Make CSS modular

public/css/guestbook.css

@@ -0,0 +1,39 @@
+.guestbook-message blockquote {
+	margin-bottom: var(--space-m);
+	margin-top: var(--space-3xs);
+}
+.guestbook-message p {
+	margin-block: 0 0;
+	position: relative;
+	z-index: 1;
+}
+.guestbook-message p b,
+.guestbook-message p small {
+	font-family: var(--meta-font-family);
+	font-size: var(--meta-font-size);
+	font-variation-settings: var(--meta-font-variation-settings);
+}
+#guestbooks___challenge-answer-container br,
+.guestbooks___input-container br {
+	display: none;
+}
+.guestbook-message-reply {
+	border-left: var(--border-details);
+	margin-left: var(--space-l);
+	margin-top: calc(var(--space-s) * -1);
+	opacity: 0.9;
+	padding-left: var(--space-s);
+	font-style: italic;
+	& blockquote {
+		margin-left: 0;
+	}
+	& blockquote::before {
+		content: "";
+	}
+	& p::before {
+		content: "Reply from ";
+		font-family: var(--meta-font-family);
+		font-size: var(--meta-font-size);
+		font-variation-settings: var(--meta-font-variation-settings);
+	}
+}