How can I change the width of main column in 2 column layout in Magento 2

Question

I want to have a 2 column layout and I want to add some margin on the left to the main column and reduce it's width. And I want this feature only on selected pages so I made a custom layout for that, please help me to achieve this goal.

Answer 1

You can add this style in your custom css file.

.page-layout-2columns-left .column.main{width:80%;}

Answer 2

Simply edit your CSS file in skin>frontend>YourTheme>YourTheme>css>styles.css

Every page has its own unique class so in CSS you can style only specific pages by writing style like:

.category-myProducts .class-name-of-my-column
{
   width:400px;
}