Fluid width fixed position

Question

Imagine:

Where:

• .outer is

Answer 1

What about using something like this fiddle ?

.outer {
    width: 20%;
    height: 1200px;
    margin-left: 5%;
    float: left;
}
.inner {
    height: 200px;
    position: fixed;
    top: 0;
    background: orange;
    right: 75%;
    left: 5%;
}