Quickly type color variables

We often declare variables for colors, mostly at the top of file, as following:

:root {
    --color-primary: #...;
}

The colors then can be reused with the `var` function:

.btn--primary {
    background-color: var(--color-primary);
}

If you're using Visual Studio Code, then you don't have to type `var(...)` completely. Instead, just type `--` and Visual Studio Code suggests the existing color variables.