Using CSS and Javascript I made a small landing page that have mainly a button that do switch between dark and light mode:

• Use function for replace dark images with light images;
• Use querySelector to search for 'input' in HTML insead of using getElementById;
• Use localStorage to set a key and value to check later for the theme launch;
• Use scroll-behavior in CSS to actually scroll smooth the nav buttons;
• Use variables in CSS to easily change between dark and light colors using Javascript;
• Use replace from classList to replace icons near switch button;