.instrument-guitar,
.instrument-bass {
    background-color: #513b2c; 
    border-left: 8px solid #f1f5f9; 
    border-right: 3px solid #cbd5e1;
}

.fret-grid {
    flex: 1;
    height: 100%;
    border-right: 2px solid #cbd5e1; 
    position: relative;
}

.string {
    position: absolute;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(to bottom, #ffffff, #94a3b8); 
    transform: translateY(-50%);
    pointer-events: none;
    z-index: 2; 
}

.position-marker {
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    width: 14px;
    height: 14px;
    background-color: rgba(255, 255, 255, 0.25); 
    border-radius: 50%;
    z-index: 1; 
}

.position-marker-top {
    position: absolute;
    left: 50%;
    top: 25%;
    transform: translate(-50%, -50%);
    width: 12px;
    height: 12px;
    background-color: rgba(255, 255, 255, 0.25);
    border-radius: 50%;
    z-index: 1;
}

.position-marker-bottom {
    position: absolute;
    left: 50%;
    top: 75%;
    transform: translate(-50%, -50%);
    width: 12px;
    height: 12px;
    background-color: rgba(255, 255, 255, 0.25);
    border-radius: 50%;
    z-index: 1;
}