html-Editor supports some of HTML elements and CSS styles.
supports keyword highlighting,
supports HTML elements: h1,h2,h3，div,span,style,p,blockquote,pre,li,a,img,b,u,i,s,font,br
HTML attributes: class, style
CSS: declared in style element and inline
CSS styles: color, background-color, margin, font-family, font-size, font-weight, font-style, text-decoration, text-align