The class name suggests it handles responsive images. What it actually does is three declarations, and none of them affects which file gets downloaded — a 2400px photo…
The grid works by putting negative margins on .row to cancel the padding on .col-*. Nesting columns directly inside a column skips that cancellation, and the inner content…
Thirty-one requests before the page could do anything, most of them under 2 KB. Concatenation in a declared order, source maps, and cache busting that proxies respect.
The grid is three classes that only work as a chain. .container supplies 15px of padding, .row cancels it with a -15px margin on each side, and .col-*…
There are two usual ways to change Bootstrap’s colours. Editing variables.less inside the vendor directory, which the next upgrade overwrites, and adding overriding rules in a stylesheet loaded…