index.css

body {
    margin-top: 20px;
}

.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 40px;
    background: #000;
    color: #fff;
    display: flex;
    justify-content: space-around;
    align-items: center;
    z-index: 999;
    border-bottom: solid 1px #fff;
}

.noselect,
.category-item>em:nth-last-of-type(2) {
    -webkit-touch-callout: none; /* iOS Safari */
      -webkit-user-select: none; /* Safari */
       -khtml-user-select: none; /* Konqueror HTML */
         -moz-user-select: none; /* Firefox */
          -ms-user-select: none; /* Internet Explorer/Edge */
              user-select: none; /* Non-prefixed version, currently
                                    supported by Chrome and Opera */
  }

.view-btn {
    cursor: pointer;
}

.copy-btn {
    cursor: pointer;
}

#html-container {
    margin: auto;
    width: 600px;
}

.category-item {
    position: relative;
}

.category-item .drag-handler,
.category-item .delete-handler {
    position: absolute;
    display: flex;
    justify-content: center;
    align-items: center;
    outline: solid 1px #000;
    text-align: center;
    width: 30px;
    height: 30px;
}
.category-item:hover {
    outline: 1px solid #d0d0d0;
    background: #f5f5f5;
}

.category-item:hover .drag-handler,
.category-item:hover .delete-handler {
    visibility: visible;
}
.category-item .drag-handler {
    right: 40px;
    top: -10px;
    background-color: #f0f0f0;
    cursor: row-resize;
    visibility: hidden;
}
.category-item .delete-handler {
    right: 5px;
    top: -10px;
    background-color: #f0f0f0;
    color: #f00;
    font-weight: bold;
    cursor: pointer;
    visibility: hidden;
}

.placeholder {
    border: 1px solid black;
    margin: 0 1em 1em 0;
    height: 100px;
    background: #f0f0f0;
}

.tooltip {
    position: relative;
    display: inline-block;
    border-bottom: 1px dotted black;
}

.tooltip .tooltiptext {
    visibility: hidden;
    width: 120px;
    background-color: #555;
    color: #fff;
    text-align: center;
    border-radius: 6px;
    padding: 5px 0;
    position: absolute;
    z-index: 1;
    bottom: 125%;
    left: 50%;
    margin-left: -60px;
    opacity: 0;
    transition: opacity 0.3s;
}

.tooltip .tooltiptext::after {
    content: "";
    position: absolute;
    top: 100%;
    left: 50%;
    margin-left: -5px;
    border-width: 5px;
    border-style: solid;
    border-color: #555 transparent transparent transparent;
}

.tooltip:hover .tooltiptext {
    visibility: visible;
    opacity: 1;
}