styles.css

html {
	font-size: 62.5%;
	box-sizing: border-box;
}

*,
*::before,
*::after {
	margin: 0;
	padding: 0;
	box-sizing: inherit;
}

body {
	font-size: 4rem;
	text-align: center;
	font-family: monospace;
	height: auto;
	width: auto;
}

input {
	width: 35%;
	height: 50px;
	background-color: lightgray;
	border: none;
	font-size: 2rem;
	text-align: center;
}

button {
	width: 15%;
	height: 50px;
	background-color: rgb(182, 195, 207);
	color: black;
	border: none;
	font-size: 1.75rem;
}

button:hover {
	background-color: black;
	cursor: pointer;
	color: rgb(182, 195, 207);
}
h1 {
	margin: 50px 0 50px 0;
}

h2 {
	margin: 50px 0 50px 0;
}

h3 {
	margin: 50px 0 50px 0;
}

h4 {
	height: 5rem;
	width: 50%;
	border: 2px black solid;
	border-radius: 15px;
	margin: 0 25% 0 25%;
	background-color: #b7bcc2;
	color: rgb(34, 36, 42);
	padding: 0.5rem;
}

.paragraph {
	font-size: 5rem;
	border: 2px solid black;
	border-radius: 15px;
	width: 60%;
	margin-bottom: 50px;
	background-color: rgb(110, 71, 71);
	color: rgb(255, 255, 255);
	padding: 18px;
}

.background--custom {
	background: linear-gradient(90deg, #6785a7, #64dffd, #abae32);
	background-size: 300% 300%;
	animation: gradient 4s alternate infinite;
	position: absolute;
	top: 0;
	left: 0;
	height: 100%;
	width: 100%;
}
@keyframes gradient {
	0% {
		background-position: 0%;
	}
	100% {
		background-position: 100%;
	}
}