/* The location pointed to by the popup tip. */
      .popup-tip-anchor {
        height: 0;
        position: absolute;
        /* The max width of the info window. */
        width: 200px;
      }
      /* The bubble is anchored above the tip. */
      .popup-bubble-anchor {
        position: absolute;
        width: 100%;
        bottom: /* TIP_HEIGHT= */ 60px;
        left: 0;
      }
      /* Draw the tip. */
      .popup-bubble-anchor::after {
        content: "";
        position: absolute;
        top: 0;
        left: 0;
        /* Center the tip horizontally. */
        transform: translate(-50%, 0);
        /* The tip is a https://css-tricks.com/snippets/css/css-triangle/ */
        width: 0;
        height: 0;
        /* The tip is 8px high, and 12px wide. */
        border-left: 6px solid transparent;
        border-right: 6px solid transparent;
        border-top: /* TIP_HEIGHT= */ 8px solid white;
      }
      /* The popup bubble itself. */
      .popup-bubble-content {
        position: absolute;
        top: 0;
        left: 0;
        transform: translate(-50%, -100%);
        /* Style the info window. */
        background-color: white;
        padding: 5px;
        border-radius: 5px;
        font-family: sans-serif;
        overflow-y: auto;
        max-height: 60px;
        box-shadow: 0px 2px 10px 1px rgba(0,0,0,0.5);
      }