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

:root {
  --c-bg: #f5f5f5;
  --c-surface: #ffffff;
  --c-surface2: #f0f0f0;
  --c-border: #e0e0e0;
  --c-text: #1a1a1a;
  --c-text-muted: #666666;
  --c-accent: #2563eb;
  --c-accent-hover: #1d4ed8;
  --c-accent-light: #eff6ff;
  --c-warning-bg: #fef9c3;
  --c-warning-text: #713f12;
  --c-badge-bg: #dbeafe;
  --c-badge-text: #1e40af;
  --c-primary: #16a34a;
  --c-shadow: 0 1px 3px rgba(0,0,0,.08), 0 1px 2px rgba(0,0,0,.06);
  --radius: 12px;
  --radius-sm: 8px;
  --font: 'Segoe UI', system-ui, -apple-system, sans-serif;
}

[data-theme="dark"] {
  --c-bg: #0f172a;
  --c-surface: #1e293b;
  --c-surface2: #273449;
  --c-border: #334155;
  --c-text: #f1f5f9;
  --c-text-muted: #94a3b8;
  --c-accent: #60a5fa;
  --c-accent-hover: #93c5fd;
  --c-accent-light: #1e3a5f;
  --c-warning-bg: #422006;
  --c-warning-text: #fde68a;
  --c-badge-bg: #1e3a5f;
  --c-badge-text: #93c5fd;
  --c-primary: #4ade80;
  --c-shadow: 0 1px 3px rgba(0,0,0,.3);
}

html { font-size: 16px; }

body {
  font-family: var(--font);
  background: var(--c-bg);
  color: var(--c-text);
  min-height: 100vh;
  line-height: 1.5;
}

/* ── Layout ───────────────────────────────────────────────────────────────── */
.app-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  padding: 1.25rem 1.5rem;
  background: var(--c-surface);
  border-bottom: 1px solid var(--c-border);
  box-shadow: var(--c-shadow);
  gap: 1rem;
}

.app-header h1 { font-size: 1.25rem; font-weight: 700; }
.subtitle { font-size: 0.8rem; color: var(--c-text-muted); margin-top: 0.15rem; }

.header-controls {
  display: flex;
  gap: 0.5rem;
  flex-shrink: 0;
}

.app-main {
  max-width: 480px;
  margin: 1.5rem auto;
  padding: 0 1rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.app-footer {
  text-align: center;
  padding: 1.5rem;
  font-size: 0.8rem;
  color: var(--c-text-muted);
}

.app-footer a { color: var(--c-accent); text-decoration: none; }
.app-footer a:hover { text-decoration: underline; }

/* ── Card ─────────────────────────────────────────────────────────────────── */
.card {
  background: var(--c-surface);
  border-radius: var(--radius);
  padding: 1.25rem;
  border: 1px solid var(--c-border);
  box-shadow: var(--c-shadow);
}

/* ── Fields ───────────────────────────────────────────────────────────────── */
.field-label {
  display: block;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--c-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 0.4rem;
}

.field-group { margin-bottom: 1rem; }
.field-group:last-child { margin-bottom: 0; }

.number-input,
.select-field {
  width: 100%;
  padding: 0.6rem 0.75rem;
  font-size: 1rem;
  color: var(--c-text);
  background: var(--c-surface2);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  outline: none;
  transition: border-color 0.15s;
}

.number-input:focus,
.select-field:focus {
  border-color: var(--c-accent);
}

/* ── Country card ─────────────────────────────────────────────────────────── */
.country-card .field-label { margin-bottom: 0.4rem; }

.badge {
  display: inline-block;
  margin-top: 0.6rem;
  padding: 0.2rem 0.6rem;
  font-size: 0.75rem;
  font-weight: 600;
  background: var(--c-badge-bg);
  color: var(--c-badge-text);
  border-radius: 999px;
}

.warning {
  margin-top: 0.6rem;
  padding: 0.5rem 0.75rem;
  background: var(--c-warning-bg);
  color: var(--c-warning-text);
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
}

.country-note {
  margin-top: 0.75rem;
  font-size: 0.875rem;
  color: var(--c-text-muted);
  line-height: 1.6;
}

/* ── Stepper ──────────────────────────────────────────────────────────────── */
.stepper {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.stepper-btn {
  width: 2.25rem;
  height: 2.25rem;
  font-size: 1.25rem;
  font-weight: 700;
  background: var(--c-surface2);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  color: var(--c-text);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.12s;
}

.stepper-btn:hover { background: var(--c-accent-light); }

.stepper-input {
  width: 4rem;
  padding: 0.4rem;
  text-align: center;
  font-size: 1rem;
  color: var(--c-text);
  background: var(--c-surface2);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  outline: none;
}

.stepper-input:focus { border-color: var(--c-accent); }

/* ── Tip slider ───────────────────────────────────────────────────────────── */
.tip-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.4rem;
}

.tip-display {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--c-accent);
}

.slider {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 6px;
  border-radius: 3px;
  background: var(--c-border);
  outline: none;
  cursor: pointer;
}

.slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--c-accent);
  cursor: pointer;
  box-shadow: 0 0 0 3px var(--c-accent-light);
}

.slider::-moz-range-thumb {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--c-accent);
  cursor: pointer;
  border: none;
}

/* ── Button groups ────────────────────────────────────────────────────────── */
.btn-group {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.quick-btn,
.round-btn {
  padding: 0.35rem 0.75rem;
  font-size: 0.85rem;
  font-weight: 600;
  background: var(--c-surface2);
  color: var(--c-text);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background 0.12s, color 0.12s, border-color 0.12s;
}

.quick-btn:hover,
.round-btn:hover {
  background: var(--c-accent-light);
  border-color: var(--c-accent);
  color: var(--c-accent);
}

.quick-btn.active,
.round-btn.active {
  background: var(--c-accent);
  color: #fff;
  border-color: var(--c-accent);
}

/* ── Icon buttons ─────────────────────────────────────────────────────────── */
.icon-btn {
  padding: 0.35rem 0.75rem;
  font-size: 0.85rem;
  font-weight: 600;
  background: var(--c-surface2);
  color: var(--c-text);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background 0.12s;
}

.icon-btn:hover { background: var(--c-accent-light); }

/* ── Results ──────────────────────────────────────────────────────────────── */
.results-heading {
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--c-text-muted);
  margin-bottom: 0.75rem;
}

.result-grid {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.result-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-sm);
  background: var(--c-surface2);
}

.result-row.highlight {
  background: var(--c-accent-light);
  border: 1px solid var(--c-border);
}

.result-label {
  font-size: 0.875rem;
  color: var(--c-text-muted);
}

.result-value {
  font-size: 1rem;
  font-weight: 700;
  color: var(--c-text);
  font-variant-numeric: tabular-nums;
}

.result-value.primary { color: var(--c-primary); font-size: 1.1rem; }
.result-value.accent  { color: var(--c-accent);  font-size: 1.1rem; }

/* ── Responsive ───────────────────────────────────────────────────────────── */
@media (max-width: 480px) {
  .app-header { padding: 1rem; }
  .app-main { padding: 0 0.75rem; }
}