css = PAGE
css {
  typeNum = 22
  config {
    additionalHeaders = Content-type: text/css
    disableAllHeaderCode = 1
  }
  stdWrap.required = 1
  stdWrap.wrap = |
  10 = TEXT
  10.value (
    .content_header_pic {
  )
  20 = TEXT
  20.data = levelmedia: -1
  20.listNum = 0
  20.wrap = background: url('uploads/media/|');
  30 = TEXT
  30.value (
    border-top: 8px solid #0D337A;
    height: 105px;
    width: 100%;
    }
  )
  30.if {
    isTrue.data = levelmedia: -1
  }
}




[...]



page = PAGE
 
page {
  headerData {
    16 = TEXT
    16.dataWrap = <link rel="stylesheet" type="text/css" href="index.php?id={field:uid}&type=22" />|
  }
}

http://typo3.schloebe.de/typoscript/dynamische-css-erzeugen-aus-mediafeld-daten/

Create dynamic css from media field data

css

TYPO3