/* ============================================================
   Andrew Nedilko — personal site design system
   ============================================================ */
:root {
  --bg-dark: #0a0f1e;
  --bg-dark2: #0e1530;
  --panel: #111a33;
  --ink: #1e293b;
  --ink-soft: #475569;
  --ink-faint: #64748b;
  --paper: #f7f9fc;
  --card: #ffffff;
  --line: #e2e8f0;
  --accent: #6366f1;
  --accent2: #22d3ee;
  --accent3: #a78bfa;
  --glow: rgba(99, 102, 241, .35);
  --code-bg: #0d1526;
  --radius: 14px;
  --shadow: 0 1px 2px rgba(15,23,42,.06), 0 8px 24px -12px rgba(15,23,42,.18);
  --shadow-lift: 0 4px 12px rgba(15,23,42,.08), 0 24px 48px -16px rgba(15,23,42,.28);
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  color: var(--ink);
  background: var(--paper);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}
code, pre, kbd { font-family: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace; }

/* ---------- scroll progress ---------- */
#progress {
  position: fixed; top: 0; left: 0; height: 3px; width: 0;
  background: linear-gradient(90deg, var(--accent), var(--accent2));
  z-index: 1000; transition: width .1s linear;
}

/* ---------- top bar ---------- */
.topbar {
  position: sticky; top: 0; z-index: 900;
  display: flex; align-items: center; justify-content: space-between; gap: 1rem;
  padding: .65rem 1.4rem;
  background: rgba(10, 15, 30, .92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid rgba(255,255,255,.08);
}
.topbar .crumbs { display: flex; align-items: center; flex-wrap: wrap; gap: .45rem; font-size: .88rem; min-width: 0; }
.topbar .crumbs a { color: #cbd5e1; text-decoration: none; transition: color .15s; white-space: nowrap; }
.topbar .crumbs a:hover { color: var(--accent2); }
.topbar .crumbs .sep { color: #475569; }
.topbar .crumbs .here { color: #fff; font-weight: 600; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.btn-home {
  flex-shrink: 0;
  display: inline-flex; align-items: center; gap: .4rem;
  padding: .42rem .95rem; border-radius: 999px;
  font-size: .82rem; font-weight: 600; letter-spacing: .02em;
  color: #fff; text-decoration: none;
  background: linear-gradient(135deg, var(--accent), #4f46e5);
  box-shadow: 0 0 0 1px rgba(255,255,255,.12) inset, 0 4px 14px -4px var(--glow);
  transition: transform .15s, box-shadow .15s;
}
.btn-home:hover { transform: translateY(-1px); box-shadow: 0 0 0 1px rgba(255,255,255,.2) inset, 0 8px 20px -4px var(--glow); }

/* ---------- page hero (section headers) ---------- */
.page-hero {
  background:
    radial-gradient(60rem 24rem at 85% -40%, rgba(99,102,241,.35), transparent 60%),
    radial-gradient(40rem 18rem at 10% -30%, rgba(34,211,238,.22), transparent 60%),
    linear-gradient(180deg, var(--bg-dark), var(--bg-dark2));
  color: #e2e8f0;
  padding: 3.2rem 1.5rem 3rem;
  text-align: center;
  border-bottom: 1px solid rgba(255,255,255,.06);
}
.page-hero .kicker {
  display: inline-block; font-size: .75rem; font-weight: 700; letter-spacing: .18em;
  text-transform: uppercase; color: var(--accent2); margin-bottom: .8rem;
}
.page-hero h1 {
  margin: 0 auto; max-width: 60rem;
  font-family: "Sora", "Inter", sans-serif;
  font-size: clamp(1.7rem, 3.6vw, 2.7rem); font-weight: 700; line-height: 1.2;
  background: linear-gradient(92deg, #fff 30%, #a5b4fc 75%, #67e8f9);
  -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent;
}
.page-hero p.lede { max-width: 46rem; margin: 1rem auto 0; color: #94a3b8; font-size: 1.02rem; }

/* ---------- main content ---------- */
main.content { max-width: 62rem; margin: 0 auto; padding: 2.2rem 1.5rem 4rem; }
main.content.wide { max-width: 72rem; }

main.content h1, main.content h2, main.content h3, main.content h4 {
  font-family: "Sora", "Inter", sans-serif; line-height: 1.3; color: #0f172a;
  scroll-margin-top: 4.5rem;
}
main.content h1, main.content h2 {
  font-size: 1.45rem; margin: 3rem 0 1rem; padding-top: 2.2rem;
  border-top: 1px solid var(--line);
}
main.content h1 { font-size: 1.6rem; }
main.content h1:first-of-type, main.content h2:first-of-type { border-top: 0; padding-top: 0; margin-top: 1.2rem; }
main.content h1::before, main.content h2::before {
  content: ""; display: block; width: 3.2rem; height: 4px; border-radius: 2px;
  margin-bottom: .8rem;
  background: linear-gradient(90deg, var(--accent), var(--accent2));
}
main.content h3 { font-size: 1.14rem; margin: 2rem 0 .6rem; }
main.content h4 { font-size: 1rem; margin: 1.5rem 0 .5rem; }
main.content a { color: #4f46e5; text-decoration: none; border-bottom: 1px solid #c7d2fe; transition: border-color .15s, color .15s; }
main.content a:hover { color: var(--accent2); border-color: var(--accent2); }
main.content img {
  max-width: 100%; height: auto; border-radius: 10px;
  box-shadow: var(--shadow); margin: .8rem auto; display: block;
  background: #fff; padding: 4px;
}
main.content table {
  border-collapse: collapse; margin: 1.2rem 0; font-size: .92rem; width: 100%;
}
main.content th, main.content td {
  border: 1px solid var(--line); padding: .55rem .75rem; text-align: left; vertical-align: top;
}
main.content th { background: #eef2ff; font-weight: 600; }
main.content tr:nth-child(even) td { background: #f8fafc; }
.table-wrap { overflow-x: auto; }
main.content blockquote {
  margin: 1rem 0; padding: .6rem 1.1rem; border-left: 4px solid var(--accent3);
  background: #f3f0ff; border-radius: 0 10px 10px 0; color: #3730a3;
}
/* Word list paragraphs arrive as blockquotes inside <li>; render them plain */
main.content li blockquote {
  margin: .15rem 0; padding: 0; border-left: none;
  background: transparent; color: inherit; border-radius: 0;
}
main.content li blockquote p { margin: .2rem 0; }
main.content li { margin: .3rem 0; }
main.content hr { border: 0; border-top: 1px solid var(--line); margin: 2.4rem 0; }
main.content code:not(pre code) {
  background: #eef2ff; color: #4338ca; border-radius: 6px;
  padding: .12em .4em; font-size: .86em;
}

/* ---------- code blocks ---------- */
.codeblock {
  position: relative; margin: 1.1rem 0; border-radius: 12px; overflow: hidden;
  background: var(--code-bg);
  box-shadow: 0 1px 0 rgba(255,255,255,.06) inset, var(--shadow);
}
.codeblock .cb-head {
  display: flex; align-items: center; justify-content: space-between;
  padding: .4rem .9rem; font-size: .72rem; letter-spacing: .1em; text-transform: uppercase;
  color: #7c8db5; background: rgba(255,255,255,.04);
  border-bottom: 1px solid rgba(255,255,255,.07);
}
.codeblock pre {
  margin: 0; padding: 1rem 1.1rem; overflow-x: auto;
  font-size: .84rem; line-height: 1.55; color: #dbe4f5;
}
.copy-btn {
  cursor: pointer; border: 1px solid rgba(255,255,255,.15); border-radius: 7px;
  background: rgba(255,255,255,.06); color: #cbd5e1;
  font-size: .7rem; font-weight: 600; letter-spacing: .05em;
  padding: .25rem .7rem; transition: all .15s; font-family: inherit;
}
.copy-btn:hover { background: var(--accent); border-color: var(--accent); color: #fff; }
.copy-btn.done { background: #059669; border-color: #059669; color: #fff; }

/* ---------- notebook outputs ---------- */
.nb-output {
  margin: -.4rem 0 1.2rem; border-left: 3px solid #94a3b8;
  background: #f1f5f9; border-radius: 0 10px 10px 0; overflow: hidden;
}
.nb-output .out-label {
  font-size: .68rem; letter-spacing: .12em; text-transform: uppercase;
  color: #64748b; padding: .35rem .9rem .1rem; font-weight: 700;
}
.nb-output pre {
  margin: 0; padding: .4rem .9rem .8rem; overflow-x: auto;
  font-size: .8rem; line-height: 1.5; color: #334155; white-space: pre-wrap;
}
.nb-output details summary { cursor: pointer; padding: .3rem .9rem; font-size: .78rem; color: #64748b; }

/* ---------- cards / hub grids ---------- */
.card-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(17rem, 1fr)); gap: 1.1rem; margin: 1.6rem 0; }
.card {
  position: relative; display: flex; flex-direction: column; gap: .5rem;
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 1.25rem 1.3rem 1.15rem; text-decoration: none !important; border-bottom: 1px solid var(--line) !important;
  color: var(--ink); box-shadow: var(--shadow);
  transition: transform .18s, box-shadow .18s, border-color .18s;
  overflow: hidden;
}
.card::after {
  content: ""; position: absolute; inset: 0 0 auto 0; height: 3px;
  background: linear-gradient(90deg, var(--accent), var(--accent2));
  opacity: 0; transition: opacity .18s;
}
.card:hover { transform: translateY(-3px); box-shadow: var(--shadow-lift); border-color: #c7d2fe; }
.card:hover::after { opacity: 1; }
.card .card-num {
  font-size: .7rem; font-weight: 700; letter-spacing: .14em; color: var(--accent);
  text-transform: uppercase;
}
.card h3 { margin: 0; font-size: 1.02rem; font-family: "Sora", "Inter", sans-serif; color: #0f172a; }
.card p { margin: 0; font-size: .86rem; color: var(--ink-faint); }
.card .card-meta { margin-top: auto; padding-top: .5rem; font-size: .75rem; color: #94a3b8; }

/* ---------- on-page TOC ---------- */
.page-toc {
  background: #eef2ff66; border: 1px solid #e0e7ff; border-radius: var(--radius);
  padding: 1rem 1.3rem; margin: 1.4rem 0 2rem; font-size: .9rem;
}
.page-toc .toc-title { font-weight: 700; font-size: .78rem; letter-spacing: .14em; text-transform: uppercase; color: var(--accent); margin-bottom: .5rem; }
.page-toc ul { margin: 0; padding-left: 1.2rem; columns: 2; column-gap: 2.5rem; }
.page-toc li { margin: .18rem 0; break-inside: avoid; }
.page-toc a { border-bottom: none !important; }
@media (max-width: 640px) { .page-toc ul { columns: 1; } }

/* ---------- prev / next footer nav ---------- */
.pager {
  display: flex; gap: 1rem; margin: 3rem 0 0; flex-wrap: wrap;
}
.pager a {
  flex: 1 1 16rem; display: block; padding: .9rem 1.2rem;
  border: 1px solid var(--line); border-radius: var(--radius);
  background: var(--card); text-decoration: none !important; border-bottom: 1px solid var(--line) !important;
  box-shadow: var(--shadow); transition: transform .15s, box-shadow .15s;
}
.pager a:hover { transform: translateY(-2px); box-shadow: var(--shadow-lift); }
.pager .dir { font-size: .72rem; letter-spacing: .12em; text-transform: uppercase; color: var(--accent); font-weight: 700; }
.pager .pager-title { color: #0f172a; font-weight: 600; font-size: .95rem; margin-top: .15rem; }
.pager a.next { text-align: right; }

/* ---------- footer ---------- */
.site-footer {
  border-top: 1px solid var(--line); margin-top: 2rem;
  padding: 1.6rem 1.5rem 2.2rem; text-align: center;
  color: #94a3b8; font-size: .82rem; background: #fff;
}
.site-footer a { color: var(--accent); text-decoration: none; }

/* ---------- back-to-top ---------- */
#toTop {
  position: fixed; right: 1.2rem; bottom: 1.2rem; z-index: 800;
  width: 2.6rem; height: 2.6rem; border-radius: 50%;
  border: none; cursor: pointer; opacity: 0; pointer-events: none;
  background: linear-gradient(135deg, var(--accent), #4f46e5); color: #fff;
  font-size: 1.1rem; box-shadow: 0 8px 20px -6px var(--glow);
  transition: opacity .25s, transform .15s;
}
#toTop.show { opacity: 1; pointer-events: auto; }
#toTop:hover { transform: translateY(-2px); }

/* ---------- challenge sections (coding pages) ---------- */
.challenge {
  margin: 2.6rem 0; padding-top: .4rem;
}
.challenge > h2 {
  display: flex; align-items: baseline; gap: .7rem;
}
.badge {
  display: inline-block; font-size: .68rem; font-weight: 700; letter-spacing: .08em;
  padding: .18rem .6rem; border-radius: 999px; text-transform: uppercase;
  background: #eef2ff; color: #4f46e5; border: 1px solid #c7d2fe;
}
.src-note {
  font-size: .78rem; color: #94a3b8; margin: .1rem 0 1rem;
}

/* ---------- misc ---------- */
.anchor { position: relative; top: -4.2rem; display: block; visibility: hidden; }
.note-callout {
  background: #ecfeff; border: 1px solid #a5f3fc; border-left: 4px solid var(--accent2);
  border-radius: 10px; padding: .8rem 1.1rem; margin: 1.2rem 0; font-size: .92rem;
}

/* pygments */
pre { line-height: 125%; }
td.linenos .normal { color: #6e7681; background-color: #0d1117; padding-left: 5px; padding-right: 5px; }
span.linenos { color: #6e7681; background-color: #0d1117; padding-left: 5px; padding-right: 5px; }
td.linenos .special { color: #e6edf3; background-color: #6e7681; padding-left: 5px; padding-right: 5px; }
span.linenos.special { color: #e6edf3; background-color: #6e7681; padding-left: 5px; padding-right: 5px; }
.codeblock pre .hll { background-color: #6e7681 }
.codeblock pre { background: #0d1117; color: #E6EDF3 }
.codeblock pre .c { color: #8B949E; font-style: italic } /* Comment */
.codeblock pre .err { color: #F85149 } /* Error */
.codeblock pre .esc { color: #E6EDF3 } /* Escape */
.codeblock pre .g { color: #E6EDF3 } /* Generic */
.codeblock pre .k { color: #FF7B72 } /* Keyword */
.codeblock pre .l { color: #A5D6FF } /* Literal */
.codeblock pre .n { color: #E6EDF3 } /* Name */
.codeblock pre .o { color: #FF7B72; font-weight: bold } /* Operator */
.codeblock pre .x { color: #E6EDF3 } /* Other */
.codeblock pre .p { color: #E6EDF3 } /* Punctuation */
.codeblock pre .ch { color: #8B949E; font-style: italic } /* Comment.Hashbang */
.codeblock pre .cm { color: #8B949E; font-style: italic } /* Comment.Multiline */
.codeblock pre .cp { color: #8B949E; font-weight: bold; font-style: italic } /* Comment.Preproc */
.codeblock pre .cpf { color: #8B949E; font-style: italic } /* Comment.PreprocFile */
.codeblock pre .c1 { color: #8B949E; font-style: italic } /* Comment.Single */
.codeblock pre .cs { color: #8B949E; font-weight: bold; font-style: italic } /* Comment.Special */
.codeblock pre .gd { color: #FFA198; background-color: #490202 } /* Generic.Deleted */
.codeblock pre .ge { color: #E6EDF3; font-style: italic } /* Generic.Emph */
.codeblock pre .ges { color: #E6EDF3; font-weight: bold; font-style: italic } /* Generic.EmphStrong */
.codeblock pre .gr { color: #FFA198 } /* Generic.Error */
.codeblock pre .gh { color: #79C0FF; font-weight: bold } /* Generic.Heading */
.codeblock pre .gi { color: #56D364; background-color: #0F5323 } /* Generic.Inserted */
.codeblock pre .go { color: #8B949E } /* Generic.Output */
.codeblock pre .gp { color: #8B949E } /* Generic.Prompt */
.codeblock pre .gs { color: #E6EDF3; font-weight: bold } /* Generic.Strong */
.codeblock pre .gu { color: #79C0FF } /* Generic.Subheading */
.codeblock pre .gt { color: #FF7B72 } /* Generic.Traceback */
.codeblock pre .g-Underline { color: #E6EDF3; text-decoration: underline } /* Generic.Underline */
.codeblock pre .kc { color: #79C0FF } /* Keyword.Constant */
.codeblock pre .kd { color: #FF7B72 } /* Keyword.Declaration */
.codeblock pre .kn { color: #FF7B72 } /* Keyword.Namespace */
.codeblock pre .kp { color: #79C0FF } /* Keyword.Pseudo */
.codeblock pre .kr { color: #FF7B72 } /* Keyword.Reserved */
.codeblock pre .kt { color: #FF7B72 } /* Keyword.Type */
.codeblock pre .ld { color: #79C0FF } /* Literal.Date */
.codeblock pre .m { color: #A5D6FF } /* Literal.Number */
.codeblock pre .s { color: #A5D6FF } /* Literal.String */
.codeblock pre .na { color: #E6EDF3 } /* Name.Attribute */
.codeblock pre .nb { color: #E6EDF3 } /* Name.Builtin */
.codeblock pre .nc { color: #F0883E; font-weight: bold } /* Name.Class */
.codeblock pre .no { color: #79C0FF; font-weight: bold } /* Name.Constant */
.codeblock pre .nd { color: #D2A8FF; font-weight: bold } /* Name.Decorator */
.codeblock pre .ni { color: #FFA657 } /* Name.Entity */
.codeblock pre .ne { color: #F0883E; font-weight: bold } /* Name.Exception */
.codeblock pre .nf { color: #D2A8FF; font-weight: bold } /* Name.Function */
.codeblock pre .nl { color: #79C0FF; font-weight: bold } /* Name.Label */
.codeblock pre .nn { color: #FF7B72 } /* Name.Namespace */
.codeblock pre .nx { color: #E6EDF3 } /* Name.Other */
.codeblock pre .py { color: #79C0FF } /* Name.Property */
.codeblock pre .nt { color: #7EE787 } /* Name.Tag */
.codeblock pre .nv { color: #79C0FF } /* Name.Variable */
.codeblock pre .ow { color: #FF7B72; font-weight: bold } /* Operator.Word */
.codeblock pre .pm { color: #E6EDF3 } /* Punctuation.Marker */
.codeblock pre .w { color: #6E7681 } /* Text.Whitespace */
.codeblock pre .mb { color: #A5D6FF } /* Literal.Number.Bin */
.codeblock pre .mf { color: #A5D6FF } /* Literal.Number.Float */
.codeblock pre .mh { color: #A5D6FF } /* Literal.Number.Hex */
.codeblock pre .mi { color: #A5D6FF } /* Literal.Number.Integer */
.codeblock pre .mo { color: #A5D6FF } /* Literal.Number.Oct */
.codeblock pre .sa { color: #79C0FF } /* Literal.String.Affix */
.codeblock pre .sb { color: #A5D6FF } /* Literal.String.Backtick */
.codeblock pre .sc { color: #A5D6FF } /* Literal.String.Char */
.codeblock pre .dl { color: #79C0FF } /* Literal.String.Delimiter */
.codeblock pre .sd { color: #A5D6FF } /* Literal.String.Doc */
.codeblock pre .s2 { color: #A5D6FF } /* Literal.String.Double */
.codeblock pre .se { color: #79C0FF } /* Literal.String.Escape */
.codeblock pre .sh { color: #79C0FF } /* Literal.String.Heredoc */
.codeblock pre .si { color: #A5D6FF } /* Literal.String.Interpol */
.codeblock pre .sx { color: #A5D6FF } /* Literal.String.Other */
.codeblock pre .sr { color: #79C0FF } /* Literal.String.Regex */
.codeblock pre .s1 { color: #A5D6FF } /* Literal.String.Single */
.codeblock pre .ss { color: #A5D6FF } /* Literal.String.Symbol */
.codeblock pre .bp { color: #E6EDF3 } /* Name.Builtin.Pseudo */
.codeblock pre .fm { color: #D2A8FF; font-weight: bold } /* Name.Function.Magic */
.codeblock pre .vc { color: #79C0FF } /* Name.Variable.Class */
.codeblock pre .vg { color: #79C0FF } /* Name.Variable.Global */
.codeblock pre .vi { color: #79C0FF } /* Name.Variable.Instance */
.codeblock pre .vm { color: #79C0FF } /* Name.Variable.Magic */
.codeblock pre .il { color: #A5D6FF } /* Literal.Number.Integer.Long */