My custom theme and css for http://writeapp.net, https://dl.dropboxusercontent.com/u/46279518/write-screenshot.png

writeapp.css

body {
    background:#ffffff;
    font-family: 'Open Sans', 'Helvetica Neue', Helvetica, Arial, sans-serif;
    font-size: 16px;
    color: #444;
    line-height: 24px;
    max-width: 800px;
    padding: 0 20px;
    margin: 20px auto 100px;
    text-align: justify;
    word-wrap: break-word;
}

img {
    max-width:90%;
}

h1, h2, h3, h4, h5, h6 {
    font-weight: bold;
    margin: 0 0 25px 0;
    color: #212121;
}

h1 {
    font-size: 32px;
}

h2 {
    font-size: 26px;
}

h3 {
    font-size: 24px;
}

h4 {
    font-size: 20px;
}

h5 {
    font-size: 16px;
}

h6 {
    font-size: 14px;
}

hr {
    height: 0.2em;
    border: 0;
    color: #CCCCCC;
    background-color: #CCCCCC;
}

ul {
    list-style: square;
}

p, ul, ol, dl, table, pre {
    margin: 15px 0;
}

table {
    border-collapse: collapse;
    margin: 20px 0 0;
    padding: 0;
}

table tr {
    border-top: 1px solid #ccc;
    background-color: #fff;
    margin: 0;
    padding: 0;
}

table tr:nth-child(2n) {
    background-color: #f8f8f8;
}

table tr th,
table tr td {
    border: 1px solid #ccc;
    text-align: left;
    margin: 0;
    padding: 6px 13px;
}

blockquote {
    margin-left: 1em;
    padding-left: 1em;
    border-left: 1px solid #ddd;
}

a, a:visited {
    color: #4183C4;
    background-color: inherit;
    text-decoration: none;
}


#message {
    border-radius: 6px;
    border: 1px solid #ccc;
    display:block;
    width:100%;
    height:60px;
    margin:6px 0px;
}

button, #ws {
    font-size: 10pt;
    padding: 4px 6px;
    border-radius: 5px;
    border: 1px solid #bbb;
    background-color: #eee;
}

#ws, #message {
    font-family: Monaco;
    font-size: 10px;
    border-radius: 3px;
    background-color: #f5f2f0;
    color: inherit;
}

/* --- */
code, pre {
  font-family: Monaco, Consolas, "Courier New", monospace;
}

code {
  padding: 2px 4px;
  font-size: 90%;
  color: #c7254e;
  background-color: #f9f2f4;
}

pre {
  display: block;
  padding: 12px;
  margin: 0 0 15px;
  font-size: 14px;
  line-height: 1.42857143;
  word-break: break-all;
  word-wrap: break-word;
  background-color: #f5f5f5;
  color: #333;
}

pre > code {
  padding: 0;
  font-size: inherit;
  color: inherit;
  white-space: pre-wrap;
  background-color: transparent;
  border-radius: 0;
}

#ws {
    background-color: #f8f8f8;
}

.send {
    color:#77bb77;
}

.server {
    color:#7799bb;
}

.error {
    color:#AA0000;
}

writeapp.txt

editor
foreground: 000000
background: ffffff
caret: 4169E1

H1
foreground: 000000
font-style: bold
font-size: +6

H2
foreground: 000000
font-style: bold
font-size:  +5

H3
foreground: 000000
font-style: bold
font-size: +4

H4
foreground: 000000
font-style: bold
font-size: +3

H5
foreground: 000000
font-style: bold
font-size: +2

H6
foreground: 000000
font-style: bold
font-size: +1

HRULE
foreground: 586e75

LIST_BULLET
foreground: b58900

LIST_ENUMERATOR
foreground: b58900

LINK
foreground: 0f7abe

AUTO_LINK_URL
foreground: 2aa198

AUTO_LINK_EMAIL
foreground: 2aa198

IMAGE
foreground: d33682

REFERENCE
foreground: 80b58900 # yellow, reduced alpha

CODE
foreground: 16A085

VERBATIM
foreground: 16A085


EMPH
foreground: 000000
font-style: italic

STRONG
foreground: 000000
font-style: bold

HTML_ENTITY
foreground: 6c71c4

COMMENT
foreground: 93a1a1

BLOCKQUOTE
foreground: d33682