但是,如果你可以使用少量的javascript,可以很容易地完成.

以下是我为您显示的代码示例：http://codepen.io/beneggett/pen/GJgVrp

所以我希望我在这里粘贴代码以及codepen,所以这里是：

HTML：

<p>Example of Syntax highlighting code at 72 characters w/ minimal javascript & css.</p>
<pre>
  <code>
    Here is my really awesome code that is nice
    and it is so cool. If you are actually reading this,well I praise you for bearing with me 
    as you can see there is some short code
    and some really,really,long boring code that is longer than 72 characters
    it just goes on forever and ever and ever and ever and ever and ever and ever and ever and ever
    The nice thing is we can tell our users when the code is short
    or when it is getting way way way way way way way way way way way way way way way way way way way too looonggggg
    oh wait,this isn't really code,it's just some gibberish text. but that's ok; the point is well made
    i could go on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on,but you'd get tired of it

    That's it for now
  </code>
</pre>

<p> This is just a simple example using tools that I'm comfortable with. There may be better methods to suit your needs,but it's a good start</p>

CSS：

pre{
  white-space: pre;
  background: #ececec;
  border: 1px solid #c3c3c3;
  overflow: auto; 
}
pre .long{
  border-left: 1px dotted red;
  color: red
}

JS(CoffeeScript)：

$(document).ready ->
  lines = $('pre code').text().split('\n')   # First we'll find all the lines of code
  $('pre code').text('')   # then,remove the old code,as we're going to redraw it with Syntax highlighting 
  $.each lines,(n,elem) -> # Loop through each line
    if elem.length > 72 # If it's longer than 72 characters,we'll split the good_code and the long_code then add some html markup to differentiate
      good_code = elem.substring(0,71)
      long_code = elem.substring(71)    
      $('pre code').append "#{good_code}<span class='long'>#{long_code}</span>\n"
    else # otherwise we will just keep the original code
     $('pre code').append elem + '\n'

这只是一个简单的例子,使用对我来说很简单的工具;但是重点是说明它是很简单的代码,可以很容易地适应你想要做的.