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Look and feel

Light and dark

Both with a switch, following the visitor’s system, or only one of them.

hugo.toml

[params.mode]
  default = "auto"   # "light", "dark", or "auto": the visitor's system setting
  toggle = true      # the switch in the header

You want	`default`	`toggle`
both, starting from the visitor’s system setting	`"auto"`	`true`
both, starting light	`"light"`	`true`
light only	`"light"`	`false`
dark only	`"dark"`	`false`
the visitor’s system setting, no switch	`"auto"`	`false`

Without these settings a site starts light, with the switch. With the switch, the visitor’s choice is remembered in their browser and wins over default on their next visit. The mode is set before the page is drawn, so it never flashes the other one.