fix(hero): 消除首屏 slogan 二次跳动与加载闪烁，加纸色遮罩护可读性

docs/githire.css

@@ -366,6 +366,22 @@ main, .topnav, .site-foot { position: relative; z-index: 1; }
   text-align: center;
   padding: 0 var(--gutter);
 }
+/* Soft paper scrim between the moving canvas and the text. Sits inside the
+   hero's stacking context (so it's above the z-0 canvas) but behind the copy,
+   lifting legibility while the starfield still reads through at the edges. */
+.hero-content::before{
+  content: "";
+  position: absolute;
+  inset: -10% -8%;
+  z-index: -1;
+  pointer-events: none;
+  background: radial-gradient(
+    ellipse 76% 66% at 50% 47%,
+    rgba(246, 241, 232, 0.85) 0%,
+    rgba(246, 241, 232, 0.66) 40%,
+    rgba(246, 241, 232, 0) 76%
+  );
+}
 .hero-title{
   font-family: var(--font-serif);
   font-weight: 500;

docs/i18n.js

@@ -937,13 +937,28 @@
     return 'en';
   }
 
+  // Normalize markup for comparison only: collapse insignificant whitespace
+  // and drop the self-closing slash on void elements. The browser serializes
+  // `<br/>` as `<br>`, so without this the dictionary source (which writes
+  // `<br/>`) would never match the DOM and we'd re-render needlessly.
+  function normMarkup(s) {
+    return s.replace(/\s+/g, ' ').replace(/\s*\/>/g, '>').trim();
+  }
+
   function applyTo(root, lang) {
     var els = root.querySelectorAll('[data-i18n]');
     for (var i = 0; i < els.length; i++) {
       var el = els[i];
       var key = el.getAttribute('data-i18n');
       var entry = T[key];
       if (!entry || typeof entry[lang] !== 'string') continue;
+      // Skip the swap when the element already renders this exact markup.
+      // The page ships in its own language, so on first load every value
+      // already matches — re-setting innerHTML would needlessly reflow the
+      // page and restart the hero's CSS entrance animation, making the
+      // slogan visibly "jump" a second time. Comparison only; a mismatch
+      // (a real language switch) still updates as before.
+      if (normMarkup(el.innerHTML) === normMarkup(entry[lang])) continue;
       el.innerHTML = entry[lang];
     }