Merge nucleic/calm-willow-ibis-dozm into main

Mirrored from corpo 1b3dc81.

src/pages/index.astro

@@ -872,12 +872,13 @@ const canonical = new URL('/', Astro.site);
        product of how many, not how much scroll each one happens to cost. */
     grid-auto-rows: 1fr;
     gap: 0.45rem;
-    /* The card's own top rule continues across this column, and the marks hang from
-       it — so the composition keeps the unbroken right edge every other rule on the
-       page is ruled to, and the track reads as part of it rather than as a widget
-       parked alongside. */
-    border-top: 1px solid var(--line);
-    padding-top: 0.6rem;
+    /* No rule of its own across this column. The card's rule belongs to the card and
+       travels with it as one card hands over to the next, so a fixed length of the
+       same hairline sitting beside it stays behind and breaks the line in two for the
+       length of the transition. The rule stops at the track instead, which also keeps
+       it clear of the marks when it moves. The pixel is the rule's, given back as
+       padding so the marks do not shift. */
+    padding-top: calc(0.6rem + 1px);
   }
 
   .is-scroll-stack .technology-track {
@@ -1537,14 +1538,23 @@ const canonical = new URL('/', Astro.site);
          already somewhere else. So a step entered at fling speed is entered slowly.
          The rule the whole thing reduces to: a gesture may cross any boundary it
          reaches at reading pace, and the moment it crosses one at fling speed, what is
-         left of that fling is held to a sixth of its weight. One flick, one product;
-         a reader who keeps pushing still gets through, just against the brakes. */
-      const CATCH_STRENGTH = 0.85;
+         left of that fling is held to a fifteenth of its weight. One flick, one
+         product; a reader who keeps pushing still gets through, just against the
+         brakes. */
+      const CATCH_STRENGTH = 0.95;
+      /* The stack answers to a shorter gesture than the page it sits in — three
+         products across nine hundred pixels means a careful two-finger drag spends
+         itself inside one of them, which reads as a page that has not noticed. So a
+         delta is worth a third again as much at reading pace, and that extra is given
+         back as the gesture speeds up, reaching nothing at fling speed. The one curve
+         answers both halves of the complaint: slow gestures cover more ground, fast
+         ones cover less, and it is the same number saying so. */
+      const SLOW_GAIN = 1.35;
       /* Below the first, a gesture is reading and is never touched; above the second
          it is a fling. Both are per-frame, so they are speeds a hand can feel — about
-         720px and 1800px a second — rather than counts of an event nobody controls. */
-      const SLOW_FRAME_PX = 12;
-      const FAST_FRAME_PX = 30;
+         840px and 2040px a second — rather than counts of an event nobody controls. */
+      const SLOW_FRAME_PX = 14;
+      const FAST_FRAME_PX = 34;
       const GESTURE_GAP_MS = 140;
 
       let wheelAt = -Infinity;
@@ -1556,15 +1566,20 @@ const canonical = new URL('/', Astro.site);
          the gesture is still free. */
       let gestureCatch = 0;
 
-      const beatDrag = () => {
+      /* Nought at reading pace, one at fling speed. Everything below reads the gesture
+         through this single number: how much a delta is worth, and how hard a boundary
+         pushes back once one has been crossed at speed. */
+      const wheelFast = () =>
+        Math.min(
+          1,
+          Math.max(0, (wheelSpeed - SLOW_FRAME_PX) / (FAST_FRAME_PX - SLOW_FRAME_PX)),
+        );
+
+      const beatDrag = (fast: number) => {
         const beat = technologyAtScroll();
         if (beat === gestureBeat) return 1;
 
         if (!gestureCatch) {
-          const fast = Math.min(
-            1,
-            Math.max(0, (wheelSpeed - SLOW_FRAME_PX) / (FAST_FRAME_PX - SLOW_FRAME_PX)),
-          );
           /* Reading pace: the gesture is entitled to the beat it has reached, and to
              the next one it reaches the same way. Only speed is ever held back. */
           if (fast <= 0) {
@@ -1609,7 +1624,10 @@ const canonical = new URL('/', Astro.site);
           }
           wheelAt = now;
 
-          scrollRoot.scrollBy({ top: pixels * beatDrag(), behavior: 'auto' });
+          const fast = wheelFast();
+          const gain = 1 + (SLOW_GAIN - 1) * (1 - fast);
+
+          scrollRoot.scrollBy({ top: pixels * gain * beatDrag(fast), behavior: 'auto' });
         },
         { capture: true, passive: false },
       );