效果預覽
![在這裏插入圖片描述]()
HTML
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<link rel="stylesheet" href="style.css">
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.4.1/jquery.min.js" charset="utf-8"></script>
</head>
<body>
<form action="index.html" class="login-form">
<h1>Log In</h1>
<div class="txtb">
<input type="text">
<span data-placeholder="Username"></span>
</div>
<div class="txtb">
<input type="password">
<span data-placeholder="Password"></span>
</div>
<input type="submit" class="logbtn" value="Log In">
<div class="bottom-text">
Don't have account? <a href="#">Sign up</a>
</div>
</form>
<script type="text/javascript">
$(".txtb input").on("focus", function(){
$(this).addClass("focus");
});
$(".txtb input").on("blur", function(){
if($(this).val() == "")
$(this).removeClass("focus");
});
</script>
</body>
</html>
CSS
*{
margin: 0;
padding: 0;
text-decoration: none;
font-family: montserrat;
box-sizing: border-box;
}
body{
min-height: 100vh;
background-image: linear-gradient(120deg, #3498db, #8e44ad);
}
.login-form{
width: 360px;
background: #f1f1f1;
height: 580px;
padding: 80px 40px;
border-radius: 10px;
position: absolute;
left: 50%;
top: 50%;
transform: translate(-50%, -50%);
}
.login-form h1{
text-align: center;
margin-bottom: 60px;
}
.txtb{
border-bottom: 2px solid #adadad;
position: relative;
margin: 30px 0;
}
.txtb input{
font-size: 15px;
color: #333;
border: none;
width: 100%;
outline: none;
background: none;
padding: 0 5px;
height: 40px;
}
.txtb span::before{
content: attr(data-placeholder);
position: absolute;
top: 50%;
left: 5px;
color: #adadad;
transform: translateY(-50%);
z-index: -1;
transition: .5s;
}
.txtb span::after{
content: '';
position: absolute;
left: 0%;
top: 100%;
width: 0%;
height: 2px;
background: linear-gradient(120deg, #3498db, #8e44ad);
transition: .5s;
}
.focus + span::before{
top: -5px;
}
.focus + span::after{
width: 100%;
}
.logbtn{
display: block;
width: 100%;
height: 50px;
border: none;
background: linear-gradient(120deg, #3498db, #8e44ad, #3498db);
background-size: 200%;
color: #fff;
outline: none;
cursor: pointer;
transition: .5s;
}
.logbtn:hover{
background-position: right;
}
.bottom-text{
margin-top: 60px;
text-align: center;
font-size: 13px;
}
