Styling improvements for the ACX Substack. To load into Safari, copy the ones you want into a file, then go to Preferences > Advanced > Style sheet and select your file.

fixed_header.css

/* Fixes the header to the top of the page */

div#entry > div#main .main-menu-content {
    position: relative !important;
    top: 0 !important;
}

div#entry > div#main .main-menu .backdrop {
    position: fixed !important;
}

div#entry > div#main .topbar-replacement {
    display: none;
}

div#entry > div#main .comment .comment-anchor {
    top: 0 !important;
}

hide_reactions.css

/* Hides reactions */

div#entry > div#main .comment-actions span:first-child {
    display: none;
}

div#entry > div#main .comment-actions span:nth-child(2) {
    margin-left: 0 !important;
}

ssc_style.css

/* Makes ACX look like the old SSC */

div#entry > div#main {
    -webkit-font-smoothing: auto !important;
}

div#entry > div#main article div p {
    color: #333 !important;
    font: 12px/20px Verdana, sans-serif !important;
}

div#entry > div#main h1.post-title.short.unpublished {
    font-size: 16px !important;
    line-height: 1.3em !important;
    margin-bottom: 10px !important;
    text-transform: uppercase !important;
    letter-spacing: 1px !important;
    font-family: Georgia, "Bitstream Charter", serif !important;
}

div#entry > div#main td.post-meta-item.post-date {
    color: #888 !important;
    font-size: 10px !important;
    font-family: Verdana, sans-serif !important;
    letter-spacing: 1px !important;
    background: #f9f9f9 !important;
    border: 1px solid #eee !important;
    padding: 5px 7px !important;
    display: inline !important;
    text-transform: uppercase !important;
    text-shadow: 1px 1px 1px #fff !important;
}

div#entry > div#main td.post-meta-item.post-date:before {
    content: "Posted " !important;
}

div#entry > div#main td.post-meta-item.post-date:after {
    content: " by Scott Alexander" !important;
}

div#entry > div#main .single-post {
    border: 1px solid #d5d5d5 !important;
    border-radius: 10px !important;
    background: #fff !important;
    padding: 20px 28px !important;
    margin-bottom: 10px !important;
}

div#entry > div#main .single-post-container {
    background: #f0f0f0 !important;
    padding: 10px 0px !important;
}

div#entry > div#main .single-post a {
    color: #0066cc !important;
    text-decoration: underline !important;
}

div#entry > div#main .post {
    padding: 0 !important;
}

div#entry > div#main blockquote {
    border-left: 4px solid #ddd !important;
    margin: 0 2em !important;
    padding: 0 1em !important;
}

div#entry > div#main blockquote p {
    margin-left: 0 !important;
    font-family: Georgia, "Bitstream Charter", serif !important;
    font-style: italic !important;
    font-size: 13px !important;
    line-height: 24px !important;
    color: #333 !important;
}

div#entry > div#main .subtitle {
    font-size: 12px !important;
    padding-bottom: 8px !important;
}

div#entry > div#main .main-menu .topbar .container .headline {
    text-decoration: none !important;
}

div#entry > div#main .main-menu .topbar .container .headline .name {
    font-size: 43px !important;
    max-height: 100px !important;
    color: white !important;
    font-family: 'Raleway', Open Sans, Arial, sans-serif !important;
    text-align: center !important;
    letter-spacing: 2px !important;
    text-decoration: none !important;
}

div#entry > div#main .topbar {
    background: linear-gradient(to bottom, rgba(139,171,232,1) 0%, rgba(79,115,193,1) 100%) !important;
    text-decoration: none !important;
}

div#entry > div#main button.button.primary.subscribe-cta.subscribe-btn {
    display: none !important;
}

div#entry > div#main .full-container-border {
    display: none !important;
}

div#entry > div#main .comments-page > .container {
    background-color: white !important;
    justify-content: center !important;
    border: 1px solid #d5d5d5 !important;
    border-radius: 10px !important;
    padding: 25px !important;
}

div#entry > div#main .comments-page .container .comments-heading {
    margin-top: 0 !important;
}

@media screen and (min-width: 768px) {
    div#entry > div#main .comments-page > .container {
        width: 675px !important;
    }
}

div#entry > div#main div.buttons.notification-container {
    filter: brightness(3) !important;
    transform: scale(.7)
}

div#entry > div#main img.logo {
    margin-right: 30px !important;
}

div#entry > div#main button.comments-page-sort-menu-button {
    background: transparent !important;
}

div#entry > div#main table.comment-content tr td {
    border: 1px solid #ddd !important;
    padding: 10px !important;
    border-radius: 10px !important;
    flex-grow: 1 !important;
    background: #fafafa !important;
}

div#entry > div#main table.comment-content.new-comment tr td {
     border: 2px solid #5a5 !important;
}

div#entry > div#main table.comment-content tr td.comment-head {
    border: none !important;
    flex-grow: 0 !important;
    background: white !important;
}

div#entry > div#main table tr {
    display: flex !important;
}

div#entry > div#main td.post-meta-item.icon {
    margin-left: 10px !important;
}

div#entry > div#main .comments-page {
    background: #f0f0f0 !important;
    padding-top: 10px !important;
}

div#entry > div#main .comment-meta span:first-child a {
    font-family: Verdana, sans-serif !important;
    font-weight: bold !important;
    color: black !important;
    text-decoration: none !important;
}

div#entry > div#main .comment-meta span:first-child  a:after {
    content: " says:" !important;
    font-weight: normal;
    font-style: italic;
}

div#entry > div#main .comment-meta span:nth-child(2) {
    display: block !important;
    padding-bottom: 10px !important;
    margin-left: 0 !important;
}

div#entry > div#main .comment-meta span:nth-child(2) a {
    font-family: Georgia, "Bitstream Charter", serif !important;
    color: #888 !important;
    text-decoration: none !important;
}

div#entry > div#main .comment-meta span:nth-child(2) a:before {
    content: "\a" !important;
    white-space: pre !important;
}

div#entry > div#main .comment-meta .highlight {
    margin-left: 0 !important;
}

div#entry > div#main .comment-body p {
    font: 12px/20px Verdana, sans-serif !important;
    color: #333 !important;
}

div#entry > div#main .comment-actions span a {
    color: #888 !important;
}

div#entry > div#main .comment.selected > .comment-content > tr > td:nth-child(2) {
    background: #de912d2c !important;
}

div#entry > div#main .comment.selected > .comment-content::before {
    background: inherit !important;
}

div#entry > div#main .profile-img-wrap img {
    border-radius: 0px !important;
    height: 40px !important;
    width: 40px !important;
    position: relative !important;
    right: 8px !important;
}