Clarify contradictory hero-tile-grid CSS comment

The comment claimed both crop classes always produce a 221px tile, but the
top-row override added afterward shrinks Viser/Newton RTX to 206px, leaving
the two rows' heights undocumented and contradicting each other. Split the
comment so it states tiles are only even within each row, and documents the
top row's override separately.

Author: matthewtrepte

docs/source/concepts/visualization.rst

@@ -40,18 +40,20 @@ This page covers:
    .viz-label.viz-label-raise { bottom:10px; }
    /* Trims pixels off each hero tile on top of whatever object-position crop is already
       applied, so the tile itself is shorter rather than just repositioning the existing crop.
-      Both classes crop to the same final 221px height so the 2x2 tile grid stays even, split
-      differently per tile: Kit/Rerun/Newton RTX crop 45px off the top and 20px off the bottom;
-      Viser crops 35px off the top and 30px off the bottom (its object-position framing already
-      leaves more headroom at the bottom, so it can take a heavier bottom crop). */
+      Both classes initially crop to the same 221px height, keeping tiles within each row even.
+      Kit/Rerun/Newton RTX crop 45px off the top and 20px off the bottom; Viser crops 35px off
+      the top and 30px off the bottom (its object-position framing already leaves more headroom
+      at the bottom, so it can take a heavier bottom crop). */
    .viz-grid-stretch.viz-grid-hero-tiles .viz-hero-wrap { height:276px; }
    .viz-grid-stretch.viz-grid-hero-tiles .viz-hero-wrap video { margin-top:-10px; }
    .viz-grid-stretch.viz-grid-hero-tiles .viz-hero-wrap.viz-crop-top25 { height:221px; }
    .viz-grid-stretch.viz-grid-hero-tiles .viz-hero-wrap.viz-crop-top25 video { margin-top:-45px; }
    .viz-grid-stretch.viz-grid-hero-tiles .viz-hero-wrap.viz-crop-mixed { height:221px; }
    .viz-grid-stretch.viz-grid-hero-tiles .viz-hero-wrap.viz-crop-mixed video { margin-top:-35px; }
-   /* Top row (Viser, Newton RTX) additionally crops 15px more off the top than the bottom row,
-      keeping bottom crop unchanged: height shrinks by 15px and margin-top grows by 15px. */
+   /* The top row (Viser, Newton RTX) overrides both tiles above to a shorter, still-even 206px:
+      15px more off the top than the bottom row, with bottom crop unchanged (height shrinks by
+      15px and margin-top grows by 15px in lockstep). The bottom row (Rerun, Kit) keeps the 221px
+      height set above. */
    .viz-hero-row-top.viz-grid-stretch.viz-grid-hero-tiles .viz-hero-wrap.viz-crop-top25 { height:206px; }
    .viz-hero-row-top.viz-grid-stretch.viz-grid-hero-tiles .viz-hero-wrap.viz-crop-top25 video { margin-top:-60px; }
    .viz-hero-row-top.viz-grid-stretch.viz-grid-hero-tiles .viz-hero-wrap.viz-crop-mixed { height:206px; }