<div class="container">
	<svg width="100" height="100" class="eye">
		<circle cx="50" cy="50" r="50" fill="white" class="eyeball_left" />
		<circle cx="50" cy="50" r="20" fill="#0D0D20" class="pupil_left" />
	</svg>
	<svg width="100" height="100" class="eye">
		<circle cx="50" cy="50" r="50" fill="white" class="eyeball_right" />
		<circle cx="50" cy="50" r="20" fill="#0D0D20" class="pupil_right" />
	</svg>
</div>

body {
	margin: 0;
	padding: 0;
	background: #282631;
	display: flex;
	width: 100%;
	height: 100vh;
}
.container {
	margin: auto;
	position: relative;
}
.container:after {
	content: "";
	width: 5em;
	height: 5px;
	display: block;
	position: relative;
	background: red;
	top: 5em;
	margin: auto;
}
.image {
	position: absolute;
	top: 250px;
	left: 620px;
	z-index: -1;
}
.pupil_left {
	position: relative;
}
.pupil_right {
	position: relative;
}

let eyeball_left = document.querySelector(".eyeball_left"),
	pupil_left = document.querySelector(".pupil_left"),
	eyeArea_left = eyeball_left.getBoundingClientRect(),
	pupil_leftArea = pupil_left.getBoundingClientRect(),
	R_left = eyeArea_left.width / 2,
	r_left = pupil_leftArea.width / 2,
	centerX_left = eyeArea_left.left + R_left,
	centerY_left = eyeArea_left.top + R_left;

let eyeball_right = document.querySelector(".eyeball_right"),
	pupil_right = document.querySelector(".pupil_right"),
	eyeArea_right = eyeball_right.getBoundingClientRect(),
	pupil_rightArea = pupil_right.getBoundingClientRect(),
	R_right = eyeArea_right.width / 2,
	r_right = pupil_rightArea.width / 2,
	centerX_right = eyeArea_right.left + R_right,
	centerY_right = eyeArea_right.top + R_right;

document.addEventListener("mousemove", (e) => {
	let x_left = e.clientX - centerX_left,
		y_left = e.clientY - centerY_left,
		theta_left = Math.atan2(y_left, x_left),
		angle_left = (theta_left * 180) / Math.PI + 360;

	let x_right = e.clientX - centerX_right,
		y_right = e.clientY - centerY_right,
		theta_right = Math.atan2(y_right, x_right),
		angle_right = (theta_right * 180) / Math.PI + 360;

	pupil_left.style.transform = `translateX(${R_left - r_left + "px"}) rotate(${
		angle_left + "deg"
	})`;
	pupil_left.style.transformOrigin = `${r_left + "px"} center`;

	pupil_right.style.transform = `translateX(${
		R_right - r_right + "px"
	}) rotate(${angle_right + "deg"})`;
	pupil_right.style.transformOrigin = `${r_right + "px"} center`;
});