/* 返回顶部 */
.back-to-top {
	position: fixed;
	right: 28px;
	bottom: 36px;
	z-index: 9990;
	display: flex;
	flex-direction: column;
	align-items: center;
	justify-content: center;
	gap: 4px;
	min-width: 56px;
	padding: 12px 10px 10px;
	border: 1px solid rgba(0, 161, 233, 0.55);
	border-radius: 4px;
	background: linear-gradient(145deg, rgba(12, 39, 72, 0.92) 0%, rgba(21, 74, 122, 0.88) 100%);
	box-shadow:
		0 0 20px rgba(0, 161, 233, 0.25),
		0 4px 16px rgba(10, 31, 61, 0.35),
		inset 0 1px 0 rgba(255, 255, 255, 0.08);
	backdrop-filter: blur(8px);
	-webkit-backdrop-filter: blur(8px);
	color: #e0f4ff;
	cursor: pointer;
	opacity: 0;
	visibility: hidden;
	transform: translateY(12px);
	transition:
		opacity 0.35s ease,
		visibility 0.35s ease,
		transform 0.35s ease,
		border-color 0.25s ease,
		box-shadow 0.25s ease;
	pointer-events: none;
	font-family: inherit;
	line-height: 1.2;
}

.back-to-top::before {
	content: "";
	position: absolute;
	inset: -1px;
	border-radius: inherit;
	padding: 1px;
	background: linear-gradient(135deg, rgba(0, 161, 233, 0.6), transparent 40%, rgba(0, 161, 233, 0.2));
	-webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
	mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
	-webkit-mask-composite: xor;
	mask-composite: exclude;
	pointer-events: none;
	opacity: 0.7;
}

.back-to-top.is-visible {
	opacity: 1;
	visibility: visible;
	transform: translateY(0);
	pointer-events: auto;
}

.back-to-top:hover {
	border-color: rgba(0, 200, 255, 0.85);
	box-shadow:
		0 0 28px rgba(0, 161, 233, 0.45),
		0 6px 20px rgba(10, 31, 61, 0.4),
		inset 0 1px 0 rgba(255, 255, 255, 0.12);
	color: #fff;
}

.back-to-top:active {
	transform: translateY(2px);
}

.back-to-top.is-visible:active {
	transform: translateY(2px);
}

.back-to-top__icon {
	display: flex;
	align-items: center;
	justify-content: center;
	width: 22px;
	height: 22px;
	filter: drop-shadow(0 0 6px rgba(0, 161, 233, 0.6));
}

.back-to-top__icon svg {
	width: 100%;
	height: 100%;
	fill: none;
	stroke: #00c8ff;
	stroke-width: 2.2;
	stroke-linecap: round;
	stroke-linejoin: round;
}

.back-to-top:hover .back-to-top__icon svg {
	stroke: #5ee4ff;
}

.back-to-top__text {
	font-size: 11px;
	letter-spacing: 0.06em;
	white-space: nowrap;
	color: rgba(224, 244, 255, 0.95);
	text-shadow: 0 0 8px rgba(0, 161, 233, 0.4);
}

@media (max-width: 768px) {
	.back-to-top {
		right: 16px;
		bottom: 24px;
		min-width: 48px;
		padding: 10px 8px 8px;
	}

	.back-to-top__text {
		font-size: 10px;
	}
}