CSS学习笔记（基础）

藏金阁的扫地僧 發表於 2020-5-25 19:27:00

<h1 class="md-end-block md-heading">css</h1>
——道阻且长，行则将至
 
<h2 class="md-end-block md-heading">1.什么是CSS?</h2>
 
<h2 class="md-end-block md-heading">2.CSS导入方式</h2>
<pre class="md-fences md-end-block md-fences-with-lineno ty-contain-cm modeLoaded"> #### 优先级：就近原则</pre>
<ol class="ol-list" start="">
<li class="md-list-item">
行内样式
<pre class="md-fences md-end-block md-fences-with-lineno ty-contain-cm modeLoaded">   <h1 style="color: coral;">标签</h1></pre>
 
</li>
<li class="md-list-item">
内部样式表
<pre class="md-fences md-end-block md-fences-with-lineno ty-contain-cm modeLoaded">   <style>      h1{          color: black;    }  </style></pre>
 
</li>
<li class="md-list-item">
外部样式表
<pre class="md-fences md-end-block md-fences-with-lineno ty-contain-cm modeLoaded">         <link rel="stylesheet" href="css/style.css">        <style>          @import "css/style.css";    </style></pre>
 
</li>
</ol>
<h2 class="md-end-block md-heading">3.CSS选择器</h2>
 
<h3 class="md-end-block md-heading">1.基本选择器</h3>
优先级： id选择器>class选择器>标签选择器
<ol class="ol-list" start="">
<li class="md-list-item">
标签选择器
<pre class="md-fences md-end-block md-fences-with-lineno ty-contain-cm modeLoaded"> <style>      /*标签选择器，会选择到页面上所有为这个标签的元素*/      h1{          color: #ffffff;          background: darkcyan;          border-radius: 10px;    }      p{          font-size: 80px;    }  </style></pre>
 
</li>
<li class="md-list-item">
类选择器
<pre class="md-fences md-end-block md-fences-with-lineno ty-contain-cm modeLoaded"> <style>      /*类选择器的格式：.class的名称{}    好处：可以多个标签归类，相当于同一个class，可以复用    */      .title1{          color: aqua;    }      .title2{          color: crimson;    }      .title3{          color: coral;    }  </style></pre>
 
</li>
<li class="md-list-item">
id选择器
<pre class="md-fences md-end-block md-fences-with-lineno ty-contain-cm modeLoaded"> <style>      /*id选择器id必须保证全局唯一    格式: #id名称{ }    */      #title1{          color: coral;    }      .title1{          color: darkkhaki;    }      .title4{          color: darkcyan;    }      h1{          color: blueviolet;    }  </style></pre>
 
</li>
</ol>
<h3 class="md-end-block md-heading">2.层次选择器</h3>
<ol class="ol-list" start="">
<li class="md-list-item">
后代选择器：在某个元素的后面（儿孙选择器）
<pre class="md-fences md-end-block md-fences-with-lineno ty-contain-cm modeLoaded"> /* 后代选择器 */  body p{      background: crimson;  }</pre>
 
</li>
<li class="md-list-item">
子选择器：只有一代（儿子选择器）
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">/*子选择器*/
body>p{
background: blueviolet;
}</pre>
 
</li>
<li class="md-list-item">
相邻兄弟选择器: 同辈向下一个（一个弟弟选择器）
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">/*相邻兄弟选择器*/
.active + p{
background: darkcyan;
}</pre>
 
</li>
<li class="md-list-item">
通用选择器：同辈向下所有（所有弟弟选择器）
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">/*通用选择器*/
.active~p{
background: cornflowerblue;
}</pre>
 
</li>
</ol>
<h3 class="md-end-block md-heading">3.结构伪类选择器</h3>
 伪类：条件
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">/*ul的第一个子元素*/
ul li:first-child{
background: cornflowerblue;
}

/*ul的最后一个子元素*/
ul li:last-child{
background: darkcyan;
}

/* 选择p1:定位到父元素选择到当前的第一个元素
选择当前p元素的父级元素，选中父级元素的第一个，并且是当前元素才生效
顺序
*/
p:nth-child(1) {
background: darkkhaki;
}
/* 选中父元素下的类型为p元素的第二个
类型
*/
p:nth-of-type(2){
background: crimson;
}

a:hover{
background: deeppink;
}</pre>
 
 
<h3 class="md-end-block md-heading">4.属性选择器（常用）</h3>
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno"><!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>

<style>
 .demo a{
 float: left;
 display: block;
 height: 50px;
 width: 50px;
 border-radius: 30px;
 background: cornflowerblue;
 text-align: center;
 text-decoration: none;
 color: crimson;
 margin-right: 10px;
 font: bold 20px/50px Arial;
 }
 /* 选择存在id属性的元素
 格式[属性名/属性名=属性值（可以是正则表达式）]{}
 */
 /*a{*/
 /* background: yellow;*/
 /*}*/
 /*a{*/
 /* background: yellow;*/
 /*}*/
 /* 选择class中有links的元素
 = :绝对等于
 *= ：包含
 ^= : 以...开头
 $= : 以...结尾
 */
 /*a{*/
 /* background: yellow;*/
 /*}*/
 /* 选择href中以http开头的元素 */
 /*a{*/
 /* background: yellow;*/
 /*}*/
 /* 选择href中以pdf结尾的元素 */
 a{
 background: deeppink;
 }
</style>
</head>
<body>


<a href="http://www.baidu.com" class="links item first" id="first" \>01</a>
<a href="http://www.baidu.com" class="links item active" target="_blank" title="test">02</a>
<a href="images/123.html" class="links item">03</a>
<a href="images/123.png" class="links item">04</a>
<a href="images/123.jpg" class="links item">05</a>
<a href="abc" class="links item">06</a>
<a href="/a.pdf" class="links item">07</a>
<a href="/abc.pdf" class="links item">08</a>
<a href="abc.doc" class="links item">09</a>
<a href="abcd.doc" class="links item last">10</a>

</body>
</html></pre>
 
 
<h2 class="md-end-block md-heading">4.美化网页元素</h2>
<h3 class="md-end-block md-heading">1.为什么要美化网页？</h3>
<ol class="ol-list" start="">
<li class="md-list-item">
有效的传递页面信息
</li>
<li class="md-list-item">
美化网页，吸引用户
</li>
<li class="md-list-item">
凸显页面主题
</li>
<li class="md-list-item">
提高用户体验
</li>
</ol>
 
span标签：重点突出的字，使用span标签（本身没有效果，约定俗成）
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno"><!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>span</title>

<style>
#title1{
 font-size: 50px;
}
</style>
</head>
<body>

欢迎学习 CSS

</body>
</html></pre>
 
<h3 class="md-end-block md-heading">2.字体样式</h3>
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">/*font-family:字体
font-size：字体大小
font-weight:字体粗细
color：字体颜色
*/
body{
font-family: "Arial Black", 楷体;
color: cornflowerblue;
}
h1{
font-size: 70px;
}
.p1{
font-weight: bold;
}
.p2{
font-weight: lighter;
}</pre>
 
<h3 class="md-end-block md-heading">3.文本样式</h3>
<ol class="ol-list" start="">
<li class="md-list-item">
颜色 color字体颜色 background背景颜色
</li>
<li class="md-list-item">
文本对齐方式 text-align
</li>
<li class="md-list-item">
首行缩进 text-indent
</li>
<li class="md-list-item">
行高 line-height 行高和高度一致就可以上下居中
</li>
<li class="md-list-item">
阴影 text-shadow
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">/*阴影水平偏移垂直偏移阴影半径阴影颜色*/
text-shadow: 10px 0px 20px dodgerblue;</pre>
</li>
<li class="md-list-item">
装饰
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">/*下划线*/
.l1{
text-decoration: underline;
}
/*中划线*/
.l2{
text-decoration: line-through;
}
/*上划线*/
.l3{
text-decoration: overline;
}
/*去除下划线： text-decoration: none;*/
a{
 text-decoration: none;
}</pre>
</li>
<li class="md-list-item">
文本图片对齐：水平：vertical-align: center; 上下：vertical-align: middle
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">/*对齐：参照物 a,b*/
img,span{
/*水平*/
vertical-align: center;
/*上下*/
vertical-align: middle;
}</pre>
</li>
</ol>
 
<h3 class="md-end-block md-heading">4.超链接伪类</h3>
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">/*默认的颜色*/
a{
text-decoration: none;
color: darkcyan;
}
/*未访问链接*/
a:link{
color: black;
}
/*鼠标悬浮时*/
a:hover{
color: orange;
background: darkcyan;
font-size: 25px;
}
/*鼠标点击未释放*/
a:active{
color: white;
}
/*已访问链接*/
a:visited{
color: khaki;
}</pre>
 
<h3 class="md-end-block md-heading">5.列表</h3>
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">/*ul li*/
/*list-style
none 去掉圆点
circle 空心圆
decimal 数字
square正方形
*/
ul li{
height: 25px;
list-style: none;
text-indent: 0em;
}</pre>
 
 
<h3 class="md-end-block md-heading">6.背景</h3>
<h4 class="md-end-block md-heading">背景颜色</h4>
 background-color
<h4 class="md-end-block md-heading">背景图片</h4>
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno"><style>
div{
 width: 1000px;
 height: 700px;
 border: 2px solid red;
 /*默认全部平铺repeat*/
 background-image: url("images/1.png");

}
.div1{
 /*水平*/
 background-repeat: repeat-x;
}
.div2{
 /*垂直*/
 background-repeat: repeat-y;
}
.div3{
 /*不平铺*/
 background-repeat: no-repeat;
 /*定位*/
 background-position: 200px 2px;
}
</style>
</pre>
 综合写法
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">/*颜色图片图片位置平铺方式*/
background:#11aebc url("../images/down.png") 205px 7px no-repeat;</pre>
<h4 class="md-end-block md-heading">渐变</h4>
 <code>我的垃圾审美</code>
<blockquote>
渐变网站
</blockquote>
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">
<style>
body{
 background-color: #08AEEA;
 background-image: linear-gradient(45deg, #08AEEA 0%, #2AF598 100%);

}</pre>
 
<h3 class="md-end-block md-heading">7. 背景透明度</h3>
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno"> /*背景透明度*/
opacity: 0.5;
filter: alpha(opacity=50);</pre>
 
 
 
 
<h2 class="md-end-block md-heading">5.盒子模型</h2>
<h3 class="md-end-block md-heading">1.什么是盒子？</h3>
<img alt="image-20200520153417967" data-local-refresh="true">
margin：外边距
padding：内边距
border：边框 
 
<h3 class="md-end-block md-heading">2.边框</h3>
<ol class="ol-list" start="">
<li class="md-list-item">
边框的粗细
</li>
<li class="md-list-item">
边框的样式
</li>
<li class="md-list-item">
边框的颜色
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno"><style>
/*body总有一个默认的外边距,所以我们通常将他们初始化为0px*/
body{
 margin: 0px;
 padding: 0px;
}
/*border:粗细，样式，颜色*/
#box{
 width: 300px;
 border:1px solid #11aebc ;
}
h2{
 font-size: 18px;
 color: white;
 line-height: 40px;
 background-color: #11aebc;
}
form{
 background-color: #29bcc9;
}
div:nth-of-type(1)>input{
 border: 2px solid #2AF598;
}
div:nth-of-type(2)>input{
 border: 2px dashed orange;
}
</style></pre>
 
</li>
</ol>
<h3 class="md-end-block md-heading">3.内、外边距</h3>
 
 margin: 0 auto; 居中
 要求：块元素，块元素有固定的宽度
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">/*
margin:全部
margin:上下左右
margin:上右下左

padding如上
*/
#box{
width: 300px;
border:1px solid #11aebc ;
margin: 0 auto;
}
h2{
margin: 0 0 0 0;
}
div:nth-of-type(1){
border: 1px solid yellow;
padding: 10px;
}</pre>
 
<h3 class="md-end-block md-heading">4.盒子的长宽计算方式</h3>
 margin+border+padding+内容宽度
 
<h3 class="md-end-block md-heading">5.圆角边框</h3>
 
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">


<style>
div{
 width: 100px;
 height: 100px;
 border: 1px solid #2AF598;
 border-radius: 100px 0px 0 0;
}
</style>css</pre>
<h3 class="md-end-block md-heading">6.阴影</h3>
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">
box-shadow: 0px 10px 10px red;</pre>
 
 
<h2 class="md-end-block md-heading">6. 浮动</h2>
<h3 class="md-end-block md-heading">1.标准文档流</h3>
 块级元素：独占一行
 h1~h6 p div 列表......
 行内元素：不独占一行
 span a img strong......
 行内元素可以被包含在块级元素中，反之则不可以。
<h3 class="md-end-block md-heading">2.display</h3>
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno"><!-—
 block:块元素
 inline:行内元素
 inline-block：是块元素，但是可以内联在一行！
 none：
-->
<style>
 div{
 width: 100px;
 height: 100px;
 border: 2px solid #11aebc;
 display: inline-block;
 }
 span{
 width: 100px;
 height: 100px;
 border: 2px solid #11aebc;
 display: inline;
 }
</style></pre>
 
<h3 class="md-end-block md-heading">3.float</h3>
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">/*左浮*/
float:left;</pre>
 
<h3 class="md-end-block md-heading">4.父级边框塌陷的问题</h3>
 
clear：
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">/*左侧不允许有浮动*/
clear:left;
/*左侧不允许有浮动*/
clear:right;
/*两侧都不允许有浮动*/
clear:both;
clear:none;</pre>
 
解决方案：
<ol class="ol-list" start="">
<li class="md-list-item">
增加父级元素的高度
</li>
<li class="md-list-item">
增加一个空的div清除浮动
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno"><div class="clear"></div>
<style>
.clear{
clear:both;
margin:0;
padding:0;
}
</style></pre>
</li>
<li class="md-list-item">
overflow
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">在父级元素中增加一个：overflow: hodden;</pre>
</li>
<li class="md-list-item">
在父类添加一个伪类：after 推荐使用
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno">#father:after{
content:'';
display:block;
clear:both;
}</pre>
 
</li>
<li class="md-list-item">
<img alt="image-20200521223243193" data-local-refresh="true">
</li>
</ol>
<h3 class="md-end-block md-heading">5.对比</h3>
<ul class="ul-list" data-mark="+">
<li class="md-list-item">
display
方向不可控制
</li>
<li class="md-list-item">
float
浮动起来会脱离标准文档流，所以要解决父级边框塌陷的问题~
</li>
</ul>
 
<h2 class="md-end-block md-heading">7.定位</h2>
<h3 class="md-end-block md-heading">1.相对定位</h3>
 相对定位position：relative
 相对于原来的位置，进行指定的偏移，相对定位的话，它仍然在标准文档流中！原来的位置会被保留。
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno"><!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>定位</title>

<style>
 body{
 padding: 50px;
 }
 div{
 margin: 10px;
 padding: 5px;
 font-size: 20px;
 line-height: 30px;
 }
 #father{
 border: 1px solid #11aebc;
 padding: 0;
 }
 #first{
 background-color: yellow;
 border: 1px dashed red;
 /*相对定位*/
 position: relative;
 top: -50px;
 left: 50px;
 }
 #second{
 background-color: cornflowerblue;
 border: 1px dashed black;
 }
 #third{
 background-color: aquamarine;
 border: 1px dashed orange;
 position: relative;
 bottom: 20px;
 }
</style>
</head>
<body>
<div id="father">
 <div id="first">第一个盒子</div>
 <div id="second">第二个盒子</div>
 <div id="third">第三个盒子</div>
</div>
</body>
</html></pre>
<img alt="image-20200521225850195" data-local-refresh="true">
<h3 class="md-end-block md-heading">2. 绝对定位</h3>
 定位：基于XXX定位，上下左右~
<ol class="ol-list" start="">
<li class="md-list-item">
没有父级元素定位的前提下，相对于浏览器边框定位
</li>
<li class="md-list-item">
假设父级元素存在定位，我们通常会相对于父级元素进行偏移
</li>
<li class="md-list-item">
在父级元素范围内移动
相对于父级或浏览器的位置，进行指定的偏移，绝对定位的话，它不在标准文档流中，原来的位置不会被保留。
</li>
</ol>
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno"> <!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>绝对定位</title>

 <style>
 body{
 padding: 50px;
 }
 div{
 margin: 10px;
 padding: 5px;
 font-size: 20px;
 line-height: 30px;
 }
 #father {
 border: 1px solid #11aebc;
 padding: 0;
 position: relative;
 }
 #father :after{
 content: '';
 display: block;
 clear:both;
 }
 #first{
 background-color: yellow;
 border: 1px dashed red;
 }
 #second{
 background-color: cornflowerblue;
 border: 1px dashed black;
 }
 #third{
 background-color: aquamarine;
 border: 1px dashed orange;
 position: absolute;
 right: 30px;
 }
 #fourth{
 background-color: red;
 border: 1px dashed orange;
 position: absolute;
 right: 10px;
 }
 #firth{
 color:white;
 background-color: black;
 border: 1px dashed orange;
 position: absolute;
 right: 60px;
 }
 </style>
</head>
<body>
<div id="father">
 <div id="first">第一个盒子</div>
 <div id="second">第二个盒子</div>
 <div id="third">
 第三个盒子
 <div id="fourth">第四个盒子</div>
 <div id="firth">第五个盒子</div>
 </div>
</div>
</body>
</body>
</html></pre>
 
<h3 class="md-end-block md-heading">3. 固定定位fixed</h3>
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno"><!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>固定定位</title>

<style>
 body{
 height: 1000px;
 }
 /*绝对定位相对于浏览器*/
 div:nth-of-type(1){
 width:100px;
 height: 100px;
 background-color: #2AF598;
 position:absolute ;
 right: 0;
 bottom: 0;
 }
 /*固定定位*/
 div:nth-of-type(2){
 width:50px;
 height: 50px;
 background-color: orange;
 position: fixed;
 right: 0;
 bottom: 0;
 }
</style>
</head>
<body>
<div>div1</div>
<div>div2</div>
</body>
</html></pre>
 
<h3 class="md-end-block md-heading">4. z-index</h3>
 图层
 z-index：默认是0，最高无限
<pre class="md-fences mock-cm md-end-block md-fences-with-lineno"><!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>z-index</title>

<style>
 #content{
 width: 200px;
 padding: 0;
 margin: 0;
 overflow: hidden;
 font-size: 12px;
 line-height: 20px;
 border: 2px solid #11aebc;
 }
 ul,li{
 padding: 0;
 margin: 0;
 list-style: none;
 }
 /*父级元素相对定位*/
 #content ul{
 position: relative;
 }
 .tipText,.tipBg{
 position: absolute;
 width: 380px;
 height: 25px;
 top: 125px;
 }
 .tipBg{
 background-color: black;
 /*背景透明度*/
 opacity: 0.5;
 filter: alpha(opacity=50);
 }
 .tipText{
 color: white;
 line-height: 25px;
 z-index: 16;
 }
</style>
</head>

<body>
<div id="content">
<ul>
 <li><img src="images/2B.jpg" alt="" width="200px" height="150px"></li>
 <li class="tipText">2B</li>
 <li class="tipBg"></li>
 <li class="time">时间：2099-01-01</li>
 <li class="address">地点：火星</li>
</ul>
</div>
</body>
</html></pre>
 
 
<h2 class="md-end-block md-heading">8. 动画</h2>
css3新特性
 
 
 
 
<h2 class="md-end-block md-heading">9. 总结</h2>
<code>待做</code> 
来源：https://www.cnblogs.com/supfit/p/12960444.html

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CSS学习笔记（基础）