When you build a complex card with multiple conditions stacked inside of each other you have to fix indentation.
Lets say you have a picture elements card and you have one entity.
image: /local/Groundfloor_crop.png
type: picture-elements
elements:
- type: state-badge
entity: sensor.uptime
style:
top: 32%
left: 40%
Simple enough. Now lets add a condition that the sensor is only visible when boolean is on.
image: /local/Groundfloor_crop.png
type: picture-elements
elements:
- conditions:
- entity: input_boolean.floor
state: 'on'
elements:
- type: state-badge
entity: sensor.uptime
style:
top: 32%
left: 40%
type: conditional
The above is now incorrect because the state-badge is indented incorrectly, all the lines that belong to state-badge needs to have two spaces extra.
I know I can CTRL and click on each line and then press space space. But if you have many lines that needs to be indented then it can be very tedious to select each line.
My suggestion is to use indentation buttons just like you have in VBA editor (for those who has used it).
Basically you select all the text that you want to indent and press more or less indentation and it adds or removes indentation.
So my suggestion is to have the same in the yaml editor, add two spaces or remove two spaces.
A very simple example of my suggestion using the buttons from VBA editor 
