/* Benny Math 网页（按 Chrome Modern Web Guidance：color-scheme、rem 字号、focus-visible、目标尺寸、text-wrap） */
:root {
  /* 原始颜色 */
  --bg-light: #fff6ec;  --bg-dark: #1c1712;
  --paper-light: #ffffff; --paper-dark: #26201a;
  --ink-light: #2b2118; --ink-dark: #f3ebe2;
  --muted-light: #6b5d50; --muted-dark: #b9ab9c;
  --link-light: #a63d0c; --link-dark: #ffab73;
  --accent: #f5c518;
  --on-accent: #2b2118;

  /* 不支持 light-dark() 的浏览器用这一套 + 下面的媒体查询 */
  --bg: var(--bg-light);
  --paper: var(--paper-light);
  --ink: var(--ink-light);
  --muted: var(--muted-light);
  --link: var(--link-light);

  /* 告诉浏览器两种配色都支持：首屏底色、滚动条跟着系统走，深色模式下不会先白一下 */
  color-scheme: light dark;
  accent-color: var(--accent);
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: var(--bg-dark);
    --paper: var(--paper-dark);
    --ink: var(--ink-dark);
    --muted: var(--muted-dark);
    --link: var(--link-dark);
  }
}
@supports (color: light-dark(white, black)) {
  :root {
    --bg: light-dark(var(--bg-light), var(--bg-dark));
    --paper: light-dark(var(--paper-light), var(--paper-dark));
    --ink: light-dark(var(--ink-light), var(--ink-dark));
    --muted: light-dark(var(--muted-light), var(--muted-dark));
    --link: light-dark(var(--link-light), var(--link-dark));
  }
}

*, *::before, *::after { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: system-ui, -apple-system, "Segoe UI", "PingFang TC", "Noto Sans TC", Roboto, sans-serif;
  font-size: 1.0625rem;
  line-height: 1.65;
}

.top, main, .foot {
  max-inline-size: 48rem;
  margin-inline: auto;
  padding-inline: 1rem;
}

.top {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
  justify-content: space-between;
  padding-block: 1.5rem;
}
.brand {
  display: flex;
  gap: 0.75rem;
  align-items: center;
  color: inherit;
  text-decoration: none;
  font-size: 1.25rem;
  font-weight: 700;
}
.brand img {
  inline-size: 3rem;
  block-size: auto;
  border: 2px solid var(--ink);
  border-radius: 0.75rem;
}

nav.lang { display: flex; flex-wrap: wrap; gap: 0.375rem; }
nav.lang button {
  font: inherit;
  font-size: 0.875rem;
  min-block-size: 2.25rem;
  padding: 0.25rem 0.75rem;
  cursor: pointer;
  background: var(--paper);
  color: var(--ink);
  border: 2px solid var(--ink);
  border-radius: 0;
}
nav.lang button[aria-pressed="true"] { background: var(--accent); color: var(--on-accent); }
@media (pointer: coarse) { nav.lang button { min-block-size: 2.75rem; } }

article {
  background: var(--paper);
  border: 2px solid var(--ink);
  box-shadow: 0.25rem 0.25rem 0 var(--ink);
  padding: 1.25rem 1.25rem 0.5rem;
}

h1 { font-size: 1.75rem; line-height: 1.25; margin: 0 0 0.25rem; }
h2 { font-size: 1.25rem; line-height: 1.3; margin: 1.75rem 0 0.375rem; }
h3 { font-size: 1.0625rem; line-height: 1.4; margin: 1.125rem 0 0.125rem; }
h1, h2, h3 { text-wrap: balance; }
p, li { margin: 0 0 0.625rem; text-wrap: pretty; }
ul, ol { padding-inline-start: 1.375rem; }
code { font-size: 0.9em; }
.sub { color: var(--muted); margin-block-end: 1rem; }
.box { border: 2px dashed var(--ink); padding: 0.625rem 0.875rem; margin-block: 0.875rem; }

a { color: var(--link); }
:where(a:any-link, button):focus-visible {
  outline: 3px solid var(--link);
  outline-offset: 3px;
}

.foot {
  padding-block: 1.75rem 4rem;
  color: var(--muted);
  font-size: 0.875rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1rem;
}

/* 语言切换：只显示当前语言；没有脚本时三种都显示 */
html.js [data-l] { display: none; }
html.js[data-lang="en"] [data-l="en"],
html.js[data-lang="es"] [data-l="es"],
html.js[data-lang="zh-Hant"] [data-l="zh-Hant"] { display: block; }
html.js[data-lang="en"] span[data-l="en"],
html.js[data-lang="es"] span[data-l="es"],
html.js[data-lang="zh-Hant"] span[data-l="zh-Hant"] { display: inline; }
html:not(.js) article[data-l] + article[data-l] { margin-block-start: 2rem; }
html:not(.js) span[data-l] + span[data-l]::before { content: " / "; }