body {
  text-align: center;
  min-width: 500px; font-family:Tahoma; font-size:12pt
}
span.GalleryItemDesc { font-size: 12px; font-family: Tahoma }
span.GalleryItemHdr { font-family: Tahoma; font-size: 14px; color: #3333CC; font-weight:bold }
span.imagesubtitle { color: #666666; font-size: 12px; font-family: Arial; font-style: italic }
span.Footertext { color: #FFFFFF; font-family: Tahoma; font-size: 10px }
span.linkprice { color: #990033; font-size: 14px }
span.ItemName { font-family: Tahoma; color: #333399; font-size: 14pt; font-weight: bold }
#wrapper {
  text-align: left;
  width: 500px;
  margin-left: auto;
  margin-right: auto;
}
Commented example:

body {
  /* MSIE 5 doesn't center based on auto left/right margins, 
     but 'text-align:center' does center top-level divs: */
  text-align: center;
  /* Specify a min-width for the body as wide as the 'wrapper'
     element itself. This prevents negative (i.e. inaccessible)
     left-margins in narrow browser windows when using 
     Navigator 6+/Mozilla on Win32: */
  min-width: 500px;
}
#wrapper {
  /* Reset alignment to compensate for 'text-align:center': */
  text-align: left;
  /* Specify the width of the element. This should be the same
     as 'body min-width': */
  width: 500px;
  /* Set left and right margins to auto, thus centering the 
     element in the containing (body) tag: */
  margin-left: auto;
  margin-right: auto;
}
h1           { font-size: 18pt; line-height:22px; font-family: Tahoma; color: #6666FF}
h2           { font-size: 16pt; line-height:20px; font-family: Tahoma; color: #6666FF}
h3           { font-size: 14pt; line-height:18px;font-family: Tahoma; color: #6666FF}
a            { font-size: 12px; font-family: Tahoma; line-height:150%; color:#505090 }