Provide base dark/light themes

[ThiefMaster]

Since Element does not support overriding just a few things from a default theme it would be nice if there were JSON themes that look exactly like the default ones, just so people have something to use as a base.

For example, I only want to change the monospace font and right now I have to copy TONS of colors from all over the place just for this.

[aaronraimist]

Was just looking at it. It won't be possible to get this exactly right because the variables they give us are not as granular as as all of the CSS variables they use.

{
    "name": "Default light theme",
    "is_dark": false,
    "colors": {
        "accent-color": "#0DBD8B",
        "primary-color": "#238CF5",
        "warning-color": "#FF4B55",

        "sidebar-color": "#27303A",
        "roomlist-background-color": "#F3F8FD",
        "roomlist-text-secondary-color": "#737D8C",
        "roomlist-highlights-color": "#FFFFFF",
        "roomlist-separator-color": "#E3E8F0",

        "timeline-background-color": "#FFFFFF",
        "timeline-text-color": "#2e2f32",
        "timeline-text-secondary-color": "#61708B",
        "timeline-highlights-color": "#F6F7F8",
        "reaction-row-button-selected-bg-color": "#e9fff9"
    }
}

is my first attempt at the default light theme but it's a bit off

[aaronraimist]

I ended up fighting with node a lot trying to fix the fonts. I may take a look at this another time but that's about as far as I got.