Hi,
Your new Joomla template has custom CSS in order to display the tabs like this.
It is made by the CSS code:
#hikashop_tabs_div > div, #hikashop_tabs_div #hikashop_comment_form {
margin-left: 250px;
}
#hikashop_tabs_div .hikashop_tabs_content {
border: none;
}
.hikashop_tabs_ul {
margin: 0;
float: left;
width: 220px;
}
.hikashop_tabs_ul li {
border: none;
display: block;
background: none;
padding: 15px 0px;
font-weight: normal;
transition: all 200ms ease-in;
}
.hikashop_tabs_ul li.hikashop_tabs_li_selected {
color: #f7335d;
padding: 15px 10px 15px 20px;
background: #f1f1f1 !important;
border-left: 3px solid #f7335d;
}
.hikashop_tabs_ul li:not(:last-child) {
border-bottom: 1px solid #f1f1f1;
}
in the file /media/templates/site/tp_shop/css/compiled-3d9f8f2f899cf8fcfd38aeb2b2713ad5.css from what I can see with the inspector tool of my browser. However, this is a CSS file compiled by your template. I don't think it's a good idea to just delete the CSS code in there. Because when the template recompile its CSS, it will probably be back.
I would recommend contacting your template provider in order to ask them what they recommend you do.