css id height

I’m guessing some or all of your containing divs are floated. You can try this fix on the parent div that contains all of your floated divs:

.clearfix:after {
content: ".";
display: block;
height: 0;
clear: both;
visibility: hidden;
}

Article is here: https://www.positioniseverything.net/easyclearing.html

thanks i bet this will help.

just to be informed about this code what does the content: “.”; do?

That content is just what it seems. A full stop or period. However by upgrading it to block level with display block and setting clear both it will prevent the next element – commonly the footer – from appearing until both the content and the menu are done. This simple technique and others which are very similar, prevents untold borkage and is the key that holds two col floated schemes together.