Firefox settings and extensions

about:config prefs

# Disable about:config warning
general.warnOnAboutConfig -> false

# Start up with tabs from last session
browser.startup.page -> 3

# Use blank new tab page
browser.newtabpage.enabled -> false

# Denser UI
browser.uidensity -> 1

# Make Linux Firefox URL bar behavior match Chrome and Windows Firefox
browser.urlbar.clickSelectsAll -> true
browser.urlbar.doubleClickSelectsAll -> false

# Enable autoscroll on Linux
general.autoScroll -> true

# Disable smooth scroll
general.smoothScroll -> false

# Disable incredibly slow fullscreen animation
toolkit.cosmeticAnimations.enabled -> false

# Enable WebRender (use about:support to confirm that it works)
gfx.webrender.enabled -> true

# Don't show menu bar when holding down Alt
ui.key.menuAccessKeyFocuses -> false

# Unnecessary with uBlock Origin installed
browser.contentblocking.enabled -> false

# Disable default search
# Firefox has the same issue as https://bugs.chromium.org/p/chromium/issues/detail?id=791259
# Use a bookmark keyword to search instead
keyword.enabled -> false

# Disable Pocket
extensions.pocket.enabled -> false

# Wrap long lines in 'View source'
view_source.wrap_long_lines -> true

# "Privacy"
beacon.enabled -> false
browser.chrome.errorReporter.enabled -> false
datareporting.healthreport.uploadEnabled -> false
browser.search.suggest.enabled -> false

userChrome.css

@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);

/**
 * https://userstyles.org/styles/131235/firefox-autocomplete-prioritize-url
 */
@-moz-document url(chrome://browser/content/browser.xul)
{
	richlistbox.autocomplete-richlistbox {
		max-height: 310px !important;
	}

	.ac-type-icon, .ac-site-icon:not([type="insecureWarning"]) {
		/* for all awesomebar suggestions icons (except those for contextual feedback on insecure passwords) */
		margin-top: 6px;
	}

	.ac-site-icon[type="insecureWarning"], .ac-site-icon[type="login"] {
		/* for the icons in contextual feedback on insecure passwords */
		margin-top: 0;
	}

	/*.ac-title,*/ .ac-separator, .ac-url, .ac-action {
		font-size: 14px !important;
	}

	.autocomplete-richlistitem[collapsed="true"] {
		height: 0 !important;
		min-height: 0 !important;
	}

	.autocomplete-richlistitem[type="favicon"] .ac-title,
	.autocomplete-richlistitem[type="favicon"] .ac-separator,
	.autocomplete-richlistitem[type="favicon"] .ac-url,
	.autocomplete-richlistitem[type="bookmark"] .ac-title,
	.autocomplete-richlistitem[type="bookmark"] .ac-separator,
	.autocomplete-richlistitem[type="bookmark"] .ac-url {
		height: 16px;
		margin-top: 6px;
	}

	.autocomplete-richlistitem[type="favicon"],
	.autocomplete-richlistitem[type="bookmark"] {
		display: flex;
	}

	.autocomplete-richlistitem[type="favicon"],
	.autocomplete-richlistitem[type="bookmark"] {
		display: flex;
	}

	.autocomplete-richlistitem[type="favicon"] .ac-title,
	.autocomplete-richlistitem[type="bookmark"] .ac-title {
		order: 3;
	}

	.ac-title-text {
	}

	.ac-tags {
	}

	.autocomplete-richlistitem[type="favicon"] .ac-separator,
	.autocomplete-richlistitem[type="bookmark"] .ac-separator {
		order: 2;
		-moz-margin-start: 6px;
		-moz-margin-end: 6px;
	}

	.autocomplete-richlistitem[type="favicon"] .ac-url,
	.autocomplete-richlistitem[type="bookmark"] .ac-url {
		order: 1;
	}

	.ac-url-text {
	}

	.ac-action {
	}

	.autocomplete-richlistitem[type="switchtab"] .ac-type-icon,
	.autocomplete-richlistitem[type="switchtab"] .ac-site-icon,
	.autocomplete-richlistitem[type="searchengine"] .ac-type-icon,
	.autocomplete-richlistitem[type="searchengine"] .ac-site-icon,
	.autocomplete-richlistitem[actiontype="visiturl"] .ac-type-icon,
	.autocomplete-richlistitem[actiontype="visiturl"] .ac-site-icon {
		margin-top: 0;
	}

	.autocomplete-richlistitem[type="switchtab"] .ac-separator,
	.autocomplete-richlistitem[type="switchtab"] .ac-action,
	.autocomplete-richlistitem[type="switchtab"] .ac-url,
	.autocomplete-richlistitem[type="searchengine"] .ac-separator,
	.autocomplete-richlistitem[type="searchengine"] .ac-action,
	.autocomplete-richlistitem[type="searchengine"] .ac-url,
	.autocomplete-richlistitem[actiontype="visiturl"] .ac-separator,
	.autocomplete-richlistitem[actiontype="visiturl"] .ac-action,
	.autocomplete-richlistitem[actiontype="visiturl"] .ac-url {
		margin-bottom: 0;
	}

	.autocomplete-richlistitem[type="favicon"] .ac-url-text,
	.autocomplete-richlistitem[type="bookmark"] .ac-url-text {
		max-width: none !important;
		/* or initial*/;
	}
}


/**
 * Hide the horizontal tabs at the top of the browser
 * https://github.com/piroor/treestyletab/wiki/Code-snippets-for-custom-style-rules#hide-horizontal-tabs-at-the-top-of-the-window-1349
 */
#main-window[tabsintitlebar="true"]:not([extradragspace="true"]) #TabsToolbar {
	opacity: 0;
	pointer-events: none;
}
#main-window:not([tabsintitlebar="true"]) #TabsToolbar {
	visibility: collapse !important;
}

/**
 * Hide the "Tree Style Tab" header at the top of the sidebar
 * https://github.com/piroor/treestyletab/wiki/Code-snippets-for-custom-style-rules#hide-the-tree-style-tab-header-at-the-top-of-the-sidebar
 */
#sidebar-box[sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"] #sidebar-header {
	display: none;
}

/**
 * Hide the sidebar when fullscreen
 * https://github.com/piroor/treestyletab/issues/1548#issuecomment-345411610
 */
#main-window[inFullscreen] #sidebar-box,
#main-window[inFullscreen] #sidebar-splitter {
	display: none !important;
	width: 0px !important;
}

userContent.css

@namespace url(http://www.w3.org/1999/xhtml);

@-moz-document url-prefix("about:reader?") {
	body.sepia {
		/* Increase text contrast */
		color: unset !important;
	}
}

Addons:

https://addons.mozilla.org/en-US/firefox/addon/ublock-origin/
https://addons.mozilla.org/en-US/firefox/addon/tree-style-tab/
https://addons.mozilla.org/en-US/firefox/addon/violentmonkey/
https://addons.mozilla.org/en-US/firefox/addon/old-reddit-redirect/
https://addons.mozilla.org/en-US/firefox/addon/restore-old-theme-of-youtube/
https://addons.mozilla.org/en-US/firefox/addon/simple-translate/
https://addons.mozilla.org/en-US/firefox/addon/who-stole-my-pictures/
https://addons.mozilla.org/en-US/firefox/addon/rikaichamp/
https://addons.mozilla.org/en-US/firefox/addon/skip-redirect/ (beware, default behavior breaks Google Translate and Wayback)