@Denis Stephanov, you can create a flex item that doesn’t shrink or grow and has a fixed width, with the following css rule:
.flex-fixed-width-item {
flex: 0 0 100px;
}
This is the short-hand for flex-grow, flex-shrink, and flex-basis. You can read more about these properties in this CSS-Tricks article.
Adding that class to your fixed width column:
<div class="container-fluid d-flex h-100">
<div class="white h-100 flex-fixed-width-item" style=" background-color: white;">
fixed 100px
</div>
...
Then keeping your column ratio the same:
...
<div class="col-2 blue h-100" style="background-color: blue;">
2
</div>
<div class="col-4 red h-100" style="background-color: red;">
4
</div>
<div class="col-2 blue h-100" style="background-color: blue;">
2
</div>
</div>
You’ll get your requested outcome, which you can view in this codeply project.