Rocket.Chat/app/threads/client/threads.css

.message.thread-main {
	padding-top: var(--default-padding);
	padding-bottom: var(--default-padding);

	border-bottom: 1px solid var(--color-gray-light);
}

.message.sequential[data-tmid] > .thread-replied > .thumb,
.message.sequential.system[data-tmid] > .thumb {
	display: block;
}

.message.sequential[data-tmid] > .message-body-wrapper > .title {
	display: none;
}

.message.thread-message {
	padding-top: 16px;
	padding-bottom: 8px;
}

.thread-message + .thread-message {
	border-top: 1px solid var(--color-gray-light);
}

.thread-empty {
	padding: calc(2 * var(--default-padding));
}

.thread-list {
	overflow: auto;

	word-wrap: break-word;
	flex-shrink: 1;
}

.message {
	& .thread-replied {

		display: inline-flex;

		display: flex;

		cursor: pointer;

		white-space: nowrap;
		text-overflow: ellipsis;

		color: var(--rc-color-link-active);

		align-items: baseline;
		flex-flow: row nowrap;
	}

	.thread-icons {
		display: block;
		flex: 0 0 20px;

		width: 20px;

		&--thread {
			position: absolute;
			left: 40px;

			width: 20px;
			height: 20px;

			color: var(--rc-color-alert-message-primary);
		}

		&--bell,
		&--bell-off {
			cursor: pointer;

			color: #a0a0a0;

			font-size: 1rem;
		}
	}

	& > .thread-quote {

		display: flex;

		margin: calc((var(--default-padding) /2) - 6px) 0 7px 0;
		align-items: center;
	}

	.thread-quote__message {

		display: flex;

		overflow: hidden;

		cursor: pointer;

		white-space: nowrap;
		text-overflow: ellipsis;

		color: var(--rc-color-alert-message-primary);

		align-items: center;

		> .message-body--unstyled {
			overflow: hidden;

			text-overflow: ellipsis;
		}
	}

	& .thread-reply-preview {
		display: none;
		overflow: hidden;

		white-space: nowrap;
		text-overflow: ellipsis;
	}

	&.collapsed .thread-reply-preview {
		display: inline;
	}
}

.message.collapsed + .message.system:not(.collapsed):not(.new-day) {
	margin-top: calc(var(--default-padding) / 2);
	margin-bottom: calc(var(--default-padding) / 2);
}

.message.collapsed + .message:not(.collapsed):not(.new-day) {
	margin-top: calc(var(--default-padding) / 2);
}

.message.collapsed > .thread-replied > .thumb {
	bottom: 0;
	left: 40px;

	width: 20px;
	height: 20px;
	margin-top: auto;
	margin-bottom: auto;
	margin-left: 0;

	& .avatar {
		width: 20px;
		height: 20px;
	}
}

.message.sequential .thread-quote {
	display: none;
}

@media (width < 500px) {
	.message {
		& .title {
			flex-wrap: wrap;
		}

		& .thread-replied {
			flex-basis: 100%;
		}
	}
}

.contextual-bar__content.thread,
.contextual-bar__content.threads {
	padding: 0;
}