Trying to make a slider that contains text - html

Question

I'm trying to make a slider. My divs are #foo, #bar and #text.
#foo is the container div
#bar is a colored div inside #foo. It fills it with variable percentage width.
#text is a transparent div inside #foo (except for the text). It should be above #bar.
Something like this (image)
How can I achieve this with CSS? My code currently looks something like this:
#foo {
background: red;
width: 100px;
height: 20px;
z-index: 1;
}
#bar {
background: green;
width: 50px;
float: left;
height: 20px;
z-index: 2;
}
#text {
z-index: 3;
}
<div id="foo">
<div id="bar"></div>
<div id="text">
Some text.
</div>
</div>

Answer 1

Something like this?
#slider {
width: 200px;
height: 30px;
background-color: black;
position: relative;
}
#percentage {
color: white;
line-height: 30px;
margin-left: 10px;
position: absolute;
}
#bar {
width: 75%;
height: 30px;
background-color: red;
position: absolute;
}
<div id="slider">
<div id="bar">
</div>
<div id="percentage">75%</div>
</div>

Answer 2

Simple make the outer box positioned relative so child elements are relative to the outer box, then position both those elements absolute inside their parent. Give the two inner boxes a position of top left. Now your z-index will work, check out this modified snippet:
#foo {
background: red;
width: 100px;
height: 20px;
z-index: 1;
position: relative;
}
/* Combined these since they share a lot in common */
#bar, #text {
/* Made width and height 100% as they are relative to the parent size now */
width: 100%;
height: 100%;
position: absolute;
left: 0;
top: 0;
z-index: 0;
}
#bar {
background: green;
width: 50px;
}
#text {
z-index: 1;
}
<div id="foo">
<div id="bar"></div>
<div id="text">
Some text.
</div>
</div>

Answer 3

The below will fill the loading bar on hover - you may wish to use jQuery for a wider range of event handlers:
<div id="foo">
<div id="bar"></div>
<div id="text">
Some text.
</div>
</div>
#foo {
background: green;
width: 100px;
height: 20px;
z-index: 1;
position: relative;
overflow: hidden;
}
#bar {
background: red;
width: 100%;
position: absolute;
left: 0;
height: 100%;
z-index: 2;
transition: left 0.5s ease-in-out;
}
#text {
z-index: 3;
position: absolute;
height: 100%;
width: 100%;
}
/* REMOVE BELOW AND EDIT #bar LEFT: VALUE FOR STATIC LOADING BAR */
#foo:hover #bar{
left: 100%;
}