To style category to colored box, like this.
You can use this code to Custom CSS.
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span.blog-item-category-wrapper a {
background-color: #f1f;
color: #fff !important;
padding: 5px 20px;
padding-bottom: 10px !important;
margin-right: 10px;
border-radius: 30px;
}
span.blog-item-category-wrapper:after {
display: none !important;
}
span.blog-item-category-wrapper {
margin-bottom: 10px;
display: inline-block;
}
If you want to use different color, use CSS code like this.
span.blog-item-category-wrapper a {
padding: 5px 20px;
padding-bottom: 10px !important;
margin-right: 10px;
border-radius: 30px;
}
span.blog-item-category-wrapper:after {
display: none !important;
}
span.blog-item-category-wrapper {
margin-bottom: 10px;
display: inline-block;
}
/* category: startup */
span.blog-item-category-wrapper a[href*="/category/Startup"] {
background-color: brown;
color: #fff;
}
/* category: ideas */
span.blog-item-category-wrapper a[href*="/category/Ideas"] {
background-color:green;
color: #fff;
}
/* category: London */
span.blog-item-category-wrapper a[href*="/category/London"] {
background-color:yellow;
color: #000;
}
Result
Remember to update Category URL + Color.