/* ─── Tokens ─────────────────────────────────────────────── */
:root {
  --bg:              #faf9f5;
  --text:            #333333;
  --link:            #2185c5;
  --link-hover:      #74a6c5;
  --toggle-hover-bg: rgba(0, 0, 0, 0.08);

  /* prose */
  --border:          #e1e4e8;
  --code-bg:         #f0eeea;
  --blockquote-border: #d0d7de;

  /* callouts */
  --note-bg:       #ddf4ff; --note-border:  #54aeff; --note-text:  #0969da;
  --tip-bg:        #dafbe1; --tip-border:   #4ac26b; --tip-text:   #1a7f37;
  --important-bg:  #fbefff; --imp-border:   #c297ff; --imp-text:   #8250df;
  --warning-bg:    #fff8c5; --warn-border:  #d4a72c; --warn-text:  #9a6700;
  --caution-bg:    #ffebe9; --caut-border:  #ff8182; --caut-text:  #cf222e;
}

[data-theme="dark"] {
  --bg:              #212121;
  --text:            #e6edf3;
  --link:            #6bb8e8;
  --link-hover:      #a3d4f5;
  --toggle-hover-bg: rgba(255, 255, 255, 0.1);

  --border:          #30363d;
  --code-bg:         #2d2d2d;
  --blockquote-border: #3d444d;

  --note-bg:       #121d2f; --note-border:  #1f6feb; --note-text:  #79c0ff;
  --tip-bg:        #0d1f17; --tip-border:   #238636; --tip-text:   #56d364;
  --important-bg:  #1e1137; --imp-border:   #8957e5; --imp-text:   #d2a8ff;
  --warning-bg:    #1f1700; --warn-border:  #9e6a03; --warn-text:  #e3b341;
  --caution-bg:    #2d1217; --caut-border:  #f85149; --caut-text:  #ff7b72;
}

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

body {
  font-family: "Jost", sans-serif;
  font-optical-sizing: auto;
  font-weight: 400;
  font-size: 1rem;
  line-height: 1.6;
  color: var(--text);
  background-color: var(--bg);
  transition: background-color 0.3s ease, color 0.3s ease;
  margin: 0;
}

/* ─── Theme toggle ───────────────────────────────────────── */
.theme-toggle {
  position: fixed;
  top: 1.5rem;
  right: 1.5rem;
  background: transparent;
  border: none;
  border-radius: 50%;
  width: 40px;
  height: 40px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text);
  transition: background-color 0.2s ease, color 0.3s ease;
  z-index: 100;
}
.theme-toggle:hover  { background: var(--toggle-hover-bg); }
.theme-toggle:focus  { outline: 2px solid var(--link); outline-offset: 2px; }

.sun-icon, .moon-icon {
  position: absolute;
  transition: opacity 0.3s ease, transform 0.3s ease;
}
:root .sun-icon, [data-theme="light"] .sun-icon { opacity: 0; transform: rotate(-90deg) scale(0.8); }
:root .moon-icon, [data-theme="light"] .moon-icon { opacity: 1; transform: rotate(0deg) scale(1); }
[data-theme="dark"] .sun-icon  { opacity: 1; transform: rotate(0deg) scale(1); }
[data-theme="dark"] .moon-icon { opacity: 0; transform: rotate(90deg) scale(0.8); }

/* ─── Layout ─────────────────────────────────────────────── */
.container {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
}

.container.home > div {
  max-width: 600px;
  padding: 2rem 1.5rem;
}

.container.page {
  align-items: flex-start;
  padding: 3rem 1.5rem 4rem;
}

/* ─── Links ──────────────────────────────────────────────── */
a {
  text-decoration: none;
  color: var(--link);
  font-weight: 600;
  transition: color 0.2s ease;
}
a:hover { color: var(--link-hover); }

.back-link {
  display: inline-block;
  margin-bottom: 1.5rem;
  font-weight: 500;
}

/* ─── Headings ───────────────────────────────────────────── */
h1 { font-weight: 600; font-size: 36px; }
h2 { font-weight: 500; font-size: 28px; }
h3 { font-weight: 500; font-size: 25px; }
h4 { font-weight: 600; font-size: 21px; }
strong { font-weight: 600; }

/* ─── Prose (notes) ──────────────────────────────────────── */
.prose {
  max-width: 720px;
  width: 100%;
}

.prose p, .prose li { font-family: "Libertinus Serif", serif; font-size: 21px; }
.prose p   { margin: 0.75em 0; }
.prose ul, .prose ol { padding-left: 1.5rem; }
.prose li  { margin: 0.35em 0; }
.prose hr  { border: none; border-top: 1px solid var(--border); margin: 2rem 0; }

/* inline code */
.prose code {
  font-family: "JetBrains Mono", monospace;
  font-optical-sizing: auto;
  font-size: 0.875em;
  background: var(--code-bg);
  border-radius: 4px;
  padding: 0.15em 0.4em;
}

/* fenced code blocks */
.prose pre {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1rem 1.25rem;
  overflow-x: auto;
  font-size: 16px;
  line-height: 1.6;
  tab-size: 4;
}
.prose pre code {
  background: none;
  padding: 0;
  border-radius: 0;
}

.copy-btn {
  position: absolute;
  top: 0.6rem;
  right: 0.6rem;
  background: transparent;
  border: none;
  cursor: pointer;
  color: var(--text);
  opacity: 0.4;
  padding: 0.25rem;
  border-radius: 4px;
  transition: opacity 0.2s ease;
  line-height: 0;
}
.copy-btn:hover { opacity: 1; }

/* plain blockquotes */
.prose blockquote {
  margin: 1rem 0;
  padding: 0.5rem 0 0.5rem 1rem;
  border-left: 4px solid var(--blockquote-border);
  color: var(--text);
  opacity: 0.8;
}
.prose blockquote p { margin: 0; }

/* ─── Tables ─────────────────────────────────────────────── */
.prose table {
  border-collapse: collapse;
  margin: 1.25rem 0;
}
.prose thead th {
  background: var(--code-bg);
  font-weight: 600;
  text-align: left;
  padding: 0.6rem 1rem;
  border: 1px solid var(--border);
}
.prose tbody td {
  padding: 0.5rem 1rem;
  border: 1px solid var(--border);
}
.prose tbody tr:nth-child(even) { background: var(--code-bg); }

/* ─── Callouts ───────────────────────────────────────────── */
.callout {
  border: 1px solid;
  border-radius: 8px;
  padding: 0.75rem 1rem;
  margin: 1.25rem 0;
}
.callout-title {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-weight: 600;
  font-size: 0.9rem;
  margin-bottom: 0.5rem;
}
.callout-title svg { flex-shrink: 0; }
.callout-body > *:first-child { margin-top: 0; }
.callout-body > *:last-child  { margin-bottom: 0; }

.callout-note      { background: var(--note-bg);      border-color: var(--note-border); }
.callout-note      .callout-title { color: var(--note-text); }
.callout-note      .callout-title svg { stroke: var(--note-text); }

.callout-tip       { background: var(--tip-bg);       border-color: var(--tip-border); }
.callout-tip       .callout-title { color: var(--tip-text); }
.callout-tip       .callout-title svg { stroke: var(--tip-text); }

.callout-important { background: var(--important-bg); border-color: var(--imp-border); }
.callout-important .callout-title { color: var(--imp-text); }
.callout-important .callout-title svg { stroke: var(--imp-text); }

.callout-warning   { background: var(--warning-bg);   border-color: var(--warn-border); }
.callout-warning   .callout-title { color: var(--warn-text); }
.callout-warning   .callout-title svg { stroke: var(--warn-text); }

.callout-caution   { background: var(--caution-bg);   border-color: var(--caut-border); }
.callout-caution   .callout-title { color: var(--caut-text); }
.callout-caution   .callout-title svg { stroke: var(--caut-text); }

/* ─── KaTeX ──────────────────────────────────────────────── */
.katex { font-size: 1em; }

/* ─── KaTeX display math ─────────────────────────────────── */
.katex-display {
  overflow-x: auto;
  overflow-y: hidden;
  padding: 0.5rem 0;
}

/* ─── Note list (index) ──────────────────────────────────── */
.note-list {
  list-style: none;
  padding: 0;
  margin: 1.5rem 0 0;
}
.note-list li {
  display: flex;
  align-items: baseline;
  gap: 1rem;
  padding: 0.5rem 0;
  border-bottom: 1px solid var(--border);
}
.note-list li:last-child { border-bottom: none; }
.note-date {
  font-size: 0.85rem;
  color: var(--text);
  opacity: 0.55;
  white-space: nowrap;
  font-weight: 400;
}

/* ─── Syntax highlighting (light: github, dark: github-dark) ─ */
/* Background */ .bg { background-color:#f7f7f7; }
/* PreWrapper */ .chroma { background-color:#f7f7f7;-webkit-text-size-adjust:none; }
/* Error */ .chroma .err { color:#f6f8fa;background-color:#82071e }
/* LineLink */ .chroma .lnlinks { outline:none;text-decoration:none;color:inherit }
/* LineTableTD */ .chroma .lntd { vertical-align:top;padding:0;margin:0;border:0; }
/* LineTable */ .chroma .lntable { border-spacing:0;padding:0;margin:0;border:0; }
/* LineHighlight */ .chroma .hl { background-color:#dedede }
/* LineNumbersTable */ .chroma .lnt { white-space:pre;-webkit-user-select:none;user-select:none;margin-right:0.4em;padding:0 0.4em 0 0.4em;color:#7f7f7f }
/* LineNumbers */ .chroma .ln { white-space:pre;-webkit-user-select:none;user-select:none;margin-right:0.4em;padding:0 0.4em 0 0.4em;color:#7f7f7f }
/* Line */ .chroma .line { display:flex; }
/* Keyword */ .chroma .k { color:#cf222e }
/* KeywordConstant */ .chroma .kc { color:#cf222e }
/* KeywordDeclaration */ .chroma .kd { color:#cf222e }
/* KeywordNamespace */ .chroma .kn { color:#cf222e }
/* KeywordPseudo */ .chroma .kp { color:#cf222e }
/* KeywordReserved */ .chroma .kr { color:#cf222e }
/* KeywordType */ .chroma .kt { color:#cf222e }
/* NameAttribute */ .chroma .na { color:#1f2328 }
/* NameClass */ .chroma .nc { color:#1f2328 }
/* NameConstant */ .chroma .no { color:#0550ae }
/* NameDecorator */ .chroma .nd { color:#0550ae }
/* NameEntity */ .chroma .ni { color:#6639ba }
/* NameLabel */ .chroma .nl { color:#900;font-weight:bold }
/* NameNamespace */ .chroma .nn { color:#24292e }
/* NameOther */ .chroma .nx { color:#1f2328 }
/* NameTag */ .chroma .nt { color:#0550ae }
/* NameBuiltin */ .chroma .nb { color:#6639ba }
/* NameBuiltinPseudo */ .chroma .bp { color:#6a737d }
/* NameVariable */ .chroma .nv { color:#953800 }
/* NameVariableClass */ .chroma .vc { color:#953800 }
/* NameVariableGlobal */ .chroma .vg { color:#953800 }
/* NameVariableInstance */ .chroma .vi { color:#953800 }
/* NameVariableMagic */ .chroma .vm { color:#953800 }
/* NameFunction */ .chroma .nf { color:#6639ba }
/* NameFunctionMagic */ .chroma .fm { color:#6639ba }
/* LiteralString */ .chroma .s { color:#0a3069 }
/* LiteralStringAffix */ .chroma .sa { color:#0a3069 }
/* LiteralStringBacktick */ .chroma .sb { color:#0a3069 }
/* LiteralStringChar */ .chroma .sc { color:#0a3069 }
/* LiteralStringDelimiter */ .chroma .dl { color:#0a3069 }
/* LiteralStringDoc */ .chroma .sd { color:#0a3069 }
/* LiteralStringDouble */ .chroma .s2 { color:#0a3069 }
/* LiteralStringEscape */ .chroma .se { color:#0a3069 }
/* LiteralStringHeredoc */ .chroma .sh { color:#0a3069 }
/* LiteralStringInterpol */ .chroma .si { color:#0a3069 }
/* LiteralStringOther */ .chroma .sx { color:#0a3069 }
/* LiteralStringRegex */ .chroma .sr { color:#0a3069 }
/* LiteralStringSingle */ .chroma .s1 { color:#0a3069 }
/* LiteralStringSymbol */ .chroma .ss { color:#032f62 }
/* LiteralNumber */ .chroma .m { color:#0550ae }
/* LiteralNumberBin */ .chroma .mb { color:#0550ae }
/* LiteralNumberFloat */ .chroma .mf { color:#0550ae }
/* LiteralNumberHex */ .chroma .mh { color:#0550ae }
/* LiteralNumberInteger */ .chroma .mi { color:#0550ae }
/* LiteralNumberIntegerLong */ .chroma .il { color:#0550ae }
/* LiteralNumberOct */ .chroma .mo { color:#0550ae }
/* Operator */ .chroma .o { color:#0550ae }
/* OperatorWord */ .chroma .ow { color:#0550ae }
/* Punctuation */ .chroma .p { color:#1f2328 }
/* Comment */ .chroma .c { color:#57606a }
/* CommentHashbang */ .chroma .ch { color:#57606a }
/* CommentMultiline */ .chroma .cm { color:#57606a }
/* CommentSingle */ .chroma .c1 { color:#57606a }
/* CommentSpecial */ .chroma .cs { color:#57606a }
/* CommentPreproc */ .chroma .cp { color:#57606a }
/* CommentPreprocFile */ .chroma .cpf { color:#57606a }
/* GenericDeleted */ .chroma .gd { color:#82071e;background-color:#ffebe9 }
/* GenericEmph */ .chroma .ge { color:#1f2328 }
/* GenericInserted */ .chroma .gi { color:#116329;background-color:#dafbe1 }
/* GenericOutput */ .chroma .go { color:#1f2328 }
/* GenericUnderline */ .chroma .gl { text-decoration:underline }
/* TextWhitespace */ .chroma .w { color:#fff }

[data-theme="dark"] .bg { color:#e6edf3;background-color:#0d1117; }
[data-theme="dark"] .chroma { color:#e6edf3;background-color:#0d1117;-webkit-text-size-adjust:none; }
[data-theme="dark"] .chroma .err { color:#f85149 }
[data-theme="dark"] .chroma .lnlinks { outline:none;text-decoration:none;color:inherit }
[data-theme="dark"] .chroma .lntd { vertical-align:top;padding:0;margin:0;border:0; }
[data-theme="dark"] .chroma .lntable { border-spacing:0;padding:0;margin:0;border:0; }
[data-theme="dark"] .chroma .hl { background-color:#6e7681 }
[data-theme="dark"] .chroma .lnt { white-space:pre;-webkit-user-select:none;user-select:none;margin-right:0.4em;padding:0 0.4em 0 0.4em;color:#737679 }
[data-theme="dark"] .chroma .ln { white-space:pre;-webkit-user-select:none;user-select:none;margin-right:0.4em;padding:0 0.4em 0 0.4em;color:#6e7681 }
[data-theme="dark"] .chroma .line { display:flex; }
[data-theme="dark"] .chroma .k { color:#ff7b72 }
[data-theme="dark"] .chroma .kc { color:#79c0ff }
[data-theme="dark"] .chroma .kd { color:#ff7b72 }
[data-theme="dark"] .chroma .kn { color:#ff7b72 }
[data-theme="dark"] .chroma .kp { color:#79c0ff }
[data-theme="dark"] .chroma .kr { color:#ff7b72 }
[data-theme="dark"] .chroma .kt { color:#ff7b72 }
[data-theme="dark"] .chroma .nc { color:#f0883e;font-weight:bold }
[data-theme="dark"] .chroma .no { color:#79c0ff;font-weight:bold }
[data-theme="dark"] .chroma .nd { color:#d2a8ff;font-weight:bold }
[data-theme="dark"] .chroma .ni { color:#ffa657 }
[data-theme="dark"] .chroma .ne { color:#f0883e;font-weight:bold }
[data-theme="dark"] .chroma .nl { color:#79c0ff;font-weight:bold }
[data-theme="dark"] .chroma .nn { color:#ff7b72 }
[data-theme="dark"] .chroma .py { color:#79c0ff }
[data-theme="dark"] .chroma .nt { color:#7ee787 }
[data-theme="dark"] .chroma .nv { color:#79c0ff }
[data-theme="dark"] .chroma .vc { color:#79c0ff }
[data-theme="dark"] .chroma .vg { color:#79c0ff }
[data-theme="dark"] .chroma .vi { color:#79c0ff }
[data-theme="dark"] .chroma .vm { color:#79c0ff }
[data-theme="dark"] .chroma .nf { color:#d2a8ff;font-weight:bold }
[data-theme="dark"] .chroma .fm { color:#d2a8ff;font-weight:bold }
[data-theme="dark"] .chroma .l { color:#a5d6ff }
[data-theme="dark"] .chroma .ld { color:#79c0ff }
[data-theme="dark"] .chroma .s { color:#a5d6ff }
[data-theme="dark"] .chroma .sa { color:#79c0ff }
[data-theme="dark"] .chroma .sb { color:#a5d6ff }
[data-theme="dark"] .chroma .sc { color:#a5d6ff }
[data-theme="dark"] .chroma .dl { color:#79c0ff }
[data-theme="dark"] .chroma .sd { color:#a5d6ff }
[data-theme="dark"] .chroma .s2 { color:#a5d6ff }
[data-theme="dark"] .chroma .se { color:#79c0ff }
[data-theme="dark"] .chroma .sh { color:#79c0ff }
[data-theme="dark"] .chroma .si { color:#a5d6ff }
[data-theme="dark"] .chroma .sx { color:#a5d6ff }
[data-theme="dark"] .chroma .sr { color:#79c0ff }
[data-theme="dark"] .chroma .s1 { color:#a5d6ff }
[data-theme="dark"] .chroma .ss { color:#a5d6ff }
[data-theme="dark"] .chroma .m { color:#a5d6ff }
[data-theme="dark"] .chroma .mb { color:#a5d6ff }
[data-theme="dark"] .chroma .mf { color:#a5d6ff }
[data-theme="dark"] .chroma .mh { color:#a5d6ff }
[data-theme="dark"] .chroma .mi { color:#a5d6ff }
[data-theme="dark"] .chroma .il { color:#a5d6ff }
[data-theme="dark"] .chroma .mo { color:#a5d6ff }
[data-theme="dark"] .chroma .o { color:#ff7b72;font-weight:bold }
[data-theme="dark"] .chroma .ow { color:#ff7b72;font-weight:bold }
[data-theme="dark"] .chroma .c { color:#8b949e;font-style:italic }
[data-theme="dark"] .chroma .ch { color:#8b949e;font-style:italic }
[data-theme="dark"] .chroma .cm { color:#8b949e;font-style:italic }
[data-theme="dark"] .chroma .c1 { color:#8b949e;font-style:italic }
[data-theme="dark"] .chroma .cs { color:#8b949e;font-weight:bold;font-style:italic }
[data-theme="dark"] .chroma .cp { color:#8b949e;font-weight:bold;font-style:italic }
[data-theme="dark"] .chroma .cpf { color:#8b949e;font-weight:bold;font-style:italic }
[data-theme="dark"] .chroma .gd { color:#ffa198;background-color:#490202 }
[data-theme="dark"] .chroma .ge { font-style:italic }
[data-theme="dark"] .chroma .gr { color:#ffa198 }
[data-theme="dark"] .chroma .gh { color:#79c0ff;font-weight:bold }
[data-theme="dark"] .chroma .gi { color:#56d364;background-color:#0f5323 }
[data-theme="dark"] .chroma .go { color:#8b949e }
[data-theme="dark"] .chroma .gp { color:#8b949e }
[data-theme="dark"] .chroma .gs { font-weight:bold }
[data-theme="dark"] .chroma .gu { color:#79c0ff }
[data-theme="dark"] .chroma .gt { color:#ff7b72 }
[data-theme="dark"] .chroma .gl { text-decoration:underline }
[data-theme="dark"] .chroma .w { color:#6e7681 }