Exemplo de bg com gradiente

exemplo.css

html { min-height: 100%; }

body {
  width: 600px;
  margin: auto;

  background: #1e1e1e;
  background-image: url('textura.png');
  background-image: url('textura.png'), -webkit-gradient(linear, left top, left bottom, from(rgba(100, 100, 100, 0.2)), to(rgba(0, 0, 0, 0.5))); /* Saf4+, Chrome */
  background-image: -webkit-linear-gradient(top, rgba(100, 100, 100, 0.2), rgba(0, 0, 0, 0.5)), url('textura.png'); /* Chrome 10+, Saf5.1+ */
  background-image:    -moz-linear-gradient(top, rgba(100, 100, 100, 0.2), rgba(0, 0, 0, 0.5)), url('textura.png'); /* FF3.6+ */
  background-image:     -ms-linear-gradient(top, rgba(100, 100, 100, 0.2), rgba(0, 0, 0, 0.5)), url('textura.png'); /* IE10 */
  background-image:      -o-linear-gradient(top, rgba(100, 100, 100, 0.2), rgba(0, 0, 0, 0.5)), url('textura.png'); /* Opera 11.10+ */
  background-image:         linear-gradient(top, rgba(100, 100, 100, 0.2), rgba(0, 0, 0, 0.5)), url('textura.png'); /* W3C */
}