body{
  background: steelblue ;/*保険用*/
  background: -moz-linear-gradient(top, steelblue 0%, ivory 100%);/*古いFireFox向け*/
  background: -webkit-linear-gradient(top, steelblue 0%,ivory 100%);/*古いSafariなど向け*/
  filter:progid:DXImageTransform.Microsoft.Gradient(
    startColorstr='steelblue',
    endColorstr='ivory',
    GradientType=0 );/*IE9以下向け*/
  background: linear-gradient(to bottom, steelblue 0%, ivory 100%);/*正規の指定*/
}