Depth Css job interview Questions

Posted by Stephen thangaraj at 04:16


What is inline style? How to link? 

Inline style is the style attached to one specific element. The style is specified directly in the start tag as a value of the STYLE attribute and will apply exclusively to this specific element occurrence.
<P STYLE="text-indent: 10pt">Indented paragraph</P>


What is imported Style Sheet? How to link? 

Imported Style Sheet is a sheet that can be imported to (combined with) another sheet. This allows creating one main sheet containing declarations that apply to the whole site and partial sheets containing declarations that apply to specific elements (or documents) that may require additional styling. By importing partial sheets to the main sheet a number of sources can be combined into one.
To import a style sheet or style sheets include the @import notation or notations in the STYLE element. The @import notations must come before any other declaration. If more than one sheet is imported they will cascade in order they are imported - the last imported sheet will override the next last; the next last will override the second last, and so on. If the imported style is in conflict with the rules declared in the main sheet then it will be overridden.<LINK REL=STYLESHEET HREF="main.css" TYPE="text/css">
<STYLE TYPE="text=css">
<!--
@import url(http://www.and.so.on.partial1.css);
@import url(http://www.and.so.on.partial2.css);
.... other statements
-->
</STYLE>


What is a Style Sheet? 

Style sheets are the way that standards-compliant Web designers define the layout, look-and-feel, and design of their pages. They are called Cascading Style Sheets or CSS. With style sheets, a designer can define many aspects of a Web page:

* fonts
* colors
* layout
* positioning
* imagery
* accessibility

Style sheets give you a lot of power to define how your pages will look. And another great thing about them is that style sheets make it really easy to update your pages when you want to make a new design. Simply load in a new style sheet onto your pages and you're done.


What is alternate Style Sheet? How to link? 

Alternate Style Sheet is a sheet defining an alternate style to be used in place of style(s) declared as persistent and/or preferred .
Persistent style is a default style that applies when style sheets are enabled but can disabled in favor of an alternate style, e.g.:

<LINK REL=Stylesheet HREF="style.css" TYPE="text/css">

Preferred style is a default style that applies automatically and is declared by setting the TITLE attribute to the LINK element. There can only be one preferred style, e.g.:

<LINK REL=Stylesheet HREF="style2.css" TYPE="text/css" TITLE="appropriate style description">

Alternate style gives an user the choice of selecting an alternative style - a very convenient way of specifying a media dependent style. Note: Each group of alternate styles must have unique TITLE, e.g.:

<LINK REL="Alternate Stylesheet" HREF="style3.css" TYPE="text/css" TITLE="appropriate style description" MEDIA=screen>
<LINK REL="Alternate Stylesheet" HREF="style4.css" TYPE="text/css" TITLE="appropriate style description" MEDIA=print>
Alternate stylesheet are not yet supported.


How can you set a minimum width for IE? 

To set a minimum width, the CSS property is 'min-width'. This can be very useful and works well in good browsers. IE doesn't understand 'min-width'. However, it has a proprietary property called 'expression' which allows us to feed it javascript via a stylesheet. Below is how to set a (780px) minimum width for IE...


<!--[if gte IE 5]> <style type="text/css">
body {
width:expression(documentElement.clientWidth < 780 ? (documentElement.clientWidth == 0 ? (body.clientWidth < 780 ? "780px" : "auto") : "780px") : "auto" );
}
</style>
<![endif]-->

As the property is non-standard, it won't validate with the W3C validator, so if we put it in the head like this (above) - in an IE conditional comment - the validator will ignore it and the page will get a clean bill of health.

Which browsers support CSS? 

It depends on your definition of "support." If you are interested in those browsers which makes some attempt at supporting CSS, no matter how partial or bug-ridden, then the list is:

* Internet Explorer 3.0 and above
* Navigator 4.0 and above
* Opera 3.6 and above
* Konqueror
* Arena
* Emacs-w3
* Amaya
* Lexicon
* XPublish by Media Design in·Progress

If instead you're interested in those browsers which are known to do a credible job of bug-free and mostly completel support for CSS1, then the list narrows somewhat dramatically:

* Internet Explorer 5.0 for Macintosh and above
* Internet Exporer 5.5 for Windows and above
* Netscape Navigator 6.0 and above
* Opera 4.0 and above

While none of these browser can be claimed to have a perfect implementation of CSS1, they are all quite good and can be relied upon to operate in a consistent fashion for most of CSS1.


How do I place text over an image?

To place text or image over an image you use the position property. The below exemple is supported by IE 4.0. All you have to do is adapt the units to your need.

<div style="position: relative; width: 200px; height: 100px">
<div style="position: absolute; top: 0; left: 0; width: 200px">
<image>
</div>
<div style="position: absolute; top: 20%; left: 20%; width: 200px">
Text that nicely wraps
</div>
</div>


what CSS is, why not start coding?

CSS is sort of like scripting language made for the web. In contrary with HTML, DHTML, JavaScript, VBScript and many others. CSS is strictly for formatting your web-page and now many new browser support it. (NOTE: Older browser do not support CSS, so please check your browser version and make sure whether it supports it or not. You may have to update your current Browser.)

The way the code goes into your Web-page is through a variety of ways. The way CSS works is that is the code is set between the<head></head> tags. You can put the CSS code after </title> which is what most people do. Now, here are the following ways of making your webpage with CSS enabled features:

1.) Writing your CSS code within your HTML source code. This is how it would look like:

<html><head><title>My First CSS!</title>
<!-- Now begin the CSS coding! -->
<STYLE TYPE = "text/css">
<!--
body {
background-color: #eeeee;
}
p {
text-align: left;
color: black;
font: Verdana;
font-size: 80%;
}
a {
text-decoration: none;
color: black;
font-weight: bold;
}
a:hover {
text-decoration: underline;
color: red;
font-weight: bold;
}
-->
</STYLE>
<!-- End CSS code -->
</head><body></body></html>

2.) Linking to your CSS file. This tells the webpage to find the .css file and use it as the CSS code. Here is the code that would allow you to do:

<html><head><title>CSS</title>
<link href="style.css" rel="stylesheet" type="text/css" />
</head><body /></html>

As you can see from the code above, the <link> tag is pretty helpful. What it does is that it links to the style.css file which has all the css code. Just like embedding an image throught he <img> tag.

Now to explain a bit from the first example. CSS code isn't very hard to understand.Take for example the body { ..} part. What it does is that it formats how the <body> tag in HTML would work. That is a very simple way of formatting the body tag with the CSS. To help you understand better, here is a simple syntax for CSS:

selector { property1: value1; property2: value2;}

The "selector" sort of relates to the html tags used for outputting etc...

We all know that <a> is a tag used for links. You will see in the example about a:hover and a itself. <br>What a does it just sets the characteristics of the format. You can set how you want a link to appear using the font size, weight etc..

Then comes the "a:hover". What does is also pretty self explanatory. It acts on when a person moves the mouse cursor over the links.

ADVANCED CSS FEATURES:

CSS can be even used to change the appearance of the scroll bar at your right side. Unfortunately, that only works with IE. You have to be using IE in order for this to work. Here is how to change some appearances of your scroll bar:


The CSS statements for doing this are:
1) scrollbar-3dlight-color
2)scrollbar-arrow-color
3) scrollbar-base-color
4) scrollbar-dark shadow-color
5) scrollbar-face-color
6) scrollbar-highlight-color
7) scrollbar-shadow-color
8) scrollbar-track-color

<style type="text/css">
<!--
BODY {
scrollbar-arrow-color: green;
scrollbar-face-color: #FFFFFF;
scrollbar-track-color: rgb(12,35,244);
}
// -->
</style>

How to customize your textboxes.
Here is the code on how to do it:

<style type="text/css">
<!--
BODY {
scrollbar-arrow-color: green;
scrollbar-face-color: #FFFFFF;
scrollbar-track-color: rgb(12,35,244);
}
TEXTAREA {
scrollbar-arrow-color: green;
scrollbar-face-color: #FFFFFF;
scrollbar-track-color: rgb(12,35,244);
}
// -->
</style>

That above code, has some similarities. The textbox area is treated with the same function statements as for the scrollbar. The scrollbar statements goes in the BODY selector.


Why does my content shift to the left on some pages (in FF)? 

That'll be the pages with more content? The ones that have a vertical scrollbar? If you look in IE there's probably a white space on the right where there would be a scrollbar if there were enough content to require one. In Firefox, the scrollbar appears when it's needed and the viewport becomes about 20px smaller, so the content seems to shift to the left when you move from a page with little content to one with lots of content. It's not a bug or something that needs to be fixed, but it does confuse and irritate some developers.

If, for some reason, you'd like Firefox to always have scrollbars - whether they're needed or not - you can do this :

CSS html {
height:100.1%;
}


How do I combine multiple sheets into one?

To combine multiple/partial style sheets into one set the TITLE attribute taking one and the same value to the LINK element. The combined style will apply as a preferred style, e.g.:

<LINK REL=Stylesheet HREF="default.css" TITLE="combined">
<LINK REL=Stylesheet HREF="fonts.css" TITLE="combined">
<LINK REL=Stylesheet HREF="tables.css" TITLE="combined">


What is attribute selector? 

Attribute selector is a selector defined by 1) the attribute set to element(s), 2) the attribute and value(s), 3) the attribute and value parts:

1a) A[title] {text-decoration: underline}
All A elements containing the TITLE attribute will be underlined

1b) A[class=name] {text-decoration: underline}
The A elements classed as 'name' will be underlined

2) A[title="attribute element"] {text-decoration: underline}
The A elements containing the TITLE attribute with a value that is an exact match of the specified value, which in this example is 'attribute element', will be underlined

3) A[title~="attribute"] {text-decoration: underline}
The A elements containing the TITLE attribute with a value containing the specified word, which in this example is 'attribute', will be underlined


What is parent-child selector? 

Parent-child selector is a selector representing the direct descendent of a parent element. Parent-child selectors are created by listing two or more tilde (~) separated selectors.

BODY ~ P {background: red; color: white}
The P element will be declared the specified style only if it directly descends from the BODY element:
<BODY> <P>Red and white paragraph </P> </BODY>

BODY ~ P ~ EM {background: red; color: white}
The EM element will be declared the specified style only if it directly descends from the P element which in its turn directly descends from the BODY element:

< <P> <EM>Red and white EM </EM> </P> </BODY>


How can I specify background images? 

With CSS, you can suggest a background image (and a background color, for those not using your image) with the background property. Here is an example:

body {
background: white url(example.gif) ;
color: black ;
}

If you specify a background image, you should also specify text, link, and background colors since the reader's default colors may not provide adequate contrast against your background image. The background color may be used by those not using your background image. Authors should not rely on the specified background image since browsers allow their users to disable image loading or to override document-specified backgrounds.


How do I have a fixed (non-scrolling) background image? 

With CSS, you can use the background-attachment property. The background attachment can be included in the shorthand background property, as in this example:

body {
background: white url(example.gif) fixed ;
color: black ;
}

Note that this CSS is supported by Internet Explorer, Mozilla, Firefox Opera, Safari, and other browsers. In contrast, Microsoft's proprietary BGPROPERTIES attribute is supported only by Internet Explorer.


What are inline, block, parent, children, replaced and floating elements? 

Inline elements which do not have line breaks. Can occur in block elements or other inline elements, cannot contain block elements.
Inline elements in HTML 3.2; EM, STRONG, DFN, CODE, SAMP, KBD, VAR, CITE, TT, I, B, U, STRIKE, BIG, SMALL, SUB, SUP, A, IMG, APPLET, FONT, BASEFONT, BR, SCRIPT, MAP, INPUT, SELECT, TEXTAREA.

Inline elements in HTML 4.0; EM, STRONG, DFN, CODE, SAMP, KBD, VAR, CITE, ABBR, ACRONYM, TT, I, B, BIG, SMALL, SUB, SUP, A, IMG, OBJECT, BR, SCRIPT, MAP, Q, SPAN, BDO, INPUT, SELECT, TEXTAREA, LABEL, BUTTON, (INS, DEL).

Inline elements in HTML 4.0 Transitional; EM, STRONG, DFN, CODE, SAMP, KBD, VAR, CITE, ABBR, ACRONYM, TT, I, B, U, S, STRIKE, BIG, SMALL, SUB, SUP, A, IMG, APPLET, OBJECT, FONT, BASEFONT, BR, SCRIPT, MAP, Q, SPAN, BDO, IFRAME, INPUT, SELECT, TEXTAREA, LABEL, BUTTON, (INS, DEL).

Block
elements which do have line breaks. May occur in other block elements, cannot occur in inline elements, may contain both block and inline elements.

Block elements in HTML 3.2; H1, H2, H3, H4, H5, H6, ADDRESS, P, DL, DT, DD, UL, OL, DIR, MENU, LI, DIV, CENTER, BLOCKQUOTE, PRE, HR, ISINDEX, TABLE, FORM.

Block elements in HTML 4.0; P, H1, H2, H3, H4, H5, H6, UL, OL, PRE, DL, DIV, NOSCRIPT, BLOCKQUOTE, FORM, HR, TABLE, FIELDSET, ADDRESS, (INS, DEL).

Block elements in HTML 4.0 Transitional; P, H1, H2, H3, H4, H5, H6, UL, OL, DIR, MENU, PRE, DL, DIV, CENTER, NOSCRIPT, NOFRAMES, BLOCKQUOTE, FORM, ISINDEX, HR, TABLE, FIELDSET, ADDRESS, (INS, DEL).

Parents and children
elements which either contain (parents) or are in the content of (children) other elements, e.g. <P>text<STRONG>text</STRONG>text</P>. P is a parent of STRONG. STRONG is a child of P. If not specified otherwise, children will inherit parent's properties.
Replaced elements which content is replaced. For example content of the IMG element is replaced with an image, content of the INPUT element is replace with a field.
Floating elements which follow the flow of a parent - inline elements.


Which set of definitions, HTML attributes or CSS properties, take precedence? 

CSS properties take precedence over HTML attributes. If both are specified, HTML attributes will be displayed in browsers without CSS support but won't have any effect in browsers with CSS support.


How do I eliminate the blue border around linked images? 

in your CSS, you can specify the border property for linked images:

a img { border: none ; } 
However, note that removing the border that indicates an image is a link makes it harder for users to distinguish quickly and easily which images on a web page are clickable.


Why call the subtended angle a "pixel", instead of something else (e.g. "subangle")?

In most cases, a CSS pixel will be equal to a device pixel. But, as you point out, the definition of a CSS pixel will sometimes be different. For example, on a laser printer, one CSS pixel can be equal to 3x3 device pixels to avoid printing illegibly small text and images. I don't recall anyone ever proposing another name for it. Subangle? Personally, I think most people would prefer the pragmatic "px" to the non-intuitive "sa".


Why was the decision made to make padding apply outside of the width of a 'box', rather than inside, which would seem to make more sense? 

It makes sense in some situations, but not in others. For example, when a child element is set to width: 100%, I don't think it should cover the padding of its parent. The box-sizing property in CSS3 addresses this issue. Ideally, the issue should have been addressed earlier, though.


How to use CSS to separate content and design ? 

The idea here is that all sites contain two major parts, the content: all your articles, text and photos and the design: rounded corners, colors and effects. Usually those two are made in different parts of a webpage’s lifetime. The design is determined at the beginning and then you start filling it with content and keep the design fixed. 

In CSS you just add the nifty <link>-tag I’ve told you about to the head of your HTML document and you have created a link to your design. In the HTML document you put content only, and that link of yours makes sure it looks right. You can also use the exact same link on many of your pages, giving them all of them the same design. You want to add content? Just write a plain HTML document and think about marking things up like “header” instead of “big blue header” and use CSS to make all headers look the way you want!

Some examples of good and bad coding. What’s wrong with this?

<font size="3">Welcome to my page</font>

Comment: The font-tag is design and design shouldn’t be in the HTML document. All design should be in the CSS-file! Instead do this:

In the HTML:
<h1>Welcome to my page</h1>

In the CSS:
h1 { font-size: 2em; }

One more example:

<b>An error occurred</b>

This looks right doesn’t it? But if you look up what <b> stands for you quickly find bold. But bold is certainly design, so it still doesn’t belong in the HTML document. A better choice is <em> that stands for emphasis or simply “this piece of text is important”. So instead of saying “this text looks like this” you are saying “this text is important” and you let the looks be decided by the CSS. Seems like a minor change, but it illustrates how to select your tags. Use this instead:

In the HTML:
<em>An error occured</em>

In the CSS:
em {
font-weight: bold;
color: Red;
}

One last example:

<table>
<tr><td><a href="">first link</a></td></tr>
<tr><td><a href="">second link</a></td></tr>
...
</table>


Can CSS be used with other than HTML documents? 

Yes. CSS can be used with any ny structured document format. e.g. XML, however, the method of linking CSS with other document types has not been decided yet.


Can Style Sheets and HTML stylistic elements be used in the same document? 

Yes. Style Sheets will be ignored in browsers without CSS-support and HTML stylistic elements used.


What are pseudo-classes? 

Pseudo-classes are fictional element types that do not exist in HTML. In CSS1 there is only one element type which can be classed this way, namely the A element (anchor). By creating three fictional types of the A element individual style can be attached to each class. These three fictional element types are: A as unvisited link, A as active link and A as visited link. Pseudo-classes are created by a colon followed by pseudo-class's name. They can also be combined with normal classes, e.g.:

A:link {background: black; color: white}
A:active {background: black; color: red}
A:visited {background: transparent; color: black}

<A HREF....>This anchor (or rather these anchors) will be displayed as declared above</A>

A.foot:link {background: black; color: white}
A.foft:active {background; black: color: red}
A.foot:visited {background: transparent; color: black}

<A CLASS=foot HREF....>This anchor and all other anchors with CLASS foot will be displayed as declared above</A>


How do I design for backward compatibility using Style Sheets? 

Existing HTML style methods (such as <font SIZE> and <b>) may be easily combined with style sheet specification methods. Browsers that do not understand style sheets will use the older HTML formatting methods, and style sheets specifications can control the appearance of these elements in browsers that support CSS1.


As a reader, how can I make my browser recognize my own style sheet? 

Netscape
It is not possible to do this in Netscape yet (as of version 4.0.) 
Internet Explorer 3.0 (Win95/NT)
[It is possible to do this at least in Windows95/NT, but no user interface is provided. Unknown how this might be accomplished on other operating systems.]

1. Open the Registry editor (Start..Run..regedit..ENTER)
2. Under the 'HKEY_LOCAL_MACHINE\Software\Microsoft\InternetExplorer\Styles' key, Edit..New..String Value
3. The new value should be called 'StyleSheet Pathname'
4. For the value, type in the full directory path of your .css style sheet. 

Internet Explorer 4.0 (Win95/NT)

1. Under the View menu, select 'Internet Options'.
2. Under the 'General' tab, choose the 'Accessibility' button.
3. Choose the 'Format documents using my style sheet' check box and 'Browse...' to the location of your .css style sheet.


How do I get rid of the gap under my image?

Images are inline elements, which means they are treated in the same way as text. Most people kind of know this - they know that if you use 'text-align:center' on an image it will be centred. What many people don't realise is that this means you will have a gap underneath an image. This gap is for the descenders of letters like j,q,p,y and g. To get rid of this gap you need to make the image block-level - like this :

CSS
img {display:block;}

One problem that this can cause is when you want to have a few images next to each other - if they are block-level, they won't be next to each other. To get around that, you can use float:left. Of course, this might present another problem - maybe you don't want the image to float left. In this case, you can use an unordered list like this :

CSS
ul, li {
list-style-type:none;
padding:0;
margin:0 auto;
}
ul {
width:150px;
}
li {
float:left;
} 
HTML
<ul>
<li><img src="wine.jpg" height="50" width="50" alt="wine" /></li>
<li><img src="wine.jpg" height="50" width="50" alt="wine" /></li>
<li><img src="wine.jpg" height="50" width="50" alt="wine" /></li>
<li><img src="wine.jpg" height="50" width="50" alt="wine" /></li>
<li><img src="wine.jpg" height="50" width="50" alt="wine" /></li>
<li><img src="wine.jpg" height="50" width="50" alt="wine" /></li>
<li><img src="wine.jpg" height="50" width="50" alt="wine" /></li>
<li><img src="wine.jpg" height="50" width="50" alt="wine" /></li>
<li><img src="wine.jpg" height="50" width="50" alt="wine" /></li>
</ul>


Why use Style Sheets? 

Style sheets allow a much greater degree of layout and display control than has ever been possible thus far in HTML. The amount of format coding necessary to control display characteristics can be greatly reduced through the use of external style sheets which can be used by a group of documents. Also, multiple style sheets can be integrated from different sources to form a cohesive tapestry of styles for a document. Style sheets are also backward compatible - They can be mixed with HTML styling elements and attributes so that older browsers can view content as intended.


What does the "Cascading" in "Cascading Style Sheets" mean? 

Style Sheets allow style information to be specified from many locations. Multiple (partial) external style sheets can be referenced to reduce redundancy, and both authors as well as readers can specify style preferences. In addition, three main methods can be employed by an author to add style information to HTML documents, and multiple approaches for style control are available in each of these methods. In the end, style can be specified for a single element using any, or all, of these methods. What style is to be used when there is a direct conflict between style specifications for an element? 
Cascading comes to the rescue. A document can have styles specified using all of these methods, but all the information will be reduced to a single, cohesive "virtual" Style Sheet. Conflict resolution is based on each style rule having an assigned weight according to its importance in the scheme of things. A rule with a higher overall importance will carry a higher weight. This will be used in place of a competing style rule with a lower weight/importance. A hierarchy of competing styles is thus formed creating a "cascade" of styles according to their assigned weights. The algorithm used to determine this cascading weight scale is fairly complex.


What is CSS rule 'at-rule'? 

There are two types of CSS rules: ruleset and at-rule. At-rule is a rule that applies to the whole style sheet and not to a specific selector only (like in ruleset). They all begin with the @ symbol followed by a keyword made up of letters a-z, A-Z, digits 0-9, dashes and escaped characters, e.g. @import or @font-face.


What is selector? 

CSS selector is equivalent of HTML element(s). It is a string identifying to which element(s) the corresponding declaration(s) will apply and as such the link between the HTML document and the style sheet. 
For example in P {text-indent: 10pt} the selector is P and is called type selector as it matches all instances of this element type in the document. 
in P, UL {text-indent: 10pt} the selector is P and UL (see grouping); in .class {text-indent: 10pt} the selector is .class (see class selector).


What is CLASS selector? 

Class selector is a "stand alone" class to which a specific style is declared. Using the CLASS attribute the declared style can then be associated with any HTML element. The class selectors are created by a period followed by the class's name. The name can contain characters a-z, A-Z, digits 0-9, period, hyphen, escaped characters, Unicode characters 161-255, as well as any Unicode character as a numeric code, however, they cannot start with a dash or a digit. (Note: in HTML the value of the CLASS attribute can contain more characters).It is a good practice to name classes according to their function than their appearance.

.footnote {font: 70%} /* class as selector */

<ADDRESS CLASS=footnote/>This element is associated with the CLASS footnote</ADDRESS>
<P CLASS=footnote>And so is this</P>


What is CSS declaration? 

CSS declaration is style attached to a specific selector. It consists of two parts; property which is equivalent of HTML attribute, e.g. text-indent: and value which is equivalent of HTML value, e.g. 10pt. NOTE: properties are always ended with a colon.


What is 'important' declaration? 

Important declaration is a declaration with increased weight. Declaration with increased weight will override declarations with normal weight. If both reader's and author's style sheet contain statements with important declarations the author's declaration will override the reader's.

BODY {background: white ! important; color: black}

In the example above the background property has increased weight while the color property has normal.


What is cascade? 

Cascade is a method of defining the weight (importance) of individual styling rules thus allowing conflicting rules to be sorted out should such rules apply to the same selector. 

Declarations with increased weight take precedence over declaration with normal weight:

P {color: white ! important} /* increased weight */
P (color: black} /* normal weight */


Are Style Sheets case sensitive? 

No. Style sheets are case insensitive. Whatever is case insensitive in HTML is also case insensitive in CSS. However, parts that are not under control of CSS like font family names and URLs can be case sensitive - IMAGE.gif and image.gif is not the same file.


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