@Blog

let btn1 = function (e) {
	//btn2
	console.clear();
	console.log("btn1");
	let p = document.getElementsByTagName("p");
	let style1 = [["backgroundColor", "fontSize", "color"], ["#000000", "20px", "#ffffff"]];
	for (const key in p) {
		if (p.hasOwnProperty(key)) {
			const element = p[key];
			for (var i = 0; i < style1[0].length; i++) {
				element.style[style1[0][i]] = style1[1][i];
			}
		}
	}
};
let btn2 = function (e) {
	//btn2
	console.clear();
	console.log("btn2");
	let p = document.getElementsByTagName("p");
	let style2 = {
		backgroundColor: "#ffffff",
		fontSize: "20px",
		color: "#000000"
	};
	for (const key in p) {
		if (p.hasOwnProperty(key)) {
			const element = p[key];
			for (const key2 in style2) {
				element.style[key2] = style2[key2];
			}
		}
	}
};
document.body.style.backgroundColor = "#0b222b";
document.getElementById("btn1").addEventListener("click",btn1);
document.getElementById("btn2").addEventListener("click",btn2);