diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 0000000..ca821f9
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,9 @@
+root = true
+
+[*]
+indent_style = tab
+indent_size = 4
+
+[*.{html,css,scss}]
+indent_style = space
+indent_size = 2
diff --git a/plugins/base/public/assets/style.css b/plugins/base/public/assets/style.css
index c27f10f..4f91f63 100644
--- a/plugins/base/public/assets/style.css
+++ b/plugins/base/public/assets/style.css
@@ -1,5 +1,5 @@
 iframe {
-	width: 100%;
-	height: 400px;
-	border: 0;
+  width: 100%;
+  height: 400px;
+  border: 0;
 }
diff --git a/plugins/base/public/compose.html b/plugins/base/public/compose.html
index 4d69c81..0db84c0 100644
--- a/plugins/base/public/compose.html
+++ b/plugins/base/public/compose.html
@@ -3,31 +3,31 @@
 <h1>koushin</h1>
 
 <p>
-	<a href="/mailbox/INBOX">Back</a>
+  <a href="/mailbox/INBOX">Back</a>
 </p>
 
 <h2>Compose new message</h2>
 
 <form method="post" action="" enctype="multipart/form-data">
-	<input type="hidden" name="in_reply_to" value="{{.Message.InReplyTo}}">
+  <input type="hidden" name="in_reply_to" value="{{.Message.InReplyTo}}">
 
-	<label for="from">From:</label>
-	<input type="email" name="from" id="from" required value="{{.Message.From}}">
-	<br><br>
-	<label for="to">To:</label>
-	<input type="email" name="to" id="to" multiple required value="{{.Message.ToString}}">
-	<br><br>
-	<label for="subject">Subject:</label>
-	<input type="text" name="subject" id="subject" value="{{.Message.Subject}}">
-	<br><br>
-	<label for="text">Body:</label><br>
-	<textarea name="text" id="text" cols="80" rows="20">{{.Message.Text}}</textarea>
-	<br><br>
-	<label for="attachments">Attachments:</label>
-	<input type="file" name="attachments" id="attachments" multiple>
-	<br><br>
-	<input type="submit" name="save_as_draft" value="Save as draft">
-	<input type="submit" value="Send">
+  <label for="from">From:</label>
+  <input type="email" name="from" id="from" required value="{{.Message.From}}">
+  <br><br>
+  <label for="to">To:</label>
+  <input type="email" name="to" id="to" multiple required value="{{.Message.ToString}}">
+  <br><br>
+  <label for="subject">Subject:</label>
+  <input type="text" name="subject" id="subject" value="{{.Message.Subject}}">
+  <br><br>
+  <label for="text">Body:</label><br>
+  <textarea name="text" id="text" cols="80" rows="20">{{.Message.Text}}</textarea>
+  <br><br>
+  <label for="attachments">Attachments:</label>
+  <input type="file" name="attachments" id="attachments" multiple>
+  <br><br>
+  <input type="submit" name="save_as_draft" value="Save as draft">
+  <input type="submit" value="Send">
 </form>
 
 {{template "foot.html"}}
diff --git a/plugins/base/public/login.html b/plugins/base/public/login.html
index 7378935..94f1b23 100644
--- a/plugins/base/public/login.html
+++ b/plugins/base/public/login.html
@@ -3,13 +3,13 @@
 <h1>koushin</h1>
 
 <form method="post" action="">
-	<label for="username">Username:</label>
-	<input type="text" name="username" id="username"/>
-	<br><br>
-	<label for="password">Password:</label>
-	<input type="password" name="password" id="password"/>
-	<br><br>
-	<input type="submit" value="Login">
+  <label for="username">Username:</label>
+  <input type="text" name="username" id="username"/>
+  <br><br>
+  <label for="password">Password:</label>
+  <input type="password" name="password" id="password"/>
+  <br><br>
+  <input type="submit" value="Login">
 </form>
 
 {{template "foot.html"}}
diff --git a/plugins/base/public/mailbox.html b/plugins/base/public/mailbox.html
index d480440..d19c73d 100644
--- a/plugins/base/public/mailbox.html
+++ b/plugins/base/public/mailbox.html
@@ -3,48 +3,48 @@
 <h1>koushin</h1>
 
 <p>
-	<a href="/logout">Logout</a> · <a href="/compose">Compose</a>
+  <a href="/logout">Logout</a> · <a href="/compose">Compose</a>
 </p>
 
 <h2>{{.Mailbox.Name}}</h2>
 
 <form method="get" action="">
-	<input type="search" name="query" value="{{.Query}}">
-	<input type="submit" value="Search">
+  <input type="search" name="query" value="{{.Query}}">
+  <input type="submit" value="Search">
 </form>
 
 <p>Mailboxes:</p>
 <ul>
-	{{range .Mailboxes}}
-		<li><a href="/mailbox/{{.Name | pathescape}}">{{.Name}}</a></li>
-	{{end}}
+  {{range .Mailboxes}}
+    <li><a href="/mailbox/{{.Name | pathescape}}">{{.Name}}</a></li>
+  {{end}}
 </ul>
 
 {{if .Messages}}
-	<p>Messages:</p>
-	<ul>
-		{{range .Messages}}
-			<li><a href="/message/{{$.Mailbox.Name | pathescape}}/{{.Uid}}?part={{.TextPartName}}">
-				{{if .Envelope.Subject}}
-					{{.Envelope.Subject}}
-				{{else}}
-					(No subject)
-				{{end}}
-			</a></li>
-		{{end}}
-	</ul>
+  <p>Messages:</p>
+  <ul>
+    {{range .Messages}}
+      <li><a href="/message/{{$.Mailbox.Name | pathescape}}/{{.Uid}}?part={{.TextPartName}}">
+        {{if .Envelope.Subject}}
+          {{.Envelope.Subject}}
+        {{else}}
+          (No subject)
+        {{end}}
+      </a></li>
+    {{end}}
+  </ul>
 
-	<p>
-		{{if ge .PrevPage 0}}
-			<a href="?page={{.PrevPage}}&query={{.Query}}">Prev</a>
-		{{end}}
-		{{if and (ge .PrevPage 0) (ge .NextPage 0)}}·{{end}}
-		{{if ge .NextPage 0}}
-			<a href="?page={{.NextPage}}&query={{.Query}}">Next</a>
-		{{end}}
-	</p>
+  <p>
+    {{if ge .PrevPage 0}}
+      <a href="?page={{.PrevPage}}&query={{.Query}}">Prev</a>
+    {{end}}
+    {{if and (ge .PrevPage 0) (ge .NextPage 0)}}·{{end}}
+    {{if ge .NextPage 0}}
+      <a href="?page={{.NextPage}}&query={{.Query}}">Next</a>
+    {{end}}
+  </p>
 {{else}}
-	<p>No message.</p>
+  <p>No message.</p>
 {{end}}
 
 {{template "foot.html"}}
diff --git a/plugins/base/public/message.html b/plugins/base/public/message.html
index 3dc7f62..a973881 100644
--- a/plugins/base/public/message.html
+++ b/plugins/base/public/message.html
@@ -3,105 +3,105 @@
 <h1>koushin</h1>
 
 <p>
-	<a href="/mailbox/{{.Mailbox.Name | pathescape}}?page={{.MailboxPage}}">
-		Back
-	</a>
+  <a href="/mailbox/{{.Mailbox.Name | pathescape}}?page={{.MailboxPage}}">
+    Back
+  </a>
 </p>
 
 <h2>
-	{{if .Message.Envelope.Subject}}
-		{{.Message.Envelope.Subject}}
-	{{else}}
-		(No subject)
-	{{end}}
+  {{if .Message.Envelope.Subject}}
+    {{.Message.Envelope.Subject}}
+  {{else}}
+    (No subject)
+  {{end}}
 </h2>
 
 <form method="post" action="{{.Message.Uid}}/move">
-	<label for="move-to">Move to:</label>
-	<select name="to" id="move-to">
-		{{range .Mailboxes}}
-			<option {{if eq .Name $.Mailbox.Name}}selected{{end}}>{{.Name}}</option>
-		{{end}}
-	</select>
-	<input type="submit" value="Move">
+  <label for="move-to">Move to:</label>
+  <select name="to" id="move-to">
+    {{range .Mailboxes}}
+      <option {{if eq .Name $.Mailbox.Name}}selected{{end}}>{{.Name}}</option>
+    {{end}}
+  </select>
+  <input type="submit" value="Move">
 </form>
 
 <form method="post" action="{{.Message.Uid}}/delete">
-	<input type="submit" value="Delete">
+  <input type="submit" value="Delete">
 </form>
 
 {{if .Flags}}
-	<form method="post" action="{{.Message.Uid}}/flag">
-		<p>Flags:</p>
-		{{range $name, $has := .Flags}}
-			{{if ismutableflag $name}}
-				<input type="checkbox" name="flags" id="flag-{{$name}}"
-					value="{{$name}}" {{if $has}}checked{{end}}>
-				<label for="flag-{{$name}}">{{$name | formatflag}}</label>
-				<br>
-			{{else}}
-				{{if $has}}
-					<input type="hidden" name="flags" value="{{$name}}">
-				{{end}}
-			{{end}}
-		{{end}}
-		<input type="submit" value="Set flags">
-	</form>
+  <form method="post" action="{{.Message.Uid}}/flag">
+    <p>Flags:</p>
+    {{range $name, $has := .Flags}}
+      {{if ismutableflag $name}}
+        <input type="checkbox" name="flags" id="flag-{{$name}}"
+          value="{{$name}}" {{if $has}}checked{{end}}>
+        <label for="flag-{{$name}}">{{$name | formatflag}}</label>
+        <br>
+      {{else}}
+        {{if $has}}
+          <input type="hidden" name="flags" value="{{$name}}">
+        {{end}}
+      {{end}}
+    {{end}}
+    <input type="submit" value="Set flags">
+  </form>
 {{end}}
 
 {{define "addr-list"}}
-	{{range $i, $addr := .}}
-		{{if $i}},{{end}}
-		{{.PersonalName}}
-		&lt;<a href="/compose?to={{.Address}}">{{.Address}}</a>&gt;
-	{{end}}
+  {{range $i, $addr := .}}
+    {{if $i}},{{end}}
+    {{.PersonalName}}
+    &lt;<a href="/compose?to={{.Address}}">{{.Address}}</a>&gt;
+  {{end}}
 {{end}}
 
 <ul>
-	<li>
-		<strong>Date</strong>: {{.Message.Envelope.Date | formatdate}}
-	</li>
-	<li>
-		<strong>From</strong>: {{template "addr-list" .Message.Envelope.From}}
-	</li>
-	<li>
-		<strong>To</strong>: {{template "addr-list" .Message.Envelope.To}}
-	</li>
-	{{if .Message.Envelope.Cc}}
-		<li>
-			<strong>Cc</strong>: {{template "addr-list" .Message.Envelope.Cc}}
-		</li>
-	{{end}}
-	{{if .Message.Envelope.Bcc}}
-		<li>
-			<strong>Bcc</strong>: {{template "addr-list" .Message.Envelope.Bcc}}
-		</li>
-	{{end}}
+  <li>
+    <strong>Date</strong>: {{.Message.Envelope.Date | formatdate}}
+  </li>
+  <li>
+    <strong>From</strong>: {{template "addr-list" .Message.Envelope.From}}
+  </li>
+  <li>
+    <strong>To</strong>: {{template "addr-list" .Message.Envelope.To}}
+  </li>
+  {{if .Message.Envelope.Cc}}
+    <li>
+      <strong>Cc</strong>: {{template "addr-list" .Message.Envelope.Cc}}
+    </li>
+  {{end}}
+  {{if .Message.Envelope.Bcc}}
+    <li>
+      <strong>Bcc</strong>: {{template "addr-list" .Message.Envelope.Bcc}}
+    </li>
+  {{end}}
 </ul>
 
 {{define "message-part-tree"}}
-	{{/* nested templates can't access the parent's context */}}
-	{{$ = index . 0}}
-	{{with index . 1}}
-		<a
-			{{if .IsText}}
-				href="{{$.Message.Uid}}?part={{.PathString}}"
-			{{else}}
-				href="{{$.Message.Uid}}/raw?part={{.PathString}}"
-			{{end}}
-		>
-			{{if eq $.PartPath .PathString}}<strong>{{end}}
-			{{.String}}
-			{{if eq $.PartPath .PathString}}</strong>{{end}}
-		</a>
-		{{if .Children}}
-		<ul>
-			{{range .Children}}
-				<li>{{template "message-part-tree" (tuple $ .)}}</li>
-			{{end}}
-		</ul>
-		{{end}}
-	{{end}}
+  {{/* nested templates can't access the parent's context */}}
+  {{$ = index . 0}}
+  {{with index . 1}}
+    <a
+      {{if .IsText}}
+        href="{{$.Message.Uid}}?part={{.PathString}}"
+      {{else}}
+        href="{{$.Message.Uid}}/raw?part={{.PathString}}"
+      {{end}}
+    >
+      {{if eq $.PartPath .PathString}}<strong>{{end}}
+      {{.String}}
+      {{if eq $.PartPath .PathString}}</strong>{{end}}
+    </a>
+    {{if .Children}}
+    <ul>
+      {{range .Children}}
+        <li>{{template "message-part-tree" (tuple $ .)}}</li>
+      {{end}}
+    </ul>
+    {{end}}
+  {{end}}
 {{end}}
 
 <p>Parts:</p>
@@ -111,23 +111,23 @@
 <hr>
 
 {{if .Body}}
-	<p>
-		{{if .Message.HasFlag "\\Draft"}}
-			<a href="{{.Message.Uid}}/edit?part={{.PartPath}}">Edit draft</a>
-		{{else}}
-			<a href="{{.Message.Uid}}/reply?part={{.PartPath}}">Reply</a>
-		{{end}}
-	</p>
-	{{if .IsHTML}}
-		<!-- allow-same-origin is required to resize the frame with its content -->
-		<!-- allow-popups is required for target="_blank" links -->
-		<iframe id="email-frame" srcdoc="{{.Body}}" sandbox="allow-same-origin allow-popups"></iframe>
-	{{else}}
-		<pre>{{.Body}}</pre>
-	{{end}}
+  <p>
+    {{if .Message.HasFlag "\\Draft"}}
+      <a href="{{.Message.Uid}}/edit?part={{.PartPath}}">Edit draft</a>
+    {{else}}
+      <a href="{{.Message.Uid}}/reply?part={{.PartPath}}">Reply</a>
+    {{end}}
+  </p>
+  {{if .IsHTML}}
+    <!-- allow-same-origin is required to resize the frame with its content -->
+    <!-- allow-popups is required for target="_blank" links -->
+    <iframe id="email-frame" srcdoc="{{.Body}}" sandbox="allow-same-origin allow-popups"></iframe>
+  {{else}}
+    <pre>{{.Body}}</pre>
+  {{end}}
 {{else}}
-	<p>Can't preview this message part.</p>
-	<a href="{{.Message.Uid}}/raw?part={{.PartPath}}">Download</a>
+  <p>Can't preview this message part.</p>
+  <a href="{{.Message.Uid}}/raw?part={{.PartPath}}">Download</a>
 {{end}}
 
 {{template "foot.html"}}