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HTML 

              
                <header>
	Form Input Label Style<br />
	<a href="https://muki.tw/tech/html-css/css-form-input-label-style" target="_blank">(https://muki.tw/tech/html-css/css-form-input-label-style)</a>
</header>

<section>
	<div class="mb-4">預設 input 樣式：</div>
	<div class="flex w-[30rem] flex-col">
		<div class="relative mb-5">
				<input type="text" class="w-full form--item" placeholder=" " />
				<label class="label">登入帳號</label>
		</div>
		<div class="relative mb-5">
				<input type="password" class="w-full form--item" placeholder=" " />
				<label class="label">登入密碼</label>
		</div>
	</div>
	
	<div class="mb-4">自動帶入帳密時：</div>
	<div class="flex w-[30rem] flex-col">
		<div class="relative mb-5">
				<input type="text" class="w-full form--item" placeholder=" " value="mmm@gmail.com" />
				<label class="label">登入帳號</label>
		</div>
		<div class="relative mb-5">
				<input type="password" class="w-full form--item" placeholder=" " value="12345" />
				<label class="label">登入密碼</label>
		</div>
	</div>
		
	<div class="mb-4">textarea：</div>
	<div class="flex w-[30rem] flex-col">
		<div class="relative mb-5">
    <textarea class="w-full form--item" placeholder=" " rows="5"></textarea>
    <label class="label">備註</label>
  </div>
	</div>
</section>
!

CSS 

              
                @import "compass/css3";

/**
Form Input Label Style
Autohr: Muki Wu
Article: https://muki.tw/tech/html-css/css-form-input-label-style
**/

/* demo code start */

.label {
	position: absolute;
	left: 1rem;
	top: 20px;
	transition: all .2s ease;
}

.form--item {
	background: rgb(38, 38, 38);
	padding: 1.75rem 1rem .75rem;
	&:focus {
		background: rgb(64, 64, 64);
		border-bottom: 2px solid #D9444A;
		outline-width: 0;
	}
}

input:focus + label, input:not(:placeholder-shown) + label,
textarea:focus + label, textarea:not(:placeholder-shown) + label {
	top: 5px;
	font-size: 13px;
	color: #D9444A;
}

input:-webkit-autofill,
input:-webkit-autofill:hover, 
input:-webkit-autofill:focus,
textarea:-webkit-autofill,
textarea:-webkit-autofill:hover,
textarea:-webkit-autofill:focus {
  -webkit-text-fill-color: rgb(163, 163, 163);
  -webkit-box-shadow: 0 0 0px 500px #262626 inset;
  transition: background-color 5000s ease-in-out 0s;
}

/* basic layout start (you can skip it) */

body {
	font-family: arial, sans-serif;
	background: #333;
	font-size: 16px;
	color: #f0f0f0;
	line-height: 1.1em;
}

a {
	text-decoration: none;
	color: #313131;
	&:hover {
		color: #000;
	}
}
section {
	max-width: 500px;
	margin: 0 auto;
	background: #555;
	padding: 1em;
}
header {
	background: #d9444a;
	text-align: center;
	color: #fff;
	padding: 0.7em 0;
	a {
		color: rgba(255, 255, 255, 0.6);
		@include text-shadow(1px 1px 1px #973735);
	}
	&:after {
		content: " ";
		position: absolute;
		width: 0;
		height: 0;
		border-width: 10px;
		border-style: solid;
		border-color: #d9444a transparent transparent transparent;
		top: 53px;
		left: 50%;
	}
}

h2 {
	font-size: 1em;
	margin: 0 0 0.5em 0;
	background: #444;
	display: inline-block;
	padding: 0.5em 1.2em;
	position: relative;
	left: -1em;
}
!

JS
!
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