style.css

* {
	outline: 0;
	font-family: Roboto, Verdana, sans-serif;
	font-weight: 300;
	transition: all .08s ease-in;
}

form {
	width: 100%;
	max-width: 500px;
	background-color: #eee;
	margin: 3rem auto 0;
	padding: 15px 40px;
	box-sizing: border-box;
}

abbr {
	text-decoration: none;
}

legend {
	font-weight: bold;
    font-size: 1.5rem;
    margin-left: -0.15em;
}

fieldset,
input {
	border: none;
}

fieldset {
	padding: 0;
	margin: 0;
}

legend,
label,
input {
	display: block;
}

div {
	position: relative;
	font-size: 1.5rem;
	padding: 1em 0 1.5em;
}

input {
	background-color: transparent;
	font-size: 1em;
	line-height: 1.6;
	padding: 0;
	-webkit-box-shadow: 0 1px rgba(0,0,0,.5);
	box-shadow: 0 1px rgba(0,0,0,.5);
	width: 100%;
	height: 2.5rem;
}

input:hover {
	-webkit-box-shadow: 0 3px rgba(0,0,0,.5); 
	box-shadow: 0 3px rgba(0,0,0,.5); 
}

input:focus,
input:active {
	-webkit-box-shadow: 0 3px cornflowerblue;
	box-shadow: 0 3px cornflowerblue;
}

input.validated:invalid {
	-webkit-box-shadow: 0 3px coral;
	box-shadow: 0 3px coral;
}

input + label[for] {
	position: absolute;
	font-size: .5em;
	font-weight: bold;
	top: .5em;
	color: #333;
	width: 100%;
}

input + label[for]:after {
	content: attr(data-error-message);
	display: block;
	position: absolute;
	font-size: 1em;
	font-weight: bold;
	color: coral;
	top: 4.2rem;
	background-color: #eee;
	width: 100%;
}

input:placeholder-shown + label[for] {
	color: transparent;
}

input:focus + label[for] {
	color: #333;
}

input:focus::-webkit-input-placeholder {
	color: transparent;
}

button {
	border: none;
	border-radius: 0;
	padding: .8em 1em;
	font-size: 1em;
	font-weight: bold;
	background-color: cornflowerblue;
	color: white;
	width: 100%;
	margin-bottom: 1em;
}

button:hover {
	background-color: dodgerblue;
}

button:focus,
button:active {
	background-color: royalblue;
}