CSS Interview Questions and Answers
Question - 91 : - Must I quote property values?
Answer - 91 : - Generally no. However, values containing white spaces, e.g. font-family names should be quoted as whitespaces surrounding the font name are ignored and whitespaces inside the font name are converted to a single space, thus font names made up of more than one word (e.g.) 'Times New Roman' are interpreted as three different names: Times, New and Roman.
Do any WYSIWYG editors support the creation of Style Sheets? Any text-based HTML editors?
As support for CSS in browsers has matured in the last year, both WYSIWYG and Text-based HTML editors have appeared that allow the creation or the assistance of creating Cascading Style Sheet syntax. There are now at least two dozen editors supporting CSS syntax in some form. The W3C maintains an up-to-date list of these WYSIWYG and text-based editors.
Question - 92 : - Which style specification method should be used? Why?
Answer - 92 : - The answer to this one is tricky. The short answer is: "it depends." The long answer is, however, another story.
If you are planning on using more than one style specification method in your document, you must also worry about Cascading Order of Style methods (see question 11.) If you are going to use only one method, then some guidelines about the nature of each method need to be kept in mind. The answer to this question is also very much related to the advantages and disadvantages to using each of them (next question.)
Method 1: External Style Sheets (The LINK [-->Index DOT Html] element)
This method should be used if you want to apply the same style to multiple documents. Each document can reference the stand-alone style sheet and use the styles contained within. Using this method, the appearance of many documents can be controlled using a single or small number of style sheets. This can save a LOT of time for an author.
Method 2: Embedded Style Sheets (The Style [-->Index DOT Html] element)
The syntax used with Method 2 is the same as that for Method 1. This method is a happy medium between External Style Sheets and Inline Styles (see below.). It should be used in place of Method 1 if you only want to specify styles for a single document. This method should also be used when you want to specify a style for multiple tag types at once or the list of style definitions is of larger size. Method 3: Inline Styles (STYLE attribute to HTML elements)
If you only have to apply style to one or a few elements in a single document, your best bet will often be an Inline Style. This method attaches a style definition within the HTML element it is modifying.
Justified Text?
You redefine the
tag like:
p {text-align: justify;}
and that renders all
s with justified text.
Another possibility is to define a class, like:
.just {text-align: justify;}
and then you style the paragraphs in question like:
text |
Note that NN 4.xx has problems with the inheri
Question - 93 : - Why can @import be at the top only?
Answer - 93 : - A style sheet that is imported into another one has a lower ranking in the cascading order: the importing style sheet overrides the imported one. Programmers may recognize this as the same model as in Java, Modula, Object-Pascal, Oberon and other modular programming languages.
However, there is a competing model, well-known to C programmers, where the imported material is not lower in rank, but is expanded in-place and becomes an integral part of the importing document.
By allowing @import only at the top of the style sheet, people that think in terms of the second model (although in principle incorrect) will still get the expected results: as long as the @import is before any other overriding rules, the two models are equivalent.
Btw. In all the modular languages import statements are only allowed at the top. In C, the #include can be put elsewhere, but in practice everybody always puts it at the top. So there may not be that much need to allow @import elsewhere in the style sheet either.
Question - 94 : - Colored Horizontal Rule?
Answer - 94 : - You can apply styles to Horizontal Rules
in IE without problems, but NN4.xx can only render the silvery HR. But there is a way around it:
.rule {border-top-width: 1px;
border-top-style: solid;
border-color: #FF0000;
margin: 0px 2%;}
that, applied to a div, should give you a red HR in NN4.xx and IE, with a 2% gap on the left and right side.
CSSharky Logo
On this page is an Example of a coloured 'Horizontal Rule'.
Update:
Thanks to Matt Del Vecchio here is an improved format for the Horizontal Rule:
hr { height:0px;
border:0px;
border-top:1px solid #ff1493; }
....this works in both IE and Netscape. It tells the browser to not render the hr rule itself, and then sets a 1px border, which looks just how most folks want to render the hr rule. It uses the
element and that is better than writing your own class as all devices will know what to do with an
tag.
Question - 95 : - Do URL's have quotes or not?
Answer - 95 : - Double or single quotes in URLs are optional. The tree following examples are equally valid:
BODY {background: url(pics/wave.png) blue}
BODY {background: url("pics/wave.png") blue}
BODY {background: url('pics/wave.png') blue}
Question - 96 : - To what are partial URLs relative?
Answer - 96 : - Partial URLs are relative to the source of the style sheet. The style sheet source can either be linked or embedded. To which source partial URLs are relative to depends on their occurrence.
If a partial URL occurs in a linked style sheet then it is relative to the linked style sheet. The URL of the linked style sheet is the URL of the directory where the sheet is kept.
If a partial URL occurs in an embedded style sheet then it is relative to the embedded style sheet. The URL of the embedded style sheet is the URL of the HTML document in which the sheet is embedded.
Note that Navigator 4.x treats partial URLs as being relative to the HTML document, regardless of the place where the partial URL occurs. This is a serious bug which forces most authors to use absolute URLs in their CSS.
Question - 97 : - What's the difference between 'class' and 'id'?
Answer - 97 : - As a person, you may have an ID card - a passport, a driving license or whatever - which identifies you as a unique individual. It's the same with CSS. If you want to apply style to one element use 'id' (e.g.
). In the stylesheet, you identify an 'id' with a '#' ie. '#myid'...
As a person, if you are in a class, you are one of many. It's the same with CSS. If you want to apply the same style to more than one element, use 'class' (e.g.
). In the stylesheet, you identify a 'class' with a '.' ie. '.myclass'...
If id's are more restrictive than classes, then why not just litter your page with classes? Well, I think the main thing is that it's simply wrong. You don't put headings in 'p' tags - you use 'h1', 'h2', etc. You don't (or shouldn't) make a list by writing asterisks or the little divider bar ( | ) - you use list tags ('ol'/'ul' + 'li') . You don't say that your footer is part of a class of elements called 'footer' - that's just stupid - you can't have more than one footer - it can't be a class. Of course, practically, the effect is about the same - the rules are applied - but that's not the point - it's semantically wrong to do it that way... However, if you try to give more than one element the same id, you will have problems - so don't do it.
An element may have an id and a class, but that's usually not necessary. You can also give an element two classes if you need to - like this : class="class1 class2". It can be very useful. Needless to say, you can't give an element two id's.
Another difference is to do with power. You can give an element an id and a class, but if any of the properties of the two conflict, the id style will win. Ids are more powerful than classes.
One more useful thing about id's is that they can be used as a link reference. Many people still think that you need named anchors to make links within a page, but that's simply not true - in fact, the name attribute is deprecated in XHTML except for in forms. One example of using id's as link references is this page. There are no named anchors on this page - the questions at the top of the page link to the id's of the divs that the answers are in.
I made a 10px-high div, but IE makes it 20px high...
Yeah
This problem sometimes comes up when you make a div just to contain the bottom border of a box,
Question - 98 : - How do I place two paragraphs next to each other?
Answer - 98 : - There are several ways to accomplish this effect, although each has its own benefits and drawbacks. We start with the simplest method of positioning two paragraphs next to each other.
Paragraph 1
Paragraph 2
Trickier is this example, which relies on positioning but does not suffer the vertical-overlap problems which plague many other positioning solutions. The problem is that it relies on an incorrect positioning implementation, and will break down dramatically in conformant browsers.
Paragraph 1
Paragraph 2
If floating is not sufficient to your purposes, or you cannot accept display variances in older browsers, then it may be best to fall back to table-based solutions.
Question - 99 : - Can you use someone else's Style Sheet without permission?
Answer - 99 : - This is a somewhat fuzzy issue. As with HTML tags, style sheet information is given using a special language syntax. Use of the language is not copyrighted, and the syntax itself does not convey any content - only rendering information.
It is not a great idea to reference an external style sheet on someone else's server. Doing this is like referencing an in-line image from someone else's server in your HTML document. This can end up overloading a server if too many pages all over the net reference the same item. It can't hurt to contact the author of a style sheet, if known, to discuss using the style sheet, but this may not be possible. In any case, a local copy should be created and used instead of referencing a remote copy.
I want my page fonts to look the same everywhere as in…
a) Why are my font sizes different in different browsers ?
b) Why are my font sizes different on different platforms ?
These questions represent the tip of the iceberg of a large topic about which whole essays have been written and a wide range of different views are held.
The WWW was originally devised to present the same content in different presentation situations and for a wide range of readers: on that basis, "looking the same" is not a design criterion, indeed different presentations would be expected to look different.
Some would have it that this original aim is no longer relevant, and that the purpose of web design is now to factor out the differences between display situations and put the author in control of the details of the presentation. Others point out that CSS was designed to give the reader a substantial amount of joint control over this process, and that this is desirable, for example to accommodate users with different visual acuity.
Reading of textual matter on a computer screen is quite a delicate business, what with the relatively coarse pixel structure of a computer display; even with a close knowledge of the display details, it isn't possible to achieve the detailed control that would be possible, say, on a printer. Whatever one's aims, the practical truth is that many of the efforts made to guarantee the precise result on the screen have seriously counterproductive side effects in a www situation.
The CSS specifications themselves recommend that authors should not use absolute size units in a situation where the properti
Question - 100 : - When is auto different from 0 in margin properties?
Answer - 100 : - In vertical margins, auto is always equal to 0. In horizontal margins, auto is only equal to 0 if the width property is also auto. Here are three examples, assume that there is a
that is a child of
:
Example 1: auto value on the width.
BODY {width: 30em;}
P {width: auto; margin-left: auto; margin-right: auto;}
Since the width property is auto, the auto values of the two margins will be ignored. The result is a P that is 30em wide, with no margins.
Example 2: two auto margins
BODY {width: 30em;}
P {width: 20em; margin-left: auto; margin-right: auto;}
The P will be 20em wide and the remaining 10em will be divided between the two margins. Paragraphs will be indented 5em at both sides.
Example 3: one auto margin
BODY {width: 30em;}
P {width: 20em; margin-left: 2em; margin-right: auto;}
In this case, paragraphs are 20em wide and are indented 2em on the left side. Since the total width available is 30em, that means the right margin will be 8em.
Note that the default value of width is auto, so setting one or both margins to auto is only useful if you set the width to something other than auto at the same time.