Babylon.js/sandbox/src/scss/main.scss

html {
    --background: #2A2342;
    --footer-background: #201936;
    --footer-height: 70px;
    --button-hover-color: #BB464B;
    --button-hover-hover: #e0684b;
    --button-hover-background:  #162D3A;
    --font-size: 20px;
}

html, body, #root {
    width: 100%;
    height: 100%;
    padding: 0;
    margin: 0;
    overflow: hidden;
    font-size: var(--font-size);
    background: var(--background);
    font-family: "acumin-pro-condensed";
    font-weight: normal;    
}

.hidden {
    display: none !important;
}

.clickInterceptor {
    position: absolute;
    width: 100%;
    height: 100%;    
    z-index: 99;
    top:0;
    left:0;
}

#droptext {
    position: absolute;
    text-align: center;
    color: #fff;
    height: 50px;
    width: 100%;
    bottom: 50px;    
}

#logoContainer {
    position: absolute;
    top:0;
    left:0;
    width: 100%;   
    height: calc(100% - 70px);
    pointer-events: none;
    display: grid;
    grid-template-rows: 100%;
    grid-template-columns: 100%;
    align-items: center;
    justify-items: center;
}

#logo {
    width: 150px;
    pointer-events: none;
}

#errorZone {
    position: absolute;
    width: 50%;
    left: 25%;
    bottom: 80px;
    background-color: #C73228;
    padding:20px;
    border-radius: 5px;
    color:white;
    display: grid;
    grid-template-columns: 1fr 32px;

        .message {
            grid-column: 1;
            grid-row: 1;
            align-self: center;
        }

        button {
            grid-column: 2;
            grid-row: 1;
            padding: 0;
            cursor: pointer;
            background: transparent;
            border: 0;
            -webkit-appearance: none;
            color: #000;
            text-shadow: 0 1px 0 #fff;
            opacity: .4;
            font-size: 1.8em;

            &:hover {
                transform: scale(1.2);
            }
        }
}

@media (max-width: 768px) {
    html {
        --footer-height: 50px;
        --font-size: 16px;
    }
}