.bg {

  background: url(https://risuka.org/bg.jpg) center no-repeat;
  background-size: cover;
  padding: 300px 0px; /*背景画像の高さを確保*/
  position: relative; /*中の要素の基準値*/
}

.bg:before {
  content: '';
  position: absolute;
  top: 0;
  right: 0;
  left: 0;
  bottom: 0;
  background-color: rgba(0,0,0,0.5); /*半透明のフィルターをかける*/
}

.bg-inner {
  text-align: center;
  position: relative;
  width: 100%;
}

h1 {
  font-size: 2em;
  color: #ffffff; 
}


h3 {
  font-size: 1.5em;
  color: #ffffff; 
}


p {
  font-size: 1em;
  color: #ffffff; 
}