main.css

* {box-sizing: border-box;}

html {
    font-family: Arial, Helvetica, sans-serif;
    overflow: hidden;
}

body {
    margin: 0;
    padding: 0;
    height: 100%;
    background-color: #f1f1f1;
}

iframe {
    border: none;
}


.main-container {
    display: flex;
    margin-left: auto;
    margin-right: auto;
    margin-top: 16px;
    padding: 0px 8px;
}

.card {
    box-shadow: 0 2px 5px 0 rgba(0,0,0,0.16),
                0 2px 10px 0 rgba(0,0,0,0.12);
    border-radius: 6px;
}

#header {
    
    display: block;
    width: 100%;
    background-color: grey;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 8px 0;

    text-shadow: 0px 0px 4px rgba(255, 255, 255, 0.8);
}


#menu {
    float: left;
    width: 33.33%;
    background-color: rgb(255,158,97);
    margin: 0px 8px;
    padding: 8px;
}

#content {
    float: left;
    width: 66.66%;
    margin: 0px 8px;
    height: calc(66vw/16*9);
}


@media only screen and (max-height: 650px) {
    #header {display: none;}
}

@media only screen and (min-width: 1400px) {
    #content {
        height: calc(1400px*0.6666/16*9)
    }
}