I'm newbie and trying to make a E-commerce website using Xampp. I'm unable to get the items in content area in a ordered way (see images). What I want 
but I am getting 
.
The code for content area in index.php is:
<!--content area in pink color-->
<div id="content_area">
<div id="products_box">
<?php getPro(); ?>
</div>
</div>
getPro() function in functions.php is:
$con = mysqli_connect("localhost","root","","ecommerce");
//get the products
function getPro () {
global $con;
$get_pro = "select * from products order by RAND() LIMIT 0,6";
$run_pro = mysqli_query($con, $get_pro);
while($row_pro=mysqli_fetch_array($run_pro)){
$pro_id = $row_pro['product_id'];
$pro_cat = $row_pro['product_cat'];
$pro_brand = $row_pro['product_brand'];
$pro_title = $row_pro['product_title'];
$pro_price = $row_pro['product_price'];
$pro_image = $row_pro['product_image'];
echo "
<div id='single_product'>
<h3>$pro_title</h3>
<img src='admin_area/product_images/$pro_image' width='180' height='180' />
<p><b>₹ $pro_price</b></p>
</div>
";
}
}
CSS code in style.css is:
#products_box {
width:780px;
text-align:center;
margin-left:30px;
margin-bottom:10px;
}
#single_product{
float:left;
margin-left:20px;
padding:10px;
}
generated HTML is:
<!DOCTYPE>
<html>
<head>
<title>My online shop</title>
<link rel="stylesheet" href="styles/style.css" media="all" />
</head>
<body>
<!--Main Container starts here-->
<div class="main_wrapper">
<!--header starts here-->
<div class="header_wrapper">
<img id="logo" src="images/logo.gif" />
<img id="banner" src="images/ad_banner.gif" />
</div>
<!--header ends here-->
<!--Navigation bar starts here-->
<div class="menubar">
<ul id="menu">
<li><a href="#">Home</a></li>
<li><a href="#">All Products</a></li>
<li><a href="#">My Account</a></li>
<li><a href="#">Sign Up</a></li>
<li><a href="#">Shopping Cart</a></li>
<li><a href="#">Contact Us</a></li>
</ul>
<div id="form">
<form method="get" action="results.php" enctype="multipart/form-data">
<input type="text" name="user_query" placeholder="search a product" />
<input type="submit" name="search" value="search" />
</form>
</div>
</div>
<!--Navigation bar ends here-->
<!--Content wrapper starts here-->
<div class="content_wrapper">
<div id="sidebar">
<!--categories-->
<div id="sidebar_title">Categories</div>
<ul id="cats">
<li><a href='#'>Laptops</a></li><li><a href='#'>Cameras</a></li><li><a href='#'>Mobiles</a></li><li><a href='#'>Tablets</a></li><li><a href='#'>media players</a></li><li><a href='#'>Ebook readers</a></li><li><a href='#'>Graphic tablets</a></li>
</ul>
<!--Brands-->
<div id="sidebar_title">Brands</div>
<ul id="cats">
<li><a href='#'>HP</a></li><li><a href='#'>DELL</a></li><li><a href='#'>LG</a></li><li><a href='#'>Samsung</a></li><li><a href='#'>Apple</a></li><li><a href='#'>Motorola</a></li><li><a href='#'>Xiamoi</a></li><li><a href='#'>Huawei</a></li><li><a href='#'>Blackberry</a></li><li><a href='#'>HTC</a></li> </ul>
</div>
<!--content area in pink color-->
<div id="content_area">
<div id="products_box">
<div class='single_product'>
<h3>Moto G5 Plus (Lunar Grey, 32 GB)</h3>
<img src='admin_area/product_images/motorola-moto-g5-plus-1.jpg' width='180' height='180' />
<p><b>₹ 15999</b></p>
</div>
<div class='single_product'>
<h3>xiamoi redmi note 3</h3>
<img src='admin_area/product_images/Redmi-Note3-32GB-SDL881680011-2-1b99d.jpg' width='180' height='180' />
<p><b>₹ 9999</b></p>
</div>
<div class='single_product'>
<h3>Dell Vostro 15 3558 15.6-inch Laptop</h3>
<img src='admin_area/product_images/Dell Vostro 15 3558 15.6-inch Laptop.jpg' width='180' height='180' />
<p><b>₹ 28000</b></p>
</div>
<div class='single_product'>
<h3>Iphone 6 (32 GB)</h3>
<img src='admin_area/product_images/SP705-iphone_6-mul.png' width='180' height='180' />
<p><b>₹ 30000</b></p>
</div>
</div>
</div>
</div>
<!--Content wrapper ends here-->
<div id="footer">
<h2 style="text-align:center; padding-top:30px;">© 2017 by Technohub
</div>
</div>
<!--Main Container ends here-->
</body>
</html>
Please explain in detail as I'm a newbie
