why in spa page component css width is given with 1024 px and not full width of the browser

@ravir73578276,

With a sensible guess, this is probably because of the page that is being edited is using a template (which may be referencing to basepage.html), which may contain a container wrapper CSS style rule; this style rule will constrict the maximum width of anything within the parsys (drag and dropable area). If you want 100% width, you may need to extend your project's basepage.html, and remove the additional CSS style rules. Or you can simply directly clean up the basepage.html.