This [size=number] without unit is kind of a standard.
It was being rendered like "font-size: 50" and that's not valid CSS style.
$Text = preg_replace("(\[color=(.*?)\](.*?)\[\/color\])ism","<span style=\"color: $1;\">$2</span>",$Text);
// Check for sized text
+ // [size=50] --> font-size: 50px (with the unit).
+ $Text = preg_replace("(\[size=(\d*?)\](.*?)\[\/size\])ism","<span style=\"font-size: $1px;\">$2</span>",$Text);
$Text = preg_replace("(\[size=(.*?)\](.*?)\[\/size\])ism","<span style=\"font-size: $1;\">$2</span>",$Text);
// Check for list text