CSS Reset for fixing various email client quirks.

e_CSS-Reset.css

<!-- CSS Reset -->
<style type="text/css">
/* ------------------------------------------------------------
 * THE BASICS - Resolve some troublesome quirks from the get-go
 * ------------------------------------------------------------ */
  /* Force Outlook to display view in browser link. */
  #outlook a { padding:0; }

  /* Remove spaces around the email design added by some email clients. */
  /* Beware: It can remove the padding / margin and add a background color to the compose a reply window. */
  html,
  body {
      Margin: 0 !important;
      padding: 0 !important;
      height: 100% !important;
      width: 100% !important;
      min-width: 100%;
  }

  /* Stop Wekbit and Windows Phone changing the font size */
  body {
    -webkit-text-size-adjust: 100%;
    -ms-text-size-adjust: 100%;
    Margin: 0 !important;
    padding: 0;
  }

  /* Force hotmail/outlook.com to display at full width (outer div) */
  .ReadMsgBody { width: 100%; }

  /* Force hotmail/outlook.com to display at full width (inner div) */
  .ExternalClass { width: 100%; }

  /* Fix the line-height bug in hotmail/outlook.com */
  .ExternalClass,
  .ExternalClass p,
  .ExternalClass span,
  .ExternalClass font,
  .ExternalClass td,
  .ExternalClass div {
    line-height:100%;
  }

  /* In case the body tag is removed (Gmail etc..)*/
  #wrappertable {
    margin:0;
    padding:0;
    width:100% !important;
    line-height:100% !important;
  }

  /* Stops email clients resizing small text. */
  * {
      -ms-text-size-adjust: 100%;
      -webkit-text-size-adjust: 100%;
  }

  /* Centers email on Android 4.4. */
  div[style*="margin: 16px 0"] {
      margin:0 !important;
      font-size:100% !important; 
  }

  /* Stops Outlook 2007+ and Gmail from adding extra spacing to tables. */
  table,
  td {
      mso-table-lspace: 0pt !important;
      mso-table-rspace: 0pt !important;
  }

  /* Fixes webkit padding issue. Fix for Yahoo mail table alignment bug. Applies table-layout to the first 2 tables then removes for anything nested deeper. */
  table {
      border-spacing: 0 !important;
      border-collapse: collapse !important;
      table-layout: fixed !important;
      Margin: 0 auto !important;
  }
  table table table {
      table-layout: auto;
  }

  /* Overrides styles added when Yahoo's auto-senses a link. */
  .yshortcuts a {
      border-bottom: none !important;
  }

/* ------------------------------------------------------------
 * ANCHOR STYLING - Styling for hyperlinks
 * (Move these inline for best compatibility)
 * ------------------------------------------------------------ */
  a, a:link {
    color: #e6057f;
    text-decoration: underline;
  }

  /* Another work-around for iOS meddling in triggered links. */
  a[x-apple-data-detectors] {
      color: inherit !important;
  }

   /* APPLE LINKS - Prevent the color of certain text content
    * i.e. dates/times being changed on iOS
    * You can add more appleLinks classes for any additional color(s)
    * you require to fix */
  .appleLinksWhite a {
    color: #ffffff !important;
    text-decoration:none !important;
  }
  .appleLinksBlack a {
    color: #000000 !important;
    text-decoration: none !important;
  }

  /* Optional hyperlink states (Not supported in all email clients)
  a:visited { color: #3c96e2; text-decoration: none; }
  a:focus { color: #3c96e2; text-decoration: underline; }
  a:hover { color: #3c96e2; text-decoration: underline; }
  */

/* ------------------------------------------------------------
 * IMAGE FIXES - Sensible image fixes
 * (Move these inline, for best compatibility)
 * ------------------------------------------------------------ */
  img {
    border: none;
    outline: none;
    text-decoration: none;
    /* Uses a better rendering method when resizing images in IE. */
    -ms-interpolation-mode:bicubic;
  }

  .img-fix { display: block; }

/* ------------------------------------------------------------
 * YAHOO! Mail - Paragraph fix
 * ------------------------------------------------------------ */
  p { margin: 1em 0; }

/* ------------------------------------------------------------
 * YAHOO! SHORTCUTS - Certain keywords being hyperlinked
 * ------------------------------------------------------------ */
  span.yshortcuts,
  a span.yshortcuts {
    color: #000000
    background-color: none;
    border: none;
   }
  span.yshortcuts:hover,
  span.yshortcuts:active,
  span.yshortcuts:focus {
    color: #000000;
    background-color: transparent;
    border: none;
  }

/* ------------------------------------------------------------
 * HOTMAIL/OUTLOOK.COM - Header tags styling color overrides
 * ------------------------------------------------------------ */
  h1, h2, h3, h4, h5, h6 {
    color: black !important;
  }
  h1 a, h2 a, h3 a, h4 a, h5 a, h6 a {
    color: blue !important;
  }
  h1 a:active,
  h2 a:active,
  h3 a:active,
  h4 a:active,
  h5 a:active,
  h6 a:active {
    color: red !important;
  }
  h1 a:visited,
  h2 a:visited,
  h3 a:visited,
  h4 a:visited,
  h5 a:visited,
  h6 a:visited {
    color: purple !important;
  }
</style><!-- /CSS Reset -->