/* =========================================================
   Fullstack Notes — shared design system
   Works with Bootstrap 5.3 (light + dark via data-bs-theme)
   ========================================================= */

:root {
  --accent: #6366f1;
  --accent-2: #8b5cf6;
  --font-sans: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Consolas, monospace;
  --nav-h: 60px;
  --radius: 14px;
  --lvl-basic: #16a34a;
  --lvl-inter: #d97706;
  --lvl-adv: #dc2626;
  --code-bg: #0d1117;
  --soft: color-mix(in srgb, var(--accent) 10%, transparent);
  --soft-2: color-mix(in srgb, var(--accent) 18%, transparent);
}

/* Per-page accent colors */
body.page-home       { --accent: #6366f1; --accent-2: #ec4899; }
body.page-frontend   { --accent: #6366f1; --accent-2: #06b6d4; }
body.page-backend    { --accent: #059669; --accent-2: #0ea5e9; }
body.page-postgres   { --accent: #3b74b8; --accent-2: #22d3ee; }
body.page-typescript { --accent: #3178c6; --accent-2: #60a5fa; }
body.page-react      { --accent: #7c3aed; --accent-2: #0ea5e9; }

[data-bs-theme="dark"] body.page-postgres   { --accent: #6aa2e6; }
[data-bs-theme="dark"] body.page-typescript { --accent: #5b9be0; }
[data-bs-theme="dark"] body.page-frontend,
[data-bs-theme="dark"] body.page-home       { --accent: #818cf8; }
[data-bs-theme="dark"] body.page-backend    { --accent: #34d399; }
[data-bs-theme="dark"] body.page-react      { --accent: #a78bfa; }

html { scroll-behavior: smooth; scroll-padding-top: calc(var(--nav-h) + 16px); }

body {
  font-family: var(--font-sans);
  background: var(--bs-body-bg);
  color: var(--bs-body-color);
  line-height: 1.75;
  font-size: 1.02rem;
  padding-top: var(--nav-h);
}

code, pre, kbd { font-family: var(--font-mono); }
:not(pre) > code {
  color: var(--accent);
  background: var(--soft);
  padding: .1em .4em;
  border-radius: 6px;
  font-size: .86em;
}

a { color: var(--accent); }
::selection { background: var(--soft-2); }

/* ---------------- Navbar ---------------- */
.site-nav {
  height: var(--nav-h);
  background: color-mix(in srgb, var(--bs-body-bg) 82%, transparent);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--bs-border-color);
}
.site-nav .navbar-brand { font-weight: 800; letter-spacing: -.02em; }
.site-nav .brand-logo {
  width: 32px; height: 32px; border-radius: 9px;
  display: inline-grid; place-items: center; color: #fff;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  margin-right: .5rem;
}
.site-nav .nav-link { font-weight: 500; font-size: .93rem; border-radius: 8px; padding: .4rem .7rem !important; }
.site-nav .nav-link.active { color: var(--accent) !important; background: var(--soft); }
.site-nav .navbar-collapse { background: var(--bs-body-bg); }
@media (min-width: 992px) { .site-nav .navbar-collapse { background: transparent; } }
@media (max-width: 991.98px) {
  .site-nav .navbar-collapse { margin: 0 -12px; padding: .5rem 12px 1rem; border-bottom: 1px solid var(--bs-border-color); }
}
.theme-btn { border: 1px solid var(--bs-border-color); border-radius: 10px; width: 38px; height: 38px; display: grid; place-items: center; background: transparent; color: var(--bs-body-color); }
.theme-btn:hover { background: var(--soft); }

/* ---------------- Hero ---------------- */
.hero {
  position: relative; overflow: hidden;
  background:
    radial-gradient(1200px 400px at 10% -10%, color-mix(in srgb, var(--accent) 35%, transparent), transparent 60%),
    radial-gradient(800px 400px at 100% 0%, color-mix(in srgb, var(--accent-2) 28%, transparent), transparent 60%),
    var(--bs-tertiary-bg);
  border-bottom: 1px solid var(--bs-border-color);
  padding: 3.5rem 0 3rem;
}
.hero h1 { font-weight: 800; letter-spacing: -.03em; font-size: clamp(2rem, 4.5vw, 3.2rem); line-height: 1.15; }
.hero .lead { color: var(--bs-secondary-color); max-width: 720px; }
.hero-icon {
  width: 72px; height: 72px; border-radius: 20px; display: grid; place-items: center;
  font-size: 2.2rem; color: #fff;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  box-shadow: 0 10px 30px color-mix(in srgb, var(--accent) 40%, transparent);
}
.chip {
  display: inline-flex; align-items: center; gap: .35rem;
  padding: .3rem .75rem; border-radius: 999px; font-size: .82rem; font-weight: 500;
  background: var(--bs-body-bg); border: 1px solid var(--bs-border-color);
}
.chip i { color: var(--accent); }

/* ---------------- Layout: TOC ---------------- */
.toc {
  position: sticky; top: calc(var(--nav-h) + 20px);
  max-height: calc(100vh - var(--nav-h) - 40px); overflow-y: auto;
  padding-right: .5rem; font-size: .9rem;
}
.toc::-webkit-scrollbar { width: 6px; }
.toc::-webkit-scrollbar-thumb { background: var(--bs-border-color); border-radius: 6px; }
.toc-title { font-size: .75rem; text-transform: uppercase; letter-spacing: .08em; font-weight: 700; color: var(--bs-secondary-color); }
.toc-group { font-size: .7rem; text-transform: uppercase; letter-spacing: .08em; font-weight: 700; margin: 1rem 0 .3rem; display: flex; align-items: center; gap: .4rem; }
.toc-group.basic { color: var(--lvl-basic); }
.toc-group.inter { color: var(--lvl-inter); }
.toc-group.adv { color: var(--lvl-adv); }
.toc a {
  display: flex; align-items: center; gap: .5rem;
  padding: .32rem .6rem; border-radius: 8px; text-decoration: none;
  color: var(--bs-secondary-color); border-left: 2px solid transparent; line-height: 1.35;
}
.toc a:hover { color: var(--bs-body-color); background: var(--bs-tertiary-bg); }
.toc a.active { color: var(--accent); background: var(--soft); border-left-color: var(--accent); font-weight: 600; }
.toc a .done-mark { margin-left: auto; color: var(--lvl-basic); font-size: .85rem; visibility: hidden; }
.toc a.is-done .done-mark { visibility: visible; }
.progress-wrap { background: var(--bs-tertiary-bg); border: 1px solid var(--bs-border-color); border-radius: 12px; padding: .75rem; }
.progress { height: 8px; background: var(--bs-secondary-bg); }
.progress-bar { background: linear-gradient(90deg, var(--accent), var(--accent-2)); }

.toc-fab {
  position: fixed; right: 16px; bottom: 16px; z-index: 1030;
  border-radius: 999px; box-shadow: 0 8px 24px rgba(0,0,0,.25);
  background: var(--accent); border: none; color: #fff; padding: .6rem 1rem; font-weight: 600;
}
.to-top {
  position: fixed; right: 16px; bottom: 72px; z-index: 1030; width: 42px; height: 42px;
  border-radius: 50%; border: 1px solid var(--bs-border-color); background: var(--bs-body-bg);
  color: var(--bs-body-color); display: grid; place-items: center; opacity: 0; pointer-events: none; transition: .2s;
}
.to-top.show { opacity: 1; pointer-events: auto; }
@media (min-width: 992px) { .to-top { bottom: 20px; } }

/* ---------------- Sections ---------------- */
main.notes { min-width: 0; }
.note-section {
  padding: 2.5rem 0 1.5rem;
  border-bottom: 1px dashed var(--bs-border-color);
}
.note-section:last-of-type { border-bottom: none; }
.note-section > h2 {
  font-weight: 800; letter-spacing: -.02em; font-size: clamp(1.45rem, 2.6vw, 1.85rem);
  display: flex; align-items: center; flex-wrap: wrap; gap: .6rem; margin-bottom: 1rem;
}
.note-section > h2 .sec-icon {
  width: 42px; height: 42px; border-radius: 12px; display: inline-grid; place-items: center;
  background: var(--soft); color: var(--accent); font-size: 1.3rem; flex-shrink: 0;
}
.note-section h3 { font-weight: 700; font-size: 1.2rem; margin-top: 1.75rem; display: flex; align-items: center; gap: .5rem; }
.note-section h3 i { color: var(--accent); }
.note-section h4 { font-weight: 700; font-size: 1.02rem; margin-top: 1.25rem; }
.sec-num { color: var(--bs-secondary-color); font-weight: 600; font-size: .95rem; }

.lvl {
  font-size: .68rem; font-weight: 700; text-transform: uppercase; letter-spacing: .06em;
  padding: .25rem .6rem; border-radius: 999px; border: 1px solid currentColor; line-height: 1.2;
}
.lvl.basic { color: var(--lvl-basic); background: color-mix(in srgb, var(--lvl-basic) 10%, transparent); }
.lvl.inter { color: var(--lvl-inter); background: color-mix(in srgb, var(--lvl-inter) 10%, transparent); }
.lvl.adv   { color: var(--lvl-adv);   background: color-mix(in srgb, var(--lvl-adv) 10%, transparent); }

.done-btn {
  margin-left: auto; font-size: .8rem; font-weight: 600; border-radius: 999px;
  border: 1px solid var(--bs-border-color); background: transparent; color: var(--bs-secondary-color);
  padding: .3rem .8rem; display: inline-flex; align-items: center; gap: .35rem;
}
.done-btn:hover { border-color: var(--lvl-basic); color: var(--lvl-basic); }
.done-btn.done { background: var(--lvl-basic); border-color: var(--lvl-basic); color: #fff; }

/* Level divider banners */
.level-banner {
  margin-top: 2.5rem; padding: 1rem 1.25rem; border-radius: var(--radius);
  display: flex; align-items: center; gap: 1rem; font-weight: 700;
  border: 1px solid var(--bs-border-color);
}
.level-banner i { font-size: 1.6rem; }
.level-banner small { display: block; font-weight: 400; color: var(--bs-secondary-color); }
.level-banner.basic { background: color-mix(in srgb, var(--lvl-basic) 9%, transparent); }
.level-banner.basic i { color: var(--lvl-basic); }
.level-banner.inter { background: color-mix(in srgb, var(--lvl-inter) 9%, transparent); }
.level-banner.inter i { color: var(--lvl-inter); }
.level-banner.adv { background: color-mix(in srgb, var(--lvl-adv) 9%, transparent); }
.level-banner.adv i { color: var(--lvl-adv); }

/* ---------------- Callouts ---------------- */
.callout {
  display: flex; gap: .85rem; padding: 1rem 1.15rem; border-radius: 12px; margin: 1.25rem 0;
  border: 1px solid var(--bs-border-color); border-left: 4px solid var(--c);
  background: color-mix(in srgb, var(--c) 7%, var(--bs-body-bg));
  --c: var(--accent);
}
.callout > i { font-size: 1.3rem; color: var(--c); line-height: 1.4; flex-shrink: 0; }
.callout > div > :last-child { margin-bottom: 0; }
.callout strong.t { display: block; color: var(--c); margin-bottom: .15rem; }
.callout.tip    { --c: #16a34a; }
.callout.info   { --c: #0284c7; }
.callout.warn   { --c: #d97706; }
.callout.danger { --c: #dc2626; }
.callout.analogy{ --c: #a855f7; }

/* ---------------- Cards ---------------- */
.n-card {
  height: 100%; border: 1px solid var(--bs-border-color); border-radius: var(--radius);
  padding: 1.15rem; background: var(--bs-body-bg); transition: transform .15s, box-shadow .15s, border-color .15s;
}
.n-card:hover { transform: translateY(-2px); border-color: color-mix(in srgb, var(--accent) 45%, var(--bs-border-color)); box-shadow: 0 10px 28px rgba(0,0,0,.07); }
.n-card .ic {
  width: 44px; height: 44px; border-radius: 12px; display: grid; place-items: center;
  font-size: 1.35rem; background: var(--soft); color: var(--accent); margin-bottom: .7rem;
}
.n-card h5 { font-weight: 700; font-size: 1.02rem; margin-bottom: .35rem; }
.n-card p { color: var(--bs-secondary-color); font-size: .92rem; margin-bottom: 0; }

/* ---------------- Diagrams ---------------- */
.diagram {
  border: 1px solid var(--bs-border-color); border-radius: var(--radius);
  padding: 1.25rem; margin: 1.5rem 0;
  background:
    radial-gradient(circle, color-mix(in srgb, var(--bs-body-color) 9%, transparent) 1px, transparent 1px) 0 0 / 18px 18px,
    var(--bs-tertiary-bg);
}
.diagram-title {
  font-size: .75rem; font-weight: 700; text-transform: uppercase; letter-spacing: .08em;
  color: var(--bs-secondary-color); margin-bottom: 1rem; display: flex; align-items: center; gap: .4rem;
}
.diagram-title i { color: var(--accent); }
.diagram-caption { font-size: .85rem; color: var(--bs-secondary-color); text-align: center; margin-top: .85rem; margin-bottom: 0; }

.flow { display: flex; align-items: center; justify-content: center; flex-wrap: wrap; gap: .35rem; }
.flow .node {
  min-width: 112px; max-width: 220px; padding: .75rem .9rem; border-radius: 12px; text-align: center;
  border: 1.5px solid var(--bs-border-color); background: var(--bs-body-bg); font-weight: 600; font-size: .9rem; line-height: 1.3;
  box-shadow: 0 2px 6px rgba(0,0,0,.04);
}
.flow .node > i { display: block; font-size: 1.55rem; color: var(--accent); margin-bottom: .25rem; }
.flow .node small { display: block; font-weight: 400; color: var(--bs-secondary-color); font-size: .74rem; margin-top: .2rem; }
.flow .node.hl { border-color: var(--accent); background: var(--soft); }
.flow .node.alt > i { color: var(--accent-2); }
.flow .node.ok { border-color: var(--lvl-basic); }
.flow .node.ok > i { color: var(--lvl-basic); }
.flow .node.bad { border-color: var(--lvl-adv); }
.flow .node.bad > i { color: var(--lvl-adv); }

.flow .arrow {
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  font-size: .7rem; color: var(--bs-secondary-color); min-width: 64px; text-align: center; line-height: 1.2; font-weight: 500;
}
.flow .arrow::after {
  content: ""; display: block; width: 64px; height: 12px; margin-top: 3px; background: var(--accent);
  -webkit-mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 64 12'%3E%3Cpath d='M0 5h55v2H0z'/%3E%3Cpath d='M54 0l10 6-10 6z'/%3E%3C/svg%3E") center / 100% 100% no-repeat;
          mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 64 12'%3E%3Cpath d='M0 5h55v2H0z'/%3E%3Cpath d='M54 0l10 6-10 6z'/%3E%3C/svg%3E") center / 100% 100% no-repeat;
}
.flow .arrow.both::after {
  -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 64 12'%3E%3Cpath d='M9 5h46v2H9z'/%3E%3Cpath d='M54 0l10 6-10 6zM10 0L0 6l10 6z'/%3E%3C/svg%3E");
          mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 64 12'%3E%3Cpath d='M9 5h46v2H9z'/%3E%3Cpath d='M54 0l10 6-10 6zM10 0L0 6l10 6z'/%3E%3C/svg%3E");
}
.flow.vertical, .flow.vertical .arrow { flex-direction: column; }
.flow.vertical .arrow::after,
.flow .arrow.down::after { width: 12px; height: 34px; -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 12 34'%3E%3Cpath d='M5 0h2v25H5z'/%3E%3Cpath d='M0 24l6 10 6-10z'/%3E%3C/svg%3E"); mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 12 34'%3E%3Cpath d='M5 0h2v25H5z'/%3E%3Cpath d='M0 24l6 10 6-10z'/%3E%3C/svg%3E"); }
@media (max-width: 767.98px) {
  .flow:not(.keep-row) { flex-direction: column; }
  .flow:not(.keep-row) .arrow::after { width: 12px; height: 30px; -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 12 34'%3E%3Cpath d='M5 0h2v25H5z'/%3E%3Cpath d='M0 24l6 10 6-10z'/%3E%3C/svg%3E"); mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 12 34'%3E%3Cpath d='M5 0h2v25H5z'/%3E%3Cpath d='M0 24l6 10 6-10z'/%3E%3C/svg%3E"); }
  .flow:not(.keep-row) .node { width: 100%; max-width: 320px; }
}

/* Layer stack */
.stack { display: flex; flex-direction: column; gap: .5rem; max-width: 640px; margin: 0 auto; }
.stack .layer {
  display: flex; align-items: center; gap: .85rem; padding: .75rem 1rem; border-radius: 12px;
  background: var(--bs-body-bg); border: 1px solid var(--bs-border-color); border-left: 5px solid var(--lc, var(--accent));
}
.stack .layer > i { font-size: 1.4rem; color: var(--lc, var(--accent)); }
.stack .layer b { display: block; line-height: 1.25; }
.stack .layer small { color: var(--bs-secondary-color); }

/* Two-column compare */
.vs { display: grid; grid-template-columns: 1fr auto 1fr; gap: 1rem; align-items: stretch; }
.vs .side { border: 1.5px solid var(--bs-border-color); border-radius: var(--radius); padding: 1rem 1.15rem; background: var(--bs-body-bg); }
.vs .side h5 { font-weight: 700; font-size: 1rem; display: flex; align-items: center; gap: .45rem; }
.vs .side ul { padding-left: 1.1rem; margin-bottom: 0; font-size: .92rem; }
.vs .mid { display: grid; place-items: center; font-weight: 800; color: var(--bs-secondary-color); }
@media (max-width: 767.98px) { .vs { grid-template-columns: 1fr; } .vs .mid { padding: .25rem 0; } }

/* Folder tree */
.tree, .tree ul { list-style: none; margin: 0; padding-left: 1.2rem; }
.tree { padding-left: 0; font-family: var(--font-mono); font-size: .85rem; line-height: 1.9; }
.tree ul { border-left: 1px dashed var(--bs-border-color); margin-left: .45rem; }
.tree li { white-space: nowrap; }
.tree i.bi-folder2-open, .tree i.bi-folder2 { color: #eab308; }
.tree i.bi-filetype-tsx, .tree i.bi-filetype-ts, .tree i.bi-file-earmark-code { color: #3b82f6; }
.tree i.bi-filetype-css { color: #ec4899; }
.tree i.bi-filetype-json, .tree i.bi-gear { color: #f97316; }
.tree .cm { color: var(--bs-secondary-color); font-family: var(--font-sans); font-size: .78rem; margin-left: .5rem; }
.tree-wrap { overflow-x: auto; }

/* Steps / timeline */
.steps { counter-reset: step; list-style: none; padding-left: 0; }
.steps > li { position: relative; padding: 0 0 1.1rem 3rem; }
.steps > li::before {
  counter-increment: step; content: counter(step);
  position: absolute; left: 0; top: 0; width: 2rem; height: 2rem; border-radius: 50%;
  display: grid; place-items: center; font-weight: 700; font-size: .85rem; color: #fff;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
}
.steps > li::after { content: ""; position: absolute; left: calc(1rem - 1px); top: 2.1rem; bottom: .2rem; width: 2px; background: var(--bs-border-color); }
.steps > li:last-child::after { display: none; }
.steps > li > b { display: block; }

/* ---------------- Code blocks ---------------- */
.code-block { margin: 1.1rem 0 1.4rem; border-radius: 12px; overflow: hidden; border: 1px solid #30363d; background: var(--code-bg); }
.code-head {
  display: flex; align-items: center; gap: .6rem; padding: .45rem .75rem;
  background: #161b22; border-bottom: 1px solid #30363d; color: #8b949e; font-size: .78rem; font-family: var(--font-mono);
}
.code-head .dots { display: inline-flex; gap: 5px; }
.code-head .dots span { width: 10px; height: 10px; border-radius: 50%; background: #ff5f56; }
.code-head .dots span:nth-child(2) { background: #ffbd2e; }
.code-head .dots span:nth-child(3) { background: #27c93f; }
.code-head .file { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.code-head .lang { margin-left: auto; text-transform: uppercase; font-size: .68rem; letter-spacing: .06em; opacity: .7; }
.code-head .copy-btn {
  border: 1px solid #30363d; background: transparent; color: #c9d1d9; border-radius: 6px;
  font-size: .72rem; padding: .15rem .55rem; font-family: var(--font-sans);
}
.code-head .copy-btn:hover { background: #21262d; }
.code-block pre { margin: 0; padding: 1rem 1.1rem; overflow-x: auto; font-size: .84rem; line-height: 1.65; }
.code-block pre code.hljs { background: transparent; padding: 0; }
.code-block pre code { color: #e6edf3; }

/* Bad / Good pairs */
.code-pair { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
.code-pair .lbl { font-size: .8rem; font-weight: 700; display: flex; align-items: center; gap: .35rem; margin-bottom: -.6rem; }
.code-pair .lbl.bad { color: var(--lvl-adv); }
.code-pair .lbl.good { color: var(--lvl-basic); }
@media (max-width: 991.98px) { .code-pair { grid-template-columns: 1fr; } }
.code-pair > div { min-width: 0; }

/* ---------------- Tables ---------------- */
.table-notes { font-size: .92rem; border-radius: 12px; overflow: hidden; border: 1px solid var(--bs-border-color); }
.table-notes thead th { background: var(--soft); color: var(--bs-body-color); font-weight: 700; border-bottom-color: var(--bs-border-color); white-space: nowrap; }
.table-notes td, .table-notes th { padding: .65rem .85rem; vertical-align: top; }
.table-notes td code { white-space: nowrap; }
.table-responsive { margin: 1rem 0 1.5rem; }

/* Key terms + misc */
.kw { font-weight: 700; color: var(--accent); }
.yes { color: var(--lvl-basic); }
.no { color: var(--lvl-adv); }
kbd { background: var(--bs-secondary-bg); color: var(--bs-body-color); border: 1px solid var(--bs-border-color); border-bottom-width: 2px; font-size: .8em; }

.accordion-notes .accordion-button { font-weight: 600; }
.accordion-notes .accordion-button:not(.collapsed) { color: var(--accent); background: var(--soft); box-shadow: none; }
.accordion-notes .accordion-button:focus { box-shadow: 0 0 0 .2rem var(--soft-2); }

.cheat { border: 1px solid var(--bs-border-color); border-radius: 12px; padding: 1rem; height: 100%; background: var(--bs-body-bg); }
.cheat h6 { font-weight: 700; display: flex; align-items: center; gap: .4rem; color: var(--accent); }
.cheat ul { list-style: none; padding: 0; margin: 0; font-size: .86rem; }
.cheat li { padding: .25rem 0; border-bottom: 1px dashed var(--bs-border-color); display: flex; justify-content: space-between; gap: .75rem; }
.cheat li:last-child { border-bottom: none; }
.cheat li code { white-space: nowrap; }
.cheat li span { color: var(--bs-secondary-color); text-align: right; }

/* SVG diagram helpers (theme aware) */
svg.dg { width: 100%; height: auto; display: block; margin: 0 auto; font-family: var(--font-sans); }
svg.dg .box { fill: var(--bs-body-bg); stroke: var(--bs-border-color); stroke-width: 1.5; }
svg.dg .box-hl { fill: color-mix(in srgb, var(--accent) 14%, var(--bs-body-bg)); stroke: var(--accent); stroke-width: 1.8; }
svg.dg .line { stroke: var(--accent); stroke-width: 2; fill: none; }
svg.dg .line-muted { stroke: var(--bs-secondary-color); stroke-width: 1.5; fill: none; stroke-dasharray: 5 4; }
svg.dg .txt { fill: var(--bs-body-color); font-size: 14px; font-weight: 600; }
svg.dg .txt-sm { fill: var(--bs-secondary-color); font-size: 12px; }
svg.dg .txt-acc { fill: var(--accent); font-size: 13px; font-weight: 700; }
svg.dg .arrowhead { fill: var(--accent); }
svg.dg .venn-a { fill: color-mix(in srgb, var(--accent) 55%, transparent); stroke: var(--accent); stroke-width: 2; }
svg.dg .venn-off { fill: transparent; stroke: var(--bs-secondary-color); stroke-width: 2; }

/* ---------------- Home page ---------------- */
.topic-card {
  display: block; text-decoration: none; color: inherit; height: 100%;
  border: 1px solid var(--bs-border-color); border-radius: 18px; padding: 1.5rem; background: var(--bs-body-bg);
  position: relative; overflow: hidden; transition: transform .2s, box-shadow .2s, border-color .2s;
}
.topic-card::before {
  content: ""; position: absolute; inset: 0 0 auto 0; height: 4px; background: linear-gradient(90deg, var(--tc), var(--tc2));
}
.topic-card:hover { transform: translateY(-4px); box-shadow: 0 18px 40px rgba(0,0,0,.1); border-color: var(--tc); color: inherit; }
.topic-card .t-icon {
  width: 56px; height: 56px; border-radius: 16px; display: grid; place-items: center; font-size: 1.6rem; color: #fff;
  background: linear-gradient(135deg, var(--tc), var(--tc2)); margin-bottom: 1rem;
}
.topic-card h3 { font-weight: 800; font-size: 1.25rem; letter-spacing: -.01em; }
.topic-card p { color: var(--bs-secondary-color); font-size: .93rem; }
.topic-card .tags span { font-size: .72rem; padding: .2rem .55rem; border-radius: 999px; background: var(--bs-tertiary-bg); border: 1px solid var(--bs-border-color); margin: 0 .25rem .3rem 0; display: inline-block; }
.topic-card .go { font-weight: 600; color: var(--tc); }
.topic-card .progress { height: 6px; }
.topic-card .progress-bar { background: linear-gradient(90deg, var(--tc), var(--tc2)); }

.roadmap { position: relative; }
.roadmap .rm-step { display: flex; gap: 1rem; position: relative; padding-bottom: 1.5rem; }
.roadmap .rm-step::before { content: ""; position: absolute; left: 23px; top: 50px; bottom: 0; width: 2px; background: var(--bs-border-color); }
.roadmap .rm-step:last-child::before { display: none; }
.roadmap .rm-dot { width: 48px; height: 48px; border-radius: 14px; flex-shrink: 0; display: grid; place-items: center; color: #fff; font-size: 1.3rem; background: linear-gradient(135deg, var(--tc), var(--tc2)); }
.roadmap .rm-body { border: 1px solid var(--bs-border-color); border-radius: 14px; padding: .85rem 1rem; background: var(--bs-body-bg); flex: 1; }
.roadmap .rm-body b { display: block; }
.roadmap .rm-body small { color: var(--bs-secondary-color); }

footer.site-footer { border-top: 1px solid var(--bs-border-color); background: var(--bs-tertiary-bg); color: var(--bs-secondary-color); font-size: .9rem; }

/* Pager */
.pager a { display: block; border: 1px solid var(--bs-border-color); border-radius: 14px; padding: 1rem 1.2rem; text-decoration: none; color: var(--bs-body-color); height: 100%; }
.pager a:hover { border-color: var(--accent); background: var(--soft); }
.pager small { color: var(--bs-secondary-color); display: block; }
.pager b { color: var(--accent); }

@media print {
  .site-nav, .toc-col, .toc-fab, .to-top, .done-btn, .copy-btn { display: none !important; }
  body { padding-top: 0; }
}

/* ---------------- Quiz ---------------- */
.quiz { border: 1px solid var(--bs-border-color); border-radius: var(--radius); padding: 1.1rem 1.2rem; margin: 1.5rem 0; background: var(--bs-tertiary-bg); }
.quiz .q { font-weight: 700; margin-bottom: .75rem; display: flex; gap: .5rem; }
.quiz button[data-opt] {
  display: block; width: 100%; text-align: left; margin-bottom: .45rem; padding: .55rem .85rem; border-radius: 10px;
  border: 1.5px solid var(--bs-border-color); background: var(--bs-body-bg); color: var(--bs-body-color); font-size: .93rem;
}
.quiz button[data-opt]:hover { border-color: var(--accent); }
.quiz button.right { border-color: var(--lvl-basic); background: color-mix(in srgb, var(--lvl-basic) 12%, var(--bs-body-bg)); }
.quiz button.wrong { border-color: var(--lvl-adv); background: color-mix(in srgb, var(--lvl-adv) 10%, var(--bs-body-bg)); }
.quiz-feedback { display: none; font-size: .9rem; margin-top: .5rem; font-weight: 500; }
.quiz-feedback.show { display: block; }
.quiz-feedback.ok { color: var(--lvl-basic); }
.quiz-feedback.bad { color: var(--lvl-adv); }