var(--space-7); }

.balance-strip {
  height: 34px;
  background: var(--color-surface);
  border: var(--border-input);
  border-radius: var(--radius-sm);
  position: relative;
  margin-bottom: var(--space-1);
}
.balance-strip__fill {
  height: 100%;
  background: var(--color-brand);
  width: 100%;
}
.balance-strip__marker {
  position: absolute;
  top: -4px; bottom: -4px;
  width: 2px;
  background: var(--color-ink);
  left: 0;
}
.balance-strip__caption {
  font: 400 14px/20px var(--font-mono);
  color: var(--color-ink-secondary);
  margin: 0 0 var(--space-6);
}
.balance-strip__caption strong { color: var(--color-ink); font-size: 16px; }

.compare {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: var(--space-4);
  align-items: start;
}
.compare__col h3 {
  font: 700 19px/28px var(--font-ui);
  margin: 0 0 4px;
}
.compare__tag {
  display: block;
  font: 400 14px/20px var(--font-ui);
  color: var(--color-ink-secondary);
  margin-top: 2px;
}
.compare__col[data-method="avalanche"] h3 { color: var(--color-brand); }
.compare__col[data-method="snowball"] h3 { color: var(--color-ink); }

.compare__figures { margin: var(--space-3) 0 0; }
.compare__figures > div {
  display: flex;
  justify-content: space-between;
  gap: var(--space-2);
  padding: var(--space-1) 0;
  border-bottom: var(--border-thin);
}
.compare__figures dt { color: var(--color-ink-secondary); font: 400 14px/20px var(--font-ui); }
.compare__figures dd {
  margin: 0;
  font: 600 19px/24px var(--font-mono);
  font-variant-numeric: tabular-nums;
  text-align: right;
}

.compare__divider { width: 1px; background: var(--color-border); align-self: stretch; }

.verdict {
  margin: var(--space-5) 0 0;
  padding: var(--space-3) var(--space-4);
  border-left: 4px solid var(--color-success);
  background: var(--color-success-bg);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  font: 400 16px/24px var(--font-ui);
}
.verdict strong { font-family: var(--font-mono); font-variant-numeric: tabular-nums; }

/* ---------------------------------- chart ----------------------------------- */

.chart-block { margin-top: var(--space-7); }
.chart-block__head {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: baseline;
  gap: var(--space-2);
  margin-bottom: var(--space-2);
}
.chart-block__head h3 { font: 700 19px/28px var(--font-ui); margin: 0; }
.chart-legend { display: flex; gap: var(--space-4); font: 400 14px/20px var(--font-ui); color: var(--color-ink-secondary); }
.swatch { display: inline-block; width: 12px; height: 12px; margin-right: 5px; vertical-align: -1px; border-radius: var(--radius-sm); }
.swatch--avalanche { background: var(--color-brand); }
.swatch--snowball { background: var(--color-ink); }
.chart-wrap { width: 100%; overflow-x: auto; }
.chart-wrap svg { display: block; width: 100%; height: auto; }

/* ---------------------------------- schedule --------------------------------- */

.schedule-block { margin-top: var(--space-7); }
.schedule-block__head {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: var(--space-3);
  margin-bottom: var(--space-2);
}
.schedule-block__head h3 { font: 700 19px/28px var(--font-ui); margin: 0; }
.schedule-controls { display: flex; gap: var(--space-2); align-items: center; }
.schedule-controls select {
  font: 400 16px/24px var(--font-ui);
  padding: 8px 10px;
  border: var(--border-input);
  border-radius: var(--radius-sm);
  background: var(--color-paper);
  color: var(--color-ink);
}
.schedule-controls select:focus-visible { outline: var(--border-focus); outline-offset: 1px; }

.schedule-table-wrap {
  max-height: 420px;
  overflow: auto;
  border: var(--border-input);
  border-radius: var(--radius-sm);
  contain: layout;
  max-width: 100%;
}
table.schedule {
  width: 100%;
  border-collapse: collapse;
  font: 400 14px/20px var(--font-ui);
}
table.schedule th, table.schedule td {
  padding: var(--space-2) var(--space-3);
  text-align: right;
  border-bottom: var(--border-thin);
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}
table.schedule th:first-child, table.schedule td:first-child { text-align: left; font-family: var(--font-ui); }
table.schedule thead th {
  position: sticky;
  top: 0;
  background: var(--color-surface);
  z-index: 1;
  font-weight: 500;
  color: var(--color-ink-secondary);
  border-bottom: 2px solid var(--color-ink);
}

/* ---------------------------------- FAQ --------------------------------------- */

.faq { padding-top: var(--space-7); padding-bottom: var(--space-2); }
.faq__item {
  padding: var(--space-4) 0;
  border-bottom: var(--border-thin);
}
.faq__item:first-of-type { border-top: var(--border-thin); }
.faq__item h3 {
  font: 700 19px/28px var(--font-ui);
  margin: 0 0 var(--space-2);
}
.faq__item p { margin: 0; color: var(--color-ink); max-width: 68ch; }

/* ---------------------------------- footer ------------------------------------- */

.footer {
  border-top: var(--border-thin);
  margin-top: var(--space-9);
  padding: var(--space-6) 0 var(--space-7);
  font: 400 14px/20px var(--font-ui);
  color: var(--color-ink-secondary);
}
.footer p { margin: 0 0 var(--space-2); max-width: 68ch; }
.footer p:last-child { margin-bottom: 0; }
.footer a { color: var(--color-ink-secondary); }

/* ---------------------------------- responsive ---------------------------------- */

@media (max-width: 640px) {
  .page { padding: 0 var(--space-3); }
  .intro h1 { font-size: 27px; line-height: 32px; }
  .page-section h2 { font-size: 21px; line-height: 28px; }
  .compare { grid-template-columns: 1fr; }
  .compare__divider { display: none; }
  .compare__col[data-method="snowball"] { padding-top: var(--space-3); border-top: var(--border-thin); }
  .schedule-block__head { align-items: flex-start; flex-direction: column; }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
}