Not exactly a mirror but does what I want it to do.

I could have phrased that better. It doesn’t say that you need to create the custom.css file from scratch if you use the official manual install.

Version 2. Tossed the YouTube in the iFrame, Replaced with National Weather Service radar page.
Got rid of the module that was past?? cloud/rain. Replaced with WeatherChart module.

Also, looks like CalendarLabs has posted 2021 calendar as it was populated with new dates this morning.

Some of the modules you need to customize things like width and or height in the custom.css file to override the default css settings for that module.
Using the Developer Tools in the view option can help to visualize where the problem or fix may be.

I have an iFrame to hold a weather radar image.
Default for iFrame is no border but I wanted one to act as border for radar image. Got border no problem and I defined color also but it behaved as if it had some sort of bevel type property that I don’t understand.
For example if I chose hex value for red, the bottom and right borders would be red, the top and left borders would be a darker red.
Anyone got any thoughts on what is going on there?

Get some sort of small quarter round type molding or use router and cut slot in frame pieces.

I read through you code and reasonably easy to follow along and you gave everything unique names which helps.
The WeatherChart OTOH that uses the same block of code but doesn’t really lay out the underlying chart.js stuff which in that case I have failed to make work.
Obviously if I can change it in the script itself I should be able to make it work in config.js but that has not been the case after trying oodles of different combinations.

I’ll volunteer although I’m no programmer I do live in South Carolina

Put in issue in on Github about why the rain amount was not converting to inches when units are specified as imperial. Author of module resolved that yesterday. Also asked about scale on vertical axis as it seems too tight and rain trend wants to bang in to temperature trends.
Just sent him picture showing that.
Several things were able to be changed directly in the script but after following your advice to do all that in ether custom.css or config.js there was no way to access those parameters.

Spent a few hours looking at chart.js to see ifI could translate that to items in module but couldn’t find anything.

I have installed the MMM-WeatherChart module ( Tatsuma Matsuki) but I am struggling to understand how to convert

        datasets.push({
            label: 'Minimum Temparature',
            backgroundColor: this.config.backgroundColor,
            borderColor: this.config.color,
            pointBackgroundColor: this.config.color,
            datalabels: {
                color: this.config.color,
                align: 'top'

In to someething resembling this below

minimumTemperatureAlign : "below",

Because I don’t see where there is anything resembling this.config.minimumTemperature .
There is just the one reference to label: `Minimum Temperature`,
In a nutshell align is referring to the text being above the Minimum Temperature trend line.
There are several blocks in this same style relating to various of what seem to be CSS elements. I don’t understand how to get from the code block to the CSS property since I think this is being done using chart.js to build the grah.

Have you looked in the 3rd Party modules section? There are several DHT sensor modules in there you can use for reference, Just do text search on DHT

This is where I get tangled up with a code block like this, of which there are several. Up in default config that is showRain: false, so I just stick a showRain: true, in the config.js file. No problem with that. It is the things like label: 'Rain Volume (mm) and the rest. Do the get a css entry along lines of

 .module.MMM-WeatherChart .showRain {
label: 'Rain Volume (mm)';
}
.module.MMM-WeatherChart .dataLabels {
align: 'bottom';
}

These blocks are scattered throughout the script

        if (this.config.showRain) {
            datasets.push({
                label: 'Rain Volume (mm)',
                backgroundColor: this.config.fillColor,
                borderColor: this.config.color,
                borderWidth: 1,
                pointBackgroundColor: this.config.color,
                datalabels: {
                    color: this.config.color,
                    align: 'top'
                },
                data: rains,
                yAxisID: "y2"

this.config.showRain = true is easy.
it is the settings enclosed in the show Rain block. Colors defined prior so just ignore them?