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Using Global CSS Styles on Websites with Third Party Controls

HOW-TO

Using Global CSS Styles on Websites with Third Party Controls

SOLUTION

Defining CSS styles globally is a common practice for controlling the layout of entire websites, but this approach may result in unexpected and unpleasant behaviors in third party controls that these websites utilize.

Basically, a global CSS definition is the use of a selector with inherited properties without a class name, for example:

table  
 {  
     border-collapse: collapse;  
     border: solid 1px red;  
     font: bold 14px Verdana, Arial, Sans-serif;  
     line-height: 2em;  
 }

Such definitions, although convenient, will apply their settings to third party controls, which have the same selectors, but do not have the properties that are explicitly defined in the global CSS definition, so:

table.RadGrid  
{  
    background: red;  
}

…will automatically result in…

table.RadGrid  
 {  
     border-collapse: collapse;  
     border: solid 1px red;  
     font: bold 14px Verdana, Arial, Sans-serif;  
     line-height: 2em;  
     background: red;  
 }

…Because the browser will apply both the global table settings and the table.RadGrid settings, and this will lead to significant changes in the design and layout of the third party control.

Basically, there are two ways of managing this issue:

Reconsidering your own HTML and CSS

When using third party controls, refrain from defining global CSS classes in your style sheets. For example, if your layout consists of div’s, give each layout div a unique class name, and define it separately, that is:

div.wrapper  
 {  
     margin: auto;  
     width: 800px;  
     border: solid 1px #404040;  
     background: lightgreen;  
 }

…instead of:

div  
 {  
     border: solid 1px #404040;  
     background: lightgreen;  
 }

Editing the Third Party Control’s CSS

The second approach is to edit the CSS styles of the third party control, which is obviously not the best way, because you will have both to understand the logic of these styles and then to override the global settings using the !important flag, or setting the missing properties and their values explicitly, that is:

table.RadGrid
{
border-collapse: separate;
border: solid 1px #000;
font: normal 12px Verdana, Arial, Sans-serif;
background: #fff;
line-height: 2.1em;
}

…In order to override the global table settings:

table
{
border-collapse: collapse;
border: solid 1px red;
font: bold 14px Verdana, Arial, Sans-serif;
background: red;
line-height: 2em;
}
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