Answer by Saurav Rastogi for Removing margin from flex items when they wrap

* {
	margin: 0;
	padding: 0;
}

html, body {
 box-sizing: border-box;
}

.container {
	width: 600px;
	margin: 0 auto;
	margin-top: 25px;
	border: 1px solid;
	padding: 5px;
}

.tags {
	list-style-type: none;
	display: flex;
	flex-direction: row;
	flex-wrap: wrap;
	justify-content: flex-start;
  padding: 5px 0 0;
}

.tag {
	padding: 5px;
	background-color: #76FF03;
	margin: 0 5px 5px;
}

<div class="container">
  <ul class="tags">
    <li class="tag item-1">Tag Item 1</li>
    <li class="tag item-2">Tag Item 2</li>
    <li class="tag item-3">Tag Item 3</li>
    <li class="tag item-4">Tag Item 4</li>
    <li class="tag item-5">Tag Item 5</li>
    <li class="tag item-6">Tag Item 6</li>
    <li class="tag item-7">Tag Item 7</li>
    <li class="tag item-8">Tag Item 8</li>
    <li class="tag item-9">Tag Item 9</li>
    <li class="tag item-10">Tag Item 10</li>
    <li class="tag item-11">Tag Item 11</li>
    <li class="tag item-12">Tag Item 12</li>
    <li class="tag item-13">Tag Item 13</li>
    <li class="tag item-14">Tag Item 14</li>
    <li class="tag item-15">Tag Item 15</li>
    <li class="tag item-16">Tag Item 16</li>
  </ul>
</div>