modals.less, line 82.

min-height: (@modal-title-padding + @modal-title-line-height);

First of all it returns not rounded value. Secondary if we not set title, header seems broken. Cross becomes near bottom border. I don't know, what was idea of this min-height, but I fixed it with this code:

min-height: round(@modal-title-padding * 2 + @font-size-h4 * @line-height-base);

Have a before/after example?

@mdo Nope, but you can do it yourself. Inspect modal title and remove it. You will see what is wrong