main {
  max-width: 100%;
}

img, video {
  max-width: 100%;
  height: auto;
}

.narrow {
  max-width: 720px;
  margin: 0 auto;
}

li ul {
  margin-bottom: 0;
  margin-top: 0.25em;
}

.sq, .h, .v {
  background-color: white;
  box-shadow: 0px 0px 1px #000;
}

.sq, .h {
  position: relative;
  width: 100%;
  height: 0;
}

.sq { padding-bottom: 100%; }
.h { padding-bottom: 33.333%; }
.v {
  position: relative;
  width: 120px;
  height: 360px;
  margin: 0 auto;
}

.sq > img,
.h > img,
.v > img {
  max-height: 100%;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translateY(-50%) translateX(-50%);
}