/* ============================================================
   Loan Calculator — style.css
   ============================================================ */

/* ─── Design tokens ─────────────────────────────────────────── */
:root {
  --color-bg: #f4f6f9;
  --color-surface: #ffffff;
  --color-surface-alt: #f9fafc;
  --color-border: #e2e8f0;
  --color-text: #1a202c;
  --color-text-muted: #718096;
  --color-primary: #3b82f6;
  --color-primary-dark: #2563eb;
  --color-accent: #f97316;
  --color-positive: #10b981;
  --color-positive-bg: #ecfdf5;
  --color-danger: #ef4444;
  --color-chart-principal: #3b82f6;
  --color-chart-interest: #f97316;
  --radius: 10px;
  --shadow: 0 1px 4px rgba(0,0,0,.08);
  --shadow-md: 0 4px 16px rgba(0,0,0,.10);
  --font: 'Helvetica Neue', Arial, 'Hiragino Kaku Gothic ProN', 'Hiragino Sans', sans-serif;
  --transition: 0.18s ease;
}

[data-theme="dark"] {
  --color-bg: #0f172a;
  --color-surface: #1e293b;
  --color-surface-alt: #162032;
  --color-border: #334155;
  --color-text: #e2e8f0;
  --color-text-muted: #94a3b8;
  --color-primary: #60a5fa;
  --color-primary-dark: #3b82f6;
  --color-accent: #fb923c;
  --color-positive: #34d399;
  --color-positive-bg: #064e3b;
  --color-danger: #f87171;
  --color-chart-principal: #60a5fa;
  --color-chart-interest: #fb923c;
  --shadow: 0 1px 4px rgba(0,0,0,.3);
  --shadow-md: 0 4px 16px rgba(0,0,0,.4);
}

/* ─── Reset / base ──────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  font-size: 15px;
  line-height: 1.6;
  background: var(--color-bg);
  color: var(--color-text);
  min-height: 100vh;
  transition: background var(--transition), color var(--transition);
}

a { color: var(--color-primary); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ─── Header ────────────────────────────────────────────────── */
.app-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  max-width: 960px;
  margin: 0 auto;
  padding: 12px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.header-title h1 {
  font-size: 1.3rem;
  font-weight: 700;
  letter-spacing: -0.01em;
}

.subtitle {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-top: 1px;
}

.header-controls {
  display: flex;
  gap: 8px;
  flex-shrink: 0;
}

/* ─── Main layout ───────────────────────────────────────────── */
.app-main {
  max-width: 960px;
  margin: 0 auto;
  padding: 24px 16px 48px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

/* ─── Card ──────────────────────────────────────────────────── */
.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
  transition: background var(--transition), border-color var(--transition);
}

.card h2 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 16px;
  color: var(--color-text);
}

/* ─── Form ──────────────────────────────────────────────────── */
.input-section { }

.form-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 16px;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.form-group--full {
  grid-column: 1 / -1;
}

label {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.input-with-unit {
  display: flex;
  border: 1.5px solid var(--color-border);
  border-radius: 6px;
  overflow: hidden;
  transition: border-color var(--transition);
  background: var(--color-surface);
}

.input-with-unit:focus-within {
  border-color: var(--color-primary);
}

.input-with-unit input {
  flex: 1;
  min-width: 0;
  padding: 9px 10px;
  border: none;
  outline: none;
  background: transparent;
  font-size: 0.95rem;
  color: var(--color-text);
  font-family: inherit;
}

.input-with-unit input::-webkit-inner-spin-button { opacity: 0.5; }

.unit-select, .unit-label {
  background: var(--color-surface-alt);
  border-left: 1.5px solid var(--color-border);
  padding: 0 10px;
  font-size: 0.82rem;
  color: var(--color-text-muted);
  display: flex;
  align-items: center;
  flex-shrink: 0;
}

.unit-select {
  border: none;
  border-left: 1.5px solid var(--color-border);
  outline: none;
  cursor: pointer;
  font-family: inherit;
  color: var(--color-text);
}

input[type="month"] {
  width: 100%;
  padding: 9px 10px;
  border: 1.5px solid var(--color-border);
  border-radius: 6px;
  background: var(--color-surface);
  color: var(--color-text);
  font-size: 0.95rem;
  font-family: inherit;
  outline: none;
  transition: border-color var(--transition);
}

input[type="month"]:focus { border-color: var(--color-primary); }

.radio-group {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.radio-label {
  display: flex;
  align-items: center;
  gap: 6px;
  cursor: pointer;
  font-size: 0.9rem;
  font-weight: 400;
  color: var(--color-text);
  text-transform: none;
  letter-spacing: 0;
}

.radio-label input[type="radio"] {
  accent-color: var(--color-primary);
  width: 16px;
  height: 16px;
  cursor: pointer;
}

.error-msg {
  color: var(--color-danger);
  font-size: 0.85rem;
  margin-top: 8px;
  padding: 8px 12px;
  background: rgba(239,68,68,.08);
  border-radius: 6px;
  border-left: 3px solid var(--color-danger);
}

.form-actions {
  display: flex;
  gap: 10px;
  margin-top: 20px;
  flex-wrap: wrap;
}

/* ─── Buttons ───────────────────────────────────────────────── */
.btn-primary, .btn-secondary, .btn-icon, .btn-text {
  font-family: inherit;
  cursor: pointer;
  border: none;
  border-radius: 6px;
  transition: background var(--transition), transform 0.1s;
}

.btn-primary {
  background: var(--color-primary);
  color: #fff;
  padding: 10px 28px;
  font-size: 0.95rem;
  font-weight: 600;
}

.btn-primary:hover { background: var(--color-primary-dark); }
.btn-primary:active { transform: scale(0.98); }

.btn-secondary {
  background: var(--color-surface-alt);
  color: var(--color-text);
  border: 1.5px solid var(--color-border);
  padding: 9px 20px;
  font-size: 0.9rem;
}

.btn-secondary:hover { background: var(--color-border); }

.btn-icon {
  background: var(--color-surface-alt);
  color: var(--color-text);
  border: 1.5px solid var(--color-border);
  padding: 6px 12px;
  font-size: 0.8rem;
  white-space: nowrap;
}

.btn-icon:hover { background: var(--color-border); }

.btn-text {
  background: transparent;
  color: var(--color-primary);
  padding: 4px 8px;
  font-size: 0.82rem;
  text-decoration: underline;
}

.btn-text:hover { opacity: 0.8; }
.btn-text:disabled { opacity: 0.4; cursor: default; }

/* ─── Stat cards ────────────────────────────────────────────── */
.cards-row {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: 12px;
}

.card-stat {
  padding: 16px;
  text-align: center;
}

.card-stat--accent {
  border-color: var(--color-accent);
  background: color-mix(in srgb, var(--color-accent) 6%, var(--color-surface));
}

.card-stat--positive {
  border-color: var(--color-positive);
  background: var(--color-positive-bg);
}

.card-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-muted);
  margin-bottom: 6px;
  font-weight: 600;
}

.card-value {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--color-text);
  word-break: break-all;
}

/* ─── Early payoff section ──────────────────────────────────── */
#early-payoff-section h2 {
  color: var(--color-positive);
}

/* ─── Chart ─────────────────────────────────────────────────── */
.chart-section { }

.chart-legend {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.82rem;
  color: var(--color-text-muted);
  margin-bottom: 12px;
  flex-wrap: wrap;
}

.legend-dot {
  width: 12px;
  height: 12px;
  border-radius: 2px;
  flex-shrink: 0;
}

.legend-principal { background: var(--color-chart-principal); }
.legend-interest  { background: var(--color-chart-interest); }

.chart-container {
  height: 160px;
  overflow-x: auto;
  overflow-y: hidden;
}

.chart-bars {
  display: flex;
  align-items: flex-end;
  height: 100%;
  gap: 1px;
  min-width: 100%;
}

.bar-group {
  flex: 1;
  min-width: 3px;
  height: 100%;
  display: flex;
  align-items: flex-end;
}

.bar-stack {
  width: 100%;
  height: 100%;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  cursor: default;
}

.bar {
  width: 100%;
  transition: height 0.3s ease;
  min-height: 1px;
}

.bar-principal {
  background: var(--color-chart-principal);
  border-radius: 1px 1px 0 0;
}

.bar-interest {
  background: var(--color-chart-interest);
  opacity: 0.85;
}

/* ─── Amortization table ────────────────────────────────────── */
.table-wrapper {
  overflow-x: auto;
  border-radius: 6px;
  border: 1px solid var(--color-border);
}

.amort-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
}

.amort-table th {
  background: var(--color-surface-alt);
  color: var(--color-text-muted);
  font-weight: 600;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  padding: 10px 12px;
  text-align: right;
  border-bottom: 1px solid var(--color-border);
  white-space: nowrap;
}

.amort-table th:first-child { text-align: center; }

.amort-table td {
  padding: 8px 12px;
  text-align: right;
  border-bottom: 1px solid var(--color-border);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

.amort-table td:first-child { text-align: center; color: var(--color-text-muted); }

.amort-table tbody tr:last-child td { border-bottom: none; }

.amort-table tbody tr:nth-child(even) {
  background: color-mix(in srgb, var(--color-surface-alt) 50%, var(--color-surface));
}

.amort-table tbody tr:hover {
  background: color-mix(in srgb, var(--color-primary) 8%, var(--color-surface));
}

.table-pager {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 12px 0 4px;
  flex-wrap: wrap;
}

.page-info {
  font-size: 0.82rem;
  color: var(--color-text-muted);
}

/* ─── Footer ────────────────────────────────────────────────── */
.app-footer {
  text-align: center;
  padding: 24px 16px;
  font-size: 0.8rem;
  color: var(--color-text-muted);
  border-top: 1px solid var(--color-border);
  background: var(--color-surface);
}

/* ─── Responsive ────────────────────────────────────────────── */
@media (max-width: 600px) {
  .header-inner { flex-wrap: wrap; }
  .header-title h1 { font-size: 1.1rem; }
  .form-grid { grid-template-columns: 1fr; }
  .cards-row { grid-template-columns: repeat(2, 1fr); }
  .card-value { font-size: 1rem; }
}

@media (max-width: 380px) {
  .cards-row { grid-template-columns: 1fr; }
}

/* ─── Scrollbar ─────────────────────────────────────────────── */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--color-border); border-radius: 3px; }