CSS Interview Questions and Answers
Related differences
Ques 21. How do I write my style sheet so that it gracefully cascades with user's personal sheet ?
You can help with this by setting properties in recommended places. Style rules that apply to the whole document should be set in the BODY element -- and only there. In this way, the user can easily modify document-wide style settings.
Ques 22. What are pseudo-elements?
Pseudo-elements are fictional elements that do not exist in HTML. They address the element\'s sub-part (non-existent in HTML) and not the element itself. In CSS1 there are two pseudo-elements: \'first-line pseudo-element\' and \'first-letter pseudo-element\'. They can be attached to block-level elements (e.g. paragraphs or headings) to allow typographical styling of their sub-parts. Pseudo-element is created by a colon followed by pseudo-element\'s name, e.g:
P:first-line
H1:first-letter
and can be combined with normal classes; e.g:
P.initial:first-line
First-line pseudo-element allows sub-parting the element\'s first line and attaching specific style exclusively to this sub-part; e.g.:
P.initial:first-line {text-transform: uppercase}
<P class=initial>The first line of this paragraph will be displayed in uppercase letters</P>
First-letter pseudo-element allows sub-parting the element\'s first letter and attaching specific style exclusively to this sub-part; e.g.:
P.initial:first-letter { font-size: 200%; color: red}
<P class=initial>The first letter of this paragraph will be displayed in red and twice as large as the remaining letters</P>
Ques 23. As a developer who works with CSS every day, I find one complication that continues to bother me in my daily work. Support for CSS has always been good on the horizontal scope, but vertical positioning has always been quite complicated. Alone the procedure to affix a footer to the bottom of a screen in dependance of the amount of content is unnecessarily difficult. The old table method provided much easier methods for this. What are your thoughts on this and do you see improvement following in future CSS revisions?
Indeed, the CSS formatting model allows more control horizontally than vertically. This is due to (typically) having a known width, but an unknown height. As such, the height is harder to deal with. However, CSS2 fixed positioning allows you to place content relative to the viewport (which is CSS-speak for window) instead of the document. For example, by setting position: fixed; bottom: 0 on an element, it will stick to the bottom. This works in Opera, Safari and Mozilla-based browsers. IE6 doesn't support it, however. It remains to be seen if IE7 will support it.
Ques 24. How can I make a page look the same in e.g. NS and MSIE ?
The simple answer is, you can't, and you shouldn't waste your time trying to make it exactly the same. Web browsers are allowed, per definition, to interpret a page as they like, subject to the general rules set down in the HTML and CSS specifications. As a web author you can not have a prior knowledge of the exact situation and/or medium that will be used to render your page, and it's almost always rather counterproductive to try to control that process. There is no necessity for a well-written page to look the same in different browsers. You may want to strive to ensure that it looks good in more than one browser, even if the actual display (in the case of graphical browsers) comes out a bit different. "Looking good" can be achieved by adopting sensible design and guidelines, such as not fixing the size or face of your fonts, not fixing the width of tables, etc? Don't fight the medium; most web users only use one browser and will never know, or bother to find out, that your page looks different, or even "better", in any other browser.
Ques 25. Is there anything that CAN'T be replaced by Style Sheets?
Quite a bit actually. Style sheets only specify information that controls display and rendering information. Virtual style elements that convey the NATURE of the content can not be replaced by style sheets, and hyperlinking and multimedia object insertion is not a part of style sheet functionality at all (although controlling how those objects appear IS part of style sheets functionality.) The CSS1 specification has gone out of its way to absorb ALL of the HTML functionality used in controlling display and layout characteristics. For more information on the possible properties in CSS, see the Index DOT Css Property Index.
Rule of Thumb: if an HTML element or attribute gives cues as to how its contents should be displayed, then some or all of its functionality has been absorbed by style sheets.
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