Theme switcher: dark mode, light mode

Reference

• https://www.youtube.com/watch?v=smnxWspZMNY
• https://github.com/divanov11/Appwrite-React-quickstart

Concept

/* ./css/styles.css*/
[data-theme= "purple"]

const setTheme = () => {
    document.querySelector('body').setAttribute('data-theme'), theme)
}