body {
      margin: 0;
      display: flex;
      flex-direction: column;
      min-height: 100vh; /* 画面いっぱいの高さを確保 */
    }
main {
      flex: 1; 
    }
.footer {
    bottom: 0;
    width: 100%;
    height: auto;
    color: #fff;
    background-color: #d9bf86;
    text-align: center;
    font-size: 12px;
    padding: 40px 0px;
    opacity: 0.9;
}

.footer small {
    font-size: 8px;
}