html,body{
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    font-family: sans-serif;
}

#editor{
    padding: 10px;
}

textarea{
    width: 100%;
    height: 180px;
    box-sizing: border-box;
    font-size: 20px;
}

button{
    margin-top: 10px;
    width: 100%;
    height: 50px;
    font-size: 20px;
}

/* 擬似フルスクリーン */
#viewer{
    display: none;

    position: fixed;
    left: 0;
    top: 0;

    width: 100vw;
    height: 100vh;

    background: #000;
    color: #fff;

    z-index: 999999;

    justify-content: center;
    align-items: center;

    padding: 20px;
    box-sizing: border-box;

    text-align: center;

    white-space: pre-wrap;
    word-break: break-word;

    font-size: 7vw;
    line-height: 1.3;

    overflow: auto;
}