Add better description of gray heatmap values

homepage/antibody_escape.md

@@ -4,7 +4,7 @@ aside: true
 
 # Escape from monoclonal antibodies
 
-The plots below show how mutations affect neutralization by a panel of monoclonal antibodies (25.10C, 12.1F, 37.7H, 25.6A, 37.2D, and 8.9F). The plots are interactive, and allow you to zoom and mouseover sites and mutations. Positive values indicate reduced neutralization by antibody while negative values indicate more neutralization.
+The plots below show how mutations affect neutralization by a panel of monoclonal antibodies (25.10C, 12.1F, 37.7H, 25.6A, 37.2D, and 8.9F). The plots are interactive, and allow you to zoom and mouseover sites and mutations. Positive values indicate reduced neutralization by antibody while negative values indicate more neutralization. Note that the two different shades of gray in the heatmaps have differing meanings: light gray means a mutation was *missing (not measured)* in the library, whereas dark gray means a mutation *was measured but was so deleterious for cell entry* it is not possible to reliably estimate its effect on antibody escape (the threshold for how deleterious a mutation must be for cell entry to be shown in dark gray is controlled by the cell entry slider at the bottom of the plot).
 
 Here is an explanation of the key elements for each plot:
  - The zoom bar at the top of the plot shows different regions of GPC, and can be used to zoom in on specific sites.

homepage/summary.md

@@ -5,7 +5,7 @@ aside: false
 # Summary of how mutations affect both antibody escape and cell entry
 
 ## Interactive plot of both antibody escape and cell entry
-The plot below shows how mutations affect antibody escape from all six antibodies and cell entry, and allows you to zoom and mouseover sites and mutations. Positive cell entry values indicate better entry than the parental GPC while negative values indicate impaired entry. Positive escape values indicate reduced neutralization by an antibody while negative values indicate more neutralization.
+The plot below shows how mutations affect antibody escape from all six antibodies and cell entry, and allows you to zoom and mouseover sites and mutations. Positive cell entry values indicate better entry than the parental GPC while negative values indicate impaired entry. Positive escape values indicate reduced neutralization by an antibody while negative values indicate more neutralization. Note that the two different shades of gray in the heatmaps have differing meanings: light gray means a mutation was *missing (not measured)* in the library, whereas dark gray means a mutation *was measured but was so deleterious for cell entry* it is not possible to reliably estimate its effect on antibody escape (the threshold for how deleterious a mutation must be for cell entry to be shown in dark gray is controlled by the cell entry slider at the bottom of the plot).
 
 Here is an explanation of the key plot elements:
  - The zoom bar at the top of the plot shows different regions of GPC, and can be used to zoom in on specific sites.