nextcloud/apps/theming/css/theming.scss

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

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

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

/* invert header icons on bright background */
@if (lightness($color-primary) > 50) {
	.searchbox input[type="search"] {
		background: transparent url('../../../core/img/actions/search.svg') no-repeat 6px center;
	}
	#appmenu li a img {
		-webkit-filter: invert(1);
		filter: invert(1);
		filter: progid:DXImageTransform.Microsoft.BasicImage(invert='1');
	}
	#contactsmenu .icon-contacts {
		background-image: url('../../../core/img/places/contacts-dark.svg');
	}
	#settings .icon-settings-white {
		background-image: url('../../../core/img/actions/settings-dark.svg');
	}
}

/* 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;
}

/* override styles for login screen in guest.css */
#header .logo,
#header .logo-icon {
	background-size: contain;
	background-image: url(#{$image-logo});
}

#body-login,
#firstrunwizard .firstrunwizard-header {
	background-image: url(#{$image-login-background});
	background-color: $color-primary;
}

input.primary {
	background-color: nc-lighten($color-primary, .9);
	border: 1px solid $color-primary;
	color: $color-primary-text;
}

@if (lightness($color-primary) > 50) {
	#body-login input.login {
		background-image: url('../../../core/img/actions/confirm.svg');
	}
}