Use grid layout for items in administration area

Introduce a new 1/2/3-column CSS grid layout in the administration area
for items on overview pages and in the search results. The column count
of the grid depends on the users viewport width.

In addition, the default value of the following configuration settings
has been changed to 12 because 12 can also be divided by 2 and 3 which
is useful for the 1/2/3-column grid layout.

ADMIN.PAGE.LIST_SIZE = 12
ADMIN.POST.LIST_SIZE = 12

24 files changed, 168 insertions, 68 deletions

diff --git a/core/application.php b/core/application.php
index be70f92..3c431f8 100644
--- a/core/application.php
+++ b/core/application.php
@@ -95,8 +95,8 @@ foreach($configuration as $name => $value) {
 # Set default configuration (for admin prefixes)
 #===============================================================================
 foreach([
-	'ADMIN.PAGE.LIST_SIZE' => Application::get('PAGE.LIST_SIZE'),
-	'ADMIN.POST.LIST_SIZE' => Application::get('POST.LIST_SIZE'),
+	'ADMIN.PAGE.LIST_SIZE' => 12, # for 1/2/3-column grid layout
+	'ADMIN.POST.LIST_SIZE' => 12, # for 1/2/3-column grid layout
 	'ADMIN.USER.LIST_SIZE' => Application::get('USER.LIST_SIZE'),
 	'ADMIN.PAGE.LIST_SORT' => Application::get('PAGE.LIST_SORT'),
 	'ADMIN.POST.LIST_SORT' => Application::get('POST.LIST_SORT'),
diff --git a/theme/admin/html/403.php b/theme/admin/html/403.php
index f9a0afd..7f23212 100644
--- a/theme/admin/html/403.php
+++ b/theme/admin/html/403.php
@@ -1,2 +1,4 @@
+<main id="main-content">
 <h1><i class="fa fa-exclamation-triangle"></i><?=$Language->text('403_heading_text')?></h1>
 <p><?=$Language->text('403_heading_desc')?></p>
+</main>
diff --git a/theme/admin/html/404.php b/theme/admin/html/404.php
index d53d1bc..7fb06d8 100644
--- a/theme/admin/html/404.php
+++ b/theme/admin/html/404.php
@@ -1,2 +1,4 @@
+<main id="main-content">
 <h1><i class="fa fa-exclamation-triangle"></i><?=$Language->text('404_heading_text')?></h1>
 <p><?=$Language->text('404_heading_desc')?></p>
+</main>
diff --git a/theme/admin/html/auth.php b/theme/admin/html/auth.php
index a7b8b74..45b7e14 100644
--- a/theme/admin/html/auth.php
+++ b/theme/admin/html/auth.php
@@ -1,3 +1,4 @@
+<main id="main-content">
 <h1><i class="fa fa-sign-in"></i><?=$Language->text('authentication_text')?></h1>
 <p><?=$Language->text('authentication_desc')?></p>
 
@@ -34,3 +35,4 @@
 		<input type="submit" name="auth" value="<?=$Language->text('login')?>" />
 	</div>
 </form>
+</main>
diff --git a/theme/admin/html/database.php b/theme/admin/html/database.php
index b661a28..da41e68 100644
--- a/theme/admin/html/database.php
+++ b/theme/admin/html/database.php
@@ -1,3 +1,4 @@
+<main id="main-content">
 <h1><i class="fa fa-database"></i><?=$Language->text('overview_database_text')?></h1>
 <p><?=$Language->text('overview_database_desc')?></p>
 
@@ -28,3 +29,4 @@
 		<input id="insert-button" type="submit" name="execute" value="Execute" />
 	</div>
 </form>
+</main>
diff --git a/theme/admin/html/home.php b/theme/admin/html/home.php
index 083ae30..5331fa8 100644
--- a/theme/admin/html/home.php
+++ b/theme/admin/html/home.php
@@ -1,3 +1,4 @@
+<main id="main-content">
 <h1><i class="fa fa-dashboard"></i><?=$Language->text('overview_dashboard_text')?></h1>
 <p><?=$Language->text('overview_dashboard_desc')?></p>
 
@@ -43,4 +44,4 @@
 <?php else: ?>
 	<p><em><?=$Language->text('home_no_users')?></em></p>
 <?php endif; ?>
-
+</main>
diff --git a/theme/admin/html/main.php b/theme/admin/html/main.php
index 874ae81..699a742 100644
--- a/theme/admin/html/main.php
+++ b/theme/admin/html/main.php
@@ -38,11 +38,9 @@
 			</div>
 		</div>
 	</header>
-	<div id="main-content">
-		<main>
-			<?=$HTML?>
-		</main>
-	</div>
+
+	<?=$HTML?>
+
 	<footer id="main-footer">
 		<ul>
 			<li><i class="fa fa-github-square"></i><a href="https://github.com/Nerdmind/Blog/releases" target="_blank">Releases</a></li>
diff --git a/theme/admin/html/page/delete.php b/theme/admin/html/page/delete.php
index ccc569f..006090e 100644
--- a/theme/admin/html/page/delete.php
+++ b/theme/admin/html/page/delete.php
@@ -1,4 +1,6 @@
+<main id="main-content">
 <h1><i class="fa fa-trash-o"></i><?=$Language->text('delete_page')?></h1>
 <p><?=$Language->text('delete_page_desc')?></p>
 
-<?=$HTML?>
\ No newline at end of file
+<?=$HTML?>
+</main>
diff --git a/theme/admin/html/page/index.php b/theme/admin/html/page/index.php
index 7067c40..bdc7f94 100644
--- a/theme/admin/html/page/index.php
+++ b/theme/admin/html/page/index.php
@@ -1,3 +1,4 @@
+<main id="main-content" class="wide">
 <h1><i class="fa fa-file-text-o"></i><?=$Language->text('page_overview')?></h1>
 <p class="actions-before"><?=$Language->text('overview_page_desc')?></p>
 <ul class="actions">
@@ -5,10 +6,11 @@
 	<li><a href="<?=Application::getAdminURL('page/search.php')?>" title="<?=$Language->text('search_page')?>"><i class="fa fa-search"></i><?=$Language->text('search')?></a></li>
 </ul>
 
-<div class="item-container page">
+<div class="item-container page grid">
 	<?php foreach($LIST['PAGES'] as $page): ?>
 		<?php echo $page; ?>
 	<?php endforeach; ?>
 </div>
 
-<?=$PAGINATION['HTML']?>
\ No newline at end of file
+<?=$PAGINATION['HTML']?>
+</main>
diff --git a/theme/admin/html/page/insert.php b/theme/admin/html/page/insert.php
index 7442200..a77e47f 100644
--- a/theme/admin/html/page/insert.php
+++ b/theme/admin/html/page/insert.php
@@ -1,4 +1,6 @@
+<main id="main-content">
 <h1><i class="fa fa-pencil-square-o"></i><?=$Language->text('insert_page')?></h1>
 <p><?=$Language->text('insert_page_desc')?></p>
 
-<?=$HTML?>
\ No newline at end of file
+<?=$HTML?>
+</main>
diff --git a/theme/admin/html/page/search.php b/theme/admin/html/page/search.php
index 6506d34..145b0f9 100644
--- a/theme/admin/html/page/search.php
+++ b/theme/admin/html/page/search.php
@@ -1,3 +1,4 @@
+<main id="main-content" <?=!$PAGES ?: 'class="wide"'?>>
 <h1><i class="fa fa-search"></i><?=$Language->text('title_page_search')?></h1>
 <p><?=$Language->text('search_page_desc')?></p>
 
@@ -10,8 +11,9 @@
 	</div>
 </form>
 
-<div class="item-container post">
+<div class="item-container post grid">
 	<?php foreach($PAGES as $page): ?>
 		<?php echo $page; ?>
 	<?php endforeach; ?>
 </div>
+</main>
diff --git a/theme/admin/html/page/update.php b/theme/admin/html/page/update.php
index 77a7eb2..ce51d2a 100644
--- a/theme/admin/html/page/update.php
+++ b/theme/admin/html/page/update.php
@@ -1,4 +1,6 @@
+<main id="main-content">
 <h1><i class="fa fa-pencil-square-o"></i><?=$Language->text('update_page')?></h1>
 <p><?=$Language->text('update_page_desc')?></p>
 
-<?=$HTML?>
\ No newline at end of file
+<?=$HTML?>
+</main>
diff --git a/theme/admin/html/post/delete.php b/theme/admin/html/post/delete.php
index 6654377..ed82197 100644
--- a/theme/admin/html/post/delete.php
+++ b/theme/admin/html/post/delete.php
@@ -1,4 +1,6 @@
+<main id="main-content">
 <h1><i class="fa fa-trash-o"></i><?=$Language->text('delete_post')?></h1>
 <p><?=$Language->text('delete_post_desc')?></p>
 
-<?=$HTML?>
\ No newline at end of file
+<?=$HTML?>
+</main>
diff --git a/theme/admin/html/post/index.php b/theme/admin/html/post/index.php
index f884b05..83dd5dc 100644
--- a/theme/admin/html/post/index.php
+++ b/theme/admin/html/post/index.php
@@ -1,3 +1,4 @@
+<main id="main-content" class="wide">
 <h1><i class="fa fa-newspaper-o"></i><?=$Language->text('post_overview')?></h1>
 <p class="actions-before"><?=$Language->text('overview_post_desc')?></p>
 <ul class="actions">
@@ -5,10 +6,11 @@
 	<li><a href="<?=Application::getAdminURL('post/search.php')?>" title="<?=$Language->text('search_post')?>"><i class="fa fa-search"></i><?=$Language->text('search')?></a></li>
 </ul>
 
-<div class="item-container post">
+<div class="item-container post grid">
 	<?php foreach($LIST['POSTS'] as $post): ?>
 		<?php echo $post; ?>
 	<?php endforeach; ?>
 </div>
 
-<?=$PAGINATION['HTML']?>
\ No newline at end of file
+<?=$PAGINATION['HTML']?>
+</main>
diff --git a/theme/admin/html/post/insert.php b/theme/admin/html/post/insert.php
index dc32c24..9b7c588 100644
--- a/theme/admin/html/post/insert.php
+++ b/theme/admin/html/post/insert.php
@@ -1,4 +1,6 @@
+<main id="main-content">
 <h1><i class="fa fa-pencil-square-o"></i><?=$Language->text('insert_post')?></h1>
 <p><?=$Language->text('insert_post_desc')?></p>
 
-<?=$HTML?>
\ No newline at end of file
+<?=$HTML?>
+</main>
diff --git a/theme/admin/html/post/search.php b/theme/admin/html/post/search.php
index 1289879..00bd016 100644
--- a/theme/admin/html/post/search.php
+++ b/theme/admin/html/post/search.php
@@ -1,3 +1,4 @@
+<main id="main-content" <?=!$POSTS ?: 'class="wide"'?>>
 <h1><i class="fa fa-search"></i><?=$Language->text('title_post_search')?></h1>
 <p><?=$Language->text('search_post_desc')?></p>
 
@@ -10,8 +11,9 @@
 	</div>
 </form>
 
-<div class="item-container post">
+<div class="item-container post grid">
 	<?php foreach($POSTS as $post): ?>
 		<?php echo $post; ?>
 	<?php endforeach; ?>
 </div>
+</main>
diff --git a/theme/admin/html/post/update.php b/theme/admin/html/post/update.php
index a577bec..aa3835d 100644
--- a/theme/admin/html/post/update.php
+++ b/theme/admin/html/post/update.php
@@ -1,4 +1,6 @@
+<main id="main-content">
 <h1><i class="fa fa-pencil-square-o"></i><?=$Language->text('update_post')?></h1>
 <p><?=$Language->text('update_post_desc')?></p>
 
-<?=$HTML?>
\ No newline at end of file
+<?=$HTML?>
+</main>
diff --git a/theme/admin/html/user/delete.php b/theme/admin/html/user/delete.php
index 01927b2..b500a12 100644
--- a/theme/admin/html/user/delete.php
+++ b/theme/admin/html/user/delete.php
@@ -1,6 +1,8 @@
+<main id="main-content">
 <h1><i class="fa fa-trash-o"></i><?=$Language->text('delete_user')?></h1>
 <p><?=$Language->text('delete_user_desc')?></p>
 
 <p class="red"><?=$Language->text('delete_user_warning')?></p>
 
-<?=$HTML?>
\ No newline at end of file
+<?=$HTML?>
+</main>
diff --git a/theme/admin/html/user/index.php b/theme/admin/html/user/index.php
index aae8ee8..7e1d794 100644
--- a/theme/admin/html/user/index.php
+++ b/theme/admin/html/user/index.php
@@ -1,3 +1,4 @@
+<main id="main-content">
 <h1><i class="fa fa-user"></i><?=$Language->text('user_overview')?></h1>
 <p class="actions-before"><?=$Language->text('overview_user_desc')?></p>
 <ul class="actions">
@@ -10,4 +11,5 @@
 	<?php endforeach; ?>
 </div>
 
-<?=$PAGINATION['HTML']?>
\ No newline at end of file
+<?=$PAGINATION['HTML']?>
+</main>
diff --git a/theme/admin/html/user/insert.php b/theme/admin/html/user/insert.php
index 5cbdd06..7c7aba2 100644
--- a/theme/admin/html/user/insert.php
+++ b/theme/admin/html/user/insert.php
@@ -1,4 +1,6 @@
+<main id="main-content">
 <h1><i class="fa fa-pencil-square-o"></i><?=$Language->text('insert_user')?></h1>
 <p><?=$Language->text('insert_user_desc')?></p>
 
-<?=$HTML?>
\ No newline at end of file
+<?=$HTML?>
+</main>
diff --git a/theme/admin/html/user/update.php b/theme/admin/html/user/update.php
index e023925..ad12677 100644
--- a/theme/admin/html/user/update.php
+++ b/theme/admin/html/user/update.php
@@ -1,4 +1,6 @@
+<main id="main-content">
 <h1><i class="fa fa-pencil-square-o"></i><?=$Language->text('update_user')?></h1>
 <p><?=$Language->text('update_user_desc')?></p>
 
-<?=$HTML?>
\ No newline at end of file
+<?=$HTML?>
+</main>
diff --git a/theme/admin/rsrc/css/import/_responsive.scss b/theme/admin/rsrc/css/import/_responsive.scss
index 2d3d62a..e387c98 100644
--- a/theme/admin/rsrc/css/import/_responsive.scss
+++ b/theme/admin/rsrc/css/import/_responsive.scss
@@ -1,17 +1,34 @@
-/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-# Responsive Level #1
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
-@media only screen and (max-width: 50em) {
+@media only screen and (max-width: 90em /*1440px*/) {
+	.item-container.grid {
+		grid-template-columns: auto auto;
+	}
+}
+
+@media only screen and (min-width: 62.5em /*1000px*/) {
+	#main-content {
+		border: 0.05rem solid #AAA;
+		border-top: none;
+		border-bottom: none;
+	}
+}
+
+@media only screen and (max-width: 62.5em /*1000px*/) {
+	.item-container.grid {
+		grid-template-columns: auto;
+	}
+}
+
+@media only screen and (max-width: 50em /*800px*/) {
 	html {
 		font-size: 1.125rem; /*18px*/
-		background-image: none !important;
 	}
 }
 
-/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-# Responsive Level #2
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
-@media only screen and (max-width: 37.5em) {
+@media only screen and (max-width: 37.5em /*600px*/) {
+	#main-content {
+		padding: 0.5rem;
+	}
+
 	#main-navi {
 		font-size: 1rem;
 
@@ -34,6 +51,13 @@
 		display: none;
 	}
 
+	.item-container.grid {
+		grid-column-gap: 0.75rem;
+		grid-row-gap: 0.75rem;
+		column-gap: 0.75rem;
+		row-gap: 0.75rem;
+	}
+
 	.form-grid {
 		grid-template-columns: auto auto;
 	}
@@ -64,8 +88,4 @@
 		font-size: 0.5rem;
 		line-height: 0.75rem;
 	}
-
-	main {
-		padding: 0.5rem;
-	}
 }
diff --git a/theme/admin/rsrc/css/main.css b/theme/admin/rsrc/css/main.css
index 2677f19..f3a39c1 100644
--- a/theme/admin/rsrc/css/main.css
+++ b/theme/admin/rsrc/css/main.css
@@ -22,7 +22,7 @@ a:focus {
 # Headings
 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
 h1, h2, h3, h4, h5, h6 {
-  margin: 0;
+  margin-bottom: 0;
   text-transform: uppercase;
 }
 h1 + p, h2 + p, h3 + p, h4 + p, h5 + p, h6 + p {
@@ -33,6 +33,7 @@ h1 .fa, h2 .fa, h3 .fa, h4 .fa, h5 .fa, h6 .fa {
 }
 
 h1 {
+  margin-top: 0;
   font-size: 0.8rem;
 }
 
@@ -81,10 +82,6 @@ body {
   flex-direction: column;
 }
 
-main {
-  padding: 0.75rem;
-}
-
 /*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 # Main content
 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
@@ -93,9 +90,10 @@ main {
   width: 100%;
   background: #FFF;
   box-sizing: border-box;
-  border: 0.05rem solid #AAA;
-  border-top: none;
-  border-bottom: none;
+  padding: 0.75rem;
+}
+#main-content.wide {
+  max-width: 90rem;
 }
 
 /*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
@@ -230,6 +228,7 @@ main {
   display: flex;
   box-sizing: border-box;
   justify-content: space-between;
+  margin-top: 0.75rem;
 }
 #site-navi > div {
   display: flex;
@@ -387,9 +386,9 @@ table, td {
 # Item Element
 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
 .item {
-  display: block;
+  display: flex;
+  flex-direction: column;
   border: 0.05rem solid #AAA;
-  margin-bottom: 1rem;
   clear: both;
 }
 .item header {
@@ -398,6 +397,9 @@ table, td {
   position: sticky;
   top: 0;
 }
+.item header h2 {
+  margin-top: 0;
+}
 .item footer {
   border-top: 0.05rem solid #AAA;
 }
@@ -430,6 +432,7 @@ table, td {
   padding: 0.75rem;
   overflow: hidden;
   font-family: inherit;
+  flex-grow: 1;
 }
 .item blockquote p {
   margin-bottom: 0;
@@ -448,6 +451,15 @@ table, td {
   background: #EEE;
   border: 0.05rem solid #AAA;
 }
+.item-container.grid {
+  width: 100%;
+  display: grid;
+  grid-template-columns: auto auto auto;
+  grid-column-gap: 1rem;
+  grid-row-gap: 1rem;
+  column-gap: 1rem;
+  row-gap: 1rem;
+}
 
 /*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 # Argument list
@@ -665,20 +677,34 @@ label:after {
   margin-bottom: 1rem;
 }
 
-/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-# Responsive Level #1
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
+@media only screen and (max-width: 90em) {
+  .item-container.grid {
+    grid-template-columns: auto auto;
+  }
+}
+@media only screen and (min-width: 62.5em) {
+  #main-content {
+    border: 0.05rem solid #AAA;
+    border-top: none;
+    border-bottom: none;
+  }
+}
+@media only screen and (max-width: 62.5em) {
+  .item-container.grid {
+    grid-template-columns: auto;
+  }
+}
 @media only screen and (max-width: 50em) {
   html {
     font-size: 1.125rem;
     /*18px*/
-    background-image: none !important;
   }
 }
-/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-# Responsive Level #2
-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
 @media only screen and (max-width: 37.5em) {
+  #main-content {
+    padding: 0.5rem;
+  }
+
   #main-navi {
     font-size: 1rem;
   }
@@ -696,6 +722,13 @@ label:after {
     display: none;
   }
 
+  .item-container.grid {
+    grid-column-gap: 0.75rem;
+    grid-row-gap: 0.75rem;
+    column-gap: 0.75rem;
+    row-gap: 0.75rem;
+  }
+
   .form-grid {
     grid-template-columns: auto auto;
   }
@@ -724,10 +757,6 @@ label:after {
     font-size: 0.5rem;
     line-height: 0.75rem;
   }
-
-  main {
-    padding: 0.5rem;
-  }
 }
 /*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 # FontAwesome Main
diff --git a/theme/admin/rsrc/css/main.scss b/theme/admin/rsrc/css/main.scss
index e00c60a..0397754 100644
--- a/theme/admin/rsrc/css/main.scss
+++ b/theme/admin/rsrc/css/main.scss
@@ -22,7 +22,7 @@ a {
 # Headings
 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
 h1, h2, h3, h4, h5, h6 {
-	margin: 0;
+	margin-bottom: 0;
 	text-transform: uppercase;
 
 	+p {
@@ -35,6 +35,7 @@ h1, h2, h3, h4, h5, h6 {
 }
 
 h1 {
+	margin-top: 0;
 	font-size: 0.80rem;
 }
 
@@ -83,10 +84,6 @@ body {
 	flex-direction: column;
 }
 
-main {
-	padding: 0.75rem;
-}
-
 /*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 # Main content
 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
@@ -95,9 +92,12 @@ main {
 	width: 100%;
 	background: #FFF;
 	box-sizing: border-box;
-	border: 0.05rem solid #AAA;
-	border-top: none;
-	border-bottom: none;
+	padding: 0.75rem;
+	// border definition in _responsive.scss
+
+	&.wide {
+		max-width: 90rem;
+	}
 }
 
 /*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
@@ -249,6 +249,7 @@ main {
 	display: flex;
 	box-sizing: border-box;
 	justify-content: space-between;
+	margin-top: 0.75rem;
 
 	> div {
 		display: flex;
@@ -422,9 +423,9 @@ table, td {
 # Item Element
 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
 .item {
-	display: block;
+	display: flex;
+	flex-direction: column;
 	border: 0.05rem solid #AAA;
-	margin-bottom: 1rem;
 	clear: both;
 
 	header {
@@ -432,6 +433,10 @@ table, td {
 		border-bottom: 0.05rem solid #AAA;
 		position: sticky;
 		top: 0;
+
+		h2 {
+			margin-top: 0;
+		}
 	}
 
 	footer {
@@ -473,6 +478,7 @@ table, td {
 		padding: 0.75rem;
 		overflow: hidden;
 		font-family: inherit;
+		flex-grow: 1;
 
 		p {
 			margin-bottom: 0;
@@ -494,6 +500,16 @@ table, td {
 		background: #EEE;
 		border: 0.05rem solid #AAA;
 	}
+
+	&-container.grid {
+		width: 100%;
+		display: grid;
+		grid-template-columns: auto auto auto;
+		grid-column-gap: 1rem;
+		grid-row-gap: 1rem;
+		column-gap: 1rem;
+		row-gap: 1rem;
+	}
 }
 
 /*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++