[Style] centering the content, margin on cover photo

site/styles/style.css

@@ -67,6 +67,7 @@ main {
   line-height: 2rem;
   max-width: 120ch;
   overflow: auto;
+  margin: 0 auto;
 }
 
 main h1 {
@@ -136,11 +137,11 @@ a:focus {
   gap: 2rem;
 }
 
-.links > a {
+.links>a {
   border-radius: 100%;
 }
 
-.links > a > img {
+.links>a>img {
   display: block;
 }
 
@@ -166,6 +167,10 @@ button {
   cursor: pointer;
 }
 
+.cover-wrap {
+  margin-bottom: 3rem;
+}
+
 @media screen and (max-height: 860px),
 screen and (max-width: 1500px) {
   #mesh {