Print a PNG icon instead of field label I needed to print a png icon instead of field label in views, so i'm posting this question and it's propper detail answer as well, in my case i need to print whatsapp icon  as a label in a field in views, this answer is based on this post, this question is flaged as closed being off-topic, but I think it may be usefull to others. this is working in D7, it may work on D8.
First, you need a png image (my case 17x17 px whatsapp.png), place it under sub-theme/images folder, then, place this css under sub-theme/css/custom.css file

.whatsappwrapper {background-
 image:url("../images/whatsapp.png");background-repeat:no-repeat;}
.whatsapplabel {display: none;}
.whatsappnumber {margin-left: 20px;}


then, set your views field styles as shown in picture
first part of image is the result of this settings. note: telephone icon is a html symbol.