Initial avatar

HTML

<div class="initial-avatar">...</div>

CSS

.initial-avatar {
    /* Center the content */
    align-items: center;
    display: flex;
    justify-content: center;

    /* Colors */
    background-color: #d1d5db;
    color: #fff;

    /* Rounded border */
    border-radius: 50%;
    height: 3rem;
    width: 3rem;
}