please don't close it with "use jquery to close DIV " example. As I can only use HTML code on my page.

can anyone help me to find the code which close DIV (message box) when clicked outside. >> And these current 4 buttons are not aligned in the same line > is there any code to align the buttons in one line as well Thanks

.alert {
	display: none;
	padding: 20px;
	background-color: #f44336;
	color: white;
}

.closebtn {
	margin-left: 15px;
	color: white;
	font-weight: bold;
	float: right;
	font-size: 22px;
	line-height: 20px;
	cursor: pointer;
	transition: 0.3s;
}

<button onclick="document.getElementById('alert1').style.display='block'">Button1</button> <div id="alert1" class="alert"> <span class="closebtn" onclick="this.parentElement.style.display='none';">&times;</span>Message 1 </div><button onclick="document.getElementById('alert2').style.display='block'">Button2</button> <div id="alert2" class="alert"> <span class="closebtn" onclick="this.parentElement.style.display='none';">&times;</span>Message 2 </div><button onclick="document.getElementById('alert3').style.display='block'">Button3</button> <div id="alert3" class="alert"> <span class="closebtn" onclick="this.parentElement.style.display='none';">&times;</span>Message 3 </div><button onclick="document.getElementById('alert4').style.display='block'">Button4</button> <div id="alert4" class="alert"> <span class="closebtn" onclick="this.parentElement.style.display='none';">&times;</span>Message 4 </div>