box-sizing: border-box changes the model of the window, so the add is removed from the height, not added to it.
So this block:
div { box-sizing: content-box; // default height: 2em; padding: .25em; }
It will be 2.5em high, and this block:
div { box-sizing: border-box; height: 2em; padding: .25em; }
will be 2em high, with a .5em interval divided to fill.
Another issue is how bootstrap determines the height of the inputs:
input[type="text"], ...other selectors.., .uneditable-input { display: inline-block; height: 20px; ... }
The reason defining the height didn't work, because input[type="text"] more specific than input , and so the bootstrap declaration overrides yours.
To solve your input problem, determine the height and use a more specific selector:
input[type="text"], textarea, select, .uneditable-input { border: 1px solid
Demo
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