: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; }

.rates-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); gap: 1rem; }
.rate-item {
    background: var(--bg-primary); padding: 1rem; border-radius: 8px; border: 1px solid var(--border);
    display: flex; justify-content: space-between; align-items: center;
}
.rate-info { display: flex; align-items: center; gap: 0.75rem; }
.rate-pair { font-weight: 600; color: var(--text-primary); }
.rate-value { color: var(--accent); font-weight: 700; }
.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; }

.chart-selector { display: flex; gap: 1rem; align-items: center; margin-bottom: 1rem; flex-wrap: wrap; }
.chart-selector select {
    padding: 0.5rem 1rem; border-radius: 6px; border: 1px solid var(--border);
    background: var(--bg-primary); color: var(--text-primary);
}
.chart-tabs { display: flex; gap: 0.5rem; margin-left: auto; }
.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; }

.empty-msg { color: var(--text-secondary); font-style: italic; }
.loading { color: var(--text-secondary); text-align: center; padding: 2rem; }

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; }
    .chart-selector { flex-direction: column; align-items: stretch; }
    .chart-tabs { margin-left: 0; }
    .chart-container { height: 300px; }
}