/* =========================================================
   BJC Theme: Learn Chess pages
   Loaded only on the landing page and the eight lessons.
   Uses the theme tokens from style.css, so light/dark and the
   S/M/L text size work automatically. Text sizes are in em so
   they follow --f-base (the text-size buttons).
   ========================================================= */

.learn-page { --lesson-col: 760px; --track-basics: #2F7D5B; --track-improve: #B45309; --track-practice: #1E3A5F; }
html[data-theme="dark"] .learn-page { --track-basics: #6FAE8B; --track-improve: #E79447; --track-practice: #9FB7D9; }

/* ---------- Lesson hero ---------- */
.lesson-hero {
  position: relative;
  padding: clamp(36px, 6vw, 72px) 0 clamp(32px, 5vw, 56px);
  background:
    radial-gradient(circle at 85% 20%, color-mix(in oklab, var(--accent) 10%, transparent), transparent 55%),
    var(--paper-2);
  border-bottom: 1px solid var(--rule);
  overflow: hidden;
}
.lesson-hero__grid {
  display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 40px; align-items: center;
}
.lesson-crumbs {
  font-family: "JetBrains Mono", monospace; font-size: .78em; letter-spacing: .12em; text-transform: uppercase;
  display: flex; gap: 10px; flex-wrap: wrap; color: var(--muted); margin-bottom: 18px;
}
.lesson-crumbs a { color: var(--accent-ink); }
.lesson-hero h1 { font-size: clamp(2.4rem, 5.4vw, 4.2rem); margin: 0 0 16px; max-width: 14em; }
.lesson-hero h1 em { font-style: italic; color: var(--accent); }
.lesson-hero__lede {
  font-family: "Fraunces", serif; font-size: 1.24em; line-height: 1.5; color: var(--ink-2);
  max-width: 34em; margin: 0 0 22px;
}
.lesson-chips { list-style: none; margin: 0; padding: 0; display: flex; flex-wrap: wrap; gap: 8px; }
.lesson-chip {
  font-family: "JetBrains Mono", monospace; font-size: .76em; letter-spacing: .06em;
  padding: 6px 12px; border-radius: 999px; border: 1px solid var(--rule); background: var(--paper); color: var(--ink-2);
}
.lesson-chip--level { color: #fff; border-color: transparent; font-weight: 600; text-transform: uppercase; letter-spacing: .12em; }
.lesson-chip--basics { background: var(--track-basics); }
.lesson-chip--improve { background: var(--track-improve); }
.lesson-chip--practice { background: var(--track-practice); }
html[data-theme="dark"] .lesson-chip--level { color: #141414; }

.lesson-hero__art { position: relative; width: clamp(150px, 20vw, 230px); }
.lesson-hero__tile {
  aspect-ratio: 1; border-radius: 28px; display: grid; place-items: center;
  background:
    conic-gradient(var(--board-dark, #b58863) 25%, var(--board-light, #f0d9b5) 0 50%, var(--board-dark, #b58863) 0 75%, var(--board-light, #f0d9b5) 0)
    0 0 / 50% 50%;
  border: 8px solid #5a3a1f; box-shadow: var(--shadow-md);
  transform: rotate(-4deg);
}
html[data-theme="dark"] .lesson-hero__tile {
  background:
    conic-gradient(#6f4a2c 25%, #d9b88f 0 50%, #6f4a2c 0 75%, #d9b88f 0) 0 0 / 50% 50%;
  border-color: #2a1a0a;
}
.lesson-hero__piece { width: 74%; height: 74%; filter: drop-shadow(0 6px 10px rgba(0,0,0,.35)); transform: rotate(4deg); }
.lesson-hero__num {
  position: absolute; right: -10px; bottom: -14px;
  font-family: "Fraunces", serif; font-size: 3.4rem; font-weight: 600; line-height: 1;
  color: var(--accent); text-shadow: 0 2px 0 var(--paper-2);
}
@media (max-width: 720px) {
  .lesson-hero__grid { grid-template-columns: 1fr; }
  .lesson-hero__art { display: none; }
}

/* ---------- Layout: TOC + body ---------- */
.lesson-layout {
  display: grid; grid-template-columns: 220px minmax(0, 1fr); gap: clamp(28px, 4vw, 56px);
  padding: clamp(36px, 5vw, 64px) 0;
}
.lesson-layout > * { min-width: 0; }
.lesson-toc nav { position: sticky; top: 96px; }
.lesson-toc__title {
  display: block; margin-bottom: 12px;
  font-family: "JetBrains Mono", monospace; font-size: .72em; letter-spacing: .16em; text-transform: uppercase; color: var(--muted);
}
.lesson-toc ol { list-style: none; margin: 0; padding: 0; counter-reset: toc; border-left: 2px solid var(--rule); }
.lesson-toc li { counter-increment: toc; }
.lesson-toc a {
  display: flex; gap: 10px; padding: 7px 0 7px 14px; margin-left: -2px;
  border-left: 2px solid transparent; border-bottom: 0;
  color: var(--ink-2); font-size: .92em; line-height: 1.35;
}
.lesson-toc a::before { content: counter(toc, decimal-leading-zero); font-family: "JetBrains Mono", monospace; font-size: .85em; color: var(--muted); padding-top: 1px; }
.lesson-toc a:hover { color: var(--ink); border-left-color: var(--rule); }
.lesson-toc a.is-active { color: var(--ink); font-weight: 600; border-left-color: var(--accent); }
.lesson-toc a.is-active::before { color: var(--accent); }

@media (max-width: 1000px) {
  .lesson-layout { grid-template-columns: minmax(0, 1fr); padding-top: 24px; }
  .lesson-toc nav { position: static; }
  .lesson-toc ol { display: flex; gap: 8px; overflow-x: auto; border: 0; padding-bottom: 6px; scrollbar-width: thin; }
  .lesson-toc a { white-space: nowrap; border: 1px solid var(--rule); border-radius: 999px; padding: 6px 14px; margin: 0; background: var(--paper-2); }
  .lesson-toc a.is-active { border-color: var(--accent); }
}

/* ---------- Sections ---------- */
.lesson-body { min-width: 0; }
.lesson-section { scroll-margin-top: 96px; padding-bottom: clamp(36px, 5vw, 64px); margin-bottom: clamp(36px, 5vw, 64px); border-bottom: 1px solid var(--rule); }
.lesson-section:last-child { border-bottom: 0; margin-bottom: 0; }
.lesson-section__head { max-width: var(--lesson-col); margin-bottom: 24px; }
.lesson-section__head h2 { font-size: clamp(1.8rem, 3.2vw, 2.4rem); margin: 4px 0 10px; }
.lesson-section__intro { font-size: 1.08em; color: var(--ink-2); margin: 0; }
.lesson-prose { max-width: var(--lesson-col); }
.lesson-prose p, .lesson-prose li { font-size: 1.02em; color: var(--ink-2); }
.lesson-prose h3 { font-size: 1.35em; margin: 1.6em 0 .5em; }
.lesson-prose strong { color: var(--ink); }
.lesson-prose ul, .lesson-prose ol { padding-left: 1.3em; }
.lesson-prose li { margin: .35em 0; }

.lesson-sub { font-size: 1.35em; margin: 40px 0 10px; }
.lesson-sub:first-child { margin-top: 0; }

/* Rules list: numbered cards */
.rules { list-style: none; margin: 18px 0 0; padding: 0; display: grid; gap: 10px; counter-reset: rule; max-width: var(--lesson-col); }
.rules > li {
  counter-increment: rule; position: relative;
  padding: 14px 16px 14px 58px; border: 1px solid var(--rule); border-radius: var(--radius); background: var(--paper);
  color: var(--ink-2); line-height: 1.5;
}
.rules > li::before {
  content: counter(rule); position: absolute; left: 14px; top: 12px;
  width: 30px; height: 30px; border-radius: 9px; display: grid; place-items: center;
  font-family: "JetBrains Mono", monospace; font-size: .85em; font-weight: 600;
  background: var(--highlight); color: var(--accent-ink);
}
.rules > li strong { color: var(--ink); }

/* Tip grid (short cards) */
.tip-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 14px; margin: 20px 0; }
.tip {
  padding: 18px; border-radius: var(--radius); border: 1px solid var(--rule); background: var(--paper);
  display: flex; flex-direction: column; gap: 6px;
}
.tip__icon { width: 40px; height: 40px; }
.tip strong { font-family: "Fraunces", serif; font-size: 1.12em; color: var(--ink); line-height: 1.25; }
.tip p { margin: 0; font-size: .95em; }

/* Big number strip */
.stat-strip { display: grid; grid-template-columns: repeat(auto-fit, minmax(170px, 1fr)); gap: 14px; margin: 20px 0; max-width: var(--lesson-col); }
.stat-strip div { padding: 16px 18px; border-radius: var(--radius); background: var(--paper-2); border: 1px solid var(--rule); }
.stat-strip b { display: block; font-family: "Fraunces", serif; font-size: 2em; line-height: 1.1; color: var(--accent); }
.stat-strip span { font-size: .9em; color: var(--ink-2); }

/* Mnemonic (e.g. COT) */
.mnemonic { display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: 12px; margin: 18px 0; max-width: var(--lesson-col); }
.mnemonic div { padding: 16px; border-radius: var(--radius); background: var(--navy); color: #fff; }
html[data-theme="dark"] .mnemonic div { background: #1C2A3F; }
.mnemonic b { display: block; font-family: "Fraunces", serif; font-size: 2.4em; line-height: 1; color: #F4B473; }
.mnemonic span { font-size: .95em; color: #E8EEF6; }

/* ---------- Callouts ---------- */
.lc {
  max-width: var(--lesson-col); margin: 22px 0; padding: 16px 20px 16px 20px;
  border-radius: var(--radius); border: 1px solid var(--rule); border-left: 5px solid var(--accent);
  background: var(--paper);
}
.lc-label { display: block; font-family: "JetBrains Mono", monospace; font-size: .72em; letter-spacing: .14em; text-transform: uppercase; color: var(--accent-ink); margin-bottom: 4px; }
.lc-title { display: block; font-family: "Fraunces", serif; font-size: 1.15em; color: var(--ink); margin-bottom: 4px; }
.lc-body p { margin: 0 0 .5em; }
.lc-body p:last-child { margin: 0; }
.lc--idea { background: var(--highlight); }
.lc--fact { border-left-color: var(--navy); }
.lc--fact .lc-label { color: var(--navy); }
.lc--warn { border-left-color: #dc2626; }
.lc--warn .lc-label { color: #b91c1c; }
html[data-theme="dark"] .lc--warn .lc-label { color: #f87171; }
.lc--coach { border-left-color: var(--success); }
.lc--coach .lc-label { color: var(--success); }

/* ---------- Boards ---------- */
.lb {
  margin: 28px 0; padding: clamp(16px, 2.4vw, 24px);
  border: 1px solid var(--rule); border-radius: var(--radius-lg); background: var(--paper-2);
  max-width: 920px; outline: none;
}
.lb:focus-visible { box-shadow: 0 0 0 3px var(--accent); }
.lb-head { display: flex; align-items: baseline; gap: 12px; flex-wrap: wrap; margin-bottom: 14px; }
.lb-tag {
  font-family: "JetBrains Mono", monospace; font-size: .7em; letter-spacing: .14em; text-transform: uppercase;
  padding: 4px 10px; border-radius: 999px; background: var(--navy); color: #fff;
}
html[data-theme="dark"] .lb-tag { color: #141414; }
.lb--try .lb-tag { background: var(--accent); color: #fff; }
.lb-title { font-size: 1.3em; margin: 0; }
.lb-grid { display: grid; grid-template-columns: minmax(0, 400px) minmax(0, 1fr); gap: clamp(16px, 2.6vw, 28px); align-items: start; }
.lb-board-col { min-width: 0; }
.lb-board.pz-board { border-width: 6px; }
.lb-board .pz-coord { font-size: 9px; }
.lb-board.no-coords .pz-coord { display: none; }
.lb .pz-howto { margin-top: 8px; }

.lb-controls { display: flex; gap: 6px; margin-top: 10px; justify-content: center; flex-wrap: wrap; }
.lb-btn {
  width: 44px; height: 38px; border-radius: 10px; border: 1px solid var(--rule); background: var(--paper);
  color: var(--ink); display: grid; place-items: center; cursor: pointer; padding: 0;
  transition: background .15s, border-color .15s;
}
.lb-btn svg { width: 18px; height: 18px; fill: currentColor; }
.lb-btn:hover:not(:disabled) { border-color: var(--ink); }
.lb-btn:disabled { opacity: .35; cursor: default; }
.lb-btn:focus-visible { outline: 3px solid var(--accent); outline-offset: 1px; }
.lb-btn--play { background: var(--ink); color: var(--paper); border-color: var(--ink); width: 54px; }
.lb-btn--flip { margin-left: 8px; }

.lb-side { min-width: 0; display: flex; flex-direction: column; gap: 12px; }
.lb-players { margin: 0; font-family: "Fraunces", serif; font-weight: 600; font-size: 1.1em; color: var(--ink); }
.lb-comment {
  min-height: 4.6em; padding: 12px 16px; border-radius: 12px;
  background: var(--paper); border-left: 4px solid var(--accent); color: var(--ink); line-height: 1.5;
  font-size: .98em;
}
.lb-comment.is-empty { border-left-color: var(--rule); }
.lb-moves {
  list-style: none; margin: 0; padding: 6px; max-height: 260px; overflow-y: auto;
  border: 1px solid var(--rule); border-radius: 12px; background: var(--paper);
  font-family: "JetBrains Mono", monospace; font-size: .88em;
  display: grid; grid-template-columns: 1fr; position: relative;
}
.lb-row { display: grid; grid-template-columns: 3.2em 1fr 1fr; align-items: center; }
.lb-row--empty { display: block; padding: 8px; color: var(--muted); font-family: "Inter", sans-serif; }
.lb-num { color: var(--muted); padding-left: 6px; }
.lb-move {
  appearance: none; border: 0; background: transparent; color: var(--ink); font: inherit; text-align: left;
  padding: 5px 16px 5px 8px; border-radius: 6px; cursor: pointer; position: relative;
  justify-self: start; min-width: 5em;
}
.lb-move:hover { background: var(--paper-2); }
.lb-move.has-comment::after { content: ""; position: absolute; top: 6px; right: 6px; width: 5px; height: 5px; border-radius: 50%; background: var(--accent); }
.lb-move.is-current { background: var(--ink); color: var(--paper); }
.lb-move--empty { cursor: default; }
.lb-move:focus-visible { outline: 2px solid var(--accent); }

.lb-side--try { padding-top: 2px; }
.lb-side--try .pz-status { margin: 4px 0; }
.lb-goal { font-family: "Fraunces", serif; font-size: 1.6em; font-weight: 600; line-height: 1.15; color: var(--ink); margin: 4px 0 0; }
.lb .lb-reset { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.lb.is-solved .pz-board { box-shadow: 0 0 0 4px var(--success), var(--shadow-md); }
.lb .pz-solution { margin-top: 0; }

.pz-sq.mk-y { box-shadow: inset 0 0 0 100px rgba(246, 180, 40, .55); }
.pz-sq.mk-r { box-shadow: inset 0 0 0 100px rgba(230, 60, 50, .55); }
.lb-grid--static .lb-comment { min-height: 0; }

.lb-caption { margin-top: 14px; color: var(--ink-2); font-size: .97em; max-width: 60em; }
.lb-caption p { margin: 0 0 .5em; }
.lb-noscript { font-family: "JetBrains Mono", monospace; font-size: .9em; color: var(--ink-2); }
.lb-missing { padding: 12px 16px; border: 2px dashed #dc2626; border-radius: 10px; color: #b91c1c; }

@media (max-width: 760px) {
  .lb-grid { grid-template-columns: 1fr; }
  .lb-board-col { max-width: 440px; margin: 0 auto; width: 100%; }
  .lb-moves { max-height: 180px; }
}

/* Two boards side by side (pairs of short endings) */
.lb-pair { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; max-width: 920px; }
.lb-pair .lb { margin: 0; }
.lb-pair .lb-grid { grid-template-columns: 1fr; }
.lb-pair .lb-moves { max-height: 130px; }
.lb-pair .lb-comment { min-height: 3.2em; }
@media (max-width: 860px) { .lb-pair { grid-template-columns: 1fr; } }
.lb-pair + .lb-pair, .lb + .lb-pair, .lb-pair + .lb { margin-top: 18px; }

/* ---------- Videos ---------- */
.lv { margin: 24px 0; max-width: 820px; }
.lv-frame {
  position: relative; display: block; aspect-ratio: 16 / 9; overflow: hidden;
  border-radius: var(--radius-lg); background: #000; border: 0; box-shadow: var(--shadow-md);
}
.lv-frame img { width: 100%; height: 100%; object-fit: cover; transition: transform .4s ease, opacity .3s; opacity: .92; }
.lv-frame iframe { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; }
.lv-frame:hover img { transform: scale(1.03); opacity: 1; }
.lv-play {
  position: absolute; left: 50%; top: 50%; translate: -50% -50%;
  width: 76px; height: 76px; border-radius: 50%; display: grid; place-items: center;
  background: var(--accent); box-shadow: 0 10px 30px rgba(0,0,0,.35); transition: transform .2s;
}
.lv-play svg { width: 34px; height: 34px; fill: #fff; margin-left: 4px; }
.lv-frame:hover .lv-play { transform: scale(1.08); }
.lv-frame:focus-visible { outline: 3px solid var(--accent); outline-offset: 3px; }
.lv-caption { display: flex; flex-wrap: wrap; align-items: baseline; gap: 4px 10px; margin-top: 12px; }
.lv-caption strong { font-family: "Fraunces", serif; font-size: 1.12em; color: var(--ink); }
.lv-badge {
  font-family: "JetBrains Mono", monospace; font-size: .68em; letter-spacing: .14em; text-transform: uppercase;
  padding: 3px 8px; border-radius: 6px; background: #c4302b; color: #fff;
}
.lv-note { color: var(--muted); font-size: .9em; }
.lv-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 20px; max-width: 920px; }
.lv-grid .lv { margin: 0; }
.lv-grid .lv-play { width: 58px; height: 58px; }
.lv-grid .lv-play svg { width: 26px; height: 26px; }
@media (prefers-reduced-motion: reduce) { .lv-frame img, .lv-play { transition: none; } }

/* ---------- Pager + CTA ---------- */
.lesson-pager {
  display: grid; grid-template-columns: 1fr auto 1fr; gap: 16px; align-items: stretch;
  padding: 12px 0 clamp(40px, 6vw, 72px);
}
.lesson-pager__card {
  display: flex; flex-direction: column; gap: 4px; padding: 18px 20px;
  border: 1px solid var(--rule); border-radius: var(--radius); background: var(--paper); color: var(--ink);
  transition: border-color .2s, transform .2s;
}
.lesson-pager__card:hover { border-color: var(--accent); transform: translateY(-2px); color: var(--ink); }
.lesson-pager__card--next { text-align: right; }
.lesson-pager__dir { font-family: "JetBrains Mono", monospace; font-size: .74em; letter-spacing: .1em; text-transform: uppercase; color: var(--accent-ink); }
.lesson-pager__card strong { font-family: "Fraunces", serif; font-size: 1.2em; }
.lesson-pager__all {
  align-self: center; padding: 10px 16px; border-radius: 999px; border: 1px solid var(--rule);
  font-family: "JetBrains Mono", monospace; font-size: .78em; letter-spacing: .08em; text-transform: uppercase; color: var(--ink);
}
.lesson-pager__all:hover { border-color: var(--ink); }
@media (max-width: 700px) {
  .lesson-pager { grid-template-columns: 1fr; }
  .lesson-pager__card--next { text-align: left; }
  .lesson-pager__all { justify-self: center; order: 3; }
}

.lesson-cta { padding-bottom: clamp(48px, 7vw, 88px); }
.lesson-cta__inner {
  position: relative; overflow: hidden;
  display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 24px; align-items: center;
  padding: clamp(24px, 4vw, 44px); border-radius: var(--radius-lg);
  background: var(--navy); color: #fff;
}
html[data-theme="dark"] .lesson-cta__inner { background: #1C2A3F; }
.lesson-cta__inner h2 { color: #fff; font-size: clamp(1.6rem, 3vw, 2.2rem); margin: 4px 0 8px; }
.lesson-cta__inner p { color: #D6DFEA; margin: 0; max-width: 34em; }
.lesson-cta__inner .eyebrow { color: #F4B473; }
.lesson-cta__inner .btn-primary { background: #F4B473; color: #141414; position: relative; z-index: 1; }
.lesson-cta__knight { position: absolute; right: 8%; bottom: -40px; width: 200px; height: 200px; opacity: .12; pointer-events: none; }
@media (max-width: 640px) { .lesson-cta__inner { grid-template-columns: 1fr; } }

/* =========================================================
   Landing page (/learn-chess/)
   ========================================================= */
.learn-hero { padding: clamp(44px, 7vw, 96px) 0 clamp(40px, 6vw, 72px); background: var(--paper-2); border-bottom: 1px solid var(--rule); overflow: hidden; }
.learn-hero__grid { display: grid; grid-template-columns: minmax(0, 1.1fr) minmax(0, .9fr); gap: clamp(28px, 5vw, 64px); align-items: center; }
.learn-hero h1 { font-size: clamp(2.6rem, 6vw, 4.8rem); margin: 10px 0 18px; }
.learn-hero h1 em { color: var(--accent); }
.learn-hero__lede { font-family: "Fraunces", serif; font-size: 1.26em; line-height: 1.5; color: var(--ink-2); max-width: 30em; }

.start-picker { margin-top: 28px; }
.start-picker__label { display: block; font-family: "JetBrains Mono", monospace; font-size: .74em; letter-spacing: .14em; text-transform: uppercase; color: var(--muted); margin-bottom: 10px; }
.start-picker__opts { display: flex; flex-wrap: wrap; gap: 10px; }
.start-opt {
  display: inline-flex; align-items: center; gap: 10px; padding: 12px 18px 12px 12px;
  border-radius: 14px; border: 1px solid var(--rule); background: var(--paper); color: var(--ink); font-weight: 600;
  transition: border-color .2s, transform .2s;
}
.start-opt:hover { border-color: var(--accent); transform: translateY(-2px); color: var(--ink); }
.start-opt svg { width: 34px; height: 34px; }
.start-opt small { display: block; font-weight: 400; color: var(--muted); font-size: .8em; }

.learn-hero__board .lb { margin: 0; background: var(--paper); box-shadow: var(--shadow-md); }
.learn-hero__board .lb-grid { grid-template-columns: 1fr; }
.learn-hero__board .lb-board-col { max-width: 320px; margin: 0 auto; width: 100%; }
.learn-hero__board .pz-howto { display: none; }
.learn-hero__board .lb-side { gap: 8px; }
.learn-hero__board .pz-status { min-height: 2.6em; }
.learn-hero__board .lb-goal { font-size: 1.3em; }

@media (max-width: 900px) { .learn-hero__grid { grid-template-columns: 1fr; } }

.track { padding: clamp(44px, 6vw, 80px) 0; scroll-margin-top: 80px; }
.track + .track { border-top: 1px solid var(--rule); }
.track:nth-of-type(even) { background: var(--paper-2); }
.track-head { display: grid; grid-template-columns: auto minmax(0, 1fr); gap: 20px 28px; align-items: start; margin-bottom: 32px; max-width: 900px; }
.track-num {
  font-family: "Fraunces", serif; font-size: clamp(3rem, 7vw, 5rem); line-height: .9; font-weight: 600;
  color: var(--track-color, var(--accent));
}
.track-head h2 { margin: 6px 0 8px; }
.track-head p { margin: 0; font-size: 1.05em; }
.track--basics { --track-color: var(--track-basics); }
.track--improve { --track-color: var(--track-improve); }
.track--practice { --track-color: var(--track-practice); }
.track .eyebrow { color: var(--track-color); }

.lesson-cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 18px; }
.lesson-card {
  position: relative; display: flex; flex-direction: column; gap: 8px;
  padding: 22px 22px 20px; min-height: 230px; overflow: hidden;
  border: 1px solid var(--rule); border-radius: var(--radius-lg); background: var(--paper); color: var(--ink);
  border-top: 5px solid var(--track-color);
  transition: transform .2s, box-shadow .2s, border-color .2s;
}
.lesson-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); color: var(--ink); }
.lesson-card__n { font-family: "JetBrains Mono", monospace; font-size: .78em; color: var(--muted); letter-spacing: .08em; }
.lesson-card h3 { font-size: 1.4em; margin: 0; padding-right: 60px; }
.lesson-card p { margin: 0; font-size: .96em; flex: 1; }
.lesson-card__meta { font-family: "JetBrains Mono", monospace; font-size: .74em; letter-spacing: .06em; color: var(--track-color); }
.lesson-card__go { font-weight: 600; font-size: .92em; }
.lesson-card__piece { position: absolute; top: 16px; right: 14px; width: 56px; height: 56px; opacity: .9; transition: transform .3s; }
.lesson-card:hover .lesson-card__piece { transform: rotate(-8deg) scale(1.08); }

.learn-tips { padding: clamp(44px, 6vw, 80px) 0; border-top: 1px solid var(--rule); }
.learn-tips .tip-grid { grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); }
.learn-tips .tip { background: var(--paper-2); }

/* =========================================================
   Square trainer (notation page)
   ========================================================= */
.sq-trainer { display: grid; grid-template-columns: minmax(0, 400px) minmax(0, 1fr); gap: 28px; align-items: start; padding: clamp(16px, 2.4vw, 24px); border: 1px solid var(--rule); border-radius: var(--radius-lg); background: var(--paper-2); max-width: 920px; margin: 24px 0; --sq-left: 1; }
.sq-trainer .pz-sq { cursor: pointer; }
.sq-target { font-family: "Fraunces", serif; font-size: 4.2em; font-weight: 600; line-height: 1; color: var(--accent); margin: 6px 0 12px; min-height: 1em; }
.sq-stats { display: flex; gap: 16px; font-family: "JetBrains Mono", monospace; font-size: .9em; color: var(--ink-2); }
.sq-stats b { color: var(--ink); }
.sq-bar { height: 8px; border-radius: 999px; background: var(--rule); overflow: hidden; margin: 14px 0; }
.sq-bar span { display: block; height: 100%; width: calc(var(--sq-left) * 100%); background: var(--accent); transition: width .2s linear; }
.sq-trainer:not(.is-running) .sq-bar span { width: 100%; background: var(--rule); }
.sq-msg { min-height: 3em; }
.sq-opts { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 10px; }
.sq-opts .btn { padding: 9px 14px; font-size: .9em; }
.sq-opts .btn[aria-pressed="true"] { background: var(--ink); color: var(--paper); }
@media (max-width: 760px) { .sq-trainer { grid-template-columns: 1fr; } }

/* =========================================================
   Checklist (bucket list)
   ========================================================= */
.bucket-progress { position: sticky; top: 76px; z-index: 5; display: flex; align-items: center; gap: 14px; padding: 12px 16px; border-radius: 14px; background: var(--paper); border: 1px solid var(--rule); box-shadow: var(--shadow-sm); max-width: 920px; margin-bottom: 24px; --progress: 0; }
.bucket-progress__bar { flex: 1; height: 10px; border-radius: 999px; background: var(--rule); overflow: hidden; }
.bucket-progress__bar span { display: block; height: 100%; width: calc(var(--progress) * 100%); background: var(--success); transition: width .3s; }
.bucket-progress__text { font-family: "JetBrains Mono", monospace; font-size: .85em; white-space: nowrap; }
.bucket-progress .btn { padding: 7px 12px; font-size: .82em; }

.skill-group { border: 1px solid var(--rule); border-radius: var(--radius-lg); background: var(--paper); margin: 0 0 16px; max-width: 920px; overflow: hidden; --progress: 0; }
.skill-group > summary {
  list-style: none; cursor: pointer; display: grid; grid-template-columns: auto minmax(0, 1fr) auto; gap: 14px; align-items: center;
  padding: 16px 18px;
}
.skill-group > summary::-webkit-details-marker { display: none; }
.skill-group__n { width: 40px; height: 40px; border-radius: 11px; display: grid; place-items: center; background: var(--navy); color: #fff; font-family: "JetBrains Mono", monospace; font-weight: 600; }
html[data-theme="dark"] .skill-group__n { color: #141414; }
.skill-group__title { font-family: "Fraunces", serif; font-size: 1.2em; font-weight: 600; color: var(--ink); }
.skill-group__phase { display: block; font-size: .8em; color: var(--muted); font-family: "Inter", sans-serif; font-weight: 400; }
.skill-group__count { font-family: "JetBrains Mono", monospace; font-size: .82em; color: var(--ink-2); display: flex; align-items: center; gap: 10px; }
.skill-group__ring { width: 28px; height: 28px; border-radius: 50%; background: conic-gradient(var(--success) calc(var(--progress) * 360deg), var(--rule) 0); position: relative; }
.skill-group__ring::after { content: ""; position: absolute; inset: 5px; border-radius: 50%; background: var(--paper); }
.skill-group[open] > summary { border-bottom: 1px solid var(--rule); }
.skill-group__body { padding: 14px 18px 18px; }
.skill-list { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 6px 16px; }
.skill-list label { display: flex; gap: 10px; align-items: flex-start; padding: 6px 4px; border-radius: 8px; cursor: pointer; color: var(--ink); line-height: 1.35; }
.skill-list label:hover { background: var(--paper-2); }
.skill-list input { width: 20px; height: 20px; accent-color: var(--success); flex: none; margin-top: 1px; }
.skill-list input:checked + span { color: var(--muted); text-decoration: line-through; text-decoration-color: color-mix(in oklab, var(--success) 60%, transparent); }
.skill-list small { display: block; font-size: .78em; color: var(--muted); text-decoration: none; }
.skill-group__videos { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 14px; padding-top: 12px; border-top: 1px dashed var(--rule); }
.skill-vid { display: inline-flex; align-items: center; gap: 8px; padding: 6px 12px 6px 8px; border-radius: 999px; border: 1px solid var(--rule); font-size: .88em; color: var(--ink); background: var(--paper-2); }
.skill-vid:hover { border-color: #c4302b; color: var(--ink); }
.skill-vid svg { width: 18px; height: 18px; fill: #c4302b; }
.skill-vid.is-playing { border-color: #c4302b; background: var(--paper); font-weight: 600; }
.skill-player { margin-top: 14px; max-width: 720px; }
.skill-player .lv-frame { box-shadow: none; }

.band-head { display: flex; align-items: baseline; gap: 14px; flex-wrap: wrap; margin: 40px 0 16px; max-width: 920px; }
.band-head:first-child { margin-top: 0; }
.band-head h3 { margin: 0; font-size: 1.5em; }
.band-rating { font-family: "JetBrains Mono", monospace; font-size: .8em; padding: 4px 10px; border-radius: 999px; background: var(--highlight); color: var(--accent-ink); }

/* =========================================================
   Games library
   ========================================================= */
.gl { display: grid; grid-template-columns: minmax(0, 1fr) 340px; gap: 24px; align-items: start; }
.gl-viewer { position: sticky; top: 88px; }
.gl-viewer .lb { margin: 0; max-width: none; }
.gl-list { border: 1px solid var(--rule); border-radius: var(--radius-lg); background: var(--paper); overflow: hidden; }
.gl-search { padding: 12px; border-bottom: 1px solid var(--rule); background: var(--paper-2); }
.gl-search input { width: 100%; padding: 10px 12px; border-radius: 10px; border: 1px solid var(--rule); background: var(--paper); color: var(--ink); font: inherit; }
.gl-filters { display: flex; gap: 6px; flex-wrap: wrap; margin-top: 8px; }
.gl-filters button { font: inherit; font-size: .8em; padding: 5px 10px; border-radius: 999px; border: 1px solid var(--rule); background: var(--paper); color: var(--ink-2); cursor: pointer; }
.gl-filters button[aria-pressed="true"] { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.gl-items { list-style: none; margin: 0; padding: 6px; max-height: 70vh; overflow-y: auto; }
.gl-item button { width: 100%; text-align: left; font: inherit; border: 0; background: transparent; color: var(--ink); padding: 10px 12px; border-radius: 10px; cursor: pointer; display: grid; gap: 2px; }
.gl-item button:hover { background: var(--paper-2); }
.gl-item button[aria-current="true"] { background: var(--highlight); box-shadow: inset 3px 0 0 var(--accent); }
.gl-item strong { font-size: .95em; line-height: 1.3; }
.gl-item span { font-size: .78em; color: var(--muted); font-family: "JetBrains Mono", monospace; }
.gl-empty { padding: 16px; color: var(--muted); }
.gl-item[hidden] { display: none; }
.gl-select { margin-left: auto; font: inherit; font-size: .85em; padding: 6px 8px; border-radius: 8px; border: 1px solid var(--rule); background: var(--paper); color: var(--ink); max-width: 100%; }
.gl-viewer .lb-grid { grid-template-columns: minmax(0, 440px) minmax(0, 1fr); }
@media (max-width: 1180px) { .gl-viewer .lb-grid { grid-template-columns: 1fr; } .gl-viewer .lb-board-col { max-width: 460px; margin: 0 auto; width: 100%; } }
@media (max-width: 980px) {
  .gl { grid-template-columns: 1fr; }
  .gl-viewer { position: static; }
  .gl-items { max-height: 360px; }
}