Style tweaks

assets/scss/style.scss

 .nav {
   background: $white;
   display: flex;
-  justify-content: space-between;
   padding: 10px 0;
 }
 
 .form__textarea,
 .form__text-field {
   border: 1px solid $medium-gray;
+  border-radius: 4px;
   font-family: $body-font-family;
   font-size: $body-font-size;
   padding: 10px;
   resize: vertical;
 }
 
+.form__preview {
+  margin-top: 20px;
+}
+
 .button.form__submit {
   background: $white;
   border: 1px solid $medium-gray;

yird/templates/posts/form.html.j2

     <h3 class="heading">
       {{ "edit post" if post else "new post" }}
     </h3>
-    <div class="form__field">
-      <label class="form__label">{{ form.title.label }}</label>
-      {{ form.title(class="form__text-field") }}
-    </div>
-    <div class="form__field">
-      <label class="form__label">{{ form.slug.label }}</label>
-      {{ form.slug(class="form__text-field") }}
-    </div>
-    <div class="form__field">
-      <label class="form__label">{{ form.date.label }}</label>
-      {{ form.date(class="form__date-field") }}
-    </div>
-    <div class="form__field">
-      <label class="form__label">{{ form.content.label }}</label>
-      {{ form.content(class="form__textarea", rows=10) }}
-    </div>
-    <div class="form__field form__field--submit">
-      <input type="submit" value="Submit" class="form__submit button">
+    <div class="form__fields">
+      <div class="form__field">
+        <label class="form__label">{{ form.title.label }}</label>
+        {{ form.title(class="form__text-field") }}
+      </div>
+      <div class="form__field">
+        <label class="form__label">{{ form.slug.label }}</label>
+        {{ form.slug(class="form__text-field") }}
+      </div>
+      <div class="form__field">
+        <label class="form__label">{{ form.date.label }}</label>
+        {{ form.date(class="form__date-field") }}
+      </div>
+      <div class="form__field">
+        <label class="form__label">{{ form.content.label }}</label>
+        {{ form.content(class="form__textarea", rows=10) }}
+      </div>
+      <div class="form__field form__field--submit">
+        <input type="submit" value="Submit" class="form__submit button">
+      </div>
     </div>
 
     {% if show_markdown_preview %}
-      <h3 class="heading">
-        Preview
-      </h3>
-      <iframe src="about:blank" width="100%">
-      </iframe>
+      <div class="form__preview">
+        <h3 class="heading">
+          Preview
+        </h3>
+        <iframe src="about:blank" width="100%"></iframe>
+      </div>
     {% endif %}
   </form>
 {% endblock %}