nextcloud-server/apps/theming/css/theming.scss

/** Calculate luma as it is also used in OCA\Theming\Util::calculateLuma */
@function luma($c) {
	$-local-red: red(rgba($c, 1.0));
	$-local-green: green(rgba($c, 1.0));
	$-local-blue: blue(rgba($c, 1.0));

	@return (0.2126 * $-local-red  + 0.7152 * $-local-green + 0.0722 * $-local-blue) / 255;
}

@mixin faded-background {
	background-color: $color-primary;

	@if ($color-primary == #0082C9) {
		background-image: linear-gradient(40deg, $color-primary 0%, lighten($color-primary, 20%) 100%);
	} @else {
		/** This will be overwritten by the faded-background-image mixin if needed */
		background-image: none;
	}
}

@mixin faded-background-image {
	@include faded-background;
	background-size: contain;

	@if ($color-primary == #0082C9) {
		background-image: $image-login-background, linear-gradient(40deg, $color-primary 0%, lighten($color-primary, 20%) 100%);
	}

	@if($has-custom-background == true) {
		background-size: cover;
		background-repeat: no-repeat;
		background-image: $image-login-background;
	}
}

$has-custom-background: variable_exists('theming-background-mime') and $theming-background-mime != '';
$has-custom-logo: variable_exists('theming-logo-mime') and $theming-logo-mime != '';
$invert: luma($color-primary) > 0.6;

@if ($has-custom-logo == false) {
	@if ($invert) {
		$image-logo: url(icon-color-path('logo', 'logo', #000000, 1, true));
	} @else {
		$image-logo: url(icon-color-path('logo', 'logo', #ffffff, 1, true));
	}
}

.nc-theming-main-background {
	background-color: $color-primary;
}

.nc-theming-main-text {
	color: $color-primary-text;
}

.nc-theming-contrast {
	color: $color-primary-text;
}

@if ($invert) {
	// too bright, use dark text to mix the primary
	$color-primary-light: mix($color-primary, $color-main-text, 10%);

	#appmenu:not(.inverted) svg {
		filter: invert(1);
	}
	#appmenu.inverted svg {
		filter: none;
	}
	.searchbox input[type="search"] {
		background-repeat: no-repeat;
		background-position: 6px center;
		background-color: transparent;
		@include icon-color('search', 'actions', $color-black, 1, true);
	}
	#contactsmenu .icon-contacts {
		@include icon-color('contacts', 'places', $color-black, 1, true);
	}
	#settings .icon-settings-white {
		@include icon-color('settings', 'actions', $color-black, 1, true);
	}
	#appmenu .icon-more-white {
		@include icon-color('more', 'actions', $color-black, 1, true);
	}
} @else {
	#appmenu:not(.inverted) svg {
		filter: none;
	}
	#appmenu.inverted svg {
		filter: invert(1);
	}
}

/* Colorized svg images */
.icon-file, .icon-filetype-text {
	background-image: url(./img/core/filetypes/text.svg?v=#{$theming-cachebuster});
}

.icon-folder, .icon-filetype-folder {
	background-image: url(./img/core/filetypes/folder.svg?v=#{$theming-cachebuster});
}

.icon-filetype-folder-drag-accept {
	background-image: url(./img/core/filetypes/folder-drag-accept.svg?v=#{$theming-cachebuster}) !important;
}

#theming-preview-logo,
#header .logo {
	background-image: $image-logo;
}

#body-user #header, #body-settings #header, #body-public #header {
	@include faded-background;
}

#body-login,
#firstrunwizard .firstrunwizard-header,
#theming-preview {
	@include faded-background-image;
}

/* override styles for login screen in guest.css */
@if ($has-custom-logo) {
	// custom logo
	#theming-preview-logo,
	#header .logo {
		background-size: contain;
	}

	#body-login #header .logo {
		margin-bottom: 22px;
	}
} @else {
	// default logo
	@if ($invert) {
		#theming-preview-logo,
		#header .logo {
			opacity: .6;
		}
	}
}

@if variable_exists('theming-logoheader-mime') and $theming-logoheader-mime != '' {
	#theming .advanced-option-logoheader .image-preview,
	body:not(#body-login) #header .logo {
		background-image: $image-logoheader;
	}
} @else {
	#theming .advanced-option-favicon .image-preview {
		background-image: none;
	}
}

@if variable_exists('theming-favicon-mime') and $theming-favicon-mime != '' {
	#theming .advanced-option-favicon .image-preview {
		background-image: $image-favicon;
	}
} @else {
	#theming .advanced-option-favicon .image-preview {
		background-image: none;
	}
}

input.primary,
#alternative-logins li a {
	background-color: $color-primary-element;
	border: 1px solid $color-primary-text;
	color: $color-primary-text;
}

@if ($invert) {
	#body-login {
		.body-login-container {
			background-color: transparentize(nc-lighten($color-primary, 30%), 0.2);
			color: $color-primary-text !important;

			h2 {
				color: $color-primary-text;
			}
			.icon-search.icon-white {
				// CSS variable is not used here since it is on the public page layout,
				// where the dark theme doesn't apply at the moment
				background-image: url('../../../core/img/actions/search.svg');
			}
		}

		input,
		#alternative-logins li a {
			border: 1px solid nc-lighten($color-primary-text, 50%);
		}
		input.primary,
		button.primary,
		#alternative-logins li a {
			background-color: $color-primary;
			color: $color-primary-text;
		}
		a,
		label,
		footer p,
		#alternative-logins legend,
		.lost-password-container #lost-password,
		.warning, .update, .error {
			color: $color-primary-text !important;
		}
		input[type='checkbox'].checkbox--white + label:before {
			border-color: nc-darken($color-primary-element, 40%) !important;
		}
		input[type='checkbox'].checkbox--white:not(:disabled):not(:checked) + label:hover:before,
		input[type='checkbox'].checkbox--white:focus + label:before {
			border-color: nc-darken($color-primary-element, 30%) !important;
		}
		input[type='checkbox'].checkbox--white:checked + label:before {
			border-color: nc-darken($color-primary-element, 30%) !important;
			background-color: nc-darken($color-primary-element, 30%) !important;
			@include icon-color('checkbox-mark', 'actions', $color-white, 1, true);
		}
		#submit-wrapper .icon-confirm-white {
			background-image: url('../../../core/img/actions/confirm.svg');
		}

		.two-factor-provider {
			&:hover, &:focus {
				border-color: $color-primary-text;
			}
			img {
				filter: invert(1);
			}
		}
	}
	#body-public #header .icon-more-white {
		background-image: var(--icon-more-000);
	}
}

// plain background color for login page
@if $image-login-plain == 'true' {
	#body-login, #firstrunwizard .firstrunwizard-header, #theming-preview {
		background-image: none !important;
	}
	#body-login {

		a, label, p {
			color: $color-primary-text;
		}

	}
}

/** Handle primary buttons for bright colors */
@if (luma($color-primary) > 0.8) {
	select,
	button, .button,
	input:not([type='range']),
	textarea,
	div[contenteditable=true],
	.pager li a {
		&.primary:not(:disabled) {
			background-color: var(--color-background-dark);
			color: var(--color-main-text);
			border-color: var(--color-text-lighter);

			&:hover, &:focus, &:active {
				background-color: var(--color-background-darker);
				color: var(--color-main-text);
				border-color: var(--color-text);
			}
		}
	}

}

@if ($color-primary == #ffffff) {
	/* show grey border below header */
	#body-user #header,
	#body-settings #header,
	#body-public #header {
		border-bottom: 1px solid #ebebeb;
	}

	/* show triangle in header in grey */
	#appmenu li a.active:before,
	.header-right #settings #expand:before {
		border-bottom-color:#ebebeb;
	}

	/* show border around quota bar in files app */
	.app-files #quota .quota-container {
		border: 1px solid #ebebeb;
	}
}

@if ($has-legal-links == 'true') {
	footer {
		height: 92px;
	}
}