/* PyPath — Python 学习站样式
   视觉关键词：蛇蜕双色（Python 蓝 × 黄）、缩进轨、REPL 提示符、鳞纹肌理 */

:root {
  --py-blue: #306998;
  --py-blue-deep: #1E3A5F;
  --py-yellow: #FFD43B;
  --py-green: #7FD962;
  --mc: var(--py-blue);

  --bg: #F6F3EB;
  --bg-2: #FFFFFF;
  --bg-3: #FBFAF5;
  --ink: #1E2A38;
  --muted: #5C6C7E;
  --line: #E3DECF;
  --line-2: #EDE9DC;
  --topbar: rgba(255, 255, 255, .82);
  --shadow: 0 1px 2px rgba(30, 42, 56, .05), 0 8px 28px rgba(30, 42, 56, .07);
  --code-bg: #0E1724;
  --code-ink: #D9E2EE;
  --mark: rgba(255, 212, 59, .45);
}
html[data-theme="dark"] {
  --bg: #101826;
  --bg-2: #16202F;
  --bg-3: #131C2A;
  --ink: #E6EDF5;
  --muted: #94A6BA;
  --line: #24334A;
  --line-2: #1E2B3F;
  --topbar: rgba(16, 24, 38, .85);
  --py-blue: #5B93C4;
  --shadow: 0 1px 2px rgba(0, 0, 0, .3), 0 10px 30px rgba(0, 0, 0, .35);
  --mark: rgba(255, 212, 59, .3);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB",
    "Source Han Sans SC", "Microsoft YaHei", "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--ink);
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--py-blue); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }
code, pre, .kp-num, .map-num, .brand-mark, .code-lang, .step-num {
  font-family: ui-monospace, "SF Mono", SFMono-Regular, Menlo, Consolas, monospace;
}
:focus-visible { outline: 2px solid var(--py-yellow); outline-offset: 2px; border-radius: 4px; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } * { transition: none !important; } }

/* 跳过导航链接：仅键盘聚焦时可见 */
.skip-link {
  position: fixed; left: 12px; top: -48px; z-index: 200;
  padding: 8px 16px; border-radius: 0 0 8px 8px;
  background: var(--py-blue); color: #fff; font-weight: 600;
  transition: top .15s ease;
}
.skip-link:focus { top: 0; }

/* ---------------------------------------------------------- topbar */
.topbar {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; gap: 18px;
  padding: 10px 22px;
  background: var(--topbar);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: baseline; gap: 8px; font-weight: 800; font-size: 18px; color: var(--ink); }
.brand:hover { text-decoration: none; }
.brand-mark { color: var(--py-green); font-weight: 700; font-size: 15px; letter-spacing: -1px; }
.brand-sub { font-size: 11.5px; font-weight: 600; color: var(--muted); letter-spacing: .08em; }
.top-nav { display: flex; gap: 4px; margin-left: 6px; }
.top-link {
  padding: 5px 11px; border-radius: 999px; font-size: 13.5px; color: var(--muted); font-weight: 500;
}
.top-link:hover { color: var(--ink); background: var(--line-2); text-decoration: none; }
.top-link.active { color: var(--py-blue-deep); background: var(--py-yellow); font-weight: 700; }
html[data-theme="dark"] .top-link.active { color: #101826; }

.search { position: relative; margin-left: auto; width: min(320px, 34vw); }
.search input {
  width: 100%; padding: 7px 12px 7px 30px; border-radius: 10px;
  border: 1px solid var(--line); background: var(--bg-2); color: var(--ink);
  font-size: 13.5px; font-family: inherit;
}
.search input:focus { border-color: var(--py-blue); outline: none; box-shadow: 0 0 0 3px rgba(48, 105, 152, .15); }
.search::before {
  content: "⌕"; position: absolute; left: 10px; top: 6px; color: var(--muted); font-size: 15px;
}
.search-results {
  position: absolute; top: calc(100% + 8px); right: 0; width: min(430px, 88vw);
  background: var(--bg-2); border: 1px solid var(--line); border-radius: 12px;
  box-shadow: var(--shadow); overflow: hidden; max-height: 66vh; overflow-y: auto;
}
.search-results[hidden] { display: none; }
.sr-item { display: block; padding: 9px 14px; border-bottom: 1px solid var(--line-2); }
.sr-item:last-child { border-bottom: 0; }
.sr-item:hover, .sr-item.sel { background: var(--bg-3); text-decoration: none; }
.sr-title { font-weight: 700; font-size: 13.5px; color: var(--ink); }
.sr-title mark { background: var(--mark); color: inherit; border-radius: 3px; padding: 0 1px; }
.sr-meta { font-size: 11.5px; color: var(--muted); }
.sr-snip { font-size: 12px; color: var(--muted); line-height: 1.55; margin-top: 2px;
  display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.sr-snip mark { background: var(--mark); color: inherit; border-radius: 3px; padding: 0 1px; }
.sr-empty { padding: 14px; font-size: 13px; color: var(--muted); }

.icon-btn {
  width: 34px; height: 34px; border-radius: 9px; border: 1px solid var(--line);
  background: var(--bg-2); color: var(--ink); font-size: 15px; cursor: pointer; flex: none;
}
.icon-btn:hover { border-color: var(--py-blue); }
.menu-btn { display: none; }

/* ---------------------------------------------------------- shell */
.shell {
  display: grid; grid-template-columns: 252px minmax(0, 1fr) 212px;
  gap: 26px; max-width: 1340px; margin: 0 auto; padding: 26px 22px 80px;
  align-items: start;
}

/* sidebar */
.sidebar {
  position: sticky; top: 66px; max-height: calc(100vh - 86px); overflow-y: auto;
  padding-right: 6px; scrollbar-width: thin;
}
.side-group { display: flex; flex-direction: column; gap: 1px; margin-bottom: 18px; }
.side-link {
  padding: 6px 10px; border-radius: 8px; font-size: 13.5px; color: var(--muted); font-weight: 600;
}
.side-link:hover { background: var(--line-2); color: var(--ink); text-decoration: none; }
.side-link.current { background: var(--line-2); color: var(--py-blue-deep); }
html[data-theme="dark"] .side-link.current { color: var(--py-yellow); }
.side-module { margin-bottom: 14px; }
.side-module-head {
  display: flex; align-items: center; gap: 8px; font-size: 12px; font-weight: 800;
  text-transform: uppercase; letter-spacing: .1em; color: var(--muted);
  padding: 4px 10px 6px;
}
.side-module-head .dot { width: 9px; height: 9px; border-radius: 3px; background: var(--mc); flex: none; }
.side-count { margin-left: auto; font-size: 10.5px; font-weight: 600; color: var(--muted); letter-spacing: 0; }
.side-kp {
  display: flex; align-items: baseline; gap: 8px; padding: 5px 10px 5px 27px;
  border-left: 2px solid transparent; margin-left: 13px;
  font-size: 13.5px; color: var(--ink); position: relative;
}
.side-kp:hover { background: var(--line-2); text-decoration: none; }
.side-kp.current { border-left-color: var(--py-yellow); background: var(--line-2); font-weight: 700; }
.kp-num { font-size: 11px; color: var(--muted); flex: none; width: 28px; }
.side-kp.done .kp-num { color: #2E9E7B; font-weight: 700; }
.side-kp.done::after { content: "✓"; margin-left: auto; color: #2E9E7B; font-size: 12px; font-weight: 800; }

/* toc */
.toc { position: sticky; top: 66px; font-size: 12.5px; }
.toc-title { font-size: 11px; font-weight: 800; letter-spacing: .12em; text-transform: uppercase; color: var(--muted); margin-bottom: 8px; }
.toc-list { list-style: none; margin: 0; padding: 0 0 0 10px; border-left: 2px solid var(--line); }
.toc-list li { margin: 3px 0; }
.toc-list a { color: var(--muted); display: block; padding: 2px 0; }
.toc-list a:hover { color: var(--py-blue); text-decoration: none; }

/* ---------------------------------------------------------- content */
.content { min-width: 0; }
.crumbs { display: flex; gap: 8px; font-size: 12.5px; color: var(--muted); margin-bottom: 14px; flex-wrap: wrap; }
.crumbs a { color: var(--muted); }
.crumbs a:hover { color: var(--py-blue); }

article.kp, .page-article, .page-head {
  background: var(--bg-2); border: 1px solid var(--line); border-radius: 16px;
  box-shadow: var(--shadow);
}
article.kp, .page-article { padding: 34px 40px 26px; position: relative; overflow: hidden; }
article.kp::before, .page-article::before {
  content: ""; position: absolute; left: 0; top: 0; bottom: 0; width: 4px;
  background: linear-gradient(180deg, var(--py-blue), var(--py-yellow));
}
.kp-head { margin-bottom: 8px; }
.kp-badges { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 12px; }
.badge {
  font-size: 11.5px; font-weight: 700; padding: 3px 10px; border-radius: 999px; letter-spacing: .02em;
}
.badge.module { background: color-mix(in srgb, var(--mc) 14%, transparent); color: var(--mc); border: 1px solid color-mix(in srgb, var(--mc) 35%, transparent); }
.badge.level { background: color-mix(in srgb, var(--py-yellow) 22%, transparent); color: var(--py-blue-deep); border: 1px solid color-mix(in srgb, var(--py-yellow) 60%, transparent); }
html[data-theme="dark"] .badge.level { color: var(--py-yellow); }
.badge.id { background: var(--line-2); color: var(--muted); font-family: ui-monospace, Menlo, monospace; }
article.kp h1, .page-head h1 { font-size: 30px; line-height: 1.3; margin: 0 0 10px; letter-spacing: -.01em; }
.kp-meta { color: var(--muted); font-size: 13.5px; margin: 0 0 6px; }
.kp-meta a { font-family: ui-monospace, Menlo, monospace; font-size: 12.5px; }

article.kp h2, .page-article h2 {
  font-size: 20px; margin: 34px 0 12px; padding-left: 12px;
  border-left: 3px solid var(--py-yellow); line-height: 1.45;
}
article.kp h3, .page-article h3 { font-size: 16.5px; margin: 24px 0 8px; }
article.kp p, .page-article p { margin: 10px 0; }
p.lead {
  font-size: 17px; line-height: 1.8; color: var(--ink);
  background: var(--bg-3); border: 1px dashed var(--line); border-radius: 12px;
  padding: 14px 16px 14px 46px; position: relative; margin-top: 14px;
}
p.lead::before {
  content: ">>>"; position: absolute; left: 15px; top: 15px;
  font-family: ui-monospace, Menlo, monospace; font-weight: 700; color: var(--py-green); font-size: 14px;
}
a.kp-ref {
  font-family: ui-monospace, Menlo, monospace; font-size: .88em;
  background: var(--line-2); padding: 1px 6px; border-radius: 6px;
}
a.kp-ref:hover { background: var(--py-yellow); color: var(--py-blue-deep); text-decoration: none; }
ul, ol { padding-left: 24px; }
li { margin: 5px 0; }
li > ul { margin: 4px 0; }
blockquote {
  margin: 14px 0; padding: 10px 16px; border-left: 3px solid var(--py-blue);
  background: var(--bg-3); border-radius: 0 10px 10px 0; color: var(--muted); font-size: 14.5px;
}
hr { border: 0; border-top: 1px dashed var(--line); margin: 26px 0; }

/* details（自测答案） */
details {
  margin: 10px 0 16px; border: 1px solid var(--line); border-radius: 10px;
  background: var(--bg-3); padding: 0 14px;
}
details[open] { padding-bottom: 10px; }
summary { cursor: pointer; font-weight: 700; font-size: 13.5px; padding: 9px 0; color: var(--py-blue); }
summary::marker { color: var(--py-yellow); }
details p { margin: 6px 0; font-size: 14px; color: var(--muted); }
details p:first-of-type { color: var(--ink); }

/* code blocks */
.codeblock {
  position: relative; margin: 16px 0; border-radius: 12px; overflow: hidden;
  background: var(--code-bg); border: 1px solid rgba(255, 255, 255, .06);
}
.code-lang {
  position: absolute; top: 8px; right: 12px; font-size: 10.5px; letter-spacing: .08em;
  color: #5E7189; text-transform: uppercase; user-select: none;
}
.copy-btn {
  position: absolute; top: 5px; right: 62px; font-size: 11px; padding: 3px 9px;
  border-radius: 7px; border: 1px solid rgba(255, 255, 255, .14);
  background: rgba(255, 255, 255, .05); color: #8CA3BD; cursor: pointer; opacity: 0;
  transition: opacity .15s;
}
.codeblock:hover .copy-btn { opacity: 1; }
.copy-btn:hover { color: #fff; border-color: rgba(255, 255, 255, .3); }
.codeblock pre { margin: 0; padding: 16px 18px; overflow-x: auto; }
.codeblock code { font-size: 13px; line-height: 1.7; color: var(--code-ink); }
p code, li code, td code, .kp-meta code, details code {
  background: var(--line-2); border-radius: 5px; padding: 1.5px 6px; font-size: .86em;
}
p code { color: var(--py-blue-deep); }
html[data-theme="dark"] p code { color: var(--py-yellow); }
.hl-kw { color: #FF8FC5; font-weight: 600; }
.hl-builtin { color: #7FD3ED; }
.hl-string { color: #FFD479; }
.hl-comment { color: #6D7F94; font-style: italic; }
.hl-number { color: #B5E48C; }
.hl-decorator { color: #F2B866; }

/* tables */
.table-wrap { overflow-x: auto; margin: 16px 0; border: 1px solid var(--line); border-radius: 12px; }
table { border-collapse: collapse; width: 100%; font-size: 13.5px; }
th, td { padding: 9px 13px; text-align: left; border-bottom: 1px solid var(--line-2); vertical-align: top; }
th { background: var(--bg-3); font-size: 12.5px; letter-spacing: .03em; color: var(--muted); white-space: nowrap; }
tr:last-child td { border-bottom: 0; }
td code { white-space: nowrap; }

/* kp footer */
.kp-foot { margin-top: 40px; border-top: 1px dashed var(--line); padding-top: 18px; }
.kp-related { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; margin-bottom: 18px; }
.rel-label { font-size: 12px; font-weight: 800; color: var(--muted); letter-spacing: .08em; }
.chip {
  font-size: 12px; padding: 4px 10px; border-radius: 999px; background: var(--line-2);
  color: var(--ink); border: 1px solid transparent;
}
.chip:hover { border-color: var(--py-blue); text-decoration: none; background: var(--bg-2); }
.rel-none { color: var(--line); }
.kp-nav { display: grid; grid-template-columns: 1fr auto 1fr; gap: 12px; align-items: stretch; }
.pn {
  display: flex; flex-direction: column; gap: 3px; padding: 12px 16px;
  border: 1px solid var(--line); border-radius: 12px; background: var(--bg-3);
  color: var(--ink); min-width: 0;
}
.pn span { font-size: 11px; color: var(--muted); }
.pn strong { font-size: 13.5px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.pn:hover { border-color: var(--py-blue); text-decoration: none; }
.pn.next { text-align: right; grid-column: 3; }
.pn.ghost { visibility: hidden; }
.done-toggle {
  align-self: center; padding: 10px 18px; border-radius: 12px; cursor: pointer;
  border: 1.5px solid var(--py-blue); background: transparent; color: var(--py-blue);
  font-weight: 700; font-size: 13.5px; font-family: inherit; white-space: nowrap;
  transition: all .15s;
}
.done-toggle:hover { background: color-mix(in srgb, var(--py-blue) 10%, transparent); }
.done-toggle.is-done {
  background: #2E9E7B; border-color: #2E9E7B; color: #fff;
}

/* ---------------------------------------------------------- index */
.hero {
  background:
    radial-gradient(circle at 1px 1px, rgba(255, 212, 59, .16) 1.6px, transparent 1.7px) 0 0 / 22px 22px,
    linear-gradient(135deg, var(--py-blue-deep) 0%, #27547F 55%, #306998 100%);
  border-radius: 20px; padding: 58px 48px 46px; color: #F2F6FB; position: relative; overflow: hidden;
  border: 1px solid rgba(255, 255, 255, .08);
}
.hero::after {
  content: ">>>"; position: absolute; right: 34px; bottom: 8px;
  font-family: ui-monospace, Menlo, monospace; font-size: 96px; font-weight: 800;
  color: rgba(255, 212, 59, .13); letter-spacing: -6px; line-height: 1;
}
.hero-kicker { font-family: ui-monospace, Menlo, monospace; color: var(--py-green); font-size: 14px; margin: 0 0 10px; }
.hero h1 { font-size: 44px; margin: 0 0 14px; letter-spacing: -.02em; }
.hero-lead { max-width: 620px; font-size: 16.5px; color: #C9D8E8; margin: 0 0 24px; }
.hero-lead code { background: rgba(255, 255, 255, .12); color: #fff; }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; }
.btn {
  padding: 11px 22px; border-radius: 12px; font-weight: 700; font-size: 14.5px;
  display: inline-block; transition: transform .12s;
}
.btn:hover { transform: translateY(-1px); text-decoration: none; }
.btn-primary { background: var(--py-yellow); color: var(--py-blue-deep); box-shadow: 0 6px 18px rgba(255, 212, 59, .25); }
.btn-ghost { border: 1.5px solid rgba(255, 255, 255, .35); color: #F2F6FB; }
.hero-stats { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 28px; }
.hero-stats span {
  font-size: 12px; padding: 5px 12px; border-radius: 999px;
  background: rgba(255, 255, 255, .1); color: #D5E2F0; border: 1px solid rgba(255, 255, 255, .12);
}
.home-section { margin-top: 34px; }
.home-section > h2 { font-size: 21px; margin: 0 0 16px; letter-spacing: -.01em; }
.mod-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 14px; }
.mod-card {
  background: var(--bg-2); border: 1px solid var(--line); border-radius: 16px;
  padding: 20px; color: var(--ink); display: block; position: relative; transition: border-color .15s;
}
.mod-card:hover { text-decoration: none; border-color: var(--mc); }
.mod-card-head { display: flex; align-items: center; gap: 9px; margin-bottom: 8px; flex-wrap: wrap; }
.mod-card-head .dot { width: 10px; height: 10px; border-radius: 3px; background: var(--mc); }
.mod-card h3 { margin: 0; font-size: 17px; white-space: nowrap; }
.mod-card .en { font-size: 11px; color: var(--muted); letter-spacing: .1em; text-transform: uppercase; }
.mod-card p { font-size: 13.5px; color: var(--muted); margin: 6px 0; }
.mod-kps { font-size: 12px !important; }
.mod-go { font-size: 13px; font-weight: 700; color: var(--mc); }
.steps { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 14px; }
.step { background: var(--bg-2); border: 1px solid var(--line); border-radius: 16px; padding: 20px; }
.step-num {
  display: inline-flex; width: 26px; height: 26px; align-items: center; justify-content: center;
  background: var(--py-blue-deep); color: var(--py-yellow); border-radius: 8px;
  font-size: 13px; font-weight: 700; margin-bottom: 10px;
}
.step p { font-size: 13.5px; color: var(--muted); margin: 6px 0 0; }
.quick-links { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 12px; }
.quick {
  display: flex; flex-direction: column; gap: 3px; padding: 16px 18px;
  background: var(--bg-2); border: 1px solid var(--line); border-radius: 14px; color: var(--ink);
}
.quick:hover { border-color: var(--py-blue); text-decoration: none; }
.quick span { font-size: 12.5px; color: var(--muted); }
.foot-note { margin-top: 34px; font-size: 12.5px; color: var(--muted); text-align: center; }

/* ---------------------------------------------------------- map / page-head */
.page-head { padding: 30px 34px; margin-bottom: 22px; }
.page-lead { color: var(--muted); font-size: 15px; margin: 8px 0 0; max-width: 640px; }
.map-progress { margin-top: 12px; font-size: 12px; color: var(--py-green); font-family: ui-monospace, Menlo, monospace; }
.map-module { margin: 26px 0 34px; --mc: var(--py-blue); }
.map-module-head { display: flex; align-items: baseline; gap: 10px; flex-wrap: wrap; margin-bottom: 4px; }
.map-module-head h2 { display: flex; align-items: center; gap: 9px; font-size: 19px; margin: 0; }
.map-module-head .dot { width: 11px; height: 11px; border-radius: 3.5px; background: var(--mc); }
.map-module-head .en { font-size: 11px; color: var(--muted); letter-spacing: .12em; text-transform: uppercase; font-weight: 600; }
.map-module-head p { width: 100%; color: var(--muted); font-size: 13.5px; margin: 4px 0 0; }
.map-count { margin-left: auto; font-size: 11.5px; color: var(--muted); font-family: ui-monospace, Menlo, monospace; }
.map-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(215px, 1fr)); gap: 10px; margin-top: 12px; }
.map-card {
  display: flex; flex-direction: column; gap: 5px; padding: 13px 15px;
  background: var(--bg-2); border: 1px solid var(--line); border-radius: 13px; color: var(--ink);
  border-top: 3px solid var(--mc); transition: transform .12s, border-color .15s;
}
.map-card:hover { transform: translateY(-2px); text-decoration: none; border-color: var(--mc); }
.map-card strong { font-size: 14px; line-height: 1.45; }
.map-num { font-family: ui-monospace, Menlo, monospace; font-size: 10.5px; color: var(--muted); }
.map-pre { font-size: 11px; color: var(--muted); display: flex; gap: 5px; flex-wrap: wrap; align-items: center; }
.map-pre::before { content: "前置"; font-weight: 700; color: var(--py-blue); flex: none; }
.map-pre-item { font-family: ui-monospace, Menlo, monospace; }
.map-pre-item.none::before { content: "—"; }
.map-card.done { background: color-mix(in srgb, #2E9E7B 8%, var(--bg-2)); border-top-color: #2E9E7B; }
.map-card.done .map-num::after { content: " ✓"; color: #2E9E7B; font-weight: 800; }

/* ---------------------------------------------------------- responsive */
.scrim { display: none; }
@media (max-width: 1160px) {
  .shell { grid-template-columns: 252px minmax(0, 1fr); }
  .toc { display: none; }
}
@media (max-width: 880px) {
  .shell { grid-template-columns: minmax(0, 1fr); padding: 18px 14px 70px; }
  .menu-btn { display: block; }
  .top-nav { display: none; }
  article.kp, .page-article { padding: 24px 20px 20px; }
  .hero { padding: 40px 24px 34px; }
  .hero h1 { font-size: 32px; }
  .sidebar {
    position: fixed; inset: 0 auto 0 0; width: 284px; max-height: none; z-index: 90;
    background: var(--bg-2); padding: 18px 14px; transform: translateX(-105%);
    transition: transform .22s ease; border-right: 1px solid var(--line); overflow-y: auto;
  }
  body.menu-open .sidebar { transform: translateX(0); box-shadow: 0 0 60px rgba(0, 0, 0, .3); }
  .scrim {
    display: block; position: fixed; inset: 0; background: rgba(10, 16, 26, .45);
    z-index: 80; opacity: 0; pointer-events: none; transition: opacity .2s;
  }
  body.menu-open .scrim { opacity: 1; pointer-events: auto; }
  .kp-nav { grid-template-columns: 1fr; }
  .pn.next { grid-column: auto; }
  .search { width: 42vw; }
}
@media (max-width: 560px) {
  .brand-sub { display: none; }
  .search { flex: 1; width: auto; min-width: 0; }
}