# Themes (/common-widget-features/styles/themes)



Overview [#overview]

A theme is a collection of styles plus the knowledge of which styles apply to which
Widget types. An active theme is applied to every newly created Widget, giving the UI
a default look that further styles can refine. Each display can use its own theme
(e.g. a colorful TFT alongside a monochrome secondary display).

Setting a theme takes two calls — initialize it, then assign it to the display:

```c title=" " lineNumbers=1
lv_theme_t * th = lv_theme_default_init(display,                 /* Use DPI, size, etc. from this display */
                                        LV_COLOR_PALETTE_BLUE,   /* Primary and secondary palette */
                                        LV_COLOR_PALETTE_CYAN,
                                        false,                   /* Dark theme?  False = light theme. */
                                        &lv_font_montserrat_10,  /* Small, normal, large fonts */
                                        &lv_font_montserrat_14,
                                        &lv_font_montserrat_18);

lv_display_set_theme(display, th); /* Assign theme to display */
```

If <ApiLink name="LV_USE_THEME_DEFAULT" /> is enabled in `lv_conf.h`, LVGL initializes and
sets the default theme automatically when a display is created.

Extending themes [#extending-themes]

<LvglExample name="lv_example_style_theme" path="styles/lv_example_style_theme" />

This extends the current theme with an extra button style. It is C-only because a
`lv_theme_*` callback has no XML form.

A custom theme can select a parent theme: the parent's styles are applied before the
custom theme's, and themes can be chained (e.g. default → custom → dark).

<ApiLink name="lv_theme_set_parent" display="lv_theme_set_parent(new_theme, base_theme)" />

extends `base_theme` with `new_theme`.