I believe there is no documentation for CSS as we can always use inspect element from our browser. Don't worry you will figure this out it's pretty straight forward. I am glad I was of some help. Have a nice day!

If you inspect your header the class navbar is getting margin-bottom:20px; from bootstrap.css:4153 if you want you can remove it or else you can write inline CSS in your_template\storefront\view\default\template\common\header.tpl  line:2 chagne it to <div class="headerstrip navbar navbar-inverse" role="navigation" style= "margin-bottom:0px;">

Hi, I am trying to add a functionality where I need to add a pop-up when they add a product to their cart. Right now on phone there is no way new customer would know that product is added to their cart other than CSS color change. I just need help with which file to start editing with. I am planning to show the cart module when they click on add to cart button showing this is your cart now with button to continue shopping or checkout.

Try $product_info['sku']

Hi I have been working with AbanteCart cart for a while now but I need some suggestion as we just started multi size options in our cart.

My question is I have a product ABC it is available in three size lets say size 1, 2 and 3
Q 1: As per my understanding from https://abantecart.atlassian.net/wiki/spaces/AD/pages/9568257/Manage+Products+Options I have to setup product ABC price with size 1 by default and then give them an option on product page where they can select size 2 and size 3.  is this correct?

Q 2: What if I want to promote product ABC with Size 3 can I directly pass something in URL so that they see final price instead of default price + price difference.

Q 3: Regarding inventory if I use size 1 as default for product ABC then if someone buys size 3 it wont be deducted from product page to view that I have to go to options and view the inventory count of size 2 and 3?

Q 4: Is there away to add custom field on checkout saying add Donation and if they enter $2.00 then we charge them at checkout. Even if there is extension do let me know.

I would really appreciate if someone can help me regarding this. 
AbanteCart Version 1.2.12

On this note. How do I handle 404 via htaccess and redirect them to home page
lets say they open example.com and some how they click example.com/page-not-available I want to redirect them to home page after lets say 3 seconds or so

Yes I know that this _number is generated for a duplicated SEO but what I am trying to say is sometimes user wont notice it and keep it as it is. The underscore and number in SEO is counted as bad link so instead of generating underscore and number you can generate dash and alphabets only for duplicate SEO links

No there is nothing that says _19 in keyword, infact its all letters no numbers. I also had similar issue with other sub-category and it showed _256 and that sub-category also had only letters. I think these numbers are randomly generated and if you can change _ to - that would solve the issue and instead of random numbers use 2 digit random letters like (AB) or (NW).
I am not an expert in this but just a suggestions as number in SEO are not that effective