How can I reposition the cart and resize the header on my ecommerce site?

[kristibajr]

I found the code for the cart in header.liquid :

{% include 'icon-cart' %} {{ 'layout.cart.title' | t }}

{{ cart.item_count }} {{ 'layout.cart.items_count' | t: count: cart.item_count }}

but I don’t know where is the css file to modify the placement and resize the header.