Classic REM Layout

1. Effects of REM and em

Q. Em?
It is a unit of length, relative unit, and the unit of font-size relative to the parent element.
If the parent element font-size = 16px, 1em = 16px
Q. What is Rem?
It is a unit of length, which is a relative unit. It is a unit of font-size relative to the root element of the document. The root element is generally an HTML element.
If the HTML element font-size = 16px, 1rem = 16px
Q. How to use it?
As the interface grows, the DIV, text, and image become larger, and the REM layout is used.

2. How to automatically set the REM Value

Use js to monitor events with screen size changes. Generally, set 1rem = 100px,
If the design draft is 750px
Rule: The whole screen width is 7.5rem.

3. Write a rem use case

Classic Layout
Navigation Bar
Content
Label bar

 

HTML section

<Div class = "navbar"> <Div class = "nav-left"> [#] </div> <Div class = "nav-title"> title </div> <Div class = "nav-Right"> Settings </div> <Div class = "content"> <Div class = "S1"> carousel images </Div> <Div class = "box"> <Div class = "S2"> popular 1 </div> <Div class = "S3"> popular 2 </div> </Div> <ul> <li> Item 1 </LI> <li> Item 2 </LI> <li> Item 3 </LI> </ul> </div> <div class = "tabbar"> <ul> <li> homepage </LI> <li> Category </LI> <li> shopping cart </LI> <li> my </LI> </ul> </div>

CSS Section

 1 body{ 2     padding: 0; 3     margin: 0; 4     font-size: 0.32rem; 5 } 6 ul,li{ 7     list-style: none; 8     margin: 0; 9     padding: 0;10 }11 .navbar{12     width: 7.5rem;13     height: 0.88rem;14     background-color: #eaeaea;15     border-bottom: 1px solid #333;16 }17 .navbar>div{18     float: left;19     font-size: 0.32rem;20     height: 0.88rem;21     line-height: 0.88rem;22     text-align: center;23 }24 .navbar .nav-left{25     width: 1rem;26 }27 .navbar .nav-title{28     width: 5.5rem;29 }30 .navbar .nav-right{31     width: 1rem;32 }33 .tabbar{34     width: 7.5rem;35     height: 0.98rem;36     background-color: #eaeaea;37     border-top: 1px solid #333;38     position: fixed;39     bottom: 0;40 }41 .tabbar ul li{42     display: block;43     float: left;44     width: 1.825rem;45     text-align: center;46     line-height: 0.98rem;47 }48 .box>div{49     float: left;50     overflow: hidden;51 }52 .s1{53     width: 7.5rem;54     height: 3.75rem;55     background-color: lightblue;56 }57 .s2{58     width: 3.75rem;59     height: 3.75rem;60     background-color: lightcoral;61 }62 .s3{63     width: 3.75rem;64     height: 3.75rem;65     background-color: lightgoldenrodyellow;66 }67 .content ul li{68     height: 0.80rem;69     width: 7.5rem;70     display: block;71     float: left;72     border-bottom: 1px solid #555;73     line-height: 0.80rem;74     padding-left: 0.1rem;75 }    

JS Section

1 var doc = document.querySelector("html")2 doc.style.fontSize = "13.33333333vw"

 

Classic REM Layout