body {
    margin: 0;
    height: 100vh;
    display: flex;
}

#left-panel {
width: 15%;
height: 100vh;
background: #222;
}

#main-view {
width: 85%;
height: 100vh;
}

#canvas {
width: 100%;
height: 100%;
display: block;
background: #000;
}