diff --git a/demo/bump/index.html b/demo/bump/index.html
index f4d3b62..1d59d18 100644
--- a/demo/bump/index.html
+++ b/demo/bump/index.html
@@ -14,16 +14,16 @@
        · 手指戳上去 = 肚皮被按下去一个窝，松手后 duang duang 回弹（欠阻尼弹簧）+ 周围一起晃；
        · 戳中鼓起处 → 被摁回去，往远离手指的方向溜走，过一两秒换个部位、换个地方再顶出来；
        · 头图下方「找找宝宝」收集条：戳回过哪个部位就点亮哪个。
-     下面的卡片是首页截图（静态），只为给头图一个真实语境。
+     v4：宝宝活在整个页面底下——头图 + 下面所有模块（首页截图）合成一张整页纹理，WebGL 画布固定铺满屏幕，
+     按滚动位置取当前这一屏来画；滑到别的模块停下来，宝宝会在这一屏里慢慢顶一下，把卡片撑成小帐篷。
      ?rec=1：录屏模式，由 __adv / __tap / __press 逐帧驱动（生成动图用）。 -->
 <style>
   html,body{margin:0;background:#F8F3EF;-webkit-tap-highlight-color:transparent;font-family:-apple-system,"PingFang SC","Noto Sans SC",sans-serif}
   .page{position:relative;max-width:480px;margin:0 auto;overflow:hidden}
-  .hero{position:relative;width:100%;aspect-ratio:375/270;touch-action:manipulation;cursor:pointer}
-  .hero canvas,.hero img{position:absolute;inset:0;width:100%;height:100%;display:block}
-  .hero img{opacity:0}               /* WebGL 起不来时退回静态头图 */
-  .hero.nogl img{opacity:1}
-  .below{display:block;width:100%;margin-top:0}
+  .page img{display:block;width:100%}  /* 真实排版用的静态图：撑出页面高度，WebGL 起不来时直接看它 */
+  /* 整页的「肚皮」：固定铺满一屏，按滚动位置画当前这一屏 */
+  #cv{position:fixed;top:0;left:50%;width:min(100vw,480px);height:100%;transform:translateX(-50%);pointer-events:none;z-index:2;opacity:0}
+  #cv.on{opacity:1}
   /* 头图下缘的「找找宝宝」收集条：和首页「记一下」同一套白色玻璃胶囊语言 */
   .hunt{position:absolute;left:0;right:0;top:0;display:flex;justify-content:center;pointer-events:none;z-index:3}
   .hunt .bar{margin-top:calc(min(100vw,480px) * 216 / 375);display:flex;align-items:center;gap:6px;padding:6px 7px 6px 13px;border-radius:999px;
@@ -46,31 +46,32 @@
 </head>
 <body>
 <div class="page">
-  <div class="hero" id="hero">
-    <img src="belly.jpg" alt="">
-    <canvas id="cv"></canvas>
-    <i class="finger" id="finger"></i>
-  </div>
+  <img src="belly.jpg" alt="">
+  <img src="below.jpg" alt="">
+  <i class="finger" id="finger"></i>
   <div class="hunt"><div class="bar" id="hunt"><span class="t">找找宝宝</span>
     <span class="c" data-k="foot"><i></i>小脚丫</span><span class="c" data-k="fist"><i></i>小拳头</span>
     <span class="c" data-k="knee"><i></i>小膝盖</span><span class="c" data-k="butt"><i></i>小屁股</span></div></div>
-  <img class="below" src="below.jpg" alt="">
 </div>
+<canvas id="cv"></canvas>
 <script>
 (function () {
-  const W = 375, H = 270, SC = 3;               // 头图逻辑尺寸（与首页一致），纹理按 3 倍画
+  const W = 375, H = 270, BH = 2551, HP = H + BH;   // 头图 375x270（与首页一致）+ 下面模块 375x2551 = 整页
   const REC = /[?&]rec=1/.test(location.search);
-  const hero = document.getElementById('hero'), cv = document.getElementById('cv');
+  const page = document.querySelector('.page'), cv = document.getElementById('cv');
   const hunt = document.getElementById('hunt'), finger = document.getElementById('finger');
   const gl = cv.getContext('webgl', { premultipliedAlpha: false, preserveDrawingBuffer: REC, antialias: true });
-  if (!gl) { hero.classList.add('nogl'); return; }
+  if (!gl) return;
+  // 整页纹理尽量按 3 倍画，但不超过显卡纹理上限和 canvas 面积上限（iOS 约 1600 万像素）
+  const SC = Math.min(3, gl.getParameter(gl.MAX_TEXTURE_SIZE) / HP, Math.sqrt(16e6 / (W * HP)));
 
   const VS = 'attribute vec2 a;varying vec2 v;void main(){v=a*.5+.5;v.y=1.-v.y;gl_Position=vec4(a,0.,1.);}';
   const FS = `
 precision highp float;
 varying vec2 v;
 uniform sampler2D T;
-uniform vec2 S;           // 逻辑尺寸 375x270
+uniform vec2 S;           // 整页逻辑尺寸 375xHP
+uniform vec2 O;           // 当前这一屏：滚动位置 y、屏幕高度（逻辑 px）
 uniform vec4 F;           // 鼓起处 x,y,角度,高度(px)
 uniform vec4 K;           // 形状 半径x,半径y,尖度(指数),脚趾显隐(0-1)
 uniform vec4 G;           // 左右脚(±1),脚趾蜷曲(0-1),拉长量,0
@@ -105,10 +106,9 @@ float dentR=33.;
 float dent(vec2 p){vec2 d=p-P.xy;return P.z*exp(-dot(d,d)/(dentR*dentR));}
 float hgt(vec2 p){return tent(p)+toes(p)*.12+dent(p);}
 void main(){
-  vec2 p=v*S;
-  vec3 c0=texture2D(T,v).rgb;
-  // 白字也接近页面底色，所以只在下缘弧线那一带（y>185）按颜色判断
-  float m=p.y<185.?1.:smoothstep(.03,.12,distance(c0,vec3(.973,.953,.937)));
+  vec2 p=vec2(v.x*S.x,O.x+v.y*O.y);
+  if(p.y<0.||p.y>S.y){gl_FragColor=vec4(.973,.953,.937,1.);return;}   // iOS 橡皮筋拉出页面外
+  float m=1.;                                 // 整页都是肚皮
   float e=1.2;
   vec2 g=vec2(hgt(p+vec2(e,0.))-hgt(p-vec2(e,0.)),hgt(p+vec2(0.,e))-hgt(p-vec2(0.,e)))/(2.*e)*m;
   float h=hgt(p)*m;
@@ -142,20 +142,22 @@ void main(){
   gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([-1, -1, 1, -1, -1, 1, 1, 1]), gl.STATIC_DRAW);
   const al = gl.getAttribLocation(pr, 'a'); gl.enableVertexAttribArray(al); gl.vertexAttribPointer(al, 2, gl.FLOAT, false, 0, 0);
   const U = n => gl.getUniformLocation(pr, n);
-  const uS = U('S'), uF = U('F'), uK = U('K'), uG = U('G'), uP = U('P'), uJ = U('J'), uT = U('Tm');
-  gl.uniform2f(uS, W, H);
+  const uO = U('O'), uS = U('S'), uF = U('F'), uK = U('K'), uG = U('G'), uP = U('P'), uJ = U('J'), uT = U('Tm');
+  gl.uniform2f(uS, W, HP);
 
   /* ---------- 纹理：canvas 现场合成，宝宝卡的悄悄话会变 ---------- */
-  const tc = document.createElement('canvas'); tc.width = W * SC; tc.height = H * SC;
+  const tc = document.createElement('canvas'); tc.width = Math.floor(W * SC); tc.height = Math.floor(HP * SC);
+  const hc = document.createElement('canvas'); hc.width = tc.width; hc.height = Math.ceil(H * SC);   // 只换头图那一截时用
   const cx = tc.getContext('2d');
-  const SRC = { bg: 'belly_bg.jpg', top: 'top.png', pill: '../_hero/pill.png', week: '../_hero/week.png', prog: '../_hero/prog.png' };
+  const SRC = { bg: 'belly_bg.jpg', top: 'top.png', pill: '../_hero/pill.png', week: '../_hero/week.png', prog: '../_hero/prog.png', below: 'below.jpg' };
   const IMG = {}; let loaded = 0;
   const tex = gl.createTexture(); let ready = false;
   const FONT = '-apple-system,"PingFang SC","Noto Sans SC",sans-serif';
   const card = { line: '我认得妈妈的声音' };
   function rr(x, y, w, h, r) { cx.beginPath(); cx.moveTo(x + r, y); cx.arcTo(x + w, y, x + w, y + h, r); cx.arcTo(x + w, y + h, x, y + h, r); cx.arcTo(x, y + h, x, y, r); cx.arcTo(x, y, x + w, y, r); cx.closePath(); }
-  function compose() {
+  function compose(full) {
     cx.setTransform(SC, 0, 0, SC, 0, 0);
+    if (full) cx.drawImage(IMG.below, 0, H, W, BH);
     cx.drawImage(IMG.bg, 0, 0, W, H);
     // 右侧原来是宝宝插画的位置：一大团很淡的暖光 + 几颗小光点，让肚皮不空
     const gr = cx.createRadialGradient(292, 118, 6, 292, 118, 120);
@@ -196,7 +198,10 @@ void main(){
     cx.fillText(ln, X + 26, Y + 101.5);
     cx.shadowColor = 'transparent';
     gl.bindTexture(gl.TEXTURE_2D, tex);
-    gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGB, gl.RGB, gl.UNSIGNED_BYTE, tc);
+    if (full) { gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGB, gl.RGB, gl.UNSIGNED_BYTE, tc); return; }
+    // 悄悄话变了：只把头图那一截重新传上去，整页纹理很大，别每次全传
+    const hx = hc.getContext('2d'); hx.drawImage(tc, 0, 0);
+    gl.texSubImage2D(gl.TEXTURE_2D, 0, 0, 0, gl.RGB, gl.UNSIGNED_BYTE, hc);
   }
   function setCard(line) { card.line = line; if (ready) compose(); }
   Object.keys(SRC).forEach(k => {
@@ -208,16 +213,19 @@ void main(){
         gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
         gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
         gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
-        ready = true; compose();
-        (document.fonts ? document.fonts.ready : Promise.resolve()).then(() => { compose(); window.__ready = true; });
+        ready = true; compose(true); cv.classList.add('on');
+        (document.fonts ? document.fonts.ready : Promise.resolve()).then(() => { compose(true); window.__ready = true; });
       }
     };
     im.src = SRC[k];
   });
 
+  // 页面 px ↔ 逻辑 px；当前这一屏在整页里的位置
+  let K = 1;
+  const view = () => { const r = page.getBoundingClientRect(); K = r.width / W; return { y: -r.top / K, h: cv.clientHeight / K }; };
   function resize() {
-    const dpr = Math.min(window.devicePixelRatio || 1, 3), r = hero.getBoundingClientRect();
-    cv.width = Math.round(r.width * dpr); cv.height = Math.round(r.height * dpr);
+    const dpr = Math.min(window.devicePixelRatio || 1, 2);   // 整屏都要算，最多 2 倍
+    cv.width = Math.round(cv.clientWidth * dpr); cv.height = Math.round(cv.clientHeight * dpr);
     gl.viewport(0, 0, cv.width, cv.height);
   }
   resize(); addEventListener('resize', resize);
@@ -243,14 +251,17 @@ void main(){
 
   // 一半以上的概率专挑字和卡片顶（大字「30」、倒计时胶囊、进度条、slogan、宝宝卡），字会被撑起来变形
   const TEXT_SPOTS = [[62, 120], [100, 74], [104, 124], [96, 166], [230, 26], [292, 104], [300, 80], [150, 168]];
+  // 只在当前这一屏里挑位置：头图露着就多半挑头图上的字，滑到下面就在下面的模块上顶
   function pickSpot() {
+    const vw = view(), y0 = Math.max(vw.y + 60, 20), y1 = Math.min(vw.y + vw.h - 70, HP - 40);
+    const spots = TEXT_SPOTS.filter(s => s[1] > y0 && s[1] < y1);
     for (let i = 0; i < 40; i++) {
       let x, y;
-      if (Math.random() < .7) { const s = TEXT_SPOTS[Math.floor(Math.random() * TEXT_SPOTS.length)]; x = s[0] + (Math.random() - .5) * 16; y = s[1] + (Math.random() - .5) * 10; }
-      else { x = 220 + Math.random() * 130; y = 70 + Math.random() * 120; }
+      if (spots.length && Math.random() < .7) { const s = spots[Math.floor(Math.random() * spots.length)]; x = s[0] + (Math.random() - .5) * 16; y = s[1] + (Math.random() - .5) * 10; }
+      else { x = 50 + Math.random() * 275; y = y0 + Math.random() * Math.max(y1 - y0, 1); }
       if (Math.hypot(x - ft.x, y - ft.y) > 80) return { x, y };
     }
-    return { x: 300, y: 120 };
+    return { x: 190, y: (y0 + y1) / 2 };
   }
   function appear() {
     const key = ORDER[seq++ % ORDER.length], P = PARTS[key];
@@ -295,16 +306,27 @@ void main(){
       jg.y.vel += 150; jg.x.vel += (Math.random() - .5) * 90;
     }
   }
-  hero.addEventListener('pointerdown', e => {
-    const r = hero.getBoundingClientRect();
-    hero.setPointerCapture && hero.setPointerCapture(e.pointerId);
-    press((e.clientX - r.left) / r.width * W, (e.clientY - r.top) / r.height * H, true);
+  page.addEventListener('pointerdown', e => {
+    const r = page.getBoundingClientRect();
+    press((e.clientX - r.left) / r.width * W, (e.clientY - r.top) / r.width * W, true);
   });
-  const up = () => press(0, 0, false);
-  hero.addEventListener('pointerup', up); hero.addEventListener('pointercancel', up);
+  page.addEventListener('pointerup', () => press(0, 0, false));
+  // 手指一滑变成滚动：浏览器会发 pointercancel，这时窝悄悄平回去，不弹
+  page.addEventListener('pointercancel', () => { if (pk.held) { pk.held = false; pk.d.to = 0; pk.d.k = 300; pk.d.c = 34; } });
 
+  let lastY = 0, still = 0;
   function step(dt) {
     t += dt;
+    // 滑动停下来 0.35 秒，看看宝宝在不在这一屏里；不在就让它挪过来，在这一屏里慢慢顶一下
+    const vw = view();
+    if (Math.abs(vw.y - lastY) > 1.5) { still = 0; lastY = vw.y; }
+    else if (still < .35 && (still += dt) >= .35) {
+      const fy = ft.y + ft.oy, seen = fy > vw.y + 30 && fy < vw.y + vw.h - 30;
+      if (!seen) {
+        if (mode === 'show' || mode === 'hide') { ft.h.v = 0; ft.h.vel = 0; mode = 'wait'; wait = .5 + Math.random() * .6; }
+        else if (mode === 'wait') wait = Math.min(wait, .5 + Math.random() * .6);
+      }
+    }
     if (mode === 'wait') { wait -= dt; if (wait <= 0) appear(); }
     else if (mode === 'show') {
       ft.life += dt;
@@ -344,6 +366,7 @@ void main(){
     gl.uniform4f(uP, pk.x, pk.y, pk.d.v, 0);
     gl.uniform2f(uJ, jg.x.v, jg.y.v);
     gl.uniform1f(uT, t);
+    const vw = view(); gl.uniform2f(uO, vw.y, vw.h);
     gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
   }
 
@@ -354,7 +377,7 @@ void main(){
     window.__tap = (x, y) => press(x, y, true);
     window.__foot = () => ({ x: ft.x + ft.ox, y: ft.y + ft.oy, h: ft.h.v, mode, key: ft.key });
     window.__finger = (x, y, on) => {
-      finger.style.left = x / W * 100 + '%'; finger.style.top = y / H * 100 + '%';
+      finger.style.left = x * K + 'px'; finger.style.top = y * K + 'px';
       finger.classList.toggle('on', !!on);
     };
     window.__seed = s => { let z = s; Math.random = () => ((z = (z * 16807) % 2147483647) / 2147483647); };