* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

.container {
    position: relative;
    width: 100%;
    height: 100vh;
    background-image: url(https://blender.codeschnipsel.dev/dist/TNA-3D-Model-von-Codeschnipsel-dev-wire.png);
    background-position: center center;
    background-size: cover;
    overflow: hidden;
}

.mask-container {
    position: absolute;
    top: 0;
    left: 0;
    height: 100%;
    width: 50%;
    overflow: hidden;
}

.mask-image-container {
    position: absolute;
    top: 0;
    left: 0;
    height: 100vh;
    width: 100vw;
    background-image: url(https://blender.codeschnipsel.dev/dist/TNA-3D-Model-von-Codeschnipsel-dev.png);
    background-position: center center;
    background-size: cover;
}

.border {
    position: absolute;
    width: 4px;
    height: 100vh;
    left: 50%;
    margin-left: -2px;
    background-color: rgba(0,0,0,0.4);
}

.circle {
    position: absolute;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background-color: steelblue;
    top: 50%;
    margin-top: -25px;
    left: 50%;
    margin-left: -25px;
    opacity: 0.9;
    cursor: ew-resize;
}