Changing CSS variables with JavaScript.

• CSS variables (actually CSS custom properties) can be used to assign values for later use in other properties.
• filter property applies various graphical effects like blur or contrast to an element.

• We used two new events. change which will be trigered when a value input changes and mousemove which trigers when you move the mouse on the element.
• data attributes can be accessed using the HTMLelement.dataset in javascript.
• We can change the variables that we have defined on the :root element with document.documentElement.style.setProperty()

• Using CSS custom properties (variables)
• filter
• change
• mousemove
• HTMLElement.dataset