Simplest and most flexible solution so far it to use table display:
HTML, left div comes first, right div comes second ... we read and write left to right, so it won't make any sense to place the divs right to left
<div class="container">
<div class="left">
left content flexible width
</div>
<div class="right">
right content fixed width
</div>
</div>
CSS:
.container {
display: table;
width: 100%;
}
.left {
display: table-cell;
width: (whatever you want: 100%, 150px, auto)
}??
.right {
display: table-cell;
width: (whatever you want: 100%, 150px, auto)
}
Cases examples:
// One div is 150px fixed width ; the other takes the rest of the width
.left {width: 150px} .right {width: 100%}
// One div is auto to its inner width ; the other takes the rest of the width
.left {width: 100%} .right {width: auto}