The Modus themes are highly configurable, though they should work well without any further tweaks. By default, all customization options are set to nil, unless otherwise noted in this manual.
Remember that all customization options must be evaluated before loading a theme (Enable and load). If the theme is already active, it must be reloaded for changes in user options to come into force.
Below is a summary of what you will learn in the subsequent sections of this manual.
(setq modus-themes-italic-constructs t
modus-themes-bold-constructs nil
modus-themes-mixed-fonts nil
modus-themes-subtle-line-numbers nil
modus-themes-intense-mouseovers nil
modus-themes-deuteranopia t
modus-themes-tabs-accented t
modus-themes-variable-pitch-ui nil
modus-themes-inhibit-reload t ; only applies to `customize-set-variable' and related
modus-themes-fringes nil ; {nil,'subtle,'intense}
;; Options for `modus-themes-lang-checkers' are either nil (the
;; default), or a list of properties that may include any of those
;; symbols: `straight-underline', `text-also', `background',
;; `intense' OR `faint'.
modus-themes-lang-checkers nil
;; Options for `modus-themes-mode-line' are either nil, or a list
;; that can combine any of `3d' OR `moody', `borderless',
;; `accented', a natural number for extra padding (or a cons cell
;; of padding and NATNUM), and a floating point for the height of
;; the text relative to the base font size (or a cons cell of
;; height and FLOAT)
modus-themes-mode-line '(accented borderless (padding . 4) (height . 0.9))
;; Same as above:
;; modus-themes-mode-line '(accented borderless 4 0.9)
;; Options for `modus-themes-markup' are either nil, or a list
;; that can combine any of `bold', `italic', `background',
;; `intense'.
modus-themes-markup '(background italic)
;; Options for `modus-themes-syntax' are either nil (the default),
;; or a list of properties that may include any of those symbols:
;; `faint', `yellow-comments', `green-strings', `alt-syntax'
modus-themes-syntax nil
;; Options for `modus-themes-hl-line' are either nil (the default),
;; or a list of properties that may include any of those symbols:
;; `accented', `underline', `intense'
modus-themes-hl-line '(underline accented)
;; Options for `modus-themes-paren-match' are either nil (the
;; default), or a list of properties that may include any of those
;; symbols: `bold', `intense', `underline'
modus-themes-paren-match '(bold intense)
;; Options for `modus-themes-links' are either nil (the default),
;; or a list of properties that may include any of those symbols:
;; `neutral-underline' OR `no-underline', `faint' OR `no-color',
;; `bold', `italic', `background'
modus-themes-links '(neutral-underline background)
;; Options for `modus-themes-box-buttons' are either nil (the
;; default), or a list that can combine any of `flat', `accented',
;; `faint', `variable-pitch', `underline', `all-buttons', the
;; symbol of any font weight as listed in `modus-themes-weights',
;; and a floating point number (e.g. 0.9) for the height of the
;; button's text.
modus-themes-box-buttons '(variable-pitch flat faint 0.9)
;; Options for `modus-themes-prompts' are either nil (the
;; default), or a list of properties that may include any of those
;; symbols: `background', `bold', `gray', `intense', `italic'
modus-themes-prompts '(intense bold)
;; The `modus-themes-completions' is an alist that reads three
;; keys: `matches', `selection', `popup'. Each accepts a nil
;; value (or empty list) or a list of properties that can include
;; any of the following (for WEIGHT read further below):
;;
;; `matches' - `background', `intense', `underline', `italic', WEIGHT
;; `selection' - `accented', `intense', `underline', `italic', `text-also' WEIGHT
;; `popup' - same as `selected'
;; `t' - applies to any key not explicitly referenced (check docs)
;;
;; WEIGHT is a symbol such as `semibold', `light', or anything
;; covered in `modus-themes-weights'. Bold is used in the absence
;; of an explicit WEIGHT.
modus-themes-completions '((matches . (extrabold))
(selection . (semibold accented))
(popup . (accented intense)))
modus-themes-mail-citations nil ; {nil,'intense,'faint,'monochrome}
;; Options for `modus-themes-region' are either nil (the default),
;; or a list of properties that may include any of those symbols:
;; `no-extend', `bg-only', `accented'
modus-themes-region '(bg-only no-extend)
;; Options for `modus-themes-diffs': nil, 'desaturated, 'bg-only
modus-themes-diffs 'desaturated
modus-themes-org-blocks 'gray-background ; {nil,'gray-background,'tinted-background}
modus-themes-org-agenda ; this is an alist: read the manual or its doc string
'((header-block . (variable-pitch 1.3))
(header-date . (grayscale workaholic bold-today 1.1))
(event . (accented varied))
(scheduled . uniform)
(habit . traffic-light))
modus-themes-headings ; this is an alist: read the manual or its doc string
'((1 . (overline background variable-pitch 1.3))
(2 . (rainbow overline 1.1))
(t . (semibold))))