定位登录页面/flex布局

定位

• position:relative; 相对定位
• position:absolute;绝对定位
• position:fixed;固定定位

登录页面

<style>
*{
    padding:0;
    margin:0;
    box-sizing:border-box;
}
.container{
    width:100vw;
    height:100vh;
    background-color: #1E9FFF;
    position: relative;
}
.container .login{
    width: 30rem;
    height: 30rem;
    position: absolute;
    top: 50%;
    left: 0;
    right: 0;
    margin: 0 auto;
    margin-top: -15rem;
    background-color: #fff;
    border: 1px solid #fff;
    border-radius: 3px;
    box-shadow: 0 0 8px #eeeeee;
    padding: 1.5rem;
}
.container .login .login-title h1{
    color: #1E9FFF;
    font-size: 2.5rem;
    font-weight: bold;
    text-align: center;
    margin-bottom:1.5rem;
}
.container .login .form {
    position: relative;
    margin-bottom:1.5rem;
}
.container .login .form label {
    margin-bottom: 1.5rem;
    clear: both;
    position: absolute;
    left: 1px;
    top: 1px;
    width: 4rem;
    line-height: 4rem;
    text-align: center;
    color: #d2d2d2;
}
.container .login .form input {
    padding-left: 4rem;
    display: block;
    width: 100%;
    height: 4rem;
    line-height: 4rem;
    background-color: #fff;
    border-radius: 2px;
    border:1px solid #ccc;
}
.container .login .form input:focus{
    outline: 0px;
    box-shadow: 0 0 10px #1e9fff;
}
.container .login .form img{
    background-color: bisque;
    position: absolute;
    right: 0px;
    top: 0px;
    width: 10rem;
    height: 4rem;
}
.container .login .form .btn{
    display: block;
    height: 4rem;
    line-height: 4rem;
    border: 0px;
    background-color: #1E9FFF;
    color: #fff;
    text-align: center;
    font-size: 1.4rem;
    border-radius: 2px;
    cursor: pointer;
    width: 100%;
}
</style>
<div class="container" >
    <div></div>
    <div class="login" >
        <div class="login-title" ><h1>登录</h1></div>
        <form action="">
            <div class="form">
                <label class="iconfont icon-yonghu" for="username"></label>
                <input type="text" name="username" placeholder="用户名" value="">
            </div>
            <div class="form">
                <label class="iconfont icon-mima" for="password"></label>
                <input type="text" name="password" placeholder="密码" value="">
            </div>
            <div class="form">
                <label class="iconfont icon-mima" for="code"></label>
                <input type="text" name="code" placeholder="验证码" value="">
                <img src="" alt="">
            </div>
            <div class="form">
                <button class="btn">登 入</button>
            </div>
        </form>
    </div>
</div>

媒体查询

移动优先

div {
    background-color:red;
}
@media only screen and (min-width: 768px) {
    div {
        background-color:slateblue;
    }
}
@media only screen and (min-width:768px) and (max-width:992px) {
    div {
        background-color:greenyellow;
    }
}
@media only screen and (min-width:992px) and (max-width:1200px) {
    div {
        background-color:wheat;
    }
}

PC优先

div {
    background-color:red;
}
@media only screen and (min-width:992px) and (max-width: 1200px) {
    div {
        background-color:wheat;
    }
}
@media only screen and (min-width:768px) and (max-width: 992px) {
    div {
        background-color:greenyellow;
    }
}
@media only screen and (max-width: 768px) {
    div {
        background-color:slateblue;
    }
}

flex布局

父级设置

设置flex属性

• display:flex;
• display:inline-flex;

设置排列方式[ row横排列 | column纵排列 ]

• flex-direction:row|column;

设置换行[ wrap允许换行 | nowrap不允许换行 ]

• flex-wrap:wrap;

上面两个简写

• flex-flow:row nowrap;

主轴分配剩余空间(align-content与justify-content的简写形式 | 第一个值align-content | 第二个值justify-content)

[ 左 | 右 | 中 | 两边对齐 | 分散对齐(中间是两倍) | 平均对齐]

• place-content:start|end|center|space-between|space-around|space-evenly;

交叉轴分配剩余空间(align-items与justify-items的简写形式 | 第一个值align-items | 第二个值justify-items)

[ 上 | 下 | 中 | 子元素等高]

• place-items:start|end|center|stretch;

子级设置

flex:放大 收缩 计算宽度; 放大 1开启 0禁止 收缩 1开启 0禁止

计算宽度auto自动 计算方式 : max-width/min-width > 计算宽度 > width

• flex:1; = flex:1 1 auto;
• flex:initial; 默认

排序[ 谁小谁前面 ]

• order:0;

案例

div{
  display: flex;
  flex:1;
  width: 100px;height: 100px;
}
/* 平均对齐 */
.d1{
  background-color: tomato;
  place-content: space-evenly;
  place-items: center;
}
/* 分散对齐 */
.d2{
  background-color: rebeccapurple;
  place-content: space-around;
  place-items: center;
}
/* 两边对齐 */
.d3{
  background-color: goldenrod;
  place-content: space-between;
  place-items: center;
}
<div class="d1">
    <span>1</span>
    <span>2</span>
    <span>3</span>
</div>
<div class="d2">
    <span>1</span>
    <span>2</span>
    <span>3</span>
</div>
<div class="d3">
    <span>1</span>
    <span>2</span>
    <span>3</span>
</div>