:root {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent: #3b82f6;
    --accent-hover: #2563eb;
    --success: #22c55e;
    --warning: #f59e0b;
    --danger: #ef4444;
    --border: #334155;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
}
.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }

header { background: var(--bg-secondary); padding: 2.5rem 0; border-bottom: 1px solid var(--border); text-align: center; }
header h1 { font-size: 2.2rem; margin-bottom: 0.5rem; }
header p { color: var(--text-secondary); font-size: 1.05rem; }

main { padding: 2rem 0; }
.card { background: var(--bg-secondary); border-radius: 12px; padding: 1.5rem; border: 1px solid var(--border); margin-bottom: 1.5rem; }
.card h2 { font-size: 1.25rem; margin-bottom: 1.25rem; color: var(--text-primary); display: flex; align-items: center; gap: 0.5rem; }
.card h3 { font-size: 1.1rem; margin-bottom: 1rem; color: var(--text-primary); }

/* Mode & Unit Toggles */
.mode-toggle, .unit-toggle { display: flex; gap: 0.5rem; flex-wrap: wrap; }
.mode-btn, .unit-btn {
    flex: 1; min-width: 120px; padding: 0.75rem; border: 1px solid var(--border);
    background: var(--bg-primary); color: var(--text-secondary); border-radius: 8px;
    cursor: pointer; font-weight: 600; transition: all 0.2s;
}
.mode-btn:hover, .unit-btn:hover { border-color: var(--accent); color: var(--text-primary); }
.mode-btn.active, .unit-btn.active { background: var(--accent); color: white; border-color: var(--accent); }
.input-header { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 1rem; margin-bottom: 1.5rem; }
.badge { background: linear-gradient(135deg, #f59e0b, #ef4444); color: white; font-size: 0.7rem; padding: 2px 8px; border-radius: 12px; font-weight: 700; margin-left: 0.5rem; }

/* Inputs */
.input-group { margin-bottom: 1rem; }
.input-group label { display: block; font-size: 0.875rem; color: var(--text-secondary); margin-bottom: 0.5rem; font-weight: 500; }
.input-group input, .input-group select {
    width: 100%; padding: 0.75rem; border-radius: 8px; border: 1px solid var(--border);
    background: var(--bg-primary); color: var(--text-primary); font-size: 1rem;
}
.input-group input:focus, .input-group select:focus { outline: none; border-color: var(--accent); }
.radio-group { display: flex; gap: 1rem; }
.radio-label { display: flex; align-items: center; gap: 0.5rem; cursor: pointer; color: var(--text-primary); }
.dual-input { display: grid; grid-template-columns: 1fr 1fr; gap: 0.5rem; }
.dual-input-advanced { display: grid; grid-template-columns: 2fr 1fr; gap: 0.5rem; }
.unit-select { padding: 0.75rem; border-radius: 8px; border: 1px solid var(--border); background: var(--bg-primary); color: var(--text-primary); }
.hint { font-size: 0.75rem; color: var(--text-secondary); margin-top: -0.5rem; margin-bottom: 1rem; display: block; }
.tooltip { color: var(--accent); cursor: help; }

/* Results */
.calculator-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1.5rem; }

/* BMI Gauge */
.bmi-gauge-container { text-align: center; padding: 1.5rem; background: var(--bg-primary); border-radius: 10px; margin-bottom: 1.5rem; border: 1px solid var(--border); }
.bmi-value { font-size: 3rem; font-weight: 700; color: var(--accent); line-height: 1; }
.bmi-category { font-size: 1.2rem; font-weight: 600; margin: 0.5rem 0 1.5rem; color: var(--text-primary); }
.gauge-bar { height: 12px; background: linear-gradient(to right, #3b82f6 0%, #22c55e 25%, #f59e0b 50%, #ef4444 75%, #7f1d1d 100%); border-radius: 6px; position: relative; margin-bottom: 0.5rem; }
.gauge-marker { position: absolute; top: -6px; width: 4px; height: 24px; background: white; border-radius: 2px; box-shadow: 0 0 4px rgba(0,0,0,0.5); transition: left 0.5s ease; left: 0%; }
.gauge-labels { display: flex; justify-content: space-between; font-size: 0.75rem; color: var(--text-secondary); }

/* Stats Grid */
.stats-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 0.75rem; margin-bottom: 1.5rem; }
.stat-box { background: var(--bg-primary); padding: 1rem; border-radius: 8px; border: 1px solid var(--border); text-align: center; }
.stat-label { font-size: 0.8rem; color: var(--text-secondary); margin-bottom: 0.25rem; }
.stat-value { font-size: 1.25rem; font-weight: 700; color: var(--text-primary); }
.stat-sub { font-size: 0.75rem; color: var(--text-secondary); margin-top: 0.25rem; }

/* Calorie Box */
.calorie-box { background: var(--bg-primary); padding: 1.25rem; border-radius: 10px; border: 1px solid var(--border); margin-bottom: 1.5rem; }
.calorie-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
.calorie-item { text-align: center; }
.calorie-label { font-size: 0.8rem; color: var(--text-secondary); margin-bottom: 0.25rem; }
.calorie-value { font-size: 1.1rem; font-weight: 700; color: var(--text-primary); }
.calorie-value.loss { color: var(--success); }
.calorie-value.gain { color: var(--warning); }

.action-buttons { display: flex; gap: 0.75rem; }
.btn-primary, .btn-secondary {
    flex: 1; padding: 0.75rem; border-radius: 8px; border: none; font-weight: 600;
    cursor: pointer; font-size: 0.95rem; transition: all 0.2s;
}
.btn-primary { background: var(--accent); color: white; }
.btn-primary:hover { background: var(--accent-hover); }
.btn-secondary { background: var(--bg-tertiary); color: var(--text-primary); }
.btn-secondary:hover { background: #475569; }

/* Info Section */
.info-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 1.5rem; }
.info-item { background: var(--bg-primary); padding: 1.25rem; border-radius: 10px; border: 1px solid var(--border); }
.info-item h3 { color: var(--accent); margin-bottom: 0.75rem; font-size: 1.05rem; }
.info-item p { color: var(--text-secondary); font-size: 0.9rem; line-height: 1.6; }

footer { text-align: center; padding: 2rem 0; color: var(--text-secondary); font-size: 0.8rem; border-top: 1px solid var(--border); margin-top: 2rem; }

@media print {
    body { background: white; color: black; }
    .card { border: 1px solid #ccc; break-inside: avoid; }
    header, footer, .action-buttons, .mode-card { display: none; }
    .calculator-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 900px) {
    .calculator-grid { grid-template-columns: 1fr; }
}
@media (max-width: 600px) {
    header h1 { font-size: 1.5rem; }
    .bmi-value { font-size: 2.5rem; }
    .stats-grid, .calorie-grid { grid-template-columns: 1fr; }
}