advanced-camera-card/docs/configuration/dimensions.md

dimensions

These options control the dimensions and aspect-ratio of the card (See Camera Dimensions to set the dimensions of a camera and not the whole card). These options configuration applies once to the entire card (including the menu, thumbnails, etc), not just to displayed media. This only applies to the card in normal render mode -- when in fullscreen, or when in expanded (popup/dialog mode) the aspect ratio is chosen dynamically to maximize the amount of content shown.

dimensions:
  # [...]

Option	Default	Description
aspect_ratio_mode	dynamic	The aspect ratio mode to use. Acceptable values: dynamic, static, unconstrained. See below.
aspect_ratio	16:9	The aspect ratio to use. Acceptable values: [W]:[H] or [W]/[H]. See below.
height	auto	The height for the card. Specified in CSS units. Generally users should not need to change this.

aspect_ratio_mode

Option	Description
dynamic	The aspect-ratio of the entire card will match the aspect-ratio of the last selected media item.
static	A fixed aspect-ratio (as defined by aspect_ratio) will be applied to the card.
unconstrained	No aspect ratio is enforced in any view, the card will expand with the content. This may be especially useful for a panel-mode dashboard, or in views that have no intrinsic aspect-ratio (e.g. the media gallery).

aspect_ratio

• 16 / 9 or 16:9: Default widescreen ratio.
• 4 / 3 or 4:3: Default fullscreen ratio.
• [W]/[H] or [W]:[H]: Any arbitrary aspect-ratio.

Note

When in a Panel View the aspect-ratio of the card are pegged to the exact size of the panel. As such, static aspect-ratio parameters will have no effect.

Fully expanded reference

dimensions:
  aspect_ratio_mode: dynamic
  aspect_ratio: 16:9
  height: auto