1. Pictures
The key consideration with pictures is that their width should automatically adjust to fit the screen width without becoming the picture becoming distorted. In technical terms, what this means is that the height to width ratio of the image (the "aspect ratio") should always stay the same. But how to do this?
If you use the rich text editor ("CKEditor") embedded in FreeToastHost, you will likely discover sooner or later that it tends to put picture sizes in terms of pixels wide by pixels high. We call these absolute dimensions because they never change regardless of the available screen dimensions. This means that if a picture is too big for the screen width, it may be cut off or you may need to scroll or zoom to see it all.
A key aspect of a "responsive layout" is that there should be no zooming or *horizontal* scrolling need to see the content, regardless of the screen width. Notice that some vertical scrolling is considered OK, but you should try to not make users excessively scroll to see content. (This is also why we tend to discourage really long home pages.)
The way to make pictures size adjust to fit the screen width is to express the width as a percentage of the available width and do not specify a height at all (do not even use zero as the height). When you do this, the browser will figure out the best height to maintain the same height to width ratio.
Here is an example (below)... Notice how I have expressed the width as a percentage.
What this does is to force the browser to scale the image to fit the available screen width.
If you are unsure how to calculate the percentage, use the current pixel width dimension of your images, divide them by 670 and multiply by 100%. That should get you close to the right percentage width. BTW, do not pay any attention to the sample in the preview window of the dialog... it is frequently misleading.