WordPress/wp-includes/css/customize-preview.css

.customize-partial-refreshing {
	opacity: 0.25;
	-webkit-transition: opacity 0.25s;
	transition: opacity 0.25s;
	cursor: progress;
}

/* Override highlight when refreshing */
.customize-partial-refreshing.widget-customizer-highlighted-widget {
	-webkit-box-shadow: none;
	box-shadow: none;
}

/* Make shortcut buttons essentially invisible */
.widget button.customize-partial-edit-shortcut,
.customize-partial-edit-shortcut {
	position: relative;
	float: left;
	width: 1px; /* required to have a size to be focusable in Safari */
	height: 1px;
	padding: 0;
	margin: -1px 0 0 -1px;
	border: 0;
	background: transparent;
	color: transparent;
	box-shadow: none;
	outline: none;
	z-index: 5;
}

.customize-partial-edit-shortcut:active {
	padding: 0;
	border: 0;
}

/* Styles for the actual shortcut */
.customize-partial-edit-shortcut:before {
	position: absolute;
	left: -36px;
	color: #fff;
	width: 30px;
	height: 30px;
	font-size: 18px;
	font-family: dashicons;
	content: '\f464';
	z-index: 5;
	background-color: #0085ba;
	border-radius: 50%;
	border: 2px solid #fff;
	box-shadow: 0 2px 1px rgba(46,68,83,0.15);
	text-align: center;
	display: flex;
	flex-direction: row;
	justify-content: center;
	align-items: center;
	cursor: pointer;
	padding: 0;
	animation-fill-mode: both;
	animation-duration: .4s;
	opacity: 0;
	pointer-events: none;
	text-shadow: 0 -1px 1px #006799,
	             1px 0 1px #006799,
	             0 1px 1px #006799,
	             -1px 0 1px #006799;
}

.customize-partial-edit-shortcut:hover:before,
.customize-partial-edit-shortcut:focus:before {
    background: #008ec2; /* matches primary buttons */
	border-color: #191e23; /* provides visual focus style with 4.5 contrast against background color */
}

body.customize-partial-edit-shortcuts-shown .customize-partial-edit-shortcut:before {
	animation-name: customize-partial-edit-shortcut-bounce-appear;
	pointer-events: auto;
}
body.customize-partial-edit-shortcuts-hidden .customize-partial-edit-shortcut:before {
	animation-name: customize-partial-edit-shortcut-bounce-disappear;
	pointer-events: none;
}

body.customize-partial-edit-shortcuts-flash .customize-partial-edit-shortcut:before {
	animation-duration: 1.5s;
	animation-delay: 0.4s;
	animation-name: customize-partial-edit-shortcut-bounce-disappear;
	pointer-events: none;
}

.page-sidebar-collapsed .customize-partial-edit-shortcut:before,
.customize-partial-edit-shortcut-hidden:before {
	visibility: hidden;
}

.customize-partial-edit-shortcut-left-margin:before {
	left: 0;
}

@keyframes customize-partial-edit-shortcut-bounce-appear {
	from, 20%, 40%, 60%, 80%, to {
		animation-timing-function: cubic-bezier(0.215, 0.610, 0.355, 1.000);
	}
	0% {
		opacity: 0;
		transform: scale3d(.3, .3, .3);
	}
	20% {
		transform: scale3d(1.1, 1.1, 1.1);
	}
	40% {
		transform: scale3d(.9, .9, .9);
	}
	60% {
		opacity: 1;
		transform: scale3d(1.03, 1.03, 1.03);
	}
	80% {
		transform: scale3d(.97, .97, .97);
	}
	to {
		opacity: 1;
		transform: scale3d(1, 1, 1);
	}
}

@keyframes customize-partial-edit-shortcut-bounce-disappear {
	from, 20%, 40%, 60%, 80%, to {
		animation-timing-function: cubic-bezier(0.215, 0.610, 0.355, 1.000);
	}
	0% {
		opacity: 1;
		transform: scale3d(1, 1, 1);
	}
	20% {
		transform: scale3d(.97, .97, .97);
	}
	40% {
		opacity: 1;
		transform: scale3d(1.03, 1.03, 1.03);
	}
	60% {
		transform: scale3d(.9, .9, .9);
	}
	80% {
		transform: scale3d(1.1, 1.1, 1.1);
	}
	to {
		opacity: 0;
		transform: scale3d(.3, .3, .3);
	}
}

@media screen and (max-width:800px) {
	.customize-partial-edit-shortcut:before {
		left: -18px; /* Assume there will be less of a margin available on smaller screens */
	}
}