ul {
  li {
    .uk-accordion-title {
      position: relative;
      
      &::before {
        background-image: none;//デフォルト記号を非表示に
        content: "\002B";//CSS用特殊記号に変換
        color: red;
        font-size: 20px;
        
        background-color: lemonchiffon;
        width: 28px;
        height: 28px;
        border-radius: 50%;
        
        //上下中央揃え
        display: flex;
        justify-content: center;
        line-height: 1.25;
        
        position: absolute;
        top: 50%;
        transform:translateY(-50%);
        right: 20px;
      }
    }
  }
}

.uk-open {
  >.uk-accordion-title {
    &::before {
      content: none;//プラスボタン非表示
    }
    &::after {
      content: "\002212";//CSS用特殊記号に変換
      color: red;
      font-size: 20px;
      
      background-color: lemonchiffon;
      width: 28px;
      height: 28px;
      border-radius: 50%;

      //上下中央揃え
      display: flex;
      justify-content: center;
      line-height: 1.25;

      position: absolute;
      top: 50%;
      transform:translateY(-50%);
      right: 20px;
    }
  }
}