I want a parent with auto height, a sibling with a height in px and the element in percentage. My only idea doesn't work and I don't have any other ideas how I can do this. I tried this (but the element height is 0; I want it to be 90% of the sibling/parent height):
#parent {
height:auto;
width:100%;
background:blue;
}
#element {
height:90%;
width:50%;
background:black;
}
#sibling {
height:400px;
width:50%;
background:red;
}
<div id="parent">
<div id="element"></div>
<div id="sibling"></div>
</div>
How can I do this?