Shock

(function(){
    var trim = function (string) {
        return string.replace(/(^\s+)|(\s+$)/g, '');
    }
    var re = {
        size  : /^\d+(em|px|%)$/i,
        size4 : /^(\d+(em|px|%) ?){1,4}$/i,
        borderStyle : /^(dotted|dashed|solid|double|groove|ridge|inset|outset|none)$/i,
        colorNames  : /^(aqua|black|blue|fuchsia|gray|green|lime|maroon|navy|olive|purple|red|silver|teal|white|yellow|cyan|magenta)$/,
        rgbColor    : /^(rgb\(\d{1,3}, ?\d{1,3}, ?\d{1,3}\))$/,
        hexColor    : /^(#[a-f0-9]{3}|#[a-f0-9]{6})$/i
    };
    var isColor = function (string) {
        return string.match(re.hexColor) || string.match(re.rgbColor) || string.match(re.colorNames);
    };
    var lib = {
        validStyles : {
            'text-align' : /^center|justify|left|right$/i,
            'border' : function (arg) {
                var parts = arg.split(' ');
                var borderStyle = 'none';
                var borderColor = 'black';
                var borderWidth = '0';
                for (var i in parts) {
                    if (parts[i].match(re.borderStyle)) {
                        borderStyle = parts[i].toLowerCase();
                    } else if (parts[i].match(re.size)) {
                        borderWidth = parts[i].toLowerCase();
                    } else if (isColor(parts[i])) {
                        borderColor = parts[i].toLowerCase();
                    }
                }

                return [borderStyle, borderColor, borderWidth].join(' ');
            },
            'background' : function (arg) {
                return isColor(arg) ? arg.toLowerCase() : null;
            },
            'display' : /^(block|inline|none)$/i,
            'padding' : re.size4,
            'margin'  : re.size4,
            'float'   : /^(left|right)$/,
            'clear'   : /^(both|left|right)$/,
            'width'   : re.size4,
            'height'  : re.size4
        }
    };
    TeX.addTag({
        name : 'style',
        args : 'unlimited',
        func : function (args) {
            var text = args.pop();
            var allStyles = lib.validStyles;
            var result = '', value;
            for (var style in args) {
                style = trim(args[style]).split(':');
                if (style.length != 2) {
                    continue;
                }
                var name = style[0].toLowerCase();
                var cur  = allStyles[name];
                if (cur) {
                    var type = typeof cur;
                    if (type === 'function') {
                        value = cur(style[1]);
                    } else if (style[1].match(cur)) {
                        value = style[1];
                    }
                    if (value) {
                        result += name + ':' + value + ';';
                    }
                }
                value = '';
            }
            return '<span style="' + result + '">' + TeX.markup(text) + '</span>';
        }
    });

})()