gnome-shell/data/theme/gnome-shell-sass/widgets/_login-dialog.scss

/* Login Dialog */

.login-dialog-banner-view {
	padding-top: 24px;
	max-width: 23em;
}

.login-dialog {
	//reset
	border: none;
	background-color: transparent;

	$_gdm_bg: lighten(#2e3436, 19%);

	StEntry {
		@extend %search_entry;
		border-radius: $base_border_radius;
		@if $variant=='dark' {
			$_gdm_entry_bg: transparentize(lighten(desaturate(#241f31, 20%), 2%), 0.5);
			background-color: $_gdm_entry_bg;
			border-color: $_gdm_entry_bg;    
			color: $osd_fg_color;
		}
	}

	.modal-dialog-button-box { spacing: 3px; }
	.modal-dialog-button {
		padding: 4px 18px;
		box-shadow: 0 1px 3px rgba(0,0,0,0.2);
		background-color: $_gdm_bg;
		border-color: $_gdm_bg;
		color: $fg_color;

		$_hover_c: lighten($_gdm_bg, 5%);
		&:hover, &:focus {
			background-color: $_hover_c;
			border-color: $_hover_c;
		}
		&:active {
			$_active_c: darken($_gdm_bg, 5%);
			box-shadow: none;
			background-color: $_active_c;
			border-color: $_active_c;
		}
		&:insensitive {
			@include button(insensitive);
			border-color: darken($_gdm_bg, 5%);
			background-color: darken($_gdm_bg, 5%);
			color: transparentize($fg_color, 0.3);
		}
		&:default {
			@include button(normal, $c:$selected_bg_color, $tc:$selected_fg_color);
			border-color: $selected_bg_color;
			&:hover, &:focus { 
				@include button(hover,$c:$selected_bg_color, $tc:$selected_fg_color);
				$_def_hover_c: lighten($selected_bg_color, 5%);
				background-color: $_def_hover_c;
				border-color: $_def_hover_c;
			}
			&:active {
				@include button(active,$c:$selected_bg_color, $tc:$selected_fg_color);
				$_def_active_c: darken($selected_bg_color, 5%);
				background-color: $_def_active_c;
				border-color: $_def_active_c;
			}
			&:insensitive {
				@include button(insensitive);
				border-color: darken($selected_bg_color, 10%);
				background-color: darken($selected_bg_color, 10%);
				color: transparentize($selected_fg_color, 0.3);
			}
		}
	}
}

.login-dialog-logo-bin { padding: 24px 0px; }
.login-dialog-banner { color: darken($osd_fg_color,10%); }
.login-dialog-button-box { spacing: 5px; }
.login-dialog-message-warning { color: $warning_color; }
.login-dialog-message-hint { padding-top: 0; padding-bottom: 20px; }
.login-dialog-user-selection-box { padding: 100px 0px; }
.login-dialog-not-listed-label {
	padding-left: 2px;
	.login-dialog-not-listed-button:focus &,
	.login-dialog-not-listed-button:hover & {
		color: $osd_fg_color;
	}
}

.login-dialog-not-listed-label {
	font-size: 90%;
	font-weight: bold;
	color: darken($osd_fg_color,30%);
	padding-top: 1em;
}

.login-dialog-user-list-view { -st-vfade-offset: 1em; }
.login-dialog-user-list {
	spacing: 12px;
	width: 23em;
	&:expanded .login-dialog-user-list-item:selected { background-color: $selected_bg_color; color: $selected_fg_color; }
	&:expanded .login-dialog-user-list-item:logged-in { border-right: 2px solid $selected_bg_color; }
}

.login-dialog-user-list-item {
	border-radius: 5px;
	padding: 6px;
	color: darken($osd_fg_color,30%);
	&:ltr .user-widget { padding-right: 1em; }
	&:rtl .user-widget { padding-left: 1em; }
	.login-dialog-timed-login-indicator {
		height: 2px;
		margin-top: 6px;
		background-color: $osd_fg_color;
	}
	&:focus .login-dialog-timed-login-indicator { background-color: $selected_fg_color; }
}

.login-dialog-username,
.user-widget-label {
	color: $osd_fg_color;
	font-size: 120%;
	font-weight: bold;
	text-align: left;
	padding-left: 15px;
}

.user-widget-label {
	&:ltr { padding-left: 14px; }
	&:rtl { padding-right: 14px; }
}

.login-dialog-prompt-layout {
	padding-top: 24px;
	padding-bottom: 12px;
	spacing: $base_spacing * 2;
	width: 23em;
}

.login-dialog-prompt-label {
	color: darken($osd_fg_color, 20%);
	font-size: 110%;
	padding-top: 1em;
}

.login-dialog-session-list-button StIcon {
	icon-size: 1.25em;
}

.login-dialog-session-list-button {
	color: darken($osd_fg_color,30%);
	&:hover,&:focus { color: $osd_fg_color; }
	&:active { color: darken($osd_fg_color, 50%); }
}