Gentle snow falling through soft holiday lights on a winter night. Three depths of flakes fall at different speeds, the far ones small and sharp and the near ones large and soft, as if close to the lens, each swaying a little on the way down. Behind them, warm gold, red and green lights glow as round, out-of-focus discs that drift slowly and twinkle, over a deep blue sky with a warm glow low down, like lit windows.

The sky, snow and light colors, how heavy the snow is, flake size, sway, near-flake blur, and the brightness and size of the lights are all settings. The demo has presets for a silent night, a warm window, blue hour, candy cane lights, snow only and a light flurry, plus a Behind text preset.

Made for the holiday season on the web: hero sections, gift guides and seasonal sales, greetings, event and market pages, stream backgrounds and video. Its reduced-motion setting holds the snow still where it is on the poster frame for visitors who ask for less motion (values in between hold some flakes and let the rest fall), and a veil setting dims the snow and lights so text reads on top. At the Behind text preset, white text keeps a contrast ratio of at least 6.5:1 against 98 % of the background under it.

What you get: a GLSL ES 3.00 fragment shader for plain WebGL2, an ES module that returns a three.js ShaderMaterial, a Shadertoy version, an offline demo page with a settings panel, a 10-second 1920 x 1080 H.264 loop that plays end to start without a seam, the same loop at 1080 x 1920 for vertical video, and the poster frame as a PNG (and a WebP for the web). One pass with no textures, about 2.1 ms of GPU time per 1920 x 1080 frame on a recent laptop, measured in headless Chromium. The README covers setup, reduced motion, every uniform and performance notes.