Streamlines of a vector field from point sources, sinks and vortices, drawn on slowly and then held.

Made as a Kadal Deck premium background, it fills whatever box you give it at its real size, in light and dark, and follows your brand colour (the --deck-accent CSS variable). Settings: poles (the poles, "x y q" separated by semicolons: x and y as fractions of the slide, q the charge, positive a source, negative a sink), density (lines per unit of charge), swirl (turns each pole into a vortex too: the lines spiral, negative: the other way), color (the lines' colour), arrows (an arrowhead on each line, showing the field's direction), animate (draw the lines on when the slide arrives, else they are simply there) and flow (send dashes along the lines at this speed; 0 holds them still once drawn). The animation pauses off screen and in background tabs, and holds still for visitors who ask for reduced motion.

What you get: a web component, one script with no framework, for a plain page, Webflow, WordPress or Framer, drawing behind your own content. A React component. Stills at 2560 x 1440 in light and dark, and transparent ones to lay over a photo. Seamless 10-second loops at 1920 x 1080, MP4 and WebM, for any video editor, and WebMs with transparency for overlays. A demo page to try the settings and print a PDF, and a README with a recipe for each.

In Kadal Deck, buying it unlocks Field Lines in every workspace you belong to (as background pro/field-lines). Pro, Team and Lifetime plans include every premium background already.