I made it within 3 hours Alhamdulillah :)

Goodjob so far,

there were some missing things, you need to lookup for it to make it fully functionally.

UI:

• Use the correct colors for keypad at first theme
• Allow user to switch them upon click as the use would not figure out the drag function
• use user-select:none at you're CSS to disable text selection

Functions:

• Restrict double dotted . numbers, so the number can only get 1 decimal dot to avoid NaN results
• Fix . key to insert decimal dot into the text as it's only allowed using keyboard
• Set default value to 0 and make it shown into the calc screen
• Allow using math functions with the result of the current process, so you can use +,-,* and / with the current result instead of getting result only by =

that's all what i got for now, goodluck and enjoy your codes.