style.css

/* Show it is fixed to the top */
body {
    padding-top: 4.5rem;
}

/* sidebar */

.bd-sidebar {
    -ms-flex-order: 0;
    order: 0;
}

@media (min-width: 768px) {
    @supports ((position:-webkit-sticky) or (position:sticky)) {
        .bd-sidebar {
            position: -webkit-sticky;
            position: sticky;
            top: 4.5rem;
            z-index: 1000;
            height: calc(100vh - 4.5rem)
        }
    }
}

/*
 * Footer
 */
.blog-footer {
    padding: 2rem 0;
    color: #727272;
    text-align: center;
    background-color: #f9f9f9;
    border-top: .05rem solid #e5e5e5;
}

.blog-footer p:last-child {
    margin-bottom: 0;
}


/*
* flex
*/

.list-item-flex {
    flex: 1;
    overflow: hidden;
}

.list-item-flex .paper-main {
    flex: 1;
    word-break: break-word; /*重点加这句，换行*/
}

.list-item-flex .paper-date {
    flex: 0 0 95px;
}

.paper-date-inner {
    display: block;
}

.paper-date {
    display: none;
}

@media (min-width: 768px) {
    .paper-date-inner {
        display: none;
    }

    .paper-date {
        display: block;
    }
}