Wikipedia Viewer Feedback please

Dear Campers, I have finished the Wikipedia viewer. just few things would like to ask. 1) when use small screen i.e iphone 4, the search box got small (shrink ), but if put in landscape it will be able see the textbox to search. how can I make it full width on the small screen. 2) the X button is outside the textbox, how can i position it inside the textbox without using the position in css if it is possible. i use bootstrap v4. Your feedback is much appreciated.
thank you for your time