style: 调整文章内容中各级标题的字体大小与间距

src/app.css

@@ -494,8 +494,8 @@ body.single-col .post-list {
 }
 
 .article-content h2 {
-	font-size: 1.6em;
-	margin: 1.5em 0 0.8em;
+	font-size: 1.5em;
+	margin: 1.005em 0 0.375em;
 	padding-left: 14px;
 	border-left: 5px solid var(--accent-color);
 	line-height: 1.4;
@@ -505,8 +505,8 @@ body.single-col .post-list {
 }
 
 .article-content h3 {
-	font-size: 1.3em;
-	margin: 1.2em 0 0.6em;
+	font-size: 1.17em;
+	margin: 1em 0 0.2925em;
 	display: flex;
 	align-items: center;
 }
@@ -520,8 +520,8 @@ body.single-col .post-list {
 }
 
 .article-content h4 {
-	font-size: 1.1em;
-	margin: 1em 0 0.5em;
+	font-size: 1em;
+	margin: 1em 0 0.35em;
 	position: relative;
 	padding-left: 12px;
 }