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.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;
		overflow: hidden;

		margin-left: 3px;

		cursor: pointer;

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

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

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

		& .rc-icon {
			position: relative;
			bottom: -0.15rem;

			min-width: 18px;
		}

		& .thread-quote {
			overflow: hidden;

			max-width: 200px;

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

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

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

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

.compact .message.collapsed {
	& .thread-replied {
		& .thread-reply-switch,
		& .thread-reply-preview {
			display: none;
		}
	}
}

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

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

.message.sequential > .body > .thread-replied {
	display: none;
}

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