/* ===== Shared styles for all notes pages ===== */
:root{
  --bg:#fbfbfa; --panel:#fff; --text:#1f2328; --muted:#6a737d;
  --line:#e6e6e3; --accent:#2f6f4e; --code-bg:#f4f4f1; --mark:#fff3bf;
  --shadow:0 1px 3px rgba(0,0,0,.06), 0 8px 24px rgba(0,0,0,.05);
}
html[data-theme="dark"]{
  --bg:#16181c; --panel:#1c1f24; --text:#e6e6e3; --muted:#9aa2ad;
  --line:#2c3037; --accent:#7fc8a0; --code-bg:#22262c; --mark:#4d4321;
  --shadow:0 1px 3px rgba(0,0,0,.4), 0 8px 24px rgba(0,0,0,.3);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--text);
  font:16px/1.68 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  -webkit-font-smoothing:antialiased;}

/* ---------- layout ---------- */
.layout{display:flex;max-width:1260px;margin:0 auto;}
aside{width:264px;flex:0 0 264px;height:100vh;position:sticky;top:0;overflow-y:auto;
  border-right:1px solid var(--line);padding:22px 16px 60px;background:var(--bg);}
aside h2{font-size:11.5px;letter-spacing:.09em;text-transform:uppercase;color:var(--muted);margin:22px 0 8px;}
aside nav a{display:block;color:var(--text);text-decoration:none;font-size:13.5px;
  padding:4px 8px;border-radius:5px;opacity:.82;}
aside nav a:hover{background:var(--code-bg);opacity:1;}
aside nav a.active{background:var(--code-bg);color:var(--accent);font-weight:600;opacity:1;}
.back-link{display:inline-block;color:var(--muted);text-decoration:none;font-size:13px;
  margin-bottom:14px;padding:2px 0;}
.back-link:hover{color:var(--accent)}
#search{width:100%;padding:8px 10px;border:1px solid var(--line);border-radius:6px;
  background:var(--panel);color:var(--text);font-size:13.5px;outline:none;}
#search:focus{border-color:var(--accent)}
main{flex:1;min-width:0;padding:26px 40px 120px;}

/* ---------- collapsible sidebar (desktop) ---------- */
.sidebar-head{display:flex;align-items:center;justify-content:space-between;gap:8px;margin-bottom:12px;}
.icon-btn{background:var(--panel);border:1px solid var(--line);color:var(--muted);
  width:28px;height:28px;border-radius:6px;cursor:pointer;flex-shrink:0;
  display:inline-flex;align-items:center;justify-content:center;
  font-size:14px;line-height:1;padding:0;font-family:inherit;}
.icon-btn:hover{color:var(--accent);border-color:var(--accent);}
body.nav-collapsed aside{display:none;}
#reopen{display:none;position:fixed;left:14px;top:18px;z-index:30;
  width:34px;height:34px;box-shadow:var(--shadow);background:var(--panel);}
body.nav-collapsed #reopen{display:inline-flex;}
body.nav-collapsed main{padding-left:64px;}

/* ---------- plain-words definition box ---------- */
.plain{border:1px solid var(--line);border-left:3px solid var(--accent);
  background:var(--panel);border-radius:0 8px 8px 0;padding:12px 16px;margin:14px 0 18px;}
.plain .plain-label{display:block;font-size:10.5px;letter-spacing:.1em;text-transform:uppercase;
  color:var(--accent);font-weight:700;margin-bottom:6px;}
.plain p{margin:5px 0;font-size:14.8px;}
.plain p.analogy{color:var(--muted);font-size:14px;}
.plain code{font-size:12.6px;}

/* ---------- diagrams ---------- */
figure.diagram{margin:20px 0;padding:16px 14px 10px;background:var(--panel);
  border:1px solid var(--line);border-radius:9px;overflow-x:auto;}
figure.diagram svg{display:block;margin:0 auto;max-width:100%;height:auto;}
figure.diagram figcaption{margin-top:10px;font-size:12.8px;color:var(--muted);
  text-align:center;line-height:1.55;}
svg .d-box{fill:var(--code-bg);stroke:var(--line);stroke-width:1.5;}
svg .d-box-accent{fill:none;stroke:var(--accent);stroke-width:1.8;}
svg .d-fill-accent{fill:var(--accent);opacity:.13;}
svg .d-label{fill:var(--text);font:600 12.5px -apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;}
svg .d-sub{fill:var(--muted);font:11.5px -apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;}
svg .d-mono{fill:var(--text);font:12px ui-monospace,SFMono-Regular,Menlo,monospace;}
svg .d-accent-text{fill:var(--accent);font:600 12px -apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;}
svg .d-line{stroke:var(--muted);stroke-width:1.5;fill:none;}
svg .d-line-accent{stroke:var(--accent);stroke-width:1.8;fill:none;}
svg .d-dash{stroke:var(--muted);stroke-width:1.3;fill:none;stroke-dasharray:4 3;}
svg .d-arrow{fill:var(--muted);}
svg .d-arrow-accent{fill:var(--accent);}

/* ---------- header ---------- */
header.top{display:flex;justify-content:space-between;align-items:flex-start;gap:16px;}
header.top h1{font-size:26px;margin:0;letter-spacing:-.02em;}
.top-actions{display:flex;gap:8px;align-items:center;flex-shrink:0;}
.sub{color:var(--muted);font-size:13.5px;margin:6px 0 26px;}
button.ghost{background:var(--panel);border:1px solid var(--line);color:var(--muted);
  padding:6px 12px;border-radius:6px;cursor:pointer;font-size:12.5px;
  font-family:inherit;white-space:nowrap;}
button.ghost:hover{color:var(--text);border-color:var(--accent);}
#menuBtn{display:none}

/* ---------- content ---------- */
section{scroll-margin-top:20px;}
.part{margin:56px 0 18px;padding-bottom:8px;border-bottom:2px solid var(--accent);
  font-size:18px;letter-spacing:.05em;text-transform:uppercase;color:var(--accent);}
h3{font-size:19.5px;margin:34px 0 8px;letter-spacing:-.01em;}
h4{font-size:15px;margin:22px 0 6px;color:var(--muted);font-weight:650;letter-spacing:.01em;}
p{margin:9px 0}
ul,ol{margin:8px 0;padding-left:20px} li{margin:5px 0}
b,strong{font-weight:650}
a{color:var(--accent)}
code{background:var(--code-bg);padding:1px 5px;border-radius:4px;
  font:13px/1.5 ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  overflow-wrap:break-word;}
pre{background:var(--code-bg);border:1px solid var(--line);border-radius:7px;
  padding:12px 14px;overflow-x:auto;margin:12px 0;}
pre code{background:none;padding:0;font-size:12.8px;line-height:1.62;white-space:pre;}
.table-wrap{overflow-x:auto;margin:12px 0;}
table{border-collapse:collapse;width:100%;font-size:14px;min-width:460px;}
th,td{border:1px solid var(--line);padding:7px 10px;text-align:left;vertical-align:top;}
th{background:var(--code-bg);font-weight:650;}
.note{border-left:3px solid var(--accent);background:var(--panel);padding:9px 14px;
  margin:14px 0;font-size:14.5px;border-radius:0 6px 6px 0;}
mark{background:var(--mark);color:inherit;}
.flow{white-space:pre;font:12.8px/1.7 ui-monospace,Menlo,Consolas,monospace;background:var(--code-bg);
  border:1px solid var(--line);border-radius:7px;padding:12px 14px;overflow-x:auto;margin:12px 0;}
.hidden{display:none !important}

/* ---------- mobile ---------- */
.scrim{display:none;position:fixed;inset:0;background:rgba(0,0,0,.42);z-index:40;}
.scrim.open{display:block}
@media (max-width:880px){
  body.nav-collapsed aside{display:block}
  body.nav-collapsed main{padding-left:18px}
  #reopen,body.nav-collapsed #reopen{display:none !important}
  .sidebar-head .icon-btn{display:none}
  aside{position:fixed;left:0;top:0;z-index:50;transform:translateX(-100%);
    transition:transform .22s ease;box-shadow:var(--shadow);width:280px;flex-basis:280px;}
  aside.open{transform:translateX(0)}
  main{padding:18px 18px 80px}
  header.top h1{font-size:21px}
  #menuBtn{display:inline-block}
  header.top{flex-wrap:wrap}
  header.top h1{flex:1 1 100%;order:2;margin-top:4px}
  .top-actions{order:1;margin-left:auto}
  .part{margin:40px 0 14px;font-size:16px}
  h3{font-size:18px}
}
@media (max-width:420px){
  body{font-size:15.5px}
  header.top h1{font-size:19px}
  button.ghost,a.ghost-link{padding:6px 9px;font-size:12px}
}

/* ---------- print ---------- */
@media print{
  aside,.top-actions,.scrim{display:none !important}
  main{padding:0} .layout{display:block}
  pre,table,.flow,section{page-break-inside:avoid}
}

/* ---------- interview Q&A pages ---------- */
.qa-tools{display:flex;gap:8px;flex-wrap:wrap;align-items:center;margin:-8px 0 20px;}
.qa-tools .count{color:var(--muted);font-size:12.5px;margin-left:auto;}
details.qa{background:var(--panel);border:1px solid var(--line);border-radius:9px;
  margin:10px 0;transition:border-color .15s ease;}
details.qa[open]{border-color:color-mix(in srgb,var(--accent) 45%,var(--line));}
details.qa summary{list-style:none;cursor:pointer;padding:12px 44px 12px 16px;position:relative;
  font-weight:600;font-size:15.2px;line-height:1.5;}
details.qa summary::-webkit-details-marker{display:none;}
details.qa summary::after{content:"";position:absolute;right:18px;top:19px;width:7px;height:7px;
  border-right:1.8px solid var(--muted);border-bottom:1.8px solid var(--muted);
  transform:rotate(45deg);transition:transform .18s ease;}
details.qa[open] summary::after{transform:rotate(225deg);top:22px;}
details.qa summary:hover{color:var(--accent);}
.lvl{display:inline-block;font-size:10px;letter-spacing:.08em;text-transform:uppercase;font-weight:700;
  padding:1px 7px;border-radius:20px;margin-right:9px;vertical-align:2px;border:1px solid currentColor;}
.lvl.b{color:var(--muted);}
.lvl.i{color:var(--accent);}
.lvl.a{color:#b4632a;}
html[data-theme="dark"] .lvl.a{color:#e0a26f;}
details.qa .answer{padding:2px 18px 14px;border-top:1px solid var(--line);font-size:15px;}
details.qa .answer > :first-child{margin-top:12px;}
.tip{font-size:13.8px;color:var(--muted);border-top:1px dashed var(--line);margin-top:12px;padding-top:9px;}
.tip b{color:var(--text);}
a.ghost-link{background:var(--panel);border:1px solid var(--line);color:var(--muted);text-decoration:none;
  padding:6px 12px;border-radius:6px;font-size:12.5px;line-height:1.45;white-space:nowrap;}
a.ghost-link:hover{color:var(--text);border-color:var(--accent);}
@media print{ details.qa .answer{display:block} .qa-tools{display:none} }

/* ---------- LeetCode cheat sheet (pastel beach palette) ---------- */
:root{
  --sand:#f8eed8; --sand-ink:#8a6526;
  --sea:#d8f1e8;  --sea-ink:#2d6f5a;
  --sky:#dcedf9;  --sky-ink:#2e5f87;
  --coral:#fbe0d7; --coral-ink:#a5503b;
  --shell:#f7e3ec; --shell-ink:#8e4a69;
  --sun:#fff3c9;  --sun-ink:#7d6415;
}
html[data-theme="dark"]{
  --sand:#3a3222; --sand-ink:#e8c98a;
  --sea:#1d3a31;  --sea-ink:#8fd9bd;
  --sky:#1e3242;  --sky-ink:#9cc9ee;
  --coral:#43282180; --coral-ink:#f2a893;
  --shell:#3b2531; --shell-ink:#eba9c7;
  --sun:#3a3319;  --sun-ink:#ecd580;
}
.tabs{display:flex;gap:6px;border-bottom:1px solid var(--line);margin:4px 0 22px;flex-wrap:wrap;}
.tab{background:none;border:0;border-bottom:3px solid transparent;padding:9px 14px 8px;margin-bottom:-1px;
  font:inherit;font-size:14.5px;font-weight:600;color:var(--muted);cursor:pointer;border-radius:6px 6px 0 0;}
.tab:hover{color:var(--text);background:var(--code-bg);}
.tab[aria-selected="true"]{color:var(--sea-ink);border-bottom-color:var(--sea-ink);background:var(--sea);}
.tab .soon{font-size:10px;letter-spacing:.07em;text-transform:uppercase;margin-left:6px;opacity:.75;}
.progress{display:flex;align-items:center;gap:12px;margin:0 0 18px;font-size:13px;color:var(--muted);}
.progress .bar{flex:1;max-width:320px;height:8px;border-radius:8px;background:var(--code-bg);overflow:hidden;border:1px solid var(--line);}
.progress .fill{height:100%;width:0;background:linear-gradient(90deg,var(--sea-ink),var(--sky-ink));transition:width .3s ease;}
.empty-tab{border:1px dashed var(--line);border-radius:12px;padding:40px 24px;text-align:center;color:var(--muted);}
.stage{margin:52px 0 6px;padding:10px 16px;border-radius:10px;background:var(--sky);color:var(--sky-ink);
  font-size:13px;letter-spacing:.08em;text-transform:uppercase;font-weight:700;}
.stage small{display:block;text-transform:none;letter-spacing:0;font-weight:500;font-size:13.5px;margin-top:2px;opacity:.9;}
.topic-intro{color:var(--muted);font-size:14.8px;margin:4px 0 14px;}
.topic-intro b{color:var(--text);}

details.lc{border:1px solid var(--line);border-left:4px solid var(--line);border-radius:10px;
  background:var(--panel);margin:10px 0;}
details.lc.diff-e{border-left-color:var(--sea-ink);}
details.lc.diff-m{border-left-color:var(--sand-ink);}
details.lc.diff-h{border-left-color:var(--coral-ink);}
details.lc[open]{box-shadow:var(--shadow);}
details.lc summary{list-style:none;cursor:pointer;display:flex;align-items:center;flex-wrap:wrap;gap:8px 10px;
  padding:12px 44px 12px 14px;position:relative;}
details.lc summary::-webkit-details-marker{display:none;}
details.lc summary::after{content:"";position:absolute;right:18px;top:20px;width:7px;height:7px;
  border-right:1.8px solid var(--muted);border-bottom:1.8px solid var(--muted);transform:rotate(45deg);transition:transform .18s ease;}
details.lc[open] summary::after{transform:rotate(225deg);top:23px;}
.lc-num{font:600 12.5px ui-monospace,SFMono-Regular,Menlo,monospace;color:var(--muted);min-width:58px;}
.lc-title{font-weight:620;font-size:15.5px;flex:1 1 200px;}
details.lc summary:hover .lc-title{color:var(--accent);}
.pill{font-size:11px;font-weight:650;padding:2px 9px;border-radius:20px;white-space:nowrap;letter-spacing:.01em;}
.pill.easy{background:var(--sea);color:var(--sea-ink);}
.pill.medium{background:var(--sun);color:var(--sun-ink);}
.pill.hard{background:var(--coral);color:var(--coral-ink);}
.pill.pat{background:var(--sky);color:var(--sky-ink);}
.solved{display:inline-flex;align-items:center;gap:6px;font:inherit;font-size:12px;color:var(--muted);cursor:pointer;
  background:none;border:1px solid var(--line);border-radius:20px;padding:2px 10px 2px 6px;}
.solved:hover{border-color:var(--sea-ink);color:var(--sea-ink);}
.solved .box{width:13px;height:13px;border-radius:4px;border:1.6px solid currentColor;display:inline-block;position:relative;}
.solved[aria-pressed="true"]{background:var(--sea);border-color:var(--sea-ink);color:var(--sea-ink);font-weight:600;}
.solved[aria-pressed="true"] .box{background:var(--sea-ink);border-color:var(--sea-ink);}
.solved[aria-pressed="true"] .box::after{content:"";position:absolute;left:3.5px;top:0.5px;width:3.5px;height:7px;
  border:solid var(--panel);border-width:0 1.8px 1.8px 0;transform:rotate(45deg);}
details.lc.done .lc-title{color:var(--muted);text-decoration:line-through;text-decoration-color:var(--sea-ink);}
.lc-body{padding:4px 18px 16px;border-top:1px solid var(--line);}
.lc-box{border-radius:9px;padding:10px 14px;margin:14px 0;}
.lc-box > :first-child{margin-top:0}
.lc-box > :last-child{margin-bottom:0}
.lc-label{display:block;font-size:10.5px;letter-spacing:.1em;text-transform:uppercase;font-weight:700;margin-bottom:4px;}
.lc-problem{background:var(--sky);} .lc-problem .lc-label{color:var(--sky-ink);}
.lc-idea{background:var(--shell);} .lc-idea .lc-label{color:var(--shell-ink);}
.lc-spot{background:var(--sand);border-left:3px solid var(--sand-ink);} .lc-spot .lc-label{color:var(--sand-ink);}
.key{background:var(--sun);border-left:3px solid var(--sun-ink);} .key .lc-label{color:var(--sun-ink);}
.trap{background:var(--coral);border-left:3px solid var(--coral-ink);} .trap .lc-label{color:var(--coral-ink);}
.lc-box code{background:rgba(255,255,255,.55);}
html[data-theme="dark"] .lc-box code{background:rgba(0,0,0,.25);}
h5.step{font-size:14px;margin:20px 0 6px;display:flex;align-items:center;gap:8px;}
h5.step .n{display:inline-grid;place-items:center;width:22px;height:22px;border-radius:50%;font-size:12px;}
h5.step.brute{color:var(--coral-ink);} h5.step.brute .n{background:var(--coral);}
h5.step.optimal{color:var(--sea-ink);} h5.step.optimal .n{background:var(--sea);}
.cx{display:flex;gap:8px;flex-wrap:wrap;margin:8px 0 4px;}
.cx span{font:600 12.3px ui-monospace,SFMono-Regular,Menlo,monospace;padding:3px 10px;border-radius:6px;}
.cx .t{background:var(--sky);color:var(--sky-ink);}
.cx .s{background:var(--shell);color:var(--shell-ink);}
.cx .bad{background:var(--coral);color:var(--coral-ink);}
.hl{background:var(--sun);color:var(--sun-ink);padding:0 4px;border-radius:4px;font-weight:600;}
.lc-links{font-size:13px;color:var(--muted);margin-top:14px;}
.lc-open{display:inline-flex;align-items:center;gap:4px;font-size:12px;font-weight:600;text-decoration:none;
  color:var(--sky-ink);border:1px solid var(--line);border-radius:20px;padding:2px 9px;white-space:nowrap;}
.lc-open:hover{background:var(--sky);border-color:var(--sky-ink);}
.lc-open svg{width:12px;height:12px;fill:none;stroke:currentColor;stroke-width:2;stroke-linecap:round;stroke-linejoin:round;}
aside .tab-off{display:none !important;}
/* pastel diagram fills */
svg .p-sea{fill:var(--sea);stroke:var(--sea-ink);stroke-width:1.4;}
svg .p-sky{fill:var(--sky);stroke:var(--sky-ink);stroke-width:1.4;}
svg .p-coral{fill:var(--coral);stroke:var(--coral-ink);stroke-width:1.4;}
svg .p-sun{fill:var(--sun);stroke:var(--sun-ink);stroke-width:1.4;}
svg .p-sand{fill:var(--sand);stroke:var(--sand-ink);stroke-width:1.4;}
svg .p-shell{fill:var(--shell);stroke:var(--shell-ink);stroke-width:1.4;}
svg .t-sea{fill:var(--sea-ink);font:600 12px -apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;}
svg .t-sky{fill:var(--sky-ink);font:600 12px -apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;}
svg .t-coral{fill:var(--coral-ink);font:600 12px -apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;}
svg .t-sun{fill:var(--sun-ink);font:600 12px -apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;}
@media print{ details.lc .lc-body{display:block} .tabs,.progress,.solved{display:none !important} }

/* ---------- breadcrumb ---------- */
.crumbs{margin:0 0 14px;font-size:13px;}
.crumbs ol{list-style:none;margin:0;padding:0;display:flex;flex-wrap:wrap;align-items:center;gap:2px 0;}
.crumbs li{display:inline-flex;align-items:center;color:var(--muted);margin:0;}
.crumbs li + li::before{content:"";width:6px;height:6px;margin:0 10px 0 8px;border-right:1.5px solid var(--muted);
  border-top:1.5px solid var(--muted);transform:rotate(45deg);opacity:.7;}
.crumbs a{color:var(--muted);text-decoration:none;}
.crumbs a:hover{color:var(--accent);text-decoration:underline;}
.crumbs [aria-current="page"]{color:var(--text);font-weight:600;}
@media (max-width:880px){ .crumbs{margin-bottom:10px;} }