Write a better CSS

Well-written CSS code can improve the rendering speed of the page. Essentially, a rule does not have the fastest resolution of the engine. The MDN splits the CSS selector into four main categories, as shown below, and the performance is reduced in turn.

• ID rule

• Class rules

• Label rules

• General rules

Avoid over-restraint
As a general rule, no unnecessary constraints are added.

1. Bad Ul#someid {..}. menu#otherid{..} Good #someid {...} #otherid {..}

The descendant selector sucks.
Not only is the performance low and the code very fragile, the HTML code and CSS code are badly coupled, the HTML code structure changes, the CSS has to be modified, which is how bad, especially in large companies, writing HTML and CSS is often not the same person.

1. It sucks. html DIV tr td {...}

Avoid chaining (intersection) selectors
This is similar to overly restrictive situations, and it is wiser to simply create a new CSS class selector.

1. Oops. Menu.left.icon {..} Okay, Menu-left-icon. {..}

Stick to the KISS principle
Imagine that we have the following DOM:

1. <ul id= "Navigator" > <li><a href= "#" class= "Twitter" >Twitter</a></li> <li><a H ref= "#" class= "Facebook" >Facebook</a></li> <li><a href= "#" class= "Dribble" >Dribbble< /a></li></ul>

1. Bad #navigator li a {...} Good #navigator {...} [b] Use compound syntax [/b] to use compound syntax whenever possible.

2. [code]//bad. SomeClass {padding-top:20px;    padding-bottom:20px;    padding-left:10px;    padding-right:10px;    Background: #000; Background-image:url (..    /imgs/carrot.png);    Background-position:bottom; Background-repeat:repeat-x;}    Okay, SomeClass. {padding:20px 10px 20px 10px; Background: #000 URL (... /imgs/carrot.png) Repeat-x Bottom;}

Avoid unnecessary namespaces

1. Oops. SomeClass table Tr.otherclass Td.somerule {..} Okay. SomeClass. otherclass td.somerule {..}

avoid unnecessary duplication
Try to combine duplicate rules as much as possible.

Bad. SomeClass {color:red;    Background:blue; font-size:15px;}.    Otherclass {color:red;    Background:blue; font-size:15px;}    Ok. SomeClass,. otherclass {color:red;    Background:blue; font-size:15px;}

streamline rules as much as possible

avoid ambiguous naming conventions
It is best to use a name that represents semantics. A good CSS class name should describe what it is and not what it looks like.

Avoid!importants
in fact, you should also be able to use other high-quality selectors.





Follow a standard declaration order
While there are some common ways of arranging CSS property order , here's a popular way I follow.

1. . SomeClass {/* positioning *//* Display & Box Model *//* Background and typography styles *//* transitions *//* Other */}




well organized code format
code readability and ease of maintenance are proportional. Here are the formatting methods I followed.

1. Oops. Someclass-a,. Someclass-b,. Someclass-c,. someclass-d {...} Ok. Someclass-a,. Someclass-b,. Someclass-c,. someclass-d {...}    Good practice. SomeClass {background-image:linear-gradient (#000, #ccc), Linear-gradient (#ccc, #ddd); box-shadow:2px 2px 2px #000, 1px 4px 1px 1px #ddd inset;}