:root {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent: #3b82f6;
    --accent-hover: #2563eb;
    --success: #22c55e;
    --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: 2rem 0; border-bottom: 1px solid var(--border); text-align: center; }
header h1 { font-size: 2rem; margin-bottom: 0.5rem; }
header p { color: var(--text-secondary); }

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

.converter-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 1rem; align-items: end; }
.input-group label { display: block; font-size: 0.875rem; color: var(--text-secondary); margin-bottom: 0.5rem; }
.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: 2px solid var(--accent); border-color: transparent; }

.table-responsive { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; min-width: 600px; }
th, td { padding: 1rem; text-align: left; border-bottom: 1px solid var(--border); }
th { color: var(--text-secondary); font-weight: 600; font-size: 0.875rem; }
tr:hover { background: rgba(255,255,255,0.02); }
.coin-info { display: flex; align-items: center; gap: 0.75rem; }
.coin-info img { width: 24px; height: 24px; border-radius: 50%; }
.change { font-weight: 600; }
.change.positive { color: var(--success); }
.change.negative { color: var(--danger); }
.btn-icon { background: none; border: none; color: var(--text-secondary); cursor: pointer; font-size: 1.25rem; transition: color 0.2s; }
.btn-icon:hover, .btn-icon.active { color: #fbbf24; }
.btn-chart {
    background: var(--accent); color: white; border: none; padding: 0.5rem 1rem;
    border-radius: 6px; cursor: pointer; font-size: 0.875rem; transition: background 0.2s;
}
.btn-chart:hover { background: var(--accent-hover); }

.watchlist-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); gap: 1rem; }
.watchlist-item {
    background: var(--bg-primary); padding: 1rem; border-radius: 8px; border: 1px solid var(--border);
    display: flex; justify-content: space-between; align-items: center;
}
.empty-msg { color: var(--text-secondary); font-style: italic; }

.modal {
    display: none; position: fixed; z-index: 1000; left: 0; top: 0; width: 100%; height: 100%;
    background-color: rgba(0,0,0,0.8); backdrop-filter: blur(4px);
}
.modal-content {
    background: var(--bg-secondary); margin: 5% auto; padding: 2rem; border-radius: 12px;
    width: 90%; max-width: 800px; position: relative; border: 1px solid var(--border);
}
.close-modal { position: absolute; right: 1.5rem; top: 1rem; font-size: 2rem; cursor: pointer; color: var(--text-secondary); }
.close-modal:hover { color: var(--text-primary); }
.chart-tabs { display: flex; gap: 0.5rem; margin-bottom: 1rem; }
.tab-btn {
    background: var(--bg-primary); border: 1px solid var(--border); color: var(--text-secondary);
    padding: 0.5rem 1rem; border-radius: 6px; cursor: pointer;
}
.tab-btn.active { background: var(--accent); color: white; border-color: var(--accent); }
.chart-container { height: 400px; position: relative; }

footer { text-align: center; padding: 2rem 0; color: var(--text-secondary); font-size: 0.875rem; border-top: 1px solid var(--border); margin-top: 2rem; }

@media (max-width: 768px) {
    .converter-grid { grid-template-columns: 1fr; }
    .modal-content { margin: 10% auto; width: 95%; padding: 1rem; }
    .chart-container { height: 300px; }
}