Add dark mode

[nidhi752]

Hi, I observed that the website currently does not have a dark mode, which can be a valuable feature for enhancing user experience. Dark mode helps in reducing eye strain, especially in low-light environments or during nighttime browsing. It also contributes to better visibility and overall comfort for users who prefer a darker interface. I would like to implement this feature to ensure that the website is more accessible and user-friendly, catering to different preferences and improving the overall usability.
Please assign this issue to me under hackoctoberfest'24