body {
    background-color: #05070a;
    color: #f8fafc;
    font-family: 'Segoe UI', sans-serif;
    margin: 0;
    height: 100vh;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

#main-header {
    width: 100%;
    padding: 15px 0;
    text-align: center;
    background: rgba(30, 41, 59, 0.5);
    border-bottom: 1px solid #1e293b;
}

#main-header h1 {
    margin: 0;
    font-size: 1.8rem;
    letter-spacing: 4px;
    text-transform: uppercase;
}

#main-container {
    display: flex;
    width: 100%;
    flex: 1;
}

#left-panel {
    width: 20%;
    padding: 30px 20px;
    background: #0f172a;
    border-right: 1px solid #1e293b;
    display: flex;
    flex-direction: column;
    z-index: 5;
}

#builder-zone {
    width: 80%;
    background: radial-gradient(circle at center, #111827 0%, #000 100%);
    position: relative;
    overflow: hidden;
}

canvas { display: block; }

.control-group h3 { 
    color: #94a3b8; 
    font-size: 0.75rem; 
    margin-bottom: 15px; 
    letter-spacing: 1.5px;
}

/* STYLE CHECKBOX */
.checkbox-container {
    display: flex;
    align-items: center;
    cursor: pointer;
    gap: 10px;
}

.checkbox-label {
    font-size: 0.85rem;
    color: #f8fafc;
}

input[type=checkbox] {
    width: 18px;
    height: 18px;
    accent-color: #38bdf8;
    cursor: pointer;
}

.instruction-box {
    margin-top: auto;
    font-size: 0.85rem;
    line-height: 1.5;
    color: #64748b;
    padding: 20px;
    background: rgba(0,0,0,0.3);
    border-radius: 12px;
    border: 1px solid #1e293b;
}

input[type=range] {
    accent-color: #38bdf8;
    cursor: pointer;
}