:root {
  --accent: #6366f1;
  --accent-soft: rgba(99, 102, 241, 0.15);
  --green: #10b981;
  --green-soft: rgba(16, 185, 129, 0.15);
  --amber: #f59e0b;
  --bg: #0c0c12;
  --surface: #14141f;
  --surface-hover: #1a1a28;
  --border: rgba(255, 255, 255, 0.08);
  --text: #e8eaf0;
  --text-muted: #8b93a7;
  --tool-nav-bg: rgba(12, 12, 18, 0.95);
  --tool-nav-border: var(--border);
  --tool-nav-text: var(--text);
  --tool-nav-muted: var(--text-muted);
  --tool-nav-accent: #818cf8;
  --nav-height: var(--tool-nav-height);
  --radius: 12px;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.25);
  --card-gap: 0.75rem;
}

@media (prefers-color-scheme: light) {
  :root {
    --bg: #f4f5f8;
    --surface: #ffffff;
    --surface-hover: #f8f9fc;
    --border: rgba(0, 0, 0, 0.08);
    --text: #111827;
    --text-muted: #6b7280;
    --tool-nav-bg: rgba(255, 255, 255, 0.92);
    --accent-soft: rgba(99, 102, 241, 0.1);
    --green-soft: rgba(16, 185, 129, 0.1);
    --shadow: 0 4px 20px rgba(0, 0, 0, 0.06);
  }
}

*, *::before, *::after { box-sizing: border-box; }

body {
  margin: 0;
  display: flex;
  flex-direction: column;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
}

/* ── layout ──────────────────────────────────────────────────────────────── */

.app {
  display: flex;
  align-items: stretch;
  flex: 1;
  min-height: 0;
}

.summary {
  flex-shrink: 0;
  width: 240px;
  padding: 1.25rem;
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  background: var(--surface);
  position: sticky;
  top: var(--nav-height);
  align-self: flex-start;
  min-height: calc(100vh - var(--nav-height));
  z-index: 10;
}

.workspace {
  flex: 1;
  min-width: 0;
  padding: 1.5rem;
}

.form-stack {
  max-width: 680px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: var(--card-gap);
}

/* ── summary cards ───────────────────────────────────────────────────────── */

.summary-card {
  padding: 1rem 1.1rem;
  border-radius: var(--radius);
  background: var(--accent-soft);
  border: 1px solid rgba(99, 102, 241, 0.25);
}

.summary-card--primary {
  border-color: rgba(99, 102, 241, 0.4);
}

.summary-card--muted {
  background: transparent;
  border-color: var(--border);
}

.summary-card--savings {
  background: var(--green-soft);
  border-color: rgba(16, 185, 129, 0.35);
}

.summary-card--savings-muted {
  background: transparent;
  border-color: rgba(16, 185, 129, 0.2);
}

.summary-label {
  margin: 0 0 0.3rem;
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--text-muted);
}

.summary-value {
  margin: 0;
  font-size: 1.55rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.15;
  display: flex;
  align-items: baseline;
  gap: 0.3rem;
  flex-wrap: wrap;
}

.summary-value--sm { font-size: 1.2rem; }
.summary-value--warn .summary-number { color: var(--amber); }
.summary-value--green .summary-number { color: var(--green); }

.summary-number { font-variant-numeric: tabular-nums; }

.summary-currency {
  font-size: 0.8em;
  font-weight: 600;
  color: var(--text-muted);
}

.summary-divider {
  height: 1px;
  background: var(--border);
  margin: 0.15rem 0;
}

/* ── cards ───────────────────────────────────────────────────────────────── */

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
}

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 1rem 1.25rem;
  min-height: 3rem;
}

.card-header-text { flex: 1; min-width: 0; }

.card-title {
  margin: 0;
  font-size: 0.95rem;
  font-weight: 600;
}

.card-hint {
  margin: 0.2rem 0 0;
  font-size: 0.78rem;
  color: var(--text-muted);
}

.card-body {
  padding: 0.85rem 1.25rem 1.25rem;
  border-top: 1px solid var(--border);
}

/* ── fields ──────────────────────────────────────────────────────────────── */

.field {
  display: grid;
  gap: 0.55rem;
}

.field + .field {
  margin-top: 0.85rem;
  padding-top: 0.85rem;
  border-top: 1px solid var(--border);
}

.field-label {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 0.5rem;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-muted);
}

.field-value {
  font-weight: 600;
  color: var(--accent);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

input[type="range"] {
  width: 100%;
  height: 6px;
  margin: 0.25rem 0.1rem;
  accent-color: var(--accent);
  cursor: pointer;
}

input[type="number"],
input[type="text"],
select {
  width: 100%;
  padding: 0.5rem 0.7rem;
  font: inherit;
  font-size: 0.875rem;
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
}

input:focus, select:focus {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}

.input-wrap {
  position: relative;
  display: inline-flex;
  align-items: center;
}

.input-suffix {
  position: absolute;
  right: 0.65rem;
  font-size: 0.79rem;
  font-weight: 500;
  color: var(--text-muted);
  pointer-events: none;
  user-select: none;
}

.num-input {
  width: 110px;
  flex-shrink: 0;
}

.input-wrap .num-input {
  padding-right: 2.8rem;
}

/* ── tabs ────────────────────────────────────────────────────────────────── */

.tab-row {
  display: flex;
  gap: 0.35rem;
  margin-bottom: 1rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 9px;
  padding: 3px;
}

.tab-btn {
  flex: 1;
  padding: 0.4rem 0.75rem;
  font: inherit;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-muted);
  background: transparent;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  transition: color 0.15s, background 0.15s;
}

.tab-btn:hover { color: var(--text); }

.tab-btn.is-active {
  color: var(--text);
  background: var(--surface);
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.2);
}

/* ── pill buttons (EURIBOR index) ────────────────────────────────────────── */

.pill-row {
  display: flex;
  gap: 0.4rem;
  flex-wrap: wrap;
}

.pill-btn {
  padding: 0.3rem 0.85rem;
  font: inherit;
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-muted);
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 20px;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s, background 0.15s;
}

.pill-btn:hover { color: var(--text); border-color: rgba(99, 102, 241, 0.35); }

.pill-btn.is-active {
  color: var(--accent);
  background: var(--accent-soft);
  border-color: rgba(99, 102, 241, 0.45);
}

/* ── effective rate badge ────────────────────────────────────────────────── */

.effective-rate {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 0.1rem;
  flex-shrink: 0;
}

.effective-rate__label {
  font-size: 0.68rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--text-muted);
}

.effective-rate__value {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--accent);
  font-variant-numeric: tabular-nums;
}

/* ── rate composition row ────────────────────────────────────────────────── */

.rate-composition {
  margin-top: 0.9rem;
  padding: 0.5rem 0.85rem 0.65rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  font-variant-numeric: tabular-nums;
}

.rc-row-labels {
  display: flex;
  justify-content: space-between;
  padding: 0 0.15rem;
  margin-bottom: 0.3rem;
}

.rc-row-labels span {
  font-size: 0.67rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
}

.rc-row-formula {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.45rem;
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text);
}

.rc-op {
  font-weight: 500;
  color: var(--text-muted);
  font-size: 0.82rem;
}

.rc-sum {
  color: var(--accent);
  font-size: 1rem;
  font-weight: 700;
}

/* ── rate panel ──────────────────────────────────────────────────────────── */

.rate-panel[hidden] { display: none; }

/* ── toggle switch ───────────────────────────────────────────────────────── */

.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;
}

.toggle-wrap { cursor: pointer; display: flex; align-items: center; }

.toggle-track {
  display: inline-block;
  width: 40px; height: 22px;
  background: rgba(255, 255, 255, 0.12);
  border-radius: 11px;
  position: relative;
  transition: background 0.2s;
}

@media (prefers-color-scheme: light) {
  .toggle-track { background: rgba(0, 0, 0, 0.14); }
}

.toggle-input:checked + .toggle-track {
  background: var(--accent);
}

.toggle-thumb {
  position: absolute;
  top: 3px; left: 3px;
  width: 16px; height: 16px;
  background: #fff;
  border-radius: 50%;
  transition: transform 0.2s cubic-bezier(.34,1.56,.64,1);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
}

.toggle-input:checked + .toggle-track .toggle-thumb {
  transform: translateX(18px);
}

/* ── summary toggle (mobile only) ───────────────────────────────────────── */

.summary-toggle {
  display: none;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-muted);
  cursor: pointer;
  padding: 0;
  flex-shrink: 0;
  transition: color 0.15s, background 0.15s;
}

.summary-toggle svg {
  width: 14px;
  height: 14px;
  transition: transform 0.2s;
}

.summary-toggle[aria-expanded="true"] svg {
  transform: rotate(180deg);
}

/* ── chart ───────────────────────────────────────────────────────────────── */

.chart-body {
  padding-bottom: 1rem;
}

.chart-svg {
  display: block;
  width: 100%;
  height: auto;
  overflow: visible;
}

/* SVG styles via CSS custom properties */
.chart-grid {
  stroke: var(--border);
  stroke-dasharray: 4 4;
}

.chart-axis {
  stroke: var(--border);
}

.chart-lbl {
  font-family: system-ui, -apple-system, sans-serif;
  font-size: 10px;
  fill: var(--text-muted);
}

.chart-line--standard {
  stroke: var(--accent);
  stroke-width: 2.5;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.chart-line--early {
  stroke: var(--green);
  stroke-width: 2.5;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-dasharray: 7 3;
}

.chart-savings-area {
  fill: var(--green-soft);
}

.chart-legend {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.25rem 0.75rem;
}

.legend-item {
  display: inline-flex;
  align-items: flex-start;
  gap: 0.35rem;
}

.legend-dot {
  width: 10px; height: 10px;
  border-radius: 50%;
  flex-shrink: 0;
  margin-top: 0.15em;
}

.legend-dot--accent { background: var(--accent); }
.legend-dot--green  { background: var(--green); }

.legend-text {
  font-size: 0.78rem;
  color: var(--text-muted);
}

/* ── breakdown bars ──────────────────────────────────────────────────────── */

.chart-breakdown {
  margin-top: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}

.breakdown-legend {
  display: flex;
  gap: 1rem;
  margin-bottom: 0.25rem;
}

.breakdown-legend-item {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.75rem;
  color: var(--text-muted);
}

.breakdown-swatch {
  width: 10px; height: 10px;
  border-radius: 2px;
  flex-shrink: 0;
}

.breakdown-swatch--principal { background: var(--accent); opacity: 0.8; }
.breakdown-swatch--interest  { background: var(--amber); opacity: 0.85; }

.breakdown-row {
  display: grid;
  grid-template-columns: 74px 1fr 90px;
  align-items: center;
  gap: 0.65rem;
}

.breakdown-label {
  font-size: 0.78rem;
  color: var(--text-muted);
  font-weight: 500;
  white-space: nowrap;
}

.breakdown-bar {
  height: 18px;
  border-radius: 4px;
  overflow: hidden;
  background: var(--bg);
  border: 1px solid var(--border);
  display: flex;
}

.breakdown-seg {
  height: 100%;
  transition: width 0.35s cubic-bezier(.4,0,.2,1);
}

.breakdown-seg--principal { background: var(--accent); opacity: 0.8; }
.breakdown-seg--interest  { background: var(--amber); opacity: 0.85; }
.breakdown-seg--interest-early { background: var(--amber); opacity: 0.6; }

.breakdown-total {
  font-size: 0.78rem;
  color: var(--text-muted);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
  text-align: right;
}

/* ── responsive ──────────────────────────────────────────────────────────── */

@media (max-width: 768px) {
  .app { flex-direction: column; }

  .summary {
    width: 100%;
    min-height: 0;
    flex-direction: row;
    flex-wrap: wrap;
    align-items: stretch;
    gap: 0.5rem;
    border-right: none;
    border-bottom: 1px solid var(--border);
    padding: 0.75rem 1rem;
    position: sticky;
    top: var(--nav-height);
    z-index: 20;
  }

  .summary-card {
    flex: 1 1 120px;
    padding: 0.6rem 0.8rem;
  }

  .summary-card--savings,
  .summary-card--savings-muted {
    flex-basis: 130px;
  }

  .summary-value { font-size: 1.2rem; }
  .summary-value--sm { font-size: 1rem; }

  .summary-divider { display: none; }

  /* flex break: forces secondary cards onto a new row */
  .summary-break {
    display: block;
    flex-basis: 100%;
    height: 0;
    margin: 0;
    padding: 0;
  }

  .summary-card--primary {
    flex: 1;
  }

  /* summary collapse toggle sits in-flow right of primary card */
  .summary-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    align-self: center;
    flex-shrink: 0;
    width: 28px;
    height: 28px;
  }

  .summary.is-collapsed .summary-card--muted,
  .summary.is-collapsed .summary-card--savings,
  .summary.is-collapsed .summary-card--savings-muted {
    display: none;
  }

  .workspace { padding: 0.85rem; }

  .form-stack { gap: 0.6rem; }
}

@media (max-width: 480px) {
  .breakdown-row {
    grid-template-columns: 60px 1fr 80px;
    gap: 0.5rem;
  }

  /* allow card header to wrap so chart legend doesn't overlap title */
  .card-header {
    flex-wrap: wrap;
    gap: 0.4rem;
  }

  .chart-legend {
    width: 100%;
  }
}