Implement more image resizing, fix responsiveness

- Two new image sizes have been added: xl and xxl.
- Image resizing has been implemented in featured images.
- Some elements were not responsive, such as the link preview and code block.

assets/css/screen.css

@@ -135,11 +135,11 @@ Used to define how every page is displayed.
 */
 
 main {
-    min-height: calc(100vh - 400px);
     display: block;
     box-sizing: border-box;
     width: 100%;
     max-width: 100%;
+    min-height: calc(100vh - 400px); /* To avoid having the footer appearing in the middle of the page */
 }
 
 .mind-content_main {
@@ -739,6 +739,7 @@ img.mind-post_feature-image {
     font-size: 18px;
     color: rgb(200, 200, 200);
     box-sizing: border-box;
+    min-height: calc(100vh - 400px); /* To avoid having the div finish in the middle of the page, leaving an empty part */
 }
 
 .mind-post_content h1, .mind-post_content h2, .mind-post_content h3, .mind-post_content h4, .mind-post_content h5, .mind-post_content h6 {
@@ -1126,6 +1127,7 @@ div.mind-policy-popup {
     }
 }
 
+/* BEGIN RESPONSIVE MEDIA QUERIES */
 @media only screen and (max-width: 1300px) {
 
     h1 {
@@ -1315,6 +1317,29 @@ div.mind-policy-popup {
         font-size: 15px;
     }
 
+    .mind-post_content pre,
+    .mind-post_content code,
+    .kg-card-hascaption figcaption,
+    .kg-bookmark-description {
+        font-size: 12px;
+    }
+
+    .kg-bookmark-title {
+        font-size: 13px;
+    }
+
+    .kg-bookmark-publisher {
+        font-size: 10px;
+    }
+
+    .kg-bookmark-content {
+        padding: 10px 10px 0;
+    }
+
+    .kg-bookmark-metadata {
+        margin-bottom: 10px;
+    }
+
     .mind-global-navbar_primary img {
         margin-left: -35px;
         width: 25px;
@@ -1363,6 +1388,11 @@ div.mind-policy-popup {
         font-size: 14px;
     }
 
+    .mind-post_content pre, .mind-post_content code {
+        font-size: 11px;
+    }
+
+
     .mind-site-footer_main {
         font-size: 16px;
     }