This issue occurs if you create a kustom page or if you create your own theme. I found the people experiencing the same issue here and here. CSS WooCommerce but the problem can be solved easily.
Add Class woocommerce
Solved, WooCommerce CSS not working by adding class ‘woocommerce’ inside <body> tag. I get it from github users Manovotnni , you can read more details here. Now open the header file in your theme and find the <body> change to
<body <?php body_class( 'woocommerce' ); ?>>
This method works well for each kustom page.