[Feature] Add text alignment and margin offset for on-screen captions

[Claudinetto2]

I have searched the existing feature requests to make sure this is not a duplicate request.

• Yes

The feature

would like configuration options for precise horizontal positioning of text overlays on images (date, time, person's name, owner, etc.).

Part 1: Basic Alignment
A primary setting (e.g., text_alignment) with values: left, center, right.

Part 2: Fine-Tuning with Offset (New Suggestion)
For advanced control, an additional setting (e.g., text_offset or caption_margin) would be excellent. It could work in two logical ways:

1. As a CSS-like margin (e.g., text_offset: "20px"), applied according to the chosen alignment.
2. Or as a percentage from screen edge (e.g., text_offset: "5%"), giving consistent relative positioning across different screen resolutions.

[damongolding]

This is already possible if you know CSS (using the custom css option).

[Claudinetto2]

I've add in config.yaml
custom_css_class: "immich-caption"

and then in css file

/* Centra tutti gli elementi di didascalia */
.immich-caption {
text-align: center !important;
justify-content: center
}

but remain on the left

do you have any suggestions?

[damongolding]

probably something like this:

.asset--metadata {
    align-items: center !important;
    width: 100% !important;
    max-width: none !important;
}

.asset--metadata--icon {
    order: unset !important;
}

Though this wont work well if you have show_image_qr set to true