.theme-thpt { background: linear-gradient(135deg, #eceff1 0%, #cfd8dc 100%); }
.theme-thpt .game-header h1 { color: #283593; }

#graph-canvas {
    display: block; margin: 15px auto; background: white; border-radius: 16px;
    box-shadow: 0 6px 25px rgba(0,0,0,0.08); border: 1px solid #e0e0e0;
    max-width: 95%;
}
.graph-options {
    display: grid; grid-template-columns: 1fr 1fr; gap: 10px;
    max-width: 400px; margin: 15px auto; padding: 0 15px;
}
.graph-opt {
    padding: 14px 10px; border: 2px solid #c5cae9; border-radius: 14px;
    background: white; text-align: center; font-size: 1.1rem;
    font-family: 'Nunito', sans-serif; font-weight: 700; color: #333;
    cursor: pointer; transition: all 0.2s;
}
.graph-opt:hover { background: #e8eaf6; border-color: #5c6bc0; }
.graph-opt.correct { background: #e8f5e9; border-color: #4caf50; color: #2e7d32; }
.graph-opt.wrong { background: #ffebee; border-color: #f44336; color: #c62828; }
.graph-opt.disabled { pointer-events: none; opacity: 0.6; }