span 100% height of parent button - css

Question

I have the following markup
<button class="filter"><div class="radio"><div class="circle"></div></div> <span>Account Management</span></button>
and CSS
.filter {
font-size: 3vw;
text-align: left;
line-height: 1.6;
padding: 0px;
display: block;
height:auto;
overflow: hidden;
margin-bottom: 3px;
}
.filter span {
background: $leithyellow;
height: 100%;
overflow:auto;
display: block;
width: calc(100% - 60px);
float: left;
margin-left:10px;
padding-left:20px;
}
I cannot get the span to expand to 100% height of the button. Can this be done?

Answer 1

Heights apply only if the heights are defined properly for the ancestors. If you want the height to work, that's a tricky one. You can use one of my favourites, but you need to make sure it works in all the cases:
Give position: relative; to the parent.
Give position: absolute; to the element that needs full height and width.
Give the element, 0 values for all the sides.
Snippet
.parent {
position: relative;
width: 100px;
height: 50px;
background: red;
}
.parent .child {
position: absolute;
top: 0;
left: 0;
bottom: 0;
right: 0;
background: skyblue;
}
<div class="parent">
<span class="child"></span>
</div>
In the above snippet, it is noted that this can also work, if you give:
.parent {
position: relative;
width: 100px;
height: 50px;
background: red;
}
.parent .child {
position: absolute;
width: 100%;
height: 100%;
background: skyblue;
}
<div class="parent">
<span class="child"></span>
</div>
One good part about this approach is, you don't need to use the dangerous calc:
.parent {
position: relative;
width: 150px;
height: 50px;
background: red;
}
.parent .child {
position: absolute;
top: 0;
left: 0;
bottom: 0;
right: 60px;
background: skyblue;
}
<div class="parent">
<span class="child"></span>
</div>
Note: On a related note, you can also have a look at this question and answer: Calc() alternative to fixed side bar with content?

Answer 2

Set display: flex to the parent
Set align-self: stretch for the child
This will stretch the height of the child div/button to fit the height of its parent without doing any trick.
By using position: absolute instead of flex-box, it won't be very nice eventually when you have more stuff added or re-arrange later on would be the nightmare.