Hello Phạm,

Usually such issues are caused by:

• custom CSS that overrides the default styles of the components
• styles that come from the containers where the components are nested, e.g., a div container element styled with and old Bootstrap version
• incorrectly loaded kendo theme

Please post:

1. The content of the application's _Layout.cshtml file, so we can check whether the required files are properly loaded. If the js and CSS files are loaded though bundles, post the content of the BundleConfig.cs file as well

2. The content of one of the views shown on the screenshots, on which you see a component that appears smaller than usual

Regards,
Ivan Danchev
Progress Telerik