I was wondering if I can use the fieldset tag without being inside a form. Because I like the way it encloses the legend & the border stuff around the inner html. When I use it to enclose li element, it does behave like its actually there(visual) inside a form.
It's valid HTML5. Paste the following HTML at the validator: http://validator.w3.org/check:
<!DOCTYPE html>
<html>
<head><title>Title</title></head>
<body>
<fieldset> <legend>Test</legend> </fieldset>
</body>
</html>
It's also valid HTML4. Replace <!DOCTYPE html> with the following, and it still passes the validation:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
You can use any form elements outside of an actual form, since most of them can be used with JavaScript utilities outside the form. The form is only needed if you plan on allowing the user to submit the data with it.
One thing to keep in mind is that you should separate structure and design. Do you want a fieldset because it is a fieldset or because the fieldset looks nice?
See also:
来源：https://stackoverflow.com/questions/9812898/is-it-wrong-to-use-the-fieldset-tag-without-form-tag