diff --git a/VERSION b/VERSION
index c39603d..131ab5f 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.3.64-beta
+0.3.65-beta
diff --git a/public/css/teach.css b/public/css/teach.css
index 828a62c..354ce52 100644
--- a/public/css/teach.css
+++ b/public/css/teach.css
@@ -123,6 +123,9 @@
   /* drawing layer on the board: sits ABOVE widgets like a transparency sheet,
      so you can annotate over everything; clicks pass through when pen is off */
   #boardInk{position:absolute; inset:0; pointer-events:none; z-index:4000;}
+  /* live-laag van de markeerstift: dekkend getekend, doorschijnend getoond;
+     bij het loslaten wordt de haal in één keer op de inktlaag gezet */
+  #boardMark{position:absolute; inset:0; pointer-events:none; z-index:4000; opacity:.32;}
   body.pen #boardInk{pointer-events:auto; cursor:crosshair;}
   body.pen.pen-text #boardInk{cursor:text;}
   body.pen.pen-hand #boardInk{pointer-events:none;} /* hand tool: interact with everything */
@@ -360,6 +363,16 @@
     box-shadow:0 2px 6px rgba(0,0,0,.25);
   }
   .dtool-opts button:hover{background:var(--accent-soft);}
+  /* lengteknop toont de maat ("10 cm") en is dus breder dan een rond knopje */
+  .dtool-opts .do-wide{width:auto; min-width:48px; padding:0 9px; border-radius:12px;}
+  /* live hoek-uitlezing tijdens het draaien van liniaal/geodriehoek */
+  .dtool-deg{
+    display:none; position:absolute; left:50%; top:50%; margin:-16px 0 0 -24px;
+    width:48px; height:32px; line-height:32px; text-align:center; pointer-events:none;
+    background:rgba(30,50,90,.85); color:#fff; font-size:14px; font-weight:800;
+    border-radius:9px; z-index:3;
+  }
+  .dtool-deg.snapped{background:var(--green);}
   .dtool-lens{z-index:4500;} /* the glass sits above the ink sheet */
   .dtool-lens canvas{
     border:5px solid #5a6c85; box-shadow:0 8px 22px rgba(0,0,0,.3);
diff --git a/public/js/board.js b/public/js/board.js
index fdabac9..5b2cd6e 100644
--- a/public/js/board.js
+++ b/public/js/board.js
@@ -352,16 +352,27 @@ const bInk = document.createElement("canvas");
 bInk.id = "boardInk";
 board.insertBefore(bInk, board.firstChild);
 const bCtx = bInk.getContext("2d");
-const bDpr = window.devicePixelRatio || 1;
+/* aparte laag voor de markeerstift: dáár tekent hij dekkend, de laag zelf is
+   doorschijnend (CSS), en pas bij het loslaten wordt de hele haal in één keer
+   met 32% op de inktlaag gezet. Zo stapelen overlappende lijnstukjes binnen
+   één haal niet meer tot donkere vlekken op elke overgang. */
+const bMark = document.createElement("canvas");
+bMark.id = "boardMark";
+board.insertBefore(bMark, bInk.nextSibling);
+const bMarkCtx = bMark.getContext("2d");
+let bDpr = window.devicePixelRatio || 1;
 function bResize(){
   const w = board.clientWidth, h = board.clientHeight;
   if(w<2 || h<2) return;
+  bDpr = window.devicePixelRatio || 1;   /* vers: verhuizen naar ander scherm/zoom */
   const keep = document.createElement("canvas");
   keep.width = bInk.width; keep.height = bInk.height;
   if(bInk.width) keep.getContext("2d").drawImage(bInk,0,0);
   bInk.width = Math.round(w*bDpr); bInk.height = Math.round(h*bDpr);
   if(keep.width) bCtx.drawImage(keep,0,0);
   bCtx.lineCap = "round"; bCtx.lineJoin = "round";
+  bMark.width = bInk.width; bMark.height = bInk.height;
+  bMarkCtx.lineCap = "round"; bMarkCtx.lineJoin = "round";
 }
 new ResizeObserver(bResize).observe(board);
 bResize();
@@ -555,11 +566,25 @@ function makeMovable(t){
       const r = t.getBoundingClientRect();
       const cx = r.left+r.width/2, cy = r.top+r.height/2;
       const start = Math.atan2(e.clientY-cy, e.clientX-cx)*180/Math.PI - ang;
+      /* klikt vast op veelvouden van 45° (waterpas/haaks in één beweging)
+         en toont tijdens het draaien de hoek in graden */
+      const badge = t.querySelector(".dtool-deg") || t.appendChild(Object.assign(document.createElement("div"), { className:"dtool-deg" }));
+      badge.style.display = "block";
       const mv = ev=>{
-        ang = Math.atan2(ev.clientY-cy, ev.clientX-cx)*180/Math.PI - start;
+        let a = Math.atan2(ev.clientY-cy, ev.clientX-cx)*180/Math.PI - start;
+        const near = Math.round(a/45)*45;
+        if(Math.abs(a-near) < 4) a = near;
+        ang = a;
         t.style.transform = `rotate(${ang}deg)`;
+        const shown = Math.round(((ang % 360) + 360) % 360);
+        badge.textContent = shown + "°";
+        badge.style.transform = `rotate(${-ang}deg)`;   /* leesbaar houden */
+        badge.classList.toggle("snapped", Math.abs(((ang % 45) + 45) % 45) < 0.01);
+      };
+      const up = ()=>{
+        badge.style.display = "none";
+        document.removeEventListener("pointermove",mv); document.removeEventListener("pointerup",up);
       };
-      const up = ()=>{ document.removeEventListener("pointermove",mv); document.removeEventListener("pointerup",up); };
       document.addEventListener("pointermove",mv); document.addEventListener("pointerup",up);
       return;
     }
@@ -582,17 +607,21 @@ function toggleDTool(kind){
   const t = document.createElement("div");
   t.className = "dtool dtool-"+kind;
   if(kind==="ruler"){
-    t._len = 600; t._hc = false;
+    /* 50px = 1 cm; logische lengtes in hele centimeters, schaal begint bij 0
+       met een kleine kantlijn zoals op een echte liniaal */
+    const RULER_CMS = [5, 10, 15, 20];
+    t._cm = 10; t._hc = false;
     const drawRuler = ()=>{
-      const L = t._len, hc = t._hc;
+      const cmLen = Math.min(t._cm, Math.max(5, Math.floor((board.clientWidth-60)/50)));
+      const pad = 18, scale = cmLen*50, L = scale + pad*2, hc = t._hc;
       const ink = hc ? "#000" : "#5a4a20";
       const bg = hc ? "rgba(255,214,0,.95)" : "rgba(255,243,205,.82)";
       let ticks = "";
-      for(let i=5; i<L; i+=5){
+      for(let i=0; i<=scale; i+=5){
         const cm = i%50===0, half = i%25===0;
         const len = cm ? 22 : half ? 14 : 8;
-        ticks += `<line x1="${i}" y1="2" x2="${i}" y2="${2+len}" stroke="${ink}" stroke-width="${cm ? (hc?2.5:1.6) : (hc?1.6:1)}"/>`;
-        if(cm) ticks += `<text x="${i}" y="${hc?46:42}" font-size="${hc?18:14}" font-weight="bold" fill="${ink}" text-anchor="middle">${i/50}</text>`;
+        ticks += `<line x1="${pad+i}" y1="2" x2="${pad+i}" y2="${2+len}" stroke="${ink}" stroke-width="${cm ? (hc?2.5:1.6) : (hc?1.6:1)}"/>`;
+        if(cm) ticks += `<text x="${pad+i}" y="${hc?46:42}" font-size="${hc?18:14}" font-weight="bold" fill="${ink}" text-anchor="middle">${i/50}</text>`;
       }
       t.style.width = L+"px";
       t.querySelector(".dtool-svg").innerHTML = `<svg viewBox="0 0 ${L} 76" width="${L}" height="76">
@@ -602,18 +631,23 @@ function toggleDTool(kind){
         <rect x="0" y="0" width="${L}" height="76" rx="9" fill="${bg}" stroke="${ink}" stroke-width="${hc?3:1.5}"/>
         <rect x="0" y="0" width="${L}" height="76" rx="9" fill="url(#rg)"/>
         <line x1="0" y1="2" x2="${L}" y2="2" stroke="${ink}" stroke-width="${hc?3:2}"/>
-        <text x="${L/2}" y="66" font-size="12" fill="${ink}" text-anchor="middle" opacity=".65">teach · cm</text>
+        <text x="${L/2}" y="68" font-size="12" fill="${ink}" text-anchor="middle" opacity=".65">${cmLen} cm</text>
         ${ticks}</svg>`;
+      const lenBtn = t.querySelector(".do-len");
+      lenBtn.textContent = cmLen + " cm";
+      lenBtn.title = T("dtLen");
     };
     t.innerHTML = `<div class="dtool-svg"></div>
       <div class="dtool-opts">
-        <button class="do-len" title="↔">↔</button>
-        <button class="do-hc" title="◐">◐</button>
+        <button class="do-len do-wide"></button>
+        <button class="do-hc">◐</button>
       </div>`;
     t.querySelector(".do-len").addEventListener("click", ()=>{
-      t._len = t._len===600 ? 800 : t._len===800 ? 400 : 600; drawRuler();
+      t._cm = RULER_CMS[(RULER_CMS.indexOf(t._cm)+1) % RULER_CMS.length]; drawRuler();
     });
-    t.querySelector(".do-hc").addEventListener("click", ()=>{ t._hc = !t._hc; drawRuler(); });
+    const hcBtn = t.querySelector(".do-hc");
+    hcBtn.title = T("dtContrast");
+    hcBtn.addEventListener("click", ()=>{ t._hc = !t._hc; drawRuler(); });
     t.style.height = "76px";
     drawRuler();
   }else if(kind==="geo"){
@@ -663,10 +697,14 @@ function toggleDTool(kind){
         <button class="do-len">↔</button>
         <button class="do-hc">◐</button>
       </div>`;
-    t.querySelector(".do-len").addEventListener("click", ()=>{
+    const geoLen = t.querySelector(".do-len");
+    geoLen.title = T("dtLen");
+    geoLen.addEventListener("click", ()=>{
       t._sz = t._sz===340 ? 440 : t._sz===440 ? 280 : 340; drawGeo();
     });
-    t.querySelector(".do-hc").addEventListener("click", ()=>{ t._hc = !t._hc; drawGeo(); });
+    const geoHc = t.querySelector(".do-hc");
+    geoHc.title = T("dtContrast");
+    geoHc.addEventListener("click", ()=>{ t._hc = !t._hc; drawGeo(); });
     drawGeo();
   }else if(kind==="light"){ /* compact traffic light directly on the board */
     let on = "green";
@@ -794,7 +832,7 @@ function startBoardText(e){
   inp.addEventListener("blur", commit);
 }
 
-let bDraw = false, bx = 0, by = 0;
+let bDraw = false, bx = 0, by = 0, bMidX = null, bMidY = null, bUsedMark = false;
 const bPos = ev=>{
   const r = bInk.getBoundingClientRect();
   /* ratio-based: correct under any display zoom */
@@ -808,6 +846,7 @@ bInk.addEventListener("pointerdown", e=>{
   bDraw = true;
   PEN.nib = PEN.size*0.8;
   [bx,by] = bPos(e);
+  bMidX = bMidY = null;
   bStroke(bx+0.01, by+0.01, e.pressure, e.pointerType);
 });
 bInk.addEventListener("pointermove", e=>{
@@ -817,7 +856,20 @@ bInk.addEventListener("pointermove", e=>{
   });
 });
 const bStop = ()=>{
-  if(bDraw) markBoardChange();
+  if(bDraw){
+    /* markeerstift: de haal staat dekkend op de overlay - nu in één keer
+       met vaste transparantie op de inktlaag zetten (egale kleur, geen
+       donkere overgangen) en de overlay leegmaken */
+    if(bUsedMark && bMark.width){
+      bCtx.globalCompositeOperation = "source-over";
+      bCtx.globalAlpha = 0.32;
+      bCtx.drawImage(bMark, 0, 0);
+      bCtx.globalAlpha = 1;
+      bMarkCtx.clearRect(0, 0, bMark.width, bMark.height);
+    }
+    bUsedMark = false;
+    markBoardChange();
+  }
   bDraw = false;
   bCtx.globalAlpha = 1;
   if(DTOOLS.lens) DTOOLS.lens.lensDraw();
@@ -825,12 +877,15 @@ const bStop = ()=>{
 bInk.addEventListener("pointerup", bStop);
 bInk.addEventListener("pointercancel", bStop);
 function bStroke(x,y,pressure,ptype){
-  bCtx.globalCompositeOperation = PEN.tool==="erase" ? "destination-out" : "source-over";
-  bCtx.globalAlpha = PEN.tool==="mark" ? 0.32 : 1;
-  bCtx.strokeStyle = PEN.color;
+  const mark = PEN.tool==="mark";
+  if(mark) bUsedMark = true;
+  const ctx = mark ? bMarkCtx : bCtx;     /* markeerstift op de eigen laag */
+  ctx.globalCompositeOperation = PEN.tool==="erase" ? "destination-out" : "source-over";
+  ctx.globalAlpha = 1;
+  ctx.strokeStyle = PEN.color;
   let w = PEN.size;
   if(PEN.tool==="erase") w = PEN.size*6;
-  else if(PEN.tool==="mark") w = PEN.size*3.5;
+  else if(mark) w = PEN.size*3.5;
   else if(PEN.tool==="vulp"){
     let target;
     if(ptype==="pen" && pressure > 0){
@@ -842,8 +897,16 @@ function bStroke(x,y,pressure,ptype){
     PEN.nib += (target - PEN.nib)*0.3;
     w = PEN.nib;
   }
-  bCtx.lineWidth = w*bDpr;
-  bCtx.beginPath(); bCtx.moveTo(bx,by); bCtx.lineTo(x,y); bCtx.stroke();
+  ctx.lineWidth = w*bDpr;
+  /* vloeiende haal: teken van middelpunt naar middelpunt met het vorige
+     punt als stuurpunt (kwadratische curve) - geen hoekige knikken meer
+     tussen de losse pointer-stapjes, ook bij snelle halen */
+  const mx = (bx + x) / 2, my = (by + y) / 2;
+  ctx.beginPath();
+  ctx.moveTo(bMidX ?? bx, bMidY ?? by);
+  ctx.quadraticCurveTo(bx, by, mx, my);
+  ctx.stroke();
+  bMidX = mx; bMidY = my;
   bx = x; by = y;
 }
 function boardInkURL(){ try{ return bInk.toDataURL("image/png"); }catch(e){ return null; } }
diff --git a/public/js/core.js b/public/js/core.js
index 726cf2f..a5a68f3 100644
--- a/public/js/core.js
+++ b/public/js/core.js
@@ -2,7 +2,7 @@
 "use strict";
 /* version — shown until /api/version resolves (or if the fetch fails, e.g. offline).
    Kept in sync by hand with the VERSION file at the repo root on every release. */
-const VERSION = "0.3.64-beta";
+const VERSION = "0.3.65-beta";
 (function(){
   const tag = document.getElementById("verTag");
   tag.textContent = "v"+VERSION;
@@ -231,6 +231,7 @@ const I18N = {
     parentUnlink:"Ontkoppel",
     parentUnlinkWarn:"Verwijdert alleen de koppeling; het account van je kind blijft bestaan.",
     parentProgress:"📈 Voortgang", parentProgressEmpty:"Nog geen voortgang.",
+    dtLen:"Lengte", dtContrast:"Hoog contrast",
     pupilEmpty:"Je leerkracht heeft nog niets voor je klaargezet.",
     pupilWatching:"meekijken",
     amUsers:"Gebruikers", amClasses:"Klassen", amSchools:"Scholen", amOverarching:"Systeem",
@@ -489,6 +490,7 @@ const I18N = {
     parentUnlink:"Unlink",
     parentUnlinkWarn:"Removes only the link; your child's account remains.",
     parentProgress:"📈 Progress", parentProgressEmpty:"No progress yet.",
+    dtLen:"Length", dtContrast:"High contrast",
     pupilEmpty:"Your teacher hasn't set up anything for you yet.",
     pupilWatching:"watching",
     amUsers:"Users", amClasses:"Classes", amSchools:"Schools", amOverarching:"System",