:root {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent: #3b82f6;
    --accent-hover: #2563eb;
    --success: #22c55e;
    --danger: #ef4444;
    --warning: #f59e0b;
    --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: 1400px; 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; }

/* Mode Toggle */
.mode-toggle { display: flex; gap: 0.5rem; flex-wrap: wrap; }
.mode-btn {
    flex: 1; min-width: 150px; padding: 0.75rem 1rem; 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 { border-color: var(--accent); color: var(--text-primary); }
.mode-btn.active { background: var(--accent); color: white; border-color: var(--accent); }

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

/* 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;
    transition: border-color 0.2s;
}
.input-group input:focus, .input-group select:focus { outline: none; border-color: var(--accent); }
.input-with-prefix, .input-with-suffix { display: flex; align-items: center; background: var(--bg-primary); border: 1px solid var(--border); border-radius: 8px; overflow: hidden; }
.input-with-prefix:focus-within, .input-with-suffix:focus-within { border-color: var(--accent); }
.input-with-prefix input, .input-with-suffix input { border: none; background: transparent; flex: 1; }
.input-with-prefix input:focus, .input-with-suffix input:focus { outline: none; }
.prefix, .suffix { padding: 0 0.75rem; color: var(--text-secondary); font-weight: 600; }
.down-payment-row { display: grid; grid-template-columns: 1fr 1fr; gap: 0.5rem; }
.hint { font-size: 0.75rem; color: var(--text-secondary); margin-top: 0.25rem; display: block; }
.tooltip { color: var(--accent); cursor: help; font-size: 0.8rem; }

/* Results */
.monthly-payment-display { text-align: center; padding: 1.5rem; background: var(--bg-primary); border-radius: 10px; margin-bottom: 1.5rem; border: 1px solid var(--border); }
.payment-label { color: var(--text-secondary); font-size: 0.9rem; text-transform: uppercase; letter-spacing: 1px; margin-bottom: 0.5rem; }
.payment-amount { font-size: 2.5rem; font-weight: 700; color: var(--accent); }

.payment-breakdown { margin-bottom: 1.5rem; }
.breakdown-item { display: flex; align-items: center; gap: 0.75rem; padding: 0.75rem; background: var(--bg-primary); border-radius: 8px; margin-bottom: 0.5rem; }
.breakdown-color { width: 12px; height: 40px; border-radius: 6px; }
.breakdown-info { flex: 1; display: flex; justify-content: space-between; align-items: center; }
.breakdown-label { color: var(--text-secondary); font-size: 0.9rem; }
.breakdown-value { font-weight: 600; color: var(--text-primary); }

.chart-container { height: 250px; position: relative; margin-bottom: 1.5rem; }

.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); }
.stat-label { font-size: 0.8rem; color: var(--text-secondary); margin-bottom: 0.25rem; }
.stat-value { font-size: 1.1rem; font-weight: 700; color: var(--text-primary); }

.savings-box, .affordability-result, .refinance-result {
    background: linear-gradient(135deg, rgba(34, 197, 94, 0.1), rgba(59, 130, 246, 0.1));
    border: 1px solid var(--success);
    border-radius: 10px;
    padding: 1.25rem;
    margin-bottom: 1rem;
}
.savings-box h3, .affordability-result h3, .refinance-result h3 { margin-bottom: 1rem; color: var(--success); }
.savings-grid, .refinance-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
.savings-label, .refinance-label { font-size: 0.85rem; color: var(--text-secondary); margin-bottom: 0.25rem; }
.savings-value, .refinance-value { font-size: 1.5rem; font-weight: 700; }
.savings-value.positive { color: var(--success); }
.afford-amount { font-size: 2rem; font-weight: 700; color: var(--accent); margin-bottom: 0.5rem; }
.afford-details div { color: var(--text-secondary); font-size: 0.9rem; }
.refinance-col { background: var(--bg-primary); padding: 1rem; border-radius: 8px; }
.refinance-col.new { border: 2px solid var(--success); }
.refinance-sub { font-size: 0.8rem; color: var(--text-secondary); margin-top: 0.5rem; }
.refinance-savings { margin-top: 1rem; padding: 0.75rem; background: var(--bg-primary); border-radius: 8px; text-align: center; font-weight: 600; }

.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-primary); color: var(--text-primary); border: 1px solid var(--border); }
.btn-secondary:hover { background: var(--bg-tertiary); }

/* Amortization */
.amortization-header { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 1rem; margin-bottom: 1rem; }
.amortization-tabs { display: flex; gap: 0.5rem; }
.tab-btn {
    padding: 0.5rem 1rem; border: 1px solid var(--border); background: var(--bg-primary);
    color: var(--text-secondary); border-radius: 6px; cursor: pointer; font-size: 0.9rem;
}
.tab-btn.active { background: var(--accent); color: white; border-color: var(--accent); }

.table-responsive { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; }
th, td { padding: 0.75rem; text-align: left; border-bottom: 1px solid var(--border); font-size: 0.9rem; }
th { color: var(--text-secondary); font-weight: 600; background: var(--bg-primary); position: sticky; top: 0; }
tr:hover { background: rgba(255,255,255,0.02); }

/* 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: 0.875rem; border-top: 1px solid var(--border); margin-top: 2rem; }

/* Print Styles */
@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; }
    .stats-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 600px) {
    header h1 { font-size: 1.5rem; }
    .payment-amount { font-size: 2rem; }
    .down-payment-row { grid-template-columns: 1fr; }
    .mode-toggle { flex-direction: column; }
    .mode-btn { min-width: 100%; }
    .savings-grid, .refinance-grid { grid-template-columns: 1fr; }
    .stats-grid { grid-template-columns: 1fr; }
}