fix(submit): raise TinyMCE fullscreen above the fixed navbar

TinyMCE's skin injects .mce-fullscreen { z-index: 100 } at editor init,
after core editor.css, so the fullscreen editor (toolbar at the viewport
top) lost to the fixed navbar (.nav-fixed .header, z-index 999). Restore
core's intended 100010 with an element+class selector that outranks the
skin regardless of injection order; it stays below the submit media
dialog (100080). Also remove the dead .mce-top-part.affix rules (no
AKSRT script drives them) and pin both in a contract test.

.gitignore

@@ -56,6 +56,7 @@
 !/tests/front-submit/
 /tests/front-submit/*
 !/tests/front-submit/video-cover-contract.test.cjs
+!/tests/front-submit/editor-fullscreen-contract.test.cjs
 !/tests/asset-ledger/
 !/tests/asset-ledger/*.php
 !/tests/visual/docker-compose.zibll.yml

assets/css/frontend/pages/submit.css

@@ -51,19 +51,18 @@
   border: 0;
 }
 
-.newposts-editor .mce-top-part.affix {
-  position: fixed;
-}
-
-.newposts-editor .mce-top-part.affix-bottom {
-  position: absolute;
-}
-
 .newposts-editor .wp-editor-container {
   overflow: hidden;
   border-radius: 0;
 }
 
+/* TinyMCE 全屏容器：skin 样式在编辑器初始化时注入（晚于核心 editor.css），
+   其 .mce-fullscreen 的 z-index:100 压不过固定导航栏（.nav-fixed .header 为 999）。
+   用元素+类选择器提高优先级，恢复 WP 核心预期的 100010，仍低于投稿媒体弹层（100080）。 */
+div.mce-fullscreen {
+  z-index: 100010;
+}
+
 .newposts-editor .mce-toolbar-grp,
 .newposts-editor div.mce-toolbar-grp {
   border-bottom: 0;
@@ -547,12 +546,30 @@ body.aksrt-editor-media-open {
   font-size: 1em;
 }
 
+/* 纯图标按钮（设置视频封面/视频/清除）：fa 字形行高与文字不同导致图标上偏，
+   用 flex 居中修正；并去掉 legacy .but 给图标加的文字间距。btn-delete 的
+   hidden 属性切换依赖默认 display，故用 :not([hidden]) 守卫。 */
+.featured-edit .btns-full .btn-video,
+.featured-edit .btns-full .btn-delete:not([hidden]) {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+}
+
 .featured-edit .btns-full .btn-video-pic {
   display: none;
 }
 
 .featured-loaded.video .btns-full .btn-video-pic {
   display: inline-flex;
+  align-items: center;
+  justify-content: center;
+}
+
+.featured-edit .btns-full .btn-video-pic > .fa,
+.featured-edit .btns-full .btn-video > .fa,
+.featured-edit .btns-full .btn-delete > .fa {
+  margin-right: 0;
 }
 
 .featured-loaded.image .btn-video,

tests/front-submit/editor-fullscreen-contract.test.cjs

@@ -0,0 +1,35 @@
+'use strict';
+
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const test = require('node:test');
+
+const root = path.resolve(__dirname, '..', '..');
+const read = (file) => fs.readFileSync(path.join(root, file), 'utf8');
+
+test('submit.css raises the TinyMCE fullscreen container above the fixed navbar', () => {
+  const css = read('assets/css/frontend/pages/submit.css');
+
+  // TinyMCE's skin injects .mce-fullscreen { z-index: 100 } at editor init,
+  // after core editor.css, so the fullscreen editor loses to the fixed navbar
+  // (.nav-fixed .header, z-index 999). The element+class selector outranks the
+  // skin regardless of injection order and restores core's intended 100010,
+  // which stays below the submit media dialog (100080).
+  assert.match(css, /div\.mce-fullscreen \{\s*\n  z-index: 100010;\s*\n\}/);
+});
+
+test('the Zibll toolbar affix rules stay removed', () => {
+  const css = read('assets/css/frontend/pages/submit.css');
+  const jsRoot = path.join(root, 'assets/js');
+  const js = fs
+    .readdirSync(jsRoot, { withFileTypes: true })
+    .filter((entry) => entry.isFile())
+    .map((entry) => read(`assets/js/${entry.name}`))
+    .join('\n');
+
+  // No AKSRT script adds .affix to .mce-top-part (that was Zibll's
+  // editextend.js), so the affix positioning rules must not come back.
+  assert.doesNotMatch(css, /mce-top-part\.affix/);
+  assert.doesNotMatch(js, /mce-top-part/);
+});