css 波浪线

.flex-content::before {

      content: "";

      position: absolute;

      bottom: 0;

      z-index: 10;

      width: 100%;

      height: 10px;

      background-image: -webkit-radial-gradient(

        circle,

        transparent,

        transparent 10px,

        #dfe5ed 10px,

        #dfe5ed

      );

      background-image: -moz-radial-gradient(

        circle,

        transparent,

        transparent 10px,

        #dfe5ed 10px,

        #dfe5ed

      );

      background-image: radial-gradient(

        circle,

        transparent,

        transparent 10px,

        #dfe5ed 10px,

        #dfe5ed

      );

      background-size: 20px 20px;

      transform: rotate(180deg);

      -webkit-transform: rotate(180deg);

    }