panel: move inline styles and confirmations out of the templates

Groundwork for the Content-Security-Policy of phase 14.A. A policy that has to
allow inline script is not worth writing — script-src 'unsafe-inline' gives
back exactly the XSS foothold the policy exists to remove — so the three
inline constructs the templates still had are moved out first:

  - the layout's <style> block becomes /static/panel.css;
  - the one style="background:#b42318" attribute becomes the .danger class
    that already existed for it;
  - the four onsubmit="return confirm(...)" handlers become data-confirm,
    handled by a delegated listener in panel.js. Delegation matters: the
    application rows are also delivered by HTMX swaps.

htmx would otherwise inject a <style> of its own for the request-indicator
classes and become the single reason the policy needs an exemption; the panel
uses no hx-indicator, so the meta config switches it off.

A guard test keeps this from silently regressing later, which it otherwise
would: an inline handler added to a template does not fail, it just quietly
stops working in the browser.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

internal/web/static/panel.css

@@ -0,0 +1,119 @@
+/* Panel stylesheet. It lives in a file rather than in a <style> block in the
+   layout so the panel's Content-Security-Policy can be a plain
+   "default-src 'self'" with no inline-style exemption (phase 14.A). Any rule
+   added here must therefore stay here: an inline style="..." attribute in a
+   template is blocked by that policy and silently does nothing. */
+
+:root { color-scheme: light dark; }
+* { box-sizing: border-box; }
+body {
+  font: 15px/1.5 system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
+  margin: 0; padding: 2rem 1rem; background: #f6f7f9; color: #1b1f24;
+}
+@media (prefers-color-scheme: dark) {
+  body { background: #14171a; color: #e6e8eb; }
+  .card { background: #1d2125 !important; border-color: #2b3138 !important; }
+  input { background: #14171a !important; color: inherit !important; border-color: #2b3138 !important; }
+}
+main { max-width: 42rem; margin: 0 auto; }
+h1 { font-size: 1.4rem; margin: 0 0 1rem; }
+.card {
+  background: #fff; border: 1px solid #e2e5e9; border-radius: 10px;
+  padding: 1.5rem; margin: 0 auto;
+}
+.card.narrow { max-width: 24rem; }
+label { display: block; font-weight: 600; margin: 0.9rem 0 0.3rem; }
+input {
+  width: 100%; padding: 0.55rem 0.7rem; font-size: 1rem;
+  border: 1px solid #cfd4da; border-radius: 6px; background: #fff;
+}
+button {
+  margin-top: 1.2rem; padding: 0.6rem 1.1rem; font-size: 1rem; font-weight: 600;
+  color: #fff; background: #2563eb; border: 0; border-radius: 6px; cursor: pointer;
+}
+button:hover { background: #1d4ed8; }
+.error { color: #b42318; margin: 0.6rem 0 0; font-weight: 600; }
+.muted { color: #6b7280; }
+.topbar { display: flex; justify-content: space-between; align-items: baseline; margin-bottom: 1.2rem; }
+.topbar .actions { display: flex; gap: 0.9rem; align-items: baseline; }
+form.inline { display: inline; margin: 0; }
+form.inline button { background: none; color: #2563eb; padding: 0; margin: 0; font-weight: 600; }
+form.inline button:hover { text-decoration: underline; background: none; }
+main { max-width: 48rem; }
+.card + .card { margin-top: 1.2rem; }
+.flash { background: #ecfdf3; border: 1px solid #abefc6; color: #067647; padding: 0.7rem 1rem; border-radius: 8px; margin-bottom: 1.2rem; }
+@media (prefers-color-scheme: dark) { .flash { background: #0d2818 !important; border-color: #1a5336 !important; color: #75d99b !important; } }
+table { width: 100%; border-collapse: collapse; }
+th, td { text-align: left; padding: 0.5rem 0.4rem; border-bottom: 1px solid #e2e5e9; }
+@media (prefers-color-scheme: dark) { th, td { border-color: #2b3138 !important; } }
+th { font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.03em; color: #6b7280; }
+td.actions { text-align: right; }
+a.danger { color: #b42318; }
+.code { display: block; white-space: pre-wrap; word-break: break-all; font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
+        font-size: 0.85rem; background: #f0f2f4; border: 1px solid #e2e5e9; border-radius: 6px; padding: 0.7rem 0.8rem; margin: 0.3rem 0 0; }
+@media (prefers-color-scheme: dark) { .code { background: #14171a !important; border-color: #2b3138 !important; } }
+h2 { font-size: 1.05rem; margin: 0 0 0.4rem; }
+.back { display: inline-block; margin-bottom: 1rem; }
+select, textarea {
+  width: 100%; padding: 0.55rem 0.7rem; font-size: 1rem;
+  border: 1px solid #cfd4da; border-radius: 6px; background: #fff; color: inherit;
+  font-family: inherit;
+}
+textarea { resize: vertical; }
+@media (prefers-color-scheme: dark) {
+  select, textarea { background: #14171a !important; color: inherit !important; border-color: #2b3138 !important; }
+}
+button.danger { background: #b42318; }
+button.danger:hover { background: #912018; }
+form.inline button.danger { background: none; color: #b42318; }
+form.inline button.danger:hover { background: none; }
+td.actions form.inline, td.actions details { margin-left: 0.6rem; }
+details summary { cursor: pointer; color: #2563eb; font-weight: 600; }
+details form { margin-top: 0.6rem; }
+.credential { border-color: #f5c518; background: #fffbeb; }
+@media (prefers-color-scheme: dark) { .credential { background: #2a2408 !important; border-color: #6b5a10 !important; } }
+/* Panel navigation: rendered once from the layout, so it is present on every
+   authenticated page without each content template having to include it. */
+.nav {
+  display: flex; flex-wrap: wrap; justify-content: space-between; align-items: baseline;
+  gap: 0.4rem 1rem; margin-bottom: 1.2rem; padding-bottom: 0.6rem;
+  border-bottom: 1px solid #e2e5e9;
+}
+@media (prefers-color-scheme: dark) { .nav { border-color: #2b3138 !important; } }
+.nav .links, .nav .session { display: flex; flex-wrap: wrap; gap: 0.2rem 0.9rem; align-items: baseline; }
+.nav .links a, .nav .links [aria-current] { padding: 0.2rem 0.5rem; border-radius: 6px; }
+.nav .links [aria-current] {
+  font-weight: 600; color: #1b1f24; background: #e6ebf5; box-shadow: inset 0 -2px 0 #2563eb;
+}
+@media (prefers-color-scheme: dark) {
+  .nav .links [aria-current] { color: #e6e8eb !important; background: #22303f !important; }
+}
+/* Status badges: one vocabulary (ok/warn/error/unknown) shared by the server
+   status page and the per-domain DNS checks, so a colour means the same thing
+   everywhere. The class suffix is the check's own status value. */
+.st {
+  display: inline-block; padding: 0.05rem 0.45rem; border-radius: 999px;
+  font-size: 0.7rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.04em;
+  vertical-align: middle; border: 1px solid transparent;
+}
+.st-ok { background: #ecfdf3; color: #067647; border-color: #abefc6; }
+.st-warn { background: #fffaeb; color: #b54708; border-color: #fedf89; }
+.st-error { background: #fef3f2; color: #b42318; border-color: #fecdca; }
+.st-unknown { background: #f0f2f4; color: #6b7280; border-color: #e2e5e9; }
+@media (prefers-color-scheme: dark) {
+  .st-ok { background: #0d2818 !important; color: #75d99b !important; border-color: #1a5336 !important; }
+  .st-warn { background: #2e2308 !important; color: #f5c86b !important; border-color: #6b5210 !important; }
+  .st-error { background: #2d1211 !important; color: #f5a29b !important; border-color: #6b201a !important; }
+  .st-unknown { background: #22262b !important; color: #9aa3ad !important; border-color: #2b3138 !important; }
+}
+.code-row { display: flex; align-items: flex-start; gap: 0.5rem; }
+.code-row .code { flex: 1; min-width: 0; }
+button.copy {
+  flex: none; margin-top: 0.3rem; padding: 0.45rem 0.7rem; font-size: 0.8rem;
+  background: #eef1f5; color: #2563eb; border: 1px solid #cfd4da;
+}
+button.copy:hover { background: #e2e7ee; }
+@media (prefers-color-scheme: dark) {
+  button.copy { background: #22262b !important; border-color: #2b3138 !important; }
+  button.copy:hover { background: #2b3138 !important; }
+}

internal/web/static/panel.js

@@ -32,6 +32,20 @@
     });
   });
 
+  // --- Confirmation on destructive forms --------------------------------
+  // Forms that delete something or invalidate a working credential carry a
+  // data-confirm message. The prompt lives here rather than in an inline
+  // onsubmit attribute because the panel's Content-Security-Policy allows no
+  // inline script (phase 14.A). The listener is delegated from the document,
+  // so it also covers markup swapped in by HTMX. With JavaScript disabled the
+  // form submits without asking — exactly as the inline handler behaved.
+  document.addEventListener("submit", function (ev) {
+    var form = ev.target.closest("form[data-confirm]");
+    if (form && !window.confirm(form.dataset.confirm)) {
+      ev.preventDefault();
+    }
+  });
+
   // --- Address list shown only in list mode -----------------------------
   // The "Addresses" field applies to list mode only; in wildcard mode the
   // server ignores it, so hiding it removes a field that does nothing. The

internal/web/templates/domain_delete.html

@@ -18,7 +18,7 @@
   invalid; remove it from DNS if you do not plan to re-add the domain.</p>
 
   <form method="post" action="/domains/{{.Domain.ID}}/delete">
-    <button type="submit" style="background:#b42318">Delete {{.Domain.Name}}</button>
+    <button type="submit" class="danger">Delete {{.Domain.Name}}</button>
   </form>
 </div>
 {{end}}

internal/web/templates/domain_detail.html

@@ -152,18 +152,18 @@
             </form>
             {{if .HasLimit}}
             <form class="inline" method="post" action="/applications/{{.ID}}/ratelimit"
-                  onsubmit="return confirm('Remove the rate limit for {{.Login}}? Only the global level-1 limit will apply.')">
+                  data-confirm="Remove the rate limit for {{.Login}}? Only the global level-1 limit will apply.">
               <input type="hidden" name="clear" value="1">
               <button type="submit" class="danger">Remove limit</button>
             </form>
             {{end}}
           </details>
           <form class="inline" method="post" action="/applications/{{.ID}}/password"
-                onsubmit="return confirm('Regenerate the password for {{.Login}}? The current password stops working immediately.')">
+                data-confirm="Regenerate the password for {{.Login}}? The current password stops working immediately.">
             <button type="submit">New password</button>
           </form>
           <form class="inline" method="post" action="/applications/{{.ID}}/delete"
-                onsubmit="return confirm('Delete application {{.Login}}? Its credentials stop working immediately.')">
+                data-confirm="Delete application {{.Login}}? Its credentials stop working immediately.">
             <button type="submit" class="danger">Delete</button>
           </form>
         </td>
@@ -204,7 +204,7 @@
   </form>
   {{if .DomainHasRL}}
   <form class="inline" method="post" action="/domains/{{.Domain.ID}}/ratelimit"
-        onsubmit="return confirm('Remove the domain rate limit? Only the global level-1 limit will apply.')">
+        data-confirm="Remove the domain rate limit? Only the global level-1 limit will apply.">
     <input type="hidden" name="clear" value="1">
     <button type="submit" class="danger">Remove limit</button>
   </form>

internal/web/templates/layout.html

@@ -5,123 +5,15 @@
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>{{.Title}}</title>
 <link rel="icon" href="/static/favicon.png" type="image/png">
+<link rel="stylesheet" href="/static/panel.css">
+{{/* Unless told otherwise, htmx injects a stylesheet element of its own into
+     the head for the request-indicator classes. The panel uses no
+     hx-indicator, and that injected element would be the one thing the
+     Content-Security-Policy (phase 14.A) has to make an exception for, so it
+     is switched off here. */}}
+<meta name="htmx-config" content='{"includeIndicatorStyles":false}'>
 <script src="/static/htmx.min.js" defer></script>
 <script src="/static/panel.js" defer></script>
-<style>
-  :root { color-scheme: light dark; }
-  * { box-sizing: border-box; }
-  body {
-    font: 15px/1.5 system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
-    margin: 0; padding: 2rem 1rem; background: #f6f7f9; color: #1b1f24;
-  }
-  @media (prefers-color-scheme: dark) {
-    body { background: #14171a; color: #e6e8eb; }
-    .card { background: #1d2125 !important; border-color: #2b3138 !important; }
-    input { background: #14171a !important; color: inherit !important; border-color: #2b3138 !important; }
-  }
-  main { max-width: 42rem; margin: 0 auto; }
-  h1 { font-size: 1.4rem; margin: 0 0 1rem; }
-  .card {
-    background: #fff; border: 1px solid #e2e5e9; border-radius: 10px;
-    padding: 1.5rem; margin: 0 auto;
-  }
-  .card.narrow { max-width: 24rem; }
-  label { display: block; font-weight: 600; margin: 0.9rem 0 0.3rem; }
-  input {
-    width: 100%; padding: 0.55rem 0.7rem; font-size: 1rem;
-    border: 1px solid #cfd4da; border-radius: 6px; background: #fff;
-  }
-  button {
-    margin-top: 1.2rem; padding: 0.6rem 1.1rem; font-size: 1rem; font-weight: 600;
-    color: #fff; background: #2563eb; border: 0; border-radius: 6px; cursor: pointer;
-  }
-  button:hover { background: #1d4ed8; }
-  .error { color: #b42318; margin: 0.6rem 0 0; font-weight: 600; }
-  .muted { color: #6b7280; }
-  .topbar { display: flex; justify-content: space-between; align-items: baseline; margin-bottom: 1.2rem; }
-  .topbar .actions { display: flex; gap: 0.9rem; align-items: baseline; }
-  form.inline { display: inline; margin: 0; }
-  form.inline button { background: none; color: #2563eb; padding: 0; margin: 0; font-weight: 600; }
-  form.inline button:hover { text-decoration: underline; background: none; }
-  main { max-width: 48rem; }
-  .card + .card { margin-top: 1.2rem; }
-  .flash { background: #ecfdf3; border: 1px solid #abefc6; color: #067647; padding: 0.7rem 1rem; border-radius: 8px; margin-bottom: 1.2rem; }
-  @media (prefers-color-scheme: dark) { .flash { background: #0d2818 !important; border-color: #1a5336 !important; color: #75d99b !important; } }
-  table { width: 100%; border-collapse: collapse; }
-  th, td { text-align: left; padding: 0.5rem 0.4rem; border-bottom: 1px solid #e2e5e9; }
-  @media (prefers-color-scheme: dark) { th, td { border-color: #2b3138 !important; } }
-  th { font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.03em; color: #6b7280; }
-  td.actions { text-align: right; }
-  a.danger { color: #b42318; }
-  .code { display: block; white-space: pre-wrap; word-break: break-all; font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
-          font-size: 0.85rem; background: #f0f2f4; border: 1px solid #e2e5e9; border-radius: 6px; padding: 0.7rem 0.8rem; margin: 0.3rem 0 0; }
-  @media (prefers-color-scheme: dark) { .code { background: #14171a !important; border-color: #2b3138 !important; } }
-  h2 { font-size: 1.05rem; margin: 0 0 0.4rem; }
-  .back { display: inline-block; margin-bottom: 1rem; }
-  select, textarea {
-    width: 100%; padding: 0.55rem 0.7rem; font-size: 1rem;
-    border: 1px solid #cfd4da; border-radius: 6px; background: #fff; color: inherit;
-    font-family: inherit;
-  }
-  textarea { resize: vertical; }
-  @media (prefers-color-scheme: dark) {
-    select, textarea { background: #14171a !important; color: inherit !important; border-color: #2b3138 !important; }
-  }
-  button.danger { background: #b42318; }
-  button.danger:hover { background: #912018; }
-  form.inline button.danger { background: none; color: #b42318; }
-  form.inline button.danger:hover { background: none; }
-  td.actions form.inline, td.actions details { margin-left: 0.6rem; }
-  details summary { cursor: pointer; color: #2563eb; font-weight: 600; }
-  details form { margin-top: 0.6rem; }
-  .credential { border-color: #f5c518; background: #fffbeb; }
-  @media (prefers-color-scheme: dark) { .credential { background: #2a2408 !important; border-color: #6b5a10 !important; } }
-  /* Panel navigation: rendered once from this layout, so it is present on every
-     authenticated page without each content template having to include it. */
-  .nav {
-    display: flex; flex-wrap: wrap; justify-content: space-between; align-items: baseline;
-    gap: 0.4rem 1rem; margin-bottom: 1.2rem; padding-bottom: 0.6rem;
-    border-bottom: 1px solid #e2e5e9;
-  }
-  @media (prefers-color-scheme: dark) { .nav { border-color: #2b3138 !important; } }
-  .nav .links, .nav .session { display: flex; flex-wrap: wrap; gap: 0.2rem 0.9rem; align-items: baseline; }
-  .nav .links a, .nav .links [aria-current] { padding: 0.2rem 0.5rem; border-radius: 6px; }
-  .nav .links [aria-current] {
-    font-weight: 600; color: #1b1f24; background: #e6ebf5; box-shadow: inset 0 -2px 0 #2563eb;
-  }
-  @media (prefers-color-scheme: dark) {
-    .nav .links [aria-current] { color: #e6e8eb !important; background: #22303f !important; }
-  }
-  /* Status badges: one vocabulary (ok/warn/error/unknown) shared by the server
-     status page and the per-domain DNS checks, so a colour means the same thing
-     everywhere. The class suffix is the check's own status value. */
-  .st {
-    display: inline-block; padding: 0.05rem 0.45rem; border-radius: 999px;
-    font-size: 0.7rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.04em;
-    vertical-align: middle; border: 1px solid transparent;
-  }
-  .st-ok { background: #ecfdf3; color: #067647; border-color: #abefc6; }
-  .st-warn { background: #fffaeb; color: #b54708; border-color: #fedf89; }
-  .st-error { background: #fef3f2; color: #b42318; border-color: #fecdca; }
-  .st-unknown { background: #f0f2f4; color: #6b7280; border-color: #e2e5e9; }
-  @media (prefers-color-scheme: dark) {
-    .st-ok { background: #0d2818 !important; color: #75d99b !important; border-color: #1a5336 !important; }
-    .st-warn { background: #2e2308 !important; color: #f5c86b !important; border-color: #6b5210 !important; }
-    .st-error { background: #2d1211 !important; color: #f5a29b !important; border-color: #6b201a !important; }
-    .st-unknown { background: #22262b !important; color: #9aa3ad !important; border-color: #2b3138 !important; }
-  }
-  .code-row { display: flex; align-items: flex-start; gap: 0.5rem; }
-  .code-row .code { flex: 1; min-width: 0; }
-  button.copy {
-    flex: none; margin-top: 0.3rem; padding: 0.45rem 0.7rem; font-size: 0.8rem;
-    background: #eef1f5; color: #2563eb; border: 1px solid #cfd4da;
-  }
-  button.copy:hover { background: #e2e7ee; }
-  @media (prefers-color-scheme: dark) {
-    button.copy { background: #22262b !important; border-color: #2b3138 !important; }
-    button.copy:hover { background: #2b3138 !important; }
-  }
-</style>
 </head>
 <body>
 <main>

internal/web/templates_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"io/fs"
 	"path"
+	"regexp"
 	"strings"
 	"testing"
 	"time"
@@ -96,6 +97,53 @@ func TestReloadFormLivesOnlyOnTheStatusPage(t *testing.T) {
 	})
 }
 
+// The panel's Content-Security-Policy is a plain default-src 'self' with no
+// inline exemption (phase 14.A), which makes inline script and inline style a
+// failure mode rather than a style question: an onclick= handler or a
+// style="..." attribute added to a template does not error, it silently stops
+// working in the browser. Behaviour belongs in static/panel.js (triggered from
+// a data- attribute), appearance in static/panel.css.
+func TestNoTemplateUsesInlineScriptOrStyle(t *testing.T) {
+	inlineHandler := regexp.MustCompile(`\son[a-z]+\s*=`)
+	inlineStyle := regexp.MustCompile(`\sstyle\s*=|<style[\s>]`)
+	scriptTag := regexp.MustCompile(`<script[^>]*>`)
+
+	forEachTemplate(t, func(name, body string) {
+		if m := inlineHandler.FindString(body); m != "" {
+			t.Errorf("%s has an inline event handler (%q); the CSP blocks it — move the behaviour into static/panel.js",
+				name, strings.TrimSpace(m))
+		}
+		if m := inlineStyle.FindString(body); m != "" {
+			t.Errorf("%s has an inline style (%q); the CSP blocks it — move the rule into static/panel.css",
+				name, strings.TrimSpace(m))
+		}
+		for _, tag := range scriptTag.FindAllString(body, -1) {
+			if !strings.Contains(tag, "src=") {
+				t.Errorf("%s has an inline script (%q); the CSP blocks it — put the code in static/panel.js", name, tag)
+			}
+		}
+	})
+}
+
+// default-src 'self' also means every asset a page pulls in must be one this
+// server actually serves, so a typo in a /static path is a blocked request,
+// not a 404 in the page's own colours.
+func TestLayoutReferencesOnlyEmbeddedAssets(t *testing.T) {
+	body, err := fs.ReadFile(assetsFS, "templates/layout.html")
+	if err != nil {
+		t.Fatalf("read layout: %v", err)
+	}
+	refs := regexp.MustCompile(`(?:src|href)="/static/([^"]+)"`).FindAllStringSubmatch(string(body), -1)
+	if len(refs) == 0 {
+		t.Fatal("the layout references no static assets at all")
+	}
+	for _, m := range refs {
+		if _, err := fs.Stat(assetsFS, "static/"+m[1]); err != nil {
+			t.Errorf("layout references /static/%s, which is not embedded: %v", m[1], err)
+		}
+	}
+}
+
 func TestStatusPageRendersEveryCheck(t *testing.T) {
 	tmpl, err := loadTemplates()
 	if err != nil {