:root {
    --app-bkgnd: #7092BE;
    --viewer-bkgnd: #50729E;
    --app-border: 10px;
    --panel-width: 350px;
}
body {
    margin: 0;
    padding: 0;              
    background-color: var(--app-bkgnd);
}
div#frame_area {
    position: relative;
    width: 100vw;
    height: 100vh;  
    height: 100dvh;  
    margin: 0;  
    padding: 0;     
    overflow: hidden;
    background: var(--app-bkgnd);
}
div#app_area {
    position: absolute;
    top: var(--app-border);
    right: var(--app-border);
    bottom: var(--app-border);
    left: var(--app-border);  
    background: var(--app-bkgnd);
}
div#viewer_area {
    position: absolute;
    margin: 0;
    padding: 0;  
    top: 0px;
    bottom: 0px; 
    width: calc(100% - 250px);
    background: var(--app-bkgnd);
}
div#controls_area {
    position: absolute;
    margin: 0;
    padding: 0;
    top: 0px;
    bottom: 0px;
    right: 0px;
    width: 250px; 
    background: var(--app-bkgnd);
}