Characteristics Selection Radio Button

Hello,

I'm afraid that only Css won't be enough to be able to add style on label from your input condition.
I detail my idea through this pseudo code :

<label class="parent">
    <input class="child" checked="checked">

Hello,

Through an override view, yes it's possible to add a class, but you want add class dynamically :

<label class="parent parentChecked">
    <input class="child" checked="checked">

<label class="parent">
    <input class="child" checked="checked">

label.parentChecked {
     background-color: blue;
}

Hello,

In order to better understand the context, and mostly better answer you can you provide an Url in order to see the page.
And little tips, you have a specific option to guide you to find HikaShop View , from Main HikaShop Configuration and go to Advanced tab, then first part "Advanced settings", active your "Display view files" option on "Front"

Hello,

We will need more elements to better understand what do you mean by "I'm stuck again because code there is to complex for me".
In order to be clear, the HikaShop team can guide you but we have to understand where is your current issue.

From what we know, you have now to add some javascript (and not necessarily in the "sub-view" show_block_characteristic) in the main show_default page, you can add through <script></script> a code that will add & remove a class link to some css.

Here is for the method, but awaiting more elements from you to better guide you.
Regards