Added h1 thru h6 bbcodes.

assets/css/misuzu/bb.css

@@ -0,0 +1,31 @@
+.bb-h1, .bb-h2,
+.bb-h3, .bb-h4,
+.bb-h5, .bb-h6 {
+    font-weight: 700;
+    line-height: 1.5em;
+    display: inline-block;
+    width: 100%;
+    margin-bottom: .25em;
+}
+
+.bb-h1 {
+    font-size: 2em;
+    border-bottom: 1px solid var(--accent-colour);
+}
+.bb-h2 {
+    font-size: 1.5em;
+    border-bottom: 1px solid var(--accent-colour);
+}
+.bb-h3 {
+    font-size: 1.25em;
+}
+.bb-h4 {
+    font-size: 1em;
+}
+.bb-h5 {
+    font-size: 0.875em;
+}
+.bb-h6 {
+    font-size: 0.85em;
+    color: var(--accent-colour);
+}

src/Parsers/BBCode/BBCodeParser.php

@@ -19,6 +19,12 @@ class BBCodeParser implements ParserInterface {
                 new Tags\VideoTag,
 
                 // Basic markup
+                new Tags\H1Tag,
+                new Tags\H2Tag,
+                new Tags\H3Tag,
+                new Tags\H4Tag,
+                new Tags\H5Tag,
+                new Tags\H6Tag,
                 new Tags\BoldTag,
                 new Tags\ItalicsTag,
                 new Tags\UnderlineTag,

src/Parsers/BBCode/Tags/H1Tag.php

@@ -0,0 +1,14 @@
+<?php
+namespace Misuzu\Parsers\BBCode\Tags;
+
+use Misuzu\Parsers\BBCode\BBCodeSimpleTag;
+
+final class H1Tag extends BBCodeSimpleTag {
+    public function getPattern(): string {
+        return "/\[h1\](.+?)\[\/h1\]/";
+    }
+
+    public function getReplacement(): string {
+        return '<h1 class="bb-h1">$1</h1>';
+    }
+}

src/Parsers/BBCode/Tags/H2Tag.php

@@ -0,0 +1,14 @@
+<?php
+namespace Misuzu\Parsers\BBCode\Tags;
+
+use Misuzu\Parsers\BBCode\BBCodeSimpleTag;
+
+final class H2Tag extends BBCodeSimpleTag {
+    public function getPattern(): string {
+        return "/\[h2\](.+?)\[\/h2\]/";
+    }
+
+    public function getReplacement(): string {
+        return '<h2 class="bb-h2">$1</h2>';
+    }
+}

src/Parsers/BBCode/Tags/H3Tag.php

@@ -0,0 +1,14 @@
+<?php
+namespace Misuzu\Parsers\BBCode\Tags;
+
+use Misuzu\Parsers\BBCode\BBCodeSimpleTag;
+
+final class H3Tag extends BBCodeSimpleTag {
+    public function getPattern(): string {
+        return "/\[h3\](.+?)\[\/h3\]/";
+    }
+
+    public function getReplacement(): string {
+        return '<h3 class="bb-h3">$1</h3>';
+    }
+}

src/Parsers/BBCode/Tags/H4Tag.php

@@ -0,0 +1,14 @@
+<?php
+namespace Misuzu\Parsers\BBCode\Tags;
+
+use Misuzu\Parsers\BBCode\BBCodeSimpleTag;
+
+final class H4Tag extends BBCodeSimpleTag {
+    public function getPattern(): string {
+        return "/\[h4\](.+?)\[\/h4\]/";
+    }
+
+    public function getReplacement(): string {
+        return '<h4 class="bb-h4">$1</h4>';
+    }
+}

src/Parsers/BBCode/Tags/H5Tag.php

@@ -0,0 +1,14 @@
+<?php
+namespace Misuzu\Parsers\BBCode\Tags;
+
+use Misuzu\Parsers\BBCode\BBCodeSimpleTag;
+
+final class H5Tag extends BBCodeSimpleTag {
+    public function getPattern(): string {
+        return "/\[h5\](.+?)\[\/h5\]/";
+    }
+
+    public function getReplacement(): string {
+        return '<h5 class="bb-h5">$1</h5>';
+    }
+}

src/Parsers/BBCode/Tags/H6Tag.php

@@ -0,0 +1,14 @@
+<?php
+namespace Misuzu\Parsers\BBCode\Tags;
+
+use Misuzu\Parsers\BBCode\BBCodeSimpleTag;
+
+final class H6Tag extends BBCodeSimpleTag {
+    public function getPattern(): string {
+        return "/\[h6\](.+?)\[\/h6\]/";
+    }
+
+    public function getReplacement(): string {
+        return '<h6 class="bb-h6">$1</h6>';
+    }
+}