Why Do Style Sheets Exist?
SGML (of which HTML is a derivative) was meant to be a device-independent method for conveying a document's structural and semantic content (its meaning.) It was never meant to convey physical formatting information. HTML has crossed this line and now contains many elements and attributes which specify visual style and formatting information. One of the main reasons for style sheets is to stop the creation of new HTML physical formatting constructs and once again separate style information from document content.
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 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.
How Do I Place Text Over An Image?
To place text or image over an image you use the position property. The below example 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>
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.
Can I Include Comments In My Style Sheet?
Yes. Comments can be written anywhere where whitespace is allowed and are treated as white space themselves. Anything written between /* and */ is treated as a comment (white space). NOTE: Comments cannot be nested.
Which Characters Can Css-names Contain?
The CSS-names; names of selectors, classes and IDs 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. The names cannot start with a dash or a digit. (Note: in HTML the value of the CLASS attribute can contain more characters).
What Browsers Support Style Sheets? To What Extent?
Microsoft's Internet Explorer version 3.0 Beta 2 and above supports CSS, as does Netscape Communicator 4.0 Beta 2 and above and Opera 3.5 and above. Take note that the early implementations in these browsers did not support ALL of the properties and syntax described in the full CSS1 specification and beyond. Later versions have been getting much closer to full CSS1 compliance, but then comes the next hurdle - CSS2...it was such a big leap over CSS1 that it has taken the browsers years to come close to supporting a majority of CSS2's features. Mozilla and Opera's current versions both offer excellent CSS standards compliance. The Macintosh version of Internet Explorer is said to be very impressive in its CSS capabilities as well, but PC IE lags behind these implementations. Quite a few other implementations of CSS now exist in browsers that are not as widely-used (such as Amaya, Arena and Emacs-W3), but coverage of features in these documents currently only covers Internet Explorer, NCSA Mosaic, Netscape and Opera browsers.
Why Shouldn't I Use Fixed Sized Fonts ?
Only in very rare situations we will find users that have a "calibrated" rendering device that shows fixed font sizes correct. This tells us that we can never know the real size of a font when it's rendered on the user end. Other people may find your choice of font size uncomfortable. A surprisingly large number of people have vision problems and require larger text than the average. Other people have good eyesight and prefer the advantage of more text on the screen that a smaller font size allows. What is comfortable to you on your system may be uncomfortable to someone else. Browsers have a default size for fonts. If a user finds this inappropriate, they can change it to something they prefer. You can never assume that your choice is better for them. So, leave the font size alone for the majority of your text. If you wish to change it in specific places (say smaller text for a copyright notice at the bottom of page), use relative units so that the size will stay in relationship to what the user may have selected already. Remember, if people find your text uncomfortable, they will not bother struggling with your web site. Very few (if any) web sites are important enough to the average user to justify fighting with the author's idea of what is best.
What Is Initial Value?
Initial value is a default value of the property, that is the value given to the root element of the document tree. All properties have an initial value. If no specific value is set and/or if a property is not inherited the initial value is used. For example the background property is not inherited, however, the background of the parent element shines through because the initial value of background property is transparent.
<P style="background: red">Hello <strong>World </strong> </P>
Content of the element P will also have red background
How Frustrating Is It To Write A Specification Knowing That You're At The Browser Vendors' Mercy?
That's part of the game. I don't think any specification has a birthright to be fully supported by all browsers. There should be healthy competition between different specifications. I believe simple, author-friendly specifications will prevail in this environment.
Microformats are another way of developing new formats. Instead of having to convince browser vendors to support your favorite specification, microformats add semantics to HTML through the CLASS attribute. And style it with CSS.
How Far Can Css Be Taken Beyond The Web Page--that Is, Have Generalized Or Non-web Specific Features For Such Things As Page Formatting Or Type Setting?
Yes, it's possible to take CSS further in several directions. W3C just published a new Working Draft which describes features for printing, e.g., footnotes, cross-references, and even generated indexes.
Another great opportunity for CSS is Web Applications. Just like documents, applications need to be styled and CSS is an intrinsic component of AJAX. The "AJAX" name sounds great.
How To Style Table Cells?
Margin, Border and Padding are difficult to apply to inline elements. Officially, the <TD> tag is a block level element because it can contain other block level elements (see Basics - Elements).
If you need to set special margins, borders, or padding inside a table cell, then use this markup
<td>
yourtext </div></td>
to apply the CSS rules to the div inside the cell. </p>
How To Style Forms?
Forms and form elements like SELECT, INPUT etc. can be styled with CSS - partially.
Checkboxes and Radiobuttons do not yet accept styles, and Netscape 4.xx has certain issues, but here is a tutorial that explains the application of CSS Styles on Form Elements.
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">
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.
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.
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.
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.
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 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 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.
How Do I Have A Non-tiling (non-repeating) Background Image?
With CSS, you can use the background-repeat property. The background repeat can be included in the short hand background property, as in this example
body {
background: white url(example.gif) no-repeat ;
color: black ;
}
SGML (of which HTML is a derivative) was meant to be a device-independent method for conveying a document's structural and semantic content (its meaning.) It was never meant to convey physical formatting information. HTML has crossed this line and now contains many elements and attributes which specify visual style and formatting information. One of the main reasons for style sheets is to stop the creation of new HTML physical formatting constructs and once again separate style information from document content.
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 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.
How Do I Place Text Over An Image?
To place text or image over an image you use the position property. The below example 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>
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.
 |
| Daum Frequently Asked HTML Interview Questions Answers |
Can I Include Comments In My Style Sheet?
Yes. Comments can be written anywhere where whitespace is allowed and are treated as white space themselves. Anything written between /* and */ is treated as a comment (white space). NOTE: Comments cannot be nested.
Which Characters Can Css-names Contain?
The CSS-names; names of selectors, classes and IDs 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. The names cannot start with a dash or a digit. (Note: in HTML the value of the CLASS attribute can contain more characters).
What Browsers Support Style Sheets? To What Extent?
Microsoft's Internet Explorer version 3.0 Beta 2 and above supports CSS, as does Netscape Communicator 4.0 Beta 2 and above and Opera 3.5 and above. Take note that the early implementations in these browsers did not support ALL of the properties and syntax described in the full CSS1 specification and beyond. Later versions have been getting much closer to full CSS1 compliance, but then comes the next hurdle - CSS2...it was such a big leap over CSS1 that it has taken the browsers years to come close to supporting a majority of CSS2's features. Mozilla and Opera's current versions both offer excellent CSS standards compliance. The Macintosh version of Internet Explorer is said to be very impressive in its CSS capabilities as well, but PC IE lags behind these implementations. Quite a few other implementations of CSS now exist in browsers that are not as widely-used (such as Amaya, Arena and Emacs-W3), but coverage of features in these documents currently only covers Internet Explorer, NCSA Mosaic, Netscape and Opera browsers.
Why Shouldn't I Use Fixed Sized Fonts ?
Only in very rare situations we will find users that have a "calibrated" rendering device that shows fixed font sizes correct. This tells us that we can never know the real size of a font when it's rendered on the user end. Other people may find your choice of font size uncomfortable. A surprisingly large number of people have vision problems and require larger text than the average. Other people have good eyesight and prefer the advantage of more text on the screen that a smaller font size allows. What is comfortable to you on your system may be uncomfortable to someone else. Browsers have a default size for fonts. If a user finds this inappropriate, they can change it to something they prefer. You can never assume that your choice is better for them. So, leave the font size alone for the majority of your text. If you wish to change it in specific places (say smaller text for a copyright notice at the bottom of page), use relative units so that the size will stay in relationship to what the user may have selected already. Remember, if people find your text uncomfortable, they will not bother struggling with your web site. Very few (if any) web sites are important enough to the average user to justify fighting with the author's idea of what is best.
What Is Initial Value?
Initial value is a default value of the property, that is the value given to the root element of the document tree. All properties have an initial value. If no specific value is set and/or if a property is not inherited the initial value is used. For example the background property is not inherited, however, the background of the parent element shines through because the initial value of background property is transparent.
<P style="background: red">Hello <strong>World </strong> </P>
Content of the element P will also have red background
How Frustrating Is It To Write A Specification Knowing That You're At The Browser Vendors' Mercy?
That's part of the game. I don't think any specification has a birthright to be fully supported by all browsers. There should be healthy competition between different specifications. I believe simple, author-friendly specifications will prevail in this environment.
Microformats are another way of developing new formats. Instead of having to convince browser vendors to support your favorite specification, microformats add semantics to HTML through the CLASS attribute. And style it with CSS.
How Far Can Css Be Taken Beyond The Web Page--that Is, Have Generalized Or Non-web Specific Features For Such Things As Page Formatting Or Type Setting?
Yes, it's possible to take CSS further in several directions. W3C just published a new Working Draft which describes features for printing, e.g., footnotes, cross-references, and even generated indexes.
Another great opportunity for CSS is Web Applications. Just like documents, applications need to be styled and CSS is an intrinsic component of AJAX. The "AJAX" name sounds great.
How To Style Table Cells?
Margin, Border and Padding are difficult to apply to inline elements. Officially, the <TD> tag is a block level element because it can contain other block level elements (see Basics - Elements).
If you need to set special margins, borders, or padding inside a table cell, then use this markup
<td>
yourtext </div></td>
to apply the CSS rules to the div inside the cell. </p>
How To Style Forms?
Forms and form elements like SELECT, INPUT etc. can be styled with CSS - partially.
Checkboxes and Radiobuttons do not yet accept styles, and Netscape 4.xx has certain issues, but here is a tutorial that explains the application of CSS Styles on Form Elements.
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">
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.
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.
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.
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.
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 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 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.
How Do I Have A Non-tiling (non-repeating) Background Image?
With CSS, you can use the background-repeat property. The background repeat can be included in the short hand background property, as in this example
body {
background: white url(example.gif) no-repeat ;
color: black ;
}