please update your css like this

/*----------ESTILOS MENU -----------*/
      .menuBtn {
        height: 30px;
        width: 30px;
        position: absolute;
        right: 20px;
        top: 10px;
        z-index: 101;
      }
      .menuBtn > span {
        background-color: var(--color-primario);
        height: var(--altura-linea);
        width: 100%;
        position: absolute;
        left: 50%;
        top: 50%;
        margin: -1px 0 0 -15px;
        transition: height 100ms;
      }
      .menuBtn > span:after,
      .menuBtn > span:before {
        content: '';
        background-color: var(--color-primario);
        height: var(--altura-linea);
        width: 100%;
        position: absolute;
        left: 50%;
        margin-left: -15px;
        transition: all 200ms;
      }
      .menuBtn > span:after {
        top: -7px;
      }
      .menuBtn > span:before {
        bottom: -7px;
      }
      .menuBtn.act > span {
        height: 0;
      }
      .menuBtn.act > span:after,
      .menuBtn.act > span:before {
        background-color: #008877;
        top: 1px;
      }
      .menuBtn.act > span:after {
        transform: rotate(45deg);
      }
      .menuBtn.act > span:before {
        transform: rotate(-45deg);
      }
      /* main menu block */
      .mainMenu {
        background-color: var(--color-blanco);
        position: fixed;
        left: 0;
        top: 0;
        z-index: 100;
        height: 100%;
        width: 100%;
        display: table;
        text-align: center;
        opacity: 0;
        transition: all 500ms cubic-bezier(0.68, -0.55, 0.265, 1.55);
        transform: scale(0);
      }
      .mainMenu.act {
        opacity: 1;
        transform: scale(1);
      }
      .mainMenu.act ul li {
        opacity: 1;
        transform: translateX(0);
      }
      .mainMenu ul {
        display: table-cell;
        vertical-align: middle;
      }
      .mainMenu li {
        padding: 8px 0;
        transition: all 400ms 510ms;
        opacity: 0;
      }
      .mainMenu li:nth-child(odd) {
        transform: translateX(30%);
      }
      .mainMenu li:nth-child(even) {
        transform: translateX(-30%);
      }
      .mainMenu li:last-child {
        transform: none;
      }
      .mainMenu a {
        color: #19b698;
        display: inline-block;
        font-size: 18px;
      }
      .mainMenu a.suBtn {
        color: var(--color-blanco);
      }
    
      .act{
        background-color: red;
      }