diff --git a/frontend/css/lab.css b/frontend/css/lab.css
index 2de00b2..b4471c9 100644
--- a/frontend/css/lab.css
+++ b/frontend/css/lab.css
@@ -1634,25 +1634,28 @@ canvas[data-draggable]:active { cursor: grabbing; }
 .ptbl-hero {
   position: relative;
   text-align: center;
-  padding: 14px 10px 10px;
+  padding: 28px 10px 12px;
   border-bottom: 1px solid rgba(255,255,255,0.07);
   flex-shrink: 0;
+  overflow: hidden;
 }
 .ptbl-hero-z {
   position: absolute;
   top: 8px;
   left: 10px;
-  font-size: .72rem;
+  font-size: .82rem;
   font-weight: 700;
-  color: rgba(255,255,255,0.35);
+  color: rgba(255,255,255,0.55);
   line-height: 1;
 }
 .ptbl-hero-sym {
-  font-size: 6rem;
+  font-size: clamp(2.4rem, 14vw, 4.4rem);
   font-weight: 900;
   color: var(--el-col, #7B8EF7);
-  line-height: 1;
-  letter-spacing: -2px;
+  line-height: 1.05;
+  letter-spacing: -1px;
+  display: block;
+  overflow: visible;
 }
 .ptbl-hero-name {
   font-size: 1rem;
diff --git a/frontend/js/labs/qualanalysis.js b/frontend/js/labs/qualanalysis.js
index 76500bf..7cb1e17 100644
--- a/frontend/js/labs/qualanalysis.js
+++ b/frontend/js/labs/qualanalysis.js
@@ -949,6 +949,25 @@ class QualAnalysisSim {
       const idx = this._hitTestTube(x, y);
       if (idx >= 0) {
         this._activeTube = idx;
+        /* in exam: switching tube allows re-submit; verdict resets */
+        if (this._mode === 'exam') {
+          const alreadyAnswered = this._examAnswered && this._examAnswered[idx];
+          this._answered = !!alreadyAnswered;
+          const verdict = document.getElementById('qa-verdict');
+          if (verdict) {
+            if (alreadyAnswered) {
+              verdict.style.display = 'block';
+              verdict.textContent = alreadyAnswered.text;
+              verdict.style.background = alreadyAnswered.bg;
+              verdict.style.color = alreadyAnswered.fg;
+              verdict.style.border = alreadyAnswered.border;
+            } else {
+              verdict.style.display = 'none';
+              verdict.textContent = '';
+            }
+          }
+        }
+        this._updateTaskText();
         this._drawScene();
       }
     });
@@ -979,6 +998,7 @@ class QualAnalysisSim {
   _startMode(mode) {
     this._mode = mode;
     this._answered = false;
+    this._examAnswered = {};      // per-tube answered tracking for exam
     this._log = [];
     this._dragReagent = null;
     this._pendingReagent = null;
@@ -991,27 +1011,44 @@ class QualAnalysisSim {
 
     const ions = QualAnalysisSim.IONS;
 
-    /* pick random ions */
+    /* pick known ions for helper tubes (visible labels) */
+    this._helperIons = [];
+    const shuffled = ions.slice().sort(() => Math.random() - 0.5);
+    for (let i = 0; i < this._tubeCount; i++) {
+      this._helperIons.push(shuffled[i % shuffled.length]);
+    }
+
+    /* pick random ions per mode */
     if (mode === 'train') {
-      this._targetIon = ions[Math.floor(Math.random() * ions.length)];
+      /* pick target distinct from helpers if possible */
+      const helperIds = new Set(this._helperIons.map(h => h.id));
+      const pool = ions.filter(i => !helperIds.has(i.id));
+      const src = pool.length > 0 ? pool : ions;
+      this._targetIon = src[Math.floor(Math.random() * src.length)];
       this._examIons = [];
     } else if (mode === 'exam') {
-      this._examIons = [];
-      const shuffled = ions.slice().sort(() => Math.random() - 0.5);
-      for (let i = 0; i < this._tubeCount; i++) {
-        this._examIons.push(shuffled[i % shuffled.length]);
-      }
+      /* exam: helper tubes hold unknown ions, no sample */
+      this._examIons = this._helperIons.slice();
+      this._helperIons = [];       // hide helper labels in exam (they're unknown)
       this._targetIon = null;
     } else {
+      /* free mode: helpers have known ions, no sample */
       this._targetIon = null;
       this._examIons = [];
     }
 
     /* reset tubes */
     this._resetTubes();
+    /* paint helper tubes with their ion colors (free + train modes) */
+    if (mode !== 'exam') {
+      for (let i = 0; i < this._tubeCount; i++) {
+        if (this._helperIons[i]) {
+          this._tubes[i].solColor = this._helperIons[i].solColor || 'rgba(100,180,255,0.15)';
+        }
+      }
+    }
     /* set solution color for sample tube in train mode */
     if (mode === 'train' && this._targetIon) {
-      /* sample = index tubeCount */
       this._tubes[this._tubeCount].solColor = this._targetIon.solColor || 'rgba(100,180,255,0.15)';
     }
     /* set colors for exam tubes */
@@ -1051,11 +1088,12 @@ class QualAnalysisSim {
     const el = document.getElementById('qa-task');
     if (!el) return;
     if (this._mode === 'free') {
-      el.textContent = 'Свободный режим — добавляй реагенты в пробирки и наблюдай реакции';
+      el.textContent = 'Свободно: в каждой пробирке известный ион (см. подпись) — пробуй реагенты, изучай реакции';
     } else if (this._mode === 'train') {
-      el.textContent = 'Тренировка: определи неизвестный ион в Образце';
+      el.textContent = 'Тренировка: определи ион в Образце (золотая рамка). В Проб1–4 — известные ионы для сравнения';
     } else {
-      el.textContent = 'Экзамен: определи неизвестный ион в каждой пробирке (выбери пробирку, затем дай ответ)';
+      const ansFor = 'Проб' + (this._activeTube + 1);
+      el.textContent = 'Экзамен: в каждой пробирке свой неизвестный ион. Кликни на пробирку → определи реакциями → ответь. Сейчас отвечаешь для: ' + ansFor;
     }
   }
 
@@ -1080,12 +1118,7 @@ class QualAnalysisSim {
   _applyReagent(tubeIdx, reagentId) {
     /* which ion is in this tube? */
     const isSample = tubeIdx === this._tubeCount;
-    let ion = null;
-    if (this._mode === 'train' && isSample) {
-      ion = this._targetIon;
-    } else if (this._mode === 'exam' && !isSample) {
-      ion = this._examIons[tubeIdx] || null;
-    }
+    let ion = this._getIonForTube(tubeIdx);
     /* if no assigned ion → free tube with blank reactions */
     /* still animate the drop but log "нет ионов" */
     if (!ion) {
@@ -1326,19 +1359,30 @@ class QualAnalysisSim {
     const totalEl = document.getElementById('qa-score-total');
     if (totalEl) totalEl.textContent = '/' + this._scoreTotal;
 
+    let vText, vBg, vFg, vBorder;
     if (correct) {
-      verdict.textContent = 'Верно! Это ' + (correctIon ? correctIon.label : chosen);
-      verdict.style.cssText = verdict.style.cssText.replace(/display:[^;]+/, 'display:block');
-      verdict.style.background = 'rgba(94,240,142,0.15)';
-      verdict.style.color = '#5EF08E';
-      verdict.style.border = '1px solid rgba(94,240,142,0.35)';
+      vText = 'Верно! Это ' + (correctIon ? correctIon.label : chosen);
+      vBg = 'rgba(94,240,142,0.15)';
+      vFg = '#5EF08E';
+      vBorder = '1px solid rgba(94,240,142,0.35)';
       if (window.LabFX) LabFX.sound.play('chime');
     } else {
       const label = correctIon ? correctIon.label : '?';
-      verdict.textContent = 'Неверно — это ' + label;
-      verdict.style.background = 'rgba(239,71,111,0.12)';
-      verdict.style.color = '#EF476F';
-      verdict.style.border = '1px solid rgba(239,71,111,0.35)';
+      vText = 'Неверно — это ' + label;
+      vBg = 'rgba(239,71,111,0.12)';
+      vFg = '#EF476F';
+      vBorder = '1px solid rgba(239,71,111,0.35)';
+    }
+    verdict.textContent = vText;
+    verdict.style.background = vBg;
+    verdict.style.color = vFg;
+    verdict.style.border = vBorder;
+    verdict.style.display = 'block';
+
+    /* exam: remember verdict per tube; allow switching to next */
+    if (this._mode === 'exam') {
+      this._examAnswered = this._examAnswered || {};
+      this._examAnswered[this._activeTube] = { text: vText, bg: vBg, fg: vFg, border: vBorder, correct };
     }
   }
 
@@ -1663,12 +1707,20 @@ class QualAnalysisSim {
         ctx.fillText('(?)', tx + tubeW / 2, labelY + 14);
       }
     } else {
-      ctx.fillStyle = isActive ? '#4CC9F0' : 'rgba(255,255,255,0.65)';
+      ctx.fillStyle = isActive ? '#4CC9F0' : 'rgba(255,255,255,0.78)';
       ctx.fillText('Проб' + (i + 1), tx + tubeW / 2, labelY);
       if (this._mode === 'exam') {
         ctx.font = '600 10px Manrope,sans-serif';
-        ctx.fillStyle = isActive ? 'rgba(76,201,240,0.65)' : 'rgba(255,255,255,0.35)';
+        ctx.fillStyle = isActive ? 'rgba(76,201,240,0.85)' : 'rgba(255,255,255,0.45)';
         ctx.fillText('(?)', tx + tubeW / 2, labelY + 14);
+      } else {
+        /* show known ion label in free / train modes */
+        const knownIon = (this._helperIons || [])[i];
+        if (knownIon) {
+          ctx.font = '700 11px Manrope,sans-serif';
+          ctx.fillStyle = isActive ? '#4CC9F0' : 'rgba(255,255,255,0.6)';
+          ctx.fillText(knownIon.label, tx + tubeW / 2, labelY + 14);
+        }
       }
     }
     ctx.restore();
@@ -1678,6 +1730,7 @@ class QualAnalysisSim {
     const isSample = tubeIdx === this._tubeCount;
     if (this._mode === 'train' && isSample) return this._targetIon;
     if (this._mode === 'exam' && !isSample) return this._examIons[tubeIdx] || null;
+    if (this._mode !== 'exam' && !isSample) return (this._helperIons || [])[tubeIdx] || null;
     return null;
   }
 
diff --git a/frontend/js/labs/stoichiometry.js b/frontend/js/labs/stoichiometry.js
index a1c7e7b..df5d829 100644
--- a/frontend/js/labs/stoichiometry.js
+++ b/frontend/js/labs/stoichiometry.js
@@ -137,6 +137,10 @@ class StoichSim {
     this._animState = 'idle';
     this._animT     = 0;
     this._raf       = null;
+    this._idleRaf   = null;
+    this._idleT     = 0;          // continuous time for wobble/bubbles
+    this._lastIdleTs = 0;
+    this._sliderPulse = 0;        // 0..1, decays after slider change
     this._canvas    = null;
     this._ctx       = null;
     this._ro        = null;
@@ -145,6 +149,25 @@ class StoichSim {
 
     this._initAmounts();
     this._build();
+    this._startIdleLoop();
+  }
+
+  /* ── Непрерывный анимационный цикл (волны, пузырьки) ───────────── */
+  _startIdleLoop() {
+    if (this._idleRaf) return;
+    this._lastIdleTs = performance.now();
+    const loop = (now) => {
+      const dt = Math.min((now - this._lastIdleTs) / 1000, 0.05);
+      this._lastIdleTs = now;
+      this._idleT += dt;
+      if (this._sliderPulse > 0) this._sliderPulse = Math.max(0, this._sliderPulse - dt * 2);
+      /* skip redraw if reaction animation owns RAF */
+      if (this._animState !== 'reacting' && this._ctx) {
+        this._draw();
+      }
+      this._idleRaf = requestAnimationFrame(loop);
+    };
+    this._idleRaf = requestAnimationFrame(loop);
   }
 
   /* ── Инициализация начальных количеств ───────────────────────────── */
@@ -880,19 +903,39 @@ class StoichSim {
       if (k === sepIdx) {
         const arrowX = x - gap * 0.5;
         const midY   = topY + boxH / 2;
+        const t = this._idleT || 0;
+        const reacting = this._animState === 'reacting';
         ctx.save();
-        ctx.strokeStyle = `rgba(255,255,255,${0.3 + animT * 0.5})`;
-        ctx.lineWidth = 2.5;
+        if (reacting) {
+          ctx.shadowColor = '#9B5DE5';
+          ctx.shadowBlur = 12 + Math.sin(t * 12) * 6;
+        }
+        const alpha = reacting ? 0.85 + 0.15 * Math.sin(t * 12) : 0.35 + animT * 0.5;
+        ctx.strokeStyle = `rgba(255,255,255,${alpha})`;
+        ctx.lineWidth = reacting ? 3.2 : 2.5;
         ctx.beginPath();
-        ctx.moveTo(arrowX - 14, midY);
+        ctx.moveTo(arrowX - 18, midY);
         ctx.lineTo(arrowX + 2,  midY);
         ctx.stroke();
         ctx.beginPath();
-        ctx.moveTo(arrowX - 6, midY - 6);
+        ctx.moveTo(arrowX - 7, midY - 7);
         ctx.lineTo(arrowX + 2, midY);
-        ctx.lineTo(arrowX - 6, midY + 6);
+        ctx.lineTo(arrowX - 7, midY + 7);
         ctx.stroke();
         ctx.restore();
+        /* sparks travelling along the arrow during reaction */
+        if (reacting) {
+          for (let s = 0; s < 3; s++) {
+            const sp = ((t * 1.5 + s * 0.33) % 1);
+            const sx = arrowX - 18 + sp * 20;
+            ctx.save();
+            ctx.fillStyle = `rgba(255,209,102,${1 - sp})`;
+            ctx.beginPath();
+            ctx.arc(sx, midY, 2.4, 0, Math.PI * 2);
+            ctx.fill();
+            ctx.restore();
+          }
+        }
       }
 
       const isLimit = isReactant && i === comp.limitIdx;
@@ -903,74 +946,153 @@ class StoichSim {
   _drawBeaker(ctx, x, y, bw, bh, sub, q, isReactant, isLimit, animT) {
     ctx.save();
 
+    const t = this._idleT || 0;
+
+    /* Pulsing border for limit */
+    const pulse = isLimit ? (0.5 + 0.5 * Math.sin(t * 3.2)) : 0;
     const borderColor = isLimit
-      ? `rgba(239,71,111,${0.45 + animT * 0.4})`
-      : 'rgba(255,255,255,0.12)';
+      ? `rgba(239,71,111,${0.55 + 0.35 * pulse + animT * 0.3})`
+      : 'rgba(255,255,255,0.14)';
     ctx.strokeStyle = borderColor;
-    ctx.lineWidth   = isLimit ? 2 : 1;
+    ctx.lineWidth   = isLimit ? 2 + pulse * 0.6 : 1;
     ctx.beginPath();
     _stRoundRect(ctx, x, y, bw, bh, 7);
     ctx.stroke();
 
+    /* Glow for limit */
+    if (isLimit) {
+      ctx.save();
+      ctx.shadowColor = '#EF476F';
+      ctx.shadowBlur = 14 + pulse * 8;
+      ctx.strokeStyle = 'rgba(239,71,111,0)';
+      ctx.beginPath();
+      _stRoundRect(ctx, x, y, bw, bh, 7);
+      ctx.stroke();
+      ctx.restore();
+    }
+
     ctx.fillStyle = 'rgba(255,255,255,0.03)';
     ctx.fill();
 
+    /* Header symbol */
     ctx.fillStyle = sub.color;
     ctx.font = 'bold 13px Manrope,sans-serif';
     ctx.textAlign = 'center';
     ctx.fillText(sub.sym, x + bw / 2, y + 18);
 
-    const maxParticles = 20;
-    const nParticles = isReactant
-      ? Math.max(1, Math.round((q.n / ((q.n + q.nExcess) || q.n)) * maxParticles))
-      : Math.max(1, Math.round(Math.min(q.n / 0.2, 1) * maxParticles));
-
     const areaX = x + 8;
     const areaY = y + 26;
     const areaW = bw - 16;
     const areaH = bh - 46;
 
-    const seed = sub.sym.split('').reduce((a, ch) => a + ch.charCodeAt(0), 0);
-    const pts  = [];
-    for (let p = 0; p < maxParticles; p++) {
-      pts.push([
-        areaX + _stLcg(seed + p * 7)     * areaW,
-        areaY + _stLcg(seed + p * 7 + 3) * areaH,
-      ]);
+    /* Liquid level: scales with amount (reactants: m; products: n) */
+    let fillFrac;
+    if (isReactant) {
+      fillFrac = Math.min(1, q.n / 0.25 + 0.18);
+      fillFrac *= Math.max(0.15, 1 - animT);
+    } else {
+      fillFrac = Math.min(1, animT * 1.2) * Math.min(1, q.n / 0.25 + 0.18);
     }
+    fillFrac = Math.max(0, Math.min(1, fillFrac));
 
-    const alpha = isReactant
-      ? Math.max(0, 1 - animT * 1.2)
-      : Math.min(1, animT * 1.5);
+    const isGas = sub.phase === 'g';
+    const liquidH   = areaH * fillFrac;
+    const liquidTop = areaY + areaH - liquidH;
+
+    if (liquidH > 1) {
+      /* wavy surface */
+      ctx.save();
+      const grad = ctx.createLinearGradient(0, liquidTop, 0, areaY + areaH);
+      grad.addColorStop(0, sub.color + 'aa');
+      grad.addColorStop(1, sub.color + '55');
+      ctx.fillStyle = grad;
 
-    ctx.globalAlpha = alpha;
-    for (let p = 0; p < nParticles; p++) {
-      const [px, py] = pts[p];
-      const jx = isReactant && animT > 0 ? (x + bw / 2 - px) * animT       : 0;
-      const jy = isReactant && animT > 0 ? (y + bh / 2 - py) * animT * 0.5 : 0;
       ctx.beginPath();
-      ctx.arc(px + jx, py + jy, 4.5, 0, Math.PI * 2);
-      ctx.fillStyle = sub.color;
+      ctx.moveTo(areaX, liquidTop);
+      const waveSeed = sub.sym.charCodeAt(0);
+      for (let xi = 0; xi <= areaW; xi += 2) {
+        const wave = Math.sin((xi / areaW) * Math.PI * 3 + t * 2 + waveSeed) * 1.4
+                   + Math.sin((xi / areaW) * Math.PI * 5 + t * 1.3) * 0.8;
+        ctx.lineTo(areaX + xi, liquidTop + wave);
+      }
+      ctx.lineTo(areaX + areaW, areaY + areaH);
+      ctx.lineTo(areaX, areaY + areaH);
+      ctx.closePath();
       ctx.fill();
-      ctx.globalAlpha = alpha * 0.5;
-      ctx.strokeStyle = '#fff';
-      ctx.lineWidth = 0.5;
-      ctx.stroke();
-      ctx.globalAlpha = alpha;
-    }
-    ctx.globalAlpha = 1;
 
+      /* highlight on surface */
+      ctx.strokeStyle = sub.color + 'cc';
+      ctx.lineWidth = 1;
+      ctx.beginPath();
+      for (let xi = 0; xi <= areaW; xi += 2) {
+        const wave = Math.sin((xi / areaW) * Math.PI * 3 + t * 2 + waveSeed) * 1.4
+                   + Math.sin((xi / areaW) * Math.PI * 5 + t * 1.3) * 0.8;
+        if (xi === 0) ctx.moveTo(areaX + xi, liquidTop + wave);
+        else ctx.lineTo(areaX + xi, liquidTop + wave);
+      }
+      ctx.stroke();
+      ctx.restore();
+
+      /* bubbles for gas products / aq solutions */
+      if (isGas || sub.phase === 'aq') {
+        const seed2 = sub.sym.split('').reduce((a, ch) => a + ch.charCodeAt(0), 0);
+        const nBub = isGas ? 7 : 3;
+        ctx.save();
+        ctx.fillStyle = 'rgba(255,255,255,0.45)';
+        for (let b = 0; b < nBub; b++) {
+          const phase = (t * (isGas ? 0.9 : 0.4) + b * 0.7 + seed2 * 0.13) % 1;
+          const bx = areaX + areaW * (0.15 + 0.7 * _stLcg(seed2 + b * 11));
+          const by = areaY + areaH - phase * liquidH;
+          const br = isGas ? (1.4 + (1 - phase) * 1.6) : (1.0 + (1 - phase) * 0.8);
+          ctx.beginPath();
+          ctx.arc(bx, by, br, 0, Math.PI * 2);
+          ctx.fill();
+        }
+        ctx.restore();
+      }
+    }
+
+    /* particles flowing on reaction (kept from original logic, simplified) */
+    if (animT > 0 && animT < 1) {
+      const maxParticles = 16;
+      const nParticles = Math.max(1, Math.round(Math.min(q.n / 0.2, 1) * maxParticles));
+      const seedP = sub.sym.split('').reduce((a, ch) => a + ch.charCodeAt(0), 0);
+      const alpha = isReactant ? Math.max(0, 1 - animT * 1.5) : Math.min(1, animT * 1.8);
+      ctx.globalAlpha = alpha;
+      ctx.fillStyle = sub.color;
+      for (let p = 0; p < nParticles; p++) {
+        const px = areaX + _stLcg(seedP + p * 7) * areaW;
+        const py = areaY + _stLcg(seedP + p * 7 + 3) * areaH;
+        const jx = isReactant ? (x + bw / 2 - px) * animT       : 0;
+        const jy = isReactant ? (y + bh / 2 - py) * animT * 0.5 : 0;
+        ctx.beginPath();
+        ctx.arc(px + jx, py + jy, 3, 0, Math.PI * 2);
+        ctx.fill();
+      }
+      ctx.globalAlpha = 1;
+    }
+
+    /* Phase label */
     const phaseText = sub.phase === 'g' ? '(г)' : sub.phase === 'aq' ? '(р-р)' : sub.phase === 'l' ? '(ж)' : '(тв)';
-    ctx.fillStyle = 'rgba(255,255,255,0.45)';
+    ctx.fillStyle = 'rgba(255,255,255,0.55)';
     ctx.font = '9px Manrope,sans-serif';
     ctx.textAlign = 'center';
     ctx.fillText(phaseText, x + bw / 2, y + bh - 18);
 
-    ctx.fillStyle = 'rgba(255,214,102,0.9)';
+    /* Mass label */
+    ctx.fillStyle = 'rgba(255,214,102,0.95)';
     ctx.font = 'bold 9px Manrope,sans-serif';
     ctx.textAlign = 'right';
     ctx.fillText(q.m.toFixed(2) + 'г', x + bw - 4, y + bh - 6);
 
+    /* LIMIT label */
+    if (isLimit) {
+      ctx.fillStyle = `rgba(239,71,111,${0.7 + 0.3 * pulse})`;
+      ctx.font = 'bold 8.5px Manrope,sans-serif';
+      ctx.textAlign = 'left';
+      ctx.fillText('ЛИМИТ', x + 4, y + bh - 6);
+    }
+
     ctx.restore();
   }
 
@@ -1041,9 +1163,12 @@ class StoichSim {
 
   destroy() {
     if (this._raf) cancelAnimationFrame(this._raf);
+    if (this._idleRaf) cancelAnimationFrame(this._idleRaf);
     if (this._ro)  this._ro.disconnect();
     this._canvas = null;
     this._ctx    = null;
+    this._idleRaf = null;
+    this._raf = null;
   }
 }