Codepens.io: A Website that Showcases Savvy Web Designers' Innovative Products.

Various web designers with experience in the more creative technical applications of HTML, CSS, and JavaScript syntax regularly post projects on the website codepen.io in order to show their fellow designers how complex interactive and animated effects can be achieved by blending the three forms of syntax. These project demonstration pages allow viewers to observe and interact with effects that are rendered natively by the web browser programs themselves rather than provided by externally loaded files that were originally created in a dedicated web animation program. Visitors can see all of the syntax being used to produce the effect by clicking the "Change View" button and choosing the "Editor View" option, and visitors are free to make temporary changes to the syntax itself to see how the dynamically generated result would be affected as such.
An interactive designer named Chris Gannon has created a fairly complex take on a function resembling a slider that stretches between the numbers 1 and 12. If the left mouse button is held down while the cursor is on any part of the rectangular stretch of space that the slider occupies, dragging the mouse in either horizontal direction will shift a white-colored "progress line" through the thin bar above the numbers accordingly. As the right end of the progress line horizontally approaches the vertical axis of a number to its right, the number steadily brightens while a square located above that respective number increases in size and fills up with a previously assigned color.
In many codepen.io projects, there is often much less syntax in the HTML file taking part in the effect than in the accompanying CSS and JavaScript files because the HTML portion primarily exists to function as the "stage" for the creative effects built within the other two types of files to be displayed on. This project, however, is an example where the brunt of the path and shape data lies within the HTML segment, and the CSS is only used to define the background color and how wide the browser window can be before the slider starts shrinking in scale. For more information click here https://codepen.io/chrisgannon/full/djjZBq/.