elastic + fixed width

from: http://jsfiddle.net/fct87qpn/1/

by Juan Lanus

HTML

<div class="container">
    <div class="right"></div>
    <div class="left">
        <input type="text" class="text"/>
    </div>
</div>

CSS

.container {
    width:100%;
    height:20px;
    border:1px solid;
}
.left {
    width:auto;
    height:20px;
    background:red;
    overflow: hidden;
}
.right {
    height:20px;
    width:30px;
    background:blue;
    float:right;
}
.text{
    width:100%;
    height:20px;
}