.mama {
  width: 80%; /* ブロックの幅を指定 */
        margin: 0 auto; /* 左右の余白を自動調整 */
}
.cracker {
  font-family: "Helvetica Neue",
    Arial,
    "Hiragino Kaku Gothic ProN",
    "Hiragino Sans",
    Meiryo,
    sans-serif;
  font-weight: bold;
  text-align: center;
}

.cracker::before {
  margin: 0 1em 0 0;
  content: '\\';
}

.cracker::after {
  margin: 0 0 0 1em;
  content: '/';
}