@LuiMai91
In your product-variants.tpl file, copy my "Span" section from here
{elseif $group.group_type == 'radio'} <ul id="group_{$id_attribute_group}"> {foreach from=$group.attributes key=id_attribute item=group_attribute} <li class="input-container float-xs-left" {if {$group.attributes_quantity[{$id_attribute|intval}]} < 1}style="pointer-events:none;"{/if}> <label> <input class="input-radio" type="radio" data-product-attribute="{$id_attribute_group}" name="group[{$id_attribute_group}]" value="{$id_attribute}" title="{$group_attribute.name}"{if $group_attribute.selected} checked="checked"{/if}> <span class="radio-label" {if {$group.attributes_quantity[{$id_attribute|intval}]} < 1}style="color:red;"><strike>{$group_attribute.name}</strike>{else}"> {$group_attribute.name}{/if}</span> </label> </li> {/foreach} </ul> {/if}