Unexpected behavior on custom stylesheet. about save-as-ebook HOT 1 OPEN

Ok, after running this through the dev tools... the browser changes the injected css a bit before the extension saves it. "-epub-writing-mode" becomes " -webkit-writing-mode", which isn't listed in the supportedCss array. Adding it to the supportedCss array lets it go through, but it still gets mixed up.

body { -webkit-writing-mode: vertical-rl; writing-mode: vertical-rl;}

The resulting CSS is still broken:
.AI0 {background-color:rgba(0, 0, 0, 0);border:0px none rgb(0, 0, 0);color:rgb(0, 0, 0);font:16px / 25.6px "Times New Roman";line-height:25.6px;list-style:outside none disc;padding:0px;text-align:start;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .BP1 {background-color:rgba(0, 0, 0, 0);border:0px none rgb(0, 0, 0);color:rgb(0, 0, 0);font:700 32px / 51.2px "Times New Roman";line-height:51.2px;list-style:outside none disc;padding:0px;text-align:start;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .ql2 {background-color:rgba(0, 0, 0, 0);border:0px none rgb(0, 0, 0);color:rgb(0, 0, 0);font:700 24px / 38.4px "Times New Roman";line-height:38.4px;list-style:outside none disc;padding:0px;text-align:start;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .Xn349 {background-color:rgba(0, 0, 0, 0);border:0px none rgb(0, 0, 0);color:rgb(0, 0, 0);font:700 20px / 25.6px "Times New Roman";line-height:25.6px;list-style:outside none disc;padding:0px;text-align:start;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .Tk354 {background-color:rgba(0, 0, 0, 0);border:0px none rgb(0, 0, 0);color:rgb(0, 0, 0);font:700 18px / 25.6px "Times New Roman";line-height:25.6px;list-style:outside none disc;padding:0px;text-align:start;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .mj357 {background-color:rgba(0, 0, 0, 0);border:0px none rgb(0, 0, 0);color:rgb(0, 0, 0);font:16px / 16px "Times New Roman";line-height:16px;list-style:outside none disc;padding:0px;text-align:start;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .yY360 {background-color:rgba(0, 0, 0, 0);border:0px none rgb(0, 0, 0);color:rgb(0, 0, 0);font:8px / 4px "Times New Roman";line-height:4px;list-style:outside none disc;padding:0px;text-align:start;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .Mp8104 {background-color:rgba(0, 0, 0, 0);border:0px none rgb(0, 0, 0);color:rgb(0, 0, 0);font:13.3333px / 25.6px "Times New Roman";line-height:25.6px;list-style:outside none disc;padding:0px;text-align:start;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .Wt24983 {background-color:rgba(0, 0, 0, 0);border:0px none rgb(255, 255, 255);color:rgb(255, 255, 255);font:16px "Open Sans", Roboto, Arial, Helvetica, sans-serif;line-height:normal;list-style:outside none disc;padding:0px;text-align:start;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .un24984 {background-color:rgb(91, 0, 92);color:rgb(255, 255, 255);font:16px "Open Sans", Roboto, Arial, Helvetica, sans-serif;line-height:normal;list-style:outside none disc;padding:0px;text-align:start;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .pM24985 {background-color:rgba(0, 0, 0, 0);border:0px none rgb(255, 255, 255);color:rgb(255, 255, 255);font:500 16px / 35px "Open Sans", Roboto, Arial, Helvetica, sans-serif;line-height:35px;list-style:outside none disc;padding:0px;text-align:center;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .fl24991 {background-color:rgba(0, 0, 0, 0);border:0px none rgb(255, 255, 255);color:rgb(255, 255, 255);font:16px "Open Sans", Roboto, Arial, Helvetica, sans-serif;line-height:normal;list-style:outside none disc;padding:5px 0px;text-align:start;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .JJ24992 {background-color:rgb(255, 255, 255);border:0px none rgb(255, 255, 255);color:rgb(255, 255, 255);font:16px "Open Sans", Roboto, Arial, Helvetica, sans-serif;line-height:normal;list-style:outside none disc;padding:0px;text-align:start;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .cT24995 {background-color:rgba(0, 0, 0, 0);border:0px none rgb(255, 255, 255);color:rgb(255, 255, 255);font:16px "Open Sans", Roboto, Arial, Helvetica, sans-serif;line-height:normal;list-style:outside none disc;padding:10px 0px 10px 5px;text-align:left;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .Mp24997 {background-color:rgba(0, 0, 0, 0);border:1px inset rgb(0, 0, 0);color:rgb(0, 0, 0);font:16px / 25.6px "Times New Roman";line-height:25.6px;list-style:outside none disc;padding:0px;text-align:start;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .IW25011 {background-color:rgba(0, 0, 0, 0);border:0px none rgb(0, 0, 238);color:rgb(0, 0, 238);font:16px / 25.6px "Times New Roman";line-height:25.6px;list-style:outside none disc;padding:0px;text-align:start;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .nu25019 {background-color:rgba(0, 0, 0, 0);border:0px none rgb(0, 0, 0);color:rgb(0, 0, 0);font:16px / 25.6px "Times New Roman";line-height:25.6px;list-style:outside none disc;padding:40px 0px 0px;text-align:start;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .XG25020 {background-color:rgba(0, 0, 0, 0);border:0px none rgb(0, 0, 0);color:rgb(0, 0, 0);font:16px / 25.6px "Times New Roman";line-height:25.6px;list-style:outside none disc;padding:0px;text-align:left;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;} .jY25029 {background-color:rgb(48, 52, 62);border:0px none rgb(0, 0, 0);color:rgb(0, 0, 0);font:16px / 25.6px "Times New Roman";line-height:25.6px;list-style:outside none disc;padding:0px;text-align:start;-webkit-writing-mode:vertical-rl;writing-mode:vertical-rl;}

The -epub-writing-mode/-webkit-writing-mode property has to be set in either the html or the body class for it to be rendered correctly.

from save-as-ebook.