For the mobile phone dialing keyboard that we are all familiar with, today we will explain the interactive effect:

When hovered or pressed, the background color of the keys of the keyboard changes;

When pressing number button, the corresponding number will be input, and the "Add Number" text and "Backspace" button will be shown at the same time;

When the "Backspace" button is clicked, the last digit of the number will be deleted; when all the digits are deleted, the "Add Number" button and the "Delete" button are hidden.