注意:我在 2021 年整理了这个问题，删除了死链接并将代码制作为现场演示。粗略检查一下，该问题似乎在当前版本的 Chrome 中已不存在。
给定一个区域，其中行高和任何边距都是 n，并且该区域的高度是 n 的倍数，并且 scrollTop 增加了n 的倍数 我发现我在 Firefox、Opera 和 NetFront 中得到了预期的结果，但在 Chrome (Windows)、Safari (Mac) 和最新的 WebKit nightly (Mac) 中有一些泄漏，我查看部分行。
在我的实际元素中(我无法分享)效果非常明显，但即使在简化的测试用例中，也可以看到上一行的底部从框的顶部窥视。
是否有可能避免这种影响？这是应该报告的 WebKit 呈现引擎中的错误吗？
缩减的测试用例如下所示。单击文档几次以滚动它，而不是框顶部的点(它们是上一行字母的底部)。
<!DOCTYPE HTML>
<html lang="en">
<head>
<meta charset="utf-8"/>
<title>scrollTop issue</title>
<style>
body {
background-color: white;
color: black;
}
#wrapper {
width: 300px;
font-size: 19px;
font-family: sans-serif;
line-height: 21px;
height: 210px; /* A multiple of line height */
overflow: hidden;
}
#wrapper * {
margin: 0;
padding: 0;
}
#wrapper p {
margin-bottom: 21px; /* Same as line height */
}
</style>
<script>
window.addEventListener('click', function () {
document.getElementById('wrapper').scrollTop += 210;
});
</script>
</head>
<body>
<h1>scrollTop issue</h1>
<div id="wrapper">
<div id="content">
<p>To Sherlock Holmes she is always <i>the</i> woman. I have seldom heard
him mention her under any other name. In his eyes she eclipses
and predominates the whole of her sex. It was not that he felt
any emotion akin to love for Irene Adler. All emotions, and that
one particularly, were abhorrent to his cold, precise but
admirably balanced mind. He was, I take it, the most perfect
reasoning and observing machine that the world has seen, but as a
lover he would have placed himself in a false position. He never
spoke of the softer passions, save with a gibe and a sneer. They
were admirable things for the observer—excellent for drawing the
veil from men’s motives and actions. But for the trained reasoner
to admit such intrusions into his own delicate and finely
adjusted temperament was to introduce a distracting factor which
might throw a doubt upon all his mental results. Grit in a
sensitive instrument, or a crack in one of his own high-power
lenses, would not be more disturbing than a strong emotion in a
nature such as his. And yet there was but one woman to him, and
that woman was the late Irene Adler, of dubious and questionable
memory.
<p>
I had seen little of Holmes lately. My marriage had drifted us
away from each other. My own complete happiness, and the
home-centred interests which rise up around the man who first
finds himself master of his own establishment, were sufficient to
absorb all my attention, while Holmes, who loathed every form of
society with his whole Bohemian soul, remained in our lodgings in
Baker Street, buried among his old books, and alternating from
week to week between cocaine and ambition, the drowsiness of the
drug, and the fierce energy of his own keen nature. He was still,
as ever, deeply attracted by the study of crime, and occupied his
immense faculties and extraordinary powers of observation in
following out those clues, and clearing up those mysteries which
had been abandoned as hopeless by the official police. From time
to time I heard some vague account of his doings: of his summons
to Odessa in the case of the Trepoff murder, of his clearing up
of the singular tragedy of the Atkinson brothers at Trincomalee,
and finally of the mission which he had accomplished so
delicately and successfully for the reigning family of Holland.
Beyond these signs of his activity, however, which I merely
shared with all the readers of the daily press, I knew little of
my former friend and companion.
<p>
One night—it was on the twentieth of March, 1888—I was
returning from a journey to a patient (for I had now returned to
civil practice), when my way led me through Baker Street. As I
passed the well-remembered door, which must always be associated
in my mind with my wooing, and with the dark incidents of the
Study in Scarlet, I was seized with a keen desire to see Holmes
again, and to know how he was employing his extraordinary powers.
His rooms were brilliantly lit, and, even as I looked up, I saw
his tall, spare figure pass twice in a dark silhouette against
the blind. He was pacing the room swiftly, eagerly, with his head
sunk upon his chest and his hands clasped behind him. To me, who
knew his every mood and habit, his attitude and manner told their
own story. He was at work again. He had risen out of his
drug-created dreams and was hot upon the scent of some new
problem. I rang the bell and was shown up to the chamber which
had formerly been in part my own.
</div>
</div>
</body>
</html>最佳答案
这似乎与行高框下方“突出”的下降部分 (qjpg) 有关。 Firefox 和 Safari 似乎就如何做到这一点达成一致——字符可以突出显示。然而，通过将尺寸扩大 x 10，我们注意到 sans-serif 有一些有趣的东西。
在 Mac OS X 中，Safari 和 Firefox 都选择了 helvetica 作为 sans-serif 的字体。但是 Firefox 将行高框中的特定字体向上移动，因此底部不会“突出”。与 arial 比较 - 微软对 helvetica 的 SCSS ，两种浏览器都让它突出显示。
我认为解决你的问题的方法是找到一个“合理的”负边距来向上抵消内容。似乎 helvetica 和 arial 在框的顶部都有一些“回旋余地”。我会使用 #wrapper #content { margin-top: -1px; } (选择器非常强大，可以克服 #wrapper *)，适用于您示例中的特定 font-size/line-height。
这是我的测试代码。它表明 geneva 和 verdana 的“突出”可能更糟。
<!DOCTYPE HTML>
<html lang="en">
<head>
<meta charset="utf-8"/>
<title>descender issue</title>
<style>
* {
margin: 0;
padding: 0;
}
.content {
margin-bottom: 30px;
background: #ffdd88;
font-size: 190px;
line-height: 210px;
}
#content1 {
font-family: sans-serif;
}
#content2 {
font-family: arial;
}
#content3 {
font-family: geneva;
}
#content4 {
font-family: helvetica;
}
#content5 {
font-family: 'trebuchet ms';
}
#content6 {
font-family: verdana;
}
#content7 {
font-family: serif;
}
#content8 {
font-family: times;
}
</style>
</head>
<body>
<h1>descender issue</h1>
sans-serif
<div class="content" id="content1">
lfgjpq
</div>
arial
<div class="content" id="content2">
lfgjpq
</div>
geneva
<div class="content" id="content3">
lfgjpq
</div>
helvetica
<div class="content" id="content4">
lfgjpq
</div>
trebuchet ms
<div class="content" id="content5">
lfgjpq
</div>
verdana
<div class="content" id="content6">
lfgjpq
</div>
serif
<div class="content" id="content7">
lfgjpq
</div>
times
<div class="content" id="content8">
lfgjpq
</div>
</body>
</html>
关于javascript - WebKit 有裁剪错误吗？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/4325440/