SubtitleEdit: Utilities#SplitEndTags

public static (string, string) SplitEndTags(string line)
        {
            int r = line.Length - 1;

            if (line.EndsWith("{\\r}", StringComparison.Ordinal))
            {
                r = line.Length - 4;
            }

            for (int l = r; l >= 0; l--)
            {
                if (line[l] == '>')
                {
                    r = l;
                }
                else if (line[l] == '<' && line[r] == '>')
                {
                    string tag = line.Substring(l, r - l + 1).ToLowerInvariant();
                    if (HtmlUtil.CommonHtmlTags.Contains(tag) || tag.StartsWith("<font", StringComparison.Ordinal))
                    {
                        r = l;
                    }
                }
                else if (line[l] != ' ')
                {
                    break;
                }
            }

            return (line.Substring(0, r), line.Substring(r));
        }