Options
Every class, attribute and CSS variable: the values it accepts and what it changes.
Master switch
The halloween body class turns the whole library on. Without it nothing runs. How it combines with the season window.
Ambient effects
The four ambient effects (eyes, witches, spider-drop, tombstones). The class for each, how it behaves, how often it appears and what limits it.
Screen corners
Static spider webs fixed to the corners of the viewport. The four corner classes, size, color, opacity and how they differ from ambient effects.
Intensity
The subtle and party intensity classes. How they change spawn rate, simultaneous effects, size and opacity, with the exact values.
Season window
When halloween.js is active. The default 18 October to 2 November window, the start and end attributes, accepted date formats, year-wrapping ranges and the fail-open rule.
Color
Change the color of webs, spiders, the witch and tombstones with --halloween-color. Which elements follow it, which do not, and how it combines with the script URL parameter.
Size and opacity
CSS variables that resize each effect and dim the whole effects layer. Every variable, its default and how it combines with the intensity classes.
Badge
The optional credit link. How to switch it on, align it left or right, place it inside your footer, restyle it with CSS variables and what it does on short pages.
Script URL parameters
The s, e and color query parameters on the script tag URL. When they work, when they do not, and how they rank against body attributes.