fix 24: updated button,field, set half page fixed

[bhanu2004]

fixes #24

1. updated the styling of input fields for dark mode
2. updated the button
3. made the right side of page fixed, scrollable and set height to full screen

[AnkitGurwan]

@bhanu2004 When we are opening preview, we are getting three scrolls, kindly make it two (similar to code). Also, if possible, make the navbar fixed. Do let me know if you face any issue.

[bhanu2004]

@AnkitGurwan i have fixed the three scroll issue also made navbar fixed and modified the height of right side since some of the content wasn't visible

[AnkitGurwan]

Thanks for contributing!!