Graceful Theme

Theme
,
148

The Canapin’s TC works for me on this theme.
This TC sets --d-max-width and --topic-body-width CSS variables.
You might have another TC or customizations that overwrites these values.

You can try manually, for example:

body {
    --d-max-width: 1500px;
    --topic-body-width: 1500px;
}