/* ── Design tokens ── */
:root {
  --clr-bg:        #f0f4f8;
  --clr-surface:   #ffffff;
  --clr-border:    #dde3ec;
  --clr-primary:   #2563eb;
  --clr-primary-h: #1d4ed8;
  --clr-accent:    #10b981;
  --clr-accent-muted: rgba(16, 185, 129, 0.12);
  --clr-text:      #0f172a;
  --clr-muted:     #64748b;
  --clr-error:     #dc2626;
  --clr-warn:      #d97706;
  --clr-header-bg: #0f172a;
  --clr-header-text: #f8fafc;

  --radius:   12px;
  --radius-sm: 8px;
  --shadow:   0 1px 3px rgba(0,0,0,.08), 0 4px 16px rgba(0,0,0,.06);
  --shadow-card: 0 2px 8px rgba(0,0,0,.07);

  --font-sans: 'Segoe UI', system-ui, -apple-system, sans-serif;
  --font-mono: 'SF Mono', 'Cascadia Code', monospace;
  --transition: 180ms ease;
}

/* ── Reset ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; -webkit-text-size-adjust: 100%; }
body {
  font-family: var(--font-sans);
  background: var(--clr-bg);
  color: var(--clr-text);
  line-height: 1.6;
  min-height: 100dvh;
}

/* ── Utility ── */
.container {
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ── Calc intro banner ── */
.calc-intro {
  background: var(--clr-header-bg);
  color: var(--clr-header-text);
  padding: 28px 0 24px;
  border-bottom: 3px solid var(--clr-primary);
}
.calc-intro h1 {
  font-size: 1.6rem;
  font-weight: 700;
  margin-bottom: 6px;
}
.calc-intro p {
  font-size: 0.97rem;
  color: #94a3b8;
  max-width: 520px;
}

/* ── Header ── */
.site-header {
  background: var(--clr-header-bg);
  color: var(--clr-header-text);
  padding: 18px 0;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 12px rgba(0,0,0,.3);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}
.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: #fff;
}
.logo-icon {
  width: 26px;
  height: 26px;
  color: var(--clr-accent);
}
.tagline {
  font-size: 0.85rem;
  color: #94a3b8;
}

/* ── Layout ── */
.main-grid {
  display: grid;
  grid-template-columns: 340px 1fr;
  gap: 20px;
  padding-top: 24px;
  padding-bottom: 40px;
  align-items: start;
}
@media (max-width: 860px) {
  .main-grid { grid-template-columns: 1fr; }
}

/* ── Cards ── */
.card {
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius);
  padding: 20px 22px;
  box-shadow: var(--shadow-card);
}
.card + .card { margin-top: 16px; }
.card-title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--clr-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 16px;
}

/* ── Presets ── */
.presets-card { padding: 14px 18px; }
.presets-label {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--clr-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 10px;
}
.preset-buttons {
  display: flex;
  gap: 8px;
}
.btn-preset {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  padding: 9px 6px;
  border: 1.5px solid var(--clr-border);
  border-radius: var(--radius-sm);
  background: var(--clr-bg);
  cursor: pointer;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--clr-muted);
  transition: all var(--transition);
  font-family: var(--font-sans);
}
.btn-preset span {
  font-size: 0.95rem;
  color: var(--clr-primary);
  font-weight: 700;
}
.btn-preset:hover {
  border-color: var(--clr-primary);
  color: var(--clr-primary);
  background: #eff6ff;
}
.btn-preset.active {
  border-color: var(--clr-primary);
  background: #eff6ff;
  color: var(--clr-primary);
}

/* ── Form fields ── */
.field-group {
  margin-bottom: 18px;
}
.field-group label {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--clr-text);
  margin-bottom: 6px;
}
.field-optional {
  font-size: 0.72rem;
  font-weight: 500;
  color: var(--clr-muted);
  background: var(--clr-bg);
  border: 1px solid var(--clr-border);
  padding: 1px 7px;
  border-radius: 99px;
  letter-spacing: 0;
  text-transform: none;
}
.years-display {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--clr-primary);
  background: #eff6ff;
  padding: 2px 8px;
  border-radius: 99px;
}
.input-wrap {
  display: flex;
  align-items: center;
  border: 1.5px solid var(--clr-border);
  border-radius: var(--radius-sm);
  background: var(--clr-surface);
  overflow: hidden;
  transition: border-color var(--transition);
}
.input-wrap:focus-within {
  border-color: var(--clr-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}
.input-wrap.error {
  border-color: var(--clr-error);
}
.input-wrap.error:focus-within {
  box-shadow: 0 0 0 3px rgba(220, 38, 38, 0.1);
}
.input-prefix, .input-suffix {
  padding: 0 11px;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--clr-muted);
  background: var(--clr-bg);
  border-right: 1.5px solid var(--clr-border);
  height: 42px;
  display: flex;
  align-items: center;
  user-select: none;
}
.input-suffix {
  border-right: none;
  border-left: 1.5px solid var(--clr-border);
}
.input-wrap input,
.input-wrap select {
  flex: 1;
  border: none;
  outline: none;
  background: transparent;
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 500;
  color: var(--clr-text);
  padding: 0 12px;
  height: 42px;
  min-width: 0;
}
.input-wrap input[type="number"]::-webkit-inner-spin-button,
.input-wrap input[type="number"]::-webkit-outer-spin-button { opacity: 1; }
.select-wrap { position: relative; }
.select-wrap::after {
  content: '▾';
  position: absolute;
  right: 12px;
  color: var(--clr-muted);
  pointer-events: none;
  font-size: 0.85rem;
}
.select-wrap select { appearance: none; cursor: pointer; padding-right: 32px; }

/* Range slider */
input[type="range"] {
  -webkit-appearance: none;
  width: 100%;
  height: 6px;
  border-radius: 99px;
  background: linear-gradient(to right, var(--clr-primary) 0%, var(--clr-border) 0%);
  outline: none;
  cursor: pointer;
  margin-bottom: 10px;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 20px; height: 20px;
  border-radius: 50%;
  background: var(--clr-primary);
  border: 3px solid white;
  box-shadow: 0 1px 4px rgba(0,0,0,.2);
  cursor: pointer;
  transition: transform var(--transition);
}
input[type="range"]::-webkit-slider-thumb:hover { transform: scale(1.15); }
.years-number-wrap { margin-top: 4px; }

.field-error {
  font-size: 0.78rem;
  color: var(--clr-error);
  margin-top: 5px;
  min-height: 18px;
  display: flex;
  align-items: center;
  gap: 4px;
}
.field-error:not(:empty)::before { content: '⚠'; }

/* Warn style */
.field-error.warn { color: var(--clr-warn); }

/* ── Buttons ── */
.form-actions {
  display: flex;
  gap: 10px;
  margin-top: 8px;
}
.btn-primary, .btn-secondary {
  flex: 1;
  padding: 12px;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 600;
  transition: all var(--transition);
  white-space: nowrap;
}
.btn-primary {
  background: var(--clr-primary);
  color: #fff;
}
.btn-primary:hover { background: var(--clr-primary-h); transform: translateY(-1px); }
.btn-primary:active { transform: translateY(0); }
.btn-secondary {
  background: var(--clr-bg);
  color: var(--clr-muted);
  border: 1.5px solid var(--clr-border);
}
.btn-secondary:hover:not(:disabled) {
  border-color: var(--clr-primary);
  color: var(--clr-primary);
  background: #eff6ff;
}
.btn-secondary:disabled { opacity: 0.5; cursor: not-allowed; }

/* ── Results ── */
.results-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-bottom: 16px;
}
.result-item {
  background: var(--clr-bg);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  border: 1px solid var(--clr-border);
}
.result-item.highlight {
  background: var(--clr-accent-muted);
  border-color: rgba(16, 185, 129, 0.3);
  grid-column: 1 / -1;
}
.result-label {
  display: block;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--clr-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 4px;
}
.result-value {
  display: block;
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--clr-text);
  font-variant-numeric: tabular-nums;
}
.result-item.highlight .result-value {
  font-size: 1.8rem;
  color: var(--clr-accent);
}
.results-actions {
  display: flex;
  gap: 8px;
}
.results-actions .btn-secondary { font-size: 0.82rem; padding: 9px 12px; }

/* ── Chart ── */
.chart-card { min-height: 340px; }
.chart-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
  flex-wrap: wrap;
  gap: 8px;
}
.chart-toggle {
  display: flex;
  border: 1.5px solid var(--clr-border);
  border-radius: var(--radius-sm);
  overflow: hidden;
}
.toggle-btn {
  padding: 5px 14px;
  border: none;
  background: transparent;
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--clr-muted);
  cursor: pointer;
  transition: all var(--transition);
}
.toggle-btn.active {
  background: var(--clr-primary);
  color: #fff;
}
.chart-wrap { position: relative; min-height: 260px; }
canvas#growth-chart { width: 100% !important; }
.chart-empty {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  color: var(--clr-muted);
}
.chart-empty svg {
  width: 64px;
  height: 64px;
  opacity: 0.3;
}
.chart-empty p { font-size: 0.88rem; text-align: center; }
.chart-empty.hidden { display: none; }

/* ── Table ── */
.table-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 14px;
  flex-wrap: wrap;
  gap: 6px;
}
.table-note {
  font-size: 0.78rem;
  color: var(--clr-muted);
}
.table-wrap {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border-radius: var(--radius-sm);
  border: 1px solid var(--clr-border);
}
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
  font-variant-numeric: tabular-nums;
}
thead th {
  background: var(--clr-bg);
  padding: 11px 14px;
  text-align: right;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--clr-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  border-bottom: 1.5px solid var(--clr-border);
  white-space: nowrap;
}
thead th:first-child { text-align: left; }
tbody tr {
  transition: background var(--transition);
}
tbody tr:not(.table-empty-row):hover { background: #f8faff; }
tbody tr:not(:last-child) td {
  border-bottom: 1px solid var(--clr-border);
}
tbody td {
  padding: 10px 14px;
  text-align: right;
  color: var(--clr-text);
}
tbody td:first-child { text-align: left; font-weight: 600; }
.table-empty-row td {
  text-align: center !important;
  color: var(--clr-muted);
  padding: 32px;
  font-size: 0.88rem;
}
.growth-positive { color: var(--clr-accent); font-weight: 600; }
tbody tr:nth-child(even) { background: rgba(240, 244, 248, 0.5); }
tbody tr:nth-child(even):hover { background: #f8faff; }

/* ── Footer ── */
.site-footer {
  background: var(--clr-header-bg);
  color: #64748b;
  text-align: center;
  padding: 16px 0;
  font-size: 0.82rem;
  margin-top: 8px;
}
.site-footer code {
  font-family: var(--font-mono);
  background: rgba(255,255,255,.08);
  padding: 1px 6px;
  border-radius: 4px;
  color: #94a3b8;
}
.footer-note { margin-top: 4px; font-size: 0.75rem; color: #475569; }

/* ── Toast ── */
.toast {
  position: fixed;
  bottom: 24px;
  right: 24px;
  background: var(--clr-text);
  color: #fff;
  padding: 12px 20px;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  font-weight: 500;
  box-shadow: var(--shadow);
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 300ms ease, transform 300ms ease;
  pointer-events: none;
  z-index: 9999;
  max-width: 320px;
}
.toast.show {
  opacity: 1;
  transform: translateY(0);
}
.toast.success { background: var(--clr-accent); }
.toast.error   { background: var(--clr-error); }

/* ── Scrollbar ── */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--clr-border); border-radius: 99px; }

/* ── Mobile ── */
@media (max-width: 540px) {
  .header-inner { flex-direction: column; align-items: flex-start; gap: 4px; }
  .results-grid { grid-template-columns: 1fr; }
  .result-item.highlight { grid-column: unset; }
  .form-actions { flex-direction: column; }
  .preset-buttons { flex-direction: column; }
  .btn-preset { flex-direction: row; justify-content: space-between; }
  .results-actions { flex-direction: column; }
  .table-note { display: none; }
}

/* ── Animated counting ── */
@keyframes count-in {
  from { opacity: 0; transform: translateY(4px); }
  to   { opacity: 1; transform: translateY(0); }
}
.result-value.animate { animation: count-in 300ms ease forwards; }