feat: Twenty Sixteen 主题，带定制 Header 布局 + mu-plugins

twentysixteen/custom.css

@@ -0,0 +1,28 @@
+/* === Logo 左侧，标题+副标题右侧上下排列 === */
+.site-branding {
+    display: flex;
+    align-items: center;
+    gap: 1.5em;
+}
+
+.custom-logo-link {
+    flex-shrink: 0;
+}
+
+.site-branding-text {
+    display: flex;
+    flex-direction: column;
+}
+
+.wp-custom-logo .site-title {
+    margin-top: 0;
+}
+
+/* 移动端恢复竖排 */
+@media screen and (max-width: 709px) {
+    .site-branding {
+        flex-direction: column;
+        align-items: flex-start;
+        gap: 0.5em;
+    }
+}