.btn-margin11 {
    width: 300px;
    height: 45px;
    margin: 15px;
}

.content {
    width: 600px;
    margin-left: calc(50% - 450px);
    padding-left: 8px;
    padding-right: 8px;
    border: 1px solid black;
}

.indent {
    text-indent: 1em;
}

.top-margin {
    margin-top: 90px;
}

.left-margin {
    margin-left: 260px;
}

.custom-hr {
    border: 0;
    height: 2px;
    background-color: #ccc; /* 灰色线条 */
    margin: 20px 0;
}