Some very good CSS skills, but they are often ignored by people_Experience exchange

1. Case Sensitive
When using CSS in XHTML, the element names defined in CSS are case sensitive. To avoid this error, I recommend using lowercase for all definition names.

2. No need to add quotes to the background image path
In order to save bytes, I recommend not to add quotes to the background image path, because the quotes are not necessary. For example:

background:url("images/***.gif") #333;

can be written as

background:url(images/***. gif) #333;

If you add quotation marks, it will cause some browser errors.


3. Specify link styles in the correct order
When you use CSS to define multiple state styles of a link, pay attention to the order in which they are written. The correct order is: :link :visited :hover :active. The first letter extracted is "LVHA", which you can remember as "LoVe HAte" (like to hate).


4. Clear floats
A very common CSS problem is that when floating is used for positioning, the layer below is covered by the floating layer, or the sub-layers nested in the layer exceed the outer layer. The scope of the layer.

The usual solution is to add an extra element behind the floating layer, such as a div or a br, and define its style as clear: both. This method is a bit far-fetched, but fortunately there is a good way to solve it. Please refer to this article "How To Clear Floats Without Structural Markup" (Note: This site will translate this article as soon as possible).

The above two methods can solve the problem of floating overflow very well, but what if you really need to clear the layer or the objects in the layer? A simple method is to use the overflow attribute. This method was originally published in "Simple Clearing of Floats" and has been widely discussed in "Clearance" and "Super simple clearing floats".

Which clear method above is more suitable for you depends on the specific situation and will not be discussed here. In addition, some excellent articles have made it very clear about the application of float. It is recommended that you read: "Floatutorial", "Containing Floats" and "Float Layouts"


5. Horizontal centering (centering) This is a simple trick, but it's worth saying again because I see so many newbie questions asking this: How to horizontally center CSS? You need to define the width of the element and define the horizontal margin. If your layout is contained in a layer (container), like this:
body {
text-align:center;
}
#wrap {
width:760px; /* Modify to the width of your layer */
margin:0 auto;
text-align:left;
}

6. Debugging skills: How big is the layer?
When debugging CSS errors, you have to be like a typewriter and analyze the CSS code line by line. I usually define a background color on the layer in question so it's obvious how much space the layer takes up.Some people suggest using border, which is generally OK, but the problem is that sometimes border will increase the size of the element, and border-top and boeder-bottom will destroy the vertical margin value, so it is safer to use background.