Full Width, Latest Post

I want to make the theme full width, it seems to be by default boxed, what code do I need to add to change it to full width.
example

Also the latest posts is always a larger size than the rest (class=”article-container”). I want all posts to be uniformed so this highlight of sorts is annoying.
example

Thx in advance. Note I want to add all custom code to additional css so modifications aren’t lost in theme update.