const body = document.getElementsByTagName('body')[0];
body.style.backgroundColor = 'black';

let yellowlogo = document.getElementsByClassName('logo')[0];
yellowlogo.style.bottom = '30px';

window.onscroll = function (event) {
	const scroll = window.pageYOffset;

	if (scroll < 750) {
		body.style.backgroundColor = 'black';
	} else {
		body.style.backgroundColor = 'white';
	}

	if (scroll < 200) {
		yellowlogo.style.bottom = '30px';
	} else {
		yellowlogo.style.bottom = '-50px';
	}
};