1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49

html, body, div, span, applet, object, iframe,
h1, h2, h3, h4, h5, h6, p, blockquote, pre,
a, abbr, acronym, address, big, cite, code,
del, dfn, em, img, ins, kbd, q, s, samp,
small, strike, strong, sub, sup, tt, var,
b, u, i, center,
dl, dt, dd, ol, ul, li,
fieldset, form, label, legend,
table, caption, tbody, tfoot, thead, tr, th, td,
article, aside, canvas, details, embed, 
figure, figcaption, footer, header, hgroup, 
menu, nav, output, ruby, section, summary,
time, mark, audio, video {
	margin: 0;
	padding: 0;
	border: 0;
	font-size: 100%;
	font: inherit;
	vertical-align: baseline;
}
article, aside, details, figcaption, figure, 
footer, header, hgroup, menu, nav, section {
	display: block;
}
body {
	line-height: 1;
}
ol, ul {
	list-style: none;
}
blockquote, q {
	quotes: none;
}
blockquote:before, blockquote:after,
q:before, q:after {
	content: '';
	content: none;
}
table {
	border-collapse: collapse;
	border-spacing: 0;
}
*,*:before,*:after{
    box-sizing: border-box;
}
img{
    max-width: 100%;
    height: auto;
}

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

/*設定當螢幕寬度在400px以上時*/
@media screen and(min-width:400px){
    body{
        background-color: red;
    }
}
/*設定當螢幕寬度在0px~600px時*/
@media screen and(max-width:600px){
    body{
        background-color: red;
    }
}
/*設定當螢幕寬度在600px以上，1000px以下時*/
@media screen and (min-width:600px) and (max-width:1000px){
    body{
        background-color: green;
    }
}
/*設定當螢幕寬度在1000px以上，1920px以下時*/
@media screen and (min-width:1000px) and (max-width:1920px){
    body{
        background-color: blue;
    }
}

1
2
3
4
5
6

.box{
    width: calc(100% - 40px); /*佔100%再減少40px*/
    width: calc(50%); /*佔50%*/
    width: calc(20% + 30%); /*佔50%*/
    width: calc(100% / 2); /*佔50%*/
}

1
2
3
4
5

.box{
    position: relative/absolute;
    left: 50px;
    width: calc(100% - 100px) /*left50px，right50px*/
}

1
2
3

<div class="box"></div>
<div class="box"></div>
<div class="box"></div>

1
2
3
4
5
6
7

.box {
  float: left;
  width: 30.33333%; /*佔3分之1*/
  height: 50px;
  margin: 1.5%; /*左右共佔3%*/
  background-color: red;
}