youtube.com.user.css

/** Override subtitle font **/

.ytp-caption-segment {
  font-family: Ubuntu, sans-serif !important;
}

/** Enforce 4 videos per row **/

ytd-rich-grid-renderer {
  --ytd-rich-grid-items-per-row: 4 !important;
  --ytd-rich-grid-posts-per-row: 4 !important;
}

/** Fit more videos in subscription page's Shorts section **/

[page-subtype="subscriptions"] ytd-rich-shelf-renderer {
  --ysc-video-per-row: 5 !important;
    
  &:has(.button-container:last-child:not([hidden])) {
    --ysc-video-per-row: 6 !important;
  }
}

/** Remove video player's border radius **/

ytd-watch-flexy[rounded-player] #ytd-player.ytd-watch-flexy {
  border-radius: 0 !important;
}

/** Fix avatar of recommended channel in sidebar **/

#avatar-section.ytd-channel-renderer {
  min-width: unset !important;
  flex: unset !important;
}

#avatar.ytd-channel-renderer {
  width: unset !important;
}

#info-section.ytd-channel-renderer {
  flex-direction: column !important;
}

/** Fix dismissed videos height **/

#dismissed.ytd-compact-video-renderer {
  max-height: 94px;
  box-sizing: border-box;
}

#dismissed.ytd-compact-video-renderer #text.ytd-notification-multi-action-renderer {
  margin: 0 8px;
}

ytd-item-section-renderer {
  .ytNotificationMultiActionRendererHost {
    height: 94.5px;
    box-sizing: border-box;
    padding: 3px 6px;
  }

  .ytNotificationMultiActionRendererTextContainer {
    margin-bottom: 0;

    .yt-core-attributed-string--white-space-pre-wrap {
      font-size: .85em;
    }
  }

  .ytNotificationMultiActionRendererButton {
    padding: 3px 0;

    .yt-spec-button-shape-next--size-m {
      height: 24px;
    }
  }
}

/** Ext: Return Youtube Dislike **/

:root {
  --colorful-rating-bar-like-color: #3ea6ff;
  --colorful-rating-bar-dislike-color: #ff2929;
}

.ryd-tooltip-bar-container {
  height: 4px !important;
  top: -9px !important;
}

#ryd-bar {
  background: var(--colorful-rating-bar-like-color) !important;
}

#ryd-bar-container {
  background: var(--colorful-rating-bar-dislike-color) !important;
  height: 100% !important;
}

/* liked button */
like-button-view-model [aria-pressed="true"] {
  .yt-spec-button-shape-next__button-text-content {
    color: var(--colorful-rating-bar-like-color) !important;
  }

  yt-animated-icon path,
  .yt-spec-icon-shape path {
    fill: var(--colorful-rating-bar-like-color) !important;
  }
}

ytd-toggle-button-renderer#like-button [aria-pressed="true"] {
  .yt-spec-button-shape-next__icon path {
    fill: var(--colorful-rating-bar-like-color) !important;
  }
  
  & + .yt-spec-button-shape-with-label__label {
    color: var(--colorful-rating-bar-like-color) !important;
  }
}

/* disliked button */
dislike-button-view-model [aria-pressed="true"] {
  .yt-spec-button-shape-next__button-text-content {
    color: var(--colorful-rating-bar-dislike-color) !important;
  }

  yt-animated-icon path,
  .yt-spec-icon-shape path {
    fill: var(--colorful-rating-bar-dislike-color) !important;
  }
}

ytd-toggle-button-renderer#dislike-button [aria-pressed="true"] {
  .yt-spec-button-shape-next__icon path {
    fill: var(--colorful-rating-bar-dislike-color) !important;
  }
  
  & + .yt-spec-button-shape-with-label__label {
    color: var(--colorful-rating-bar-dislike-color) !important;
  }
}

/* comments liked/disliked buttons */
#like-button.ytd-comment-engagement-bar [aria-pressed="true"] path {
  fill: var(--colorful-rating-bar-like-color);
}

#dislike-button.ytd-comment-engagement-bar [aria-pressed="true"] path {
  fill: var(--colorful-rating-bar-dislike-color);
}

/** Watched videos **/

ytd-thumbnail:has(#progress[style="width: 100%;"]),
yt-thumbnail-view-model:has(.ytThumbnailOverlayProgressBarHostWatchedProgressBarSegment[style="width: 100%;"]) {
  &::after {
    content: "WATCHED";
    z-index: 2;
    color: white;
    top: 40%;
    font-size: 1.4rem;
    font-weight: 600;
    text-align: center;
    position: absolute;
    width: 100%;
  }

  > #thumbnail,
  > .yt-thumbnail-view-model__image,
  > .ytThumbnailViewModelImage {
    opacity: 0.35;
  }
}

/** Ext: PocketTube **/

/* disable PocketTube's notification */
body > .isa_info.on {
  display: none;
}

/* disable PocketTube's Deck */
#items > .ysm-deck-open {
  display: none;
}

/* disable built-in Subscriptions section */
#sections > ytd-guide-section-renderer:has(+ .yms-block-groups) {
  display: none !important;
}

/* disable built-in sections after PocketTube's, excluding the last one (Settings/Help/etc.) */
#sections > .yms-block-groups ~ ytd-guide-section-renderer:not(:last-child) {
  display: none !important;
}

/* undo stylings related to enforced "N videos per row" in subscriptions page, when modified by PocketTube **/
.ysm-subscription-filter:has(iframe[src*="pockettube"]) {
  ~ #contents.ytd-rich-grid-renderer {
    padding-left: 0 !important;
  }

  ~ * ytd-rich-item-renderer[rendered-from-rich-grid][is-in-first-column] {
    margin-left: 0 !important;
  }

  ~ * #content.ytd-rich-section-renderer {
    margin-left: calc(var(--ytd-rich-grid-item-margin) / 2) !important;
  }
}

/** Ext: Tweaks for YouTube **/

ytd-watch-flexy:not([theater]):not([fullscreen]):not([show-engagement-panel-scrim__]) #secondary-inner {
  height: calc(100vh - var(--ytd-watch-flexy-masthead-height) - var(--ytd-margin-6x));
}


/* fix Clean Page > Home - Header chips */
#frosted-glass.ytd-app {
  height: 56px !important;
}


/** Fix: YouTube-DeepDark: Ambient Mode Support **/

#content ytd-watch-flexy[cinematics-enabled] #cinematics.ytd-watch-flexy {
  display: unset !important;
}

#content ytd-watch-flexy[cinematics-enabled] [class*="ytd-watch-flexy"] {
  background-color: unset !important;
}

Recommended Extensions

• Return YouTube Dislike
  https://www.returnyoutubedislike.com/
• SponsorBlock
  https://sponsor.ajay.app/
• DeArrow
  https://dearrow.ajay.app/
• Tweaks for YouTube
  https://inzk.dev/tweaks-for-youtube/
• BlockTube
  https://github.com/amitbl/blocktube
  Patch while waiting for official update: amitbl/blocktube#569 (comment)

My Userscript

• Hide force-pushed low-view videos
  https://greasyfork.org/en/scripts/535120-youtube-hide-force-pushed-low-view-videos