[FR] If locked - set a specified background color to the row/card [may be achieved by card-mod]

[ildar170975]

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When the row/card is locked, the whole row/card has a specified background-color:

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The background may be set as a CSS style to the div#overlay element:

    background: rgba(66, 66, 66, 0.1);

The color must be specified by an option:
background_locked: rgba(...) or not specified (default)

Also, a special CSS variable may be defined to set the background color for cards in HA.

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[ildar170975]

Currently this functionality may be achieved by card-mod:
https://community.home-assistant.io/t/card-mod-add-css-styles-to-any-lovelace-card/120744/4849?u=ildar_gabdullin

[ildar170975]

Added in 1.2.11 (#126)