问题
I have a HTML select element that uses Bootstrap Select. If I use HTML5, the button element, that is generated by Boostrap Select to render the select, has a correct height of 24.
If I do not use HTML5, it then has a height of 8.875 on Blink (Opera 56.0) and of 8.8833 on Gecko (Firefox 60.3,) resulting in a broken display.
By using HTML5, I mean having (or not) the DOCTYPE <!doctype html>
as the first line (no server config as I tested from files on the FS).
Any idea of what precisely is causing this behaviour?
Here is a complete repro (just save it as a file, and either keep or remove the first line):
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.13.2/css/bootstrap-select.min.css">
<title>Hello, world!</title>
</head>
<body>
<h1>Hello, world!</h1>
<div class="container">
<div class="form-group row">
<label for="foobar" class="col-sm-2 col-form-label">Sauce</label>
<div class="col-sm-10">
<select class="form-control selectpicker">
<option>Mustard</option>
<option>Ketchup</option>
<option>Barbecue</option>
</select>
</div>
</div>
</div>
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/js/bootstrap.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.13.2/js/bootstrap-select.min.js"></script>
</body>
</html>
回答1:
If you are not specifying a correct doctype, the browser switches to quirks mode. It is a fallback solution for older sites whose stylesheets were written before CSS was specified in the current way. MDN provides a "rough" list of differences in layouting in firefox, but there are subtle differences between browsers.
I didn't find a specific rule causing the bug you found, but it has something to do with the percentage height calculation with absolutely positioned children. If you remove position: absolute
from .bootstrap-select .dropdown-toggle .filter-option
, the height gets calculated correctly (even though you would have to adjust the placement of the carret afterwards).
来源:https://stackoverflow.com/questions/53277514/different-height-of-select-with-html5-and-bootstrap-select