how to increase the with of add to cart button in liquid theme

[flex1234]

url:- https://0c56dd-3.myshopify.com

[SomeUsernameHe]

You would use the following CSS to adjust the width: 

form[class*="shopify-product"]>div.product_payments_btns {
    max-width: 400px;
}

Just adjust the `400` number to 100% or a number you see fit. 

[flex1234]

pls also guide to these code what there was place step by step because i am new

[SomeUsernameHe]

I would first check your Theme Customize > Theme Settings for something called "Custom CSS" and try placing it there. 

If not, you will have to edit your theme files and place it at the bottom of base.css/main.css file or right before the closing </head> tag of your theme.liquid file. 

[flex1234]

nothing will work sir please can you solve that problem 

store url ;- https://0c56dd-3.myshopify.com/

[SomeUsernameHe · Accepted solution]

form[class*="shopify-product"]>div.product_payments_btns {
    max-width: 100% !important;
}

Try this code with `!important`

[flex1234]

no work sir 

if you have no problem so can you share your gmail i will add you in my staff acount and you help me to edit code