style: 调整文章标题和标题字号及边距样式

src/app.css

@@ -519,7 +519,7 @@ body.single-col .post-list {
 	text-align: center;
 	font-weight: 600;
 	word-break: break-word;
-	font-size: 1.75rem;
+	font-size: 1.6rem;
 	line-height: 1.4;
 	margin: 0 0 0.5rem;
 	color: var(--title-color);
@@ -527,7 +527,7 @@ body.single-col .post-list {
 
 @media screen and (max-width: 767px) {
 	.banner-title .post-title {
-		font-size: 1.35rem;
+		font-size: 1.3rem;
 	}
 }
 
@@ -571,13 +571,13 @@ body.single-col .post-list {
 }
 
 .article-content h1 {
-	font-size: 1.8em;
-	margin: 1.206em 0 0.36em;
+	font-size: 1.5em;
+	margin: 1.1em 0 0.36em;
 }
 
 .article-content > h1 {
 	margin-top: 0;
-	font-size: 2.2em;
+	font-size: 1.5em;
 }
 
 .article-content h2 {