.content-grid {  
    display: grid;
    grid-template-columns: 1fr;
    grid-template-rows: repeat(3, auto);
    grid-column-gap: 0px;
    grid-row-gap: 0em;
    color: white;
}

.edition { 
    grid-area: 1 / 1 / 2 / 2; 
    }

.demo { grid-area: 2 / 1 / 3 / 2; } 
   
.demo iframe {
    border: 2px solid #df85a5;
    padding: 10px;
    display: block;
    margin: auto;
}
.guide {
    grid-area: 3 / 1 / 4 / 2;
    width: 80%;
    padding: 2em;
    margin: auto;
}