1. 简书类

实现效果

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html代码

<div class="container">
<form action="" class="parent">
<input type="text" class="search" placeholder="搜索">
<input type="button" name="" id="" class="btn">
</form>
</div>

css代码

* {
margin: 0;
padding: 0;
}
.container {
height: 70px;
width: 800px;
margin: 100px auto 0 auto;
}
.parent {
position: relative;
}
.search {
width: 300px;
height: 40px;
border-radius: 18px;
outline: none;
border: 1px solid #ccc;
padding-left: 20px;
position: absolute;
}
.btn {
height: 35px;
width: 35px;
position: absolute;
background: url("images/topbar.png") no-repeat -2px -99px;
top: 6px;
left: 285px;
border: none;
outline: none;
cursor: pointer;
}

2. 百度类

实现效果

html代码

<div class="container">
<form action="" class="parent">
<input type="text">
<input type="button" value="百度一下">
</form>
</div>

css代码

.container {
width: 500px;
height: 50px;
margin: 100px auto;
}
.parent {
width: 100%;
height: 42px;
top: 4px;
position: relative;
}
.parent>input:first-of-type {
/*输入框高度设置为40px, border占据2px，总高度为42px*/
width: 380px;
height: 40px;
border: 1px solid #ccc;
font-size: 16px;
outline: none;
}
.parent>input:first-of-type:focus {
border: 1px solid #317ef3;
padding-left: 10px;
}
.parent>input:last-of-type {
/*button按钮border并不占据外围大小，设置高度42px*/
width: 100px;
height: 44px;
position: absolute;
background: #317ef3;
border: 1px solid #317ef3;
color: #fff;
font-size: 16px;
outline: none;
}

重点：

1.当input框foucus时，border颜色改变，而不是保留outline

2.button按钮默认box-sizing: border-box

.container {
width: 500px;
height: 50px;
margin: 100px auto;
}
.parent {
width: 100%;
height: 42px;
top: 4px;
position: relative;
}
.parent>input:first-of-type {
/*输入框高度设置为40px, border占据2px，总高度为42px*/ width: 380px;
height: 40px;
border: 1px solid #ccc;
font-size: 16px;
outline: none;
}
.parent>input:first-of-type:focus {
border: 1px solid #317ef3;
padding-left: 10px;
}
.parent>input:last-of-type {
/*button按钮border并不占据外围大小，设置高度42px*/ width: 100px;
height: 44px;
position: absolute;
background: #317ef3;
border: 1px solid #317ef3;
color: #fff;
font-size: 16px;
outline: none;
}