.background-fixed-q {
  margin-top: 80px;
  margin-bottom: 80px;
  min-height: 40vh;
  color: #fff;
  text-shadow: 0 0 15px rgba(0, 0, 0, 0.5);
  display: flex;
  flex-direction: column;
  justify-content: center;
  font-size: 15px;
  overflow: hidden;
}

/*supports是寫給部分瀏覽器讀的，意思是看得懂括弧內的參數的瀏覽器才會執行的意思*/
@supports (clip-path: inset(0 0 0 0)) { 
  .background-fixed-q {
    clip-path: inset(0 0 0 0); /*inset的是形狀遮罩，例如像SVG裡就會看見*/
  }
}

.background-fixed-q + .background-fixed-q {
  margin-top: -80px;
}

.background-fixed-q--dark {
  color: #000;
  text-shadow: 0 0 15px rgba(255, 255, 255, 0.5);
}

.background-fixed-q__background {
  background-repeat: no-repeat;
  background-position: center;
  background-attachment: fixed;
  background-size: cover;
  position: absolute;
  left: 0;
  top: 0;
  width: 100vw;
  height: 100vh;
  pointer-events: none;
}

@supports (clip-path: inset(0 0 0 0)) {
  .background-fixed-q__background {
    position: fixed;
    background-attachment: scroll;
  }
}

.background-fixed-q__background::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: #000;
  opacity: 0;
  z-index: 0;
}

.background-fixed-q--dark .background-fixed-q__background::before {
  background: #fff;
}

/* Opacity levels for .background-fixed-q__background */
.background-fixed-q__background--opacity-10::before { opacity: 0.1; }
.background-fixed-q__background--opacity-20::before { opacity: 0.2; }
.background-fixed-q__background--opacity-30::before { opacity: 0.3; }
.background-fixed-q__background--opacity-40::before { opacity: 0.4; }
.background-fixed-q__background--opacity-50::before { opacity: 0.5; }
.background-fixed-q__background--opacity-60::before { opacity: 0.6; }
.background-fixed-q__background--opacity-70::before { opacity: 0.7; }
.background-fixed-q__background--opacity-80::before { opacity: 0.8; }
.background-fixed-q__background--opacity-90::before { opacity: 0.9; }

.background-fixed-q__content {
  max-width: calc(960px + 2em);
  width: 100%;
  margin: 0 auto;
  position: relative;
  z-index: 1;
  padding: 4em 2em;
}

.background-fixed-q__content > div {
  max-width: 600px;
}

/* Basic demo styling */
/* body {
  padding: 100vh 0;
} */

/* body > :first-child {
  margin-top: -10vh;
} */