How to insert HTML ASCII art from document?

At the moment i'm trying to read .txt files which could contain ASCII arts and display them in my HTML document with JQuery. Simple text is displayed right but i have formatting problems with the arts.

How can i fix this ?

$(document).ready(function(e) {

    $.get('/test/posts/header.txt', function(data) {

    var lines = data.split('n');

    for (var i = 0, len = lines.length; i < len; i++) {

    $(".stream").append('<div class="line"><p class="header">' + lines[i] + '</p></div>');
    }

  });
});