.billy-app-container {
    --billy-orange: #F5A623; 
    --billy-dark: #333; 
    --billy-blue: #008080; 
    --bg-light: #f9f9f9; 
    --slate-200: #e2e8f0;
    --slate-500: #64748b;
    --slate-800: #1e293b;
    --red-500: #ef4444;
    --blue-500: #3b82f6;
    --green-500: #10b981;
    --amber-500: #f59e0b;
    
    font-family: 'Segoe UI', 'Microsoft JhengHei', sans-serif;
    -webkit-font-smoothing: antialiased;
    width: 100%;
    max-width: 800px;
    margin: 0 auto;
    color: var(--billy-dark);
}

.billy-app-container * { box-sizing: border-box; }
.zh-text { color: #666; font-size: 0.9em; display: inline; font-weight: normal; }

.note-card { 
    background: var(--bg-light); border-radius: 12px; padding: 0; margin: 20px 0; 
    box-shadow: 0 4px 15px rgba(0,0,0,0.05); border-top: 4px solid var(--billy-blue); overflow: hidden;
}

.card-header {
    padding: 20px 25px; border-bottom: 1px solid var(--slate-200);
    display: flex; flex-direction: column; justify-content: center; align-items: center; background: #fff; gap: 15px;
}

.hud-display {
    text-align: center; width: 100%; padding: 15px; background: var(--bg-light); border-radius: 8px; border: 1px solid var(--slate-200); position: relative; overflow: hidden; display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 10px;
}
@media (max-width: 600px) { .hud-display { grid-template-columns: 1fr; } }
.hud-display::before {
    content: ''; position: absolute; top: 0; left: 0; right: 0; height: 4px; background: linear-gradient(90deg, var(--billy-blue), var(--billy-orange));
}
.hud-label { font-size: 0.85rem; font-weight: bold; text-transform: uppercase; }
.hud-val { font-size: 1.25rem; font-weight: bold; color: var(--slate-800); line-height: 1.2; margin-top: 4px; }

.diagram-container { position: relative; width: 100%; background: #0f172a; border-bottom: 1px solid var(--slate-200); padding: 0; line-height: 0; aspect-ratio: 16/10; overflow: hidden; }
.diagram-container svg line, .diagram-container svg path, .diagram-container svg text, .diagram-container svg g { transition: all 0.5s cubic-bezier(0.4, 0, 0.2, 1); }

.controls { padding: 25px; display: flex; flex-direction: column; gap: 20px; background: #fff; }
.control-group { display: flex; flex-direction: column; gap: 10px; }
.control-title { font-size: 0.875rem; font-weight: bold; color: var(--slate-500); text-transform: uppercase; letter-spacing: 0.05em; display: flex; align-items: center; gap: 8px; }
.btn-group { display: flex; gap: 10px; width: 100%; flex-wrap: wrap; }
.btn-toggle { flex: 1; min-width: 120px; padding: 10px; border-radius: 8px; font-weight: bold; font-size: 0.95rem; cursor: pointer; transition: all 0.2s; border: 2px solid var(--slate-200); background: white; color: var(--slate-600); display: flex; align-items: center; justify-content: center; gap: 8px; text-align: center; }
.btn-toggle:hover { background: var(--bg-light); }
.btn-toggle.active-amber { background: var(--amber-500); color: white; border-color: var(--amber-500); }
.btn-toggle.active-green { background: var(--green-500); color: white; border-color: var(--green-500); }

.info-box { margin: 0 25px 25px 25px; padding: 20px; background: #fffbf0; border-left: 5px solid var(--billy-orange); border-radius: 0 8px 8px 0; color: #333; font-size: 0.95rem; line-height: 1.6; }
.no-select { user-select: none; -webkit-user-select: none; }