Hello!
```yaml
colorscheme:
    outline: 
        r: 1
        g: 3
        b: 4
    fill: 
        r: 3
        g: 6
        b: 34
    text: 
        r: 255
        g: 255
        b: 255
    hover: 
        r: 100
        g: 100
        b: 100
    opaqueness: 50
```
Could you please tell me if this is valid YAML text?
and if not what exactly is wrong with it.
Hello!

Based on the indentation of the text, it appears to be a valid YAML code. However, please note that YAML is a human-readable data serialization language, which means that the validity of the code also depends on the context in which it is being used.

Assuming that this code is part of a larger YAML document or configuration file, and assuming that the format and syntax of the other parts of the document are correct, this code snippet appears to be valid.

One thing to note is that the opaqueness key is not a standard YAML key, so it may not be recognized by all parsers. If you're using this YAML code in a specific application, you may want to check its documentation to make sure that this key is supported.