/* ============================================================
   curso.css — sistema de diseño del Curso de Fine-Tuning
   Reutilizado por pensum.html (índice) y m00–m11.html (lecciones)
   Marca Jhonacode: negro #0a0a0a + verde #39ff14, Inter/JetBrains Mono
   ============================================================ */
:root {
    --bg: #0a0a0a;
    --panel: #111311;
    --panel-2: #0d0f0d;
    --line: #1d221d;
    --line-soft: #161a16;
    --green: #39ff14;
    --green-2: #2ee010;
    --green-dim: rgba(57, 255, 20, 0.12);
    --green-faint: rgba(57, 255, 20, 0.06);
    --amber: #ffc34d;
    --red: #ff6b5e;
    --text: #ffffff;
    --muted: #a1a1a1;
    --faint: #6b726b;
    --mono: "JetBrains Mono", monospace;
}

.pensum-body { background: var(--bg); }

.p-doc { max-width: 1200px; margin: 0 auto; padding: 0 2rem; }
.p-doc.narrow { max-width: 860px; }

.p-back {
    font-family: var(--mono); font-size: 0.8rem; color: var(--faint); letter-spacing: 0.04em;
}
.p-back:hover { color: var(--green); }

/* ---------- eyebrow / headings shared ---------- */
.p-eyebrow {
    font-family: var(--mono); font-size: 0.78rem; letter-spacing: 0.28em;
    text-transform: uppercase; color: var(--green);
    display: inline-flex; align-items: center; gap: 0.6rem; margin-bottom: 1.5rem;
}
.p-eyebrow::before { content: ""; width: 28px; height: 1px; background: var(--green); display: inline-block; }

.p-h2 { font-size: 1.9rem; letter-spacing: -0.01em; }
.p-h2 .rn { font-family: var(--mono); font-size: 0.9rem; color: var(--green); vertical-align: super; margin-right: 0.4rem; }
.p-sub { color: var(--muted); max-width: 60ch; margin-top: -0.4rem; }

/* ---------- pensum hero ---------- */
.p-hero { padding: 8rem 0 3rem; border-bottom: 1px solid var(--line); }
.p-hero h1 {
    font-size: clamp(2.2rem, 5vw, 3.6rem); line-height: 1.05; letter-spacing: -0.02em;
    max-width: 20ch; margin-bottom: 1.4rem;
}
.p-hero h1 em { font-style: normal; color: var(--green); }
.p-lede { font-size: 1.12rem; color: var(--muted); max-width: 62ch; line-height: 1.65; margin-bottom: 2.2rem; }
.p-meta { display: flex; flex-wrap: wrap; gap: 0.6rem 0.5rem; font-family: var(--mono); font-size: 0.8rem; }
.p-tag { border: 1px solid var(--line); border-radius: 2px; padding: 0.4rem 0.75rem; color: var(--muted); background: var(--panel-2); }
.p-tag b { color: var(--green); font-weight: 500; }

/* ---------- cards ---------- */
.p-signature { margin-top: 3rem; display: grid; grid-template-columns: 1.25fr 1fr; gap: 1.25rem; }
.p-card { background: var(--panel); border: 1px solid var(--line); border-radius: 4px; overflow: hidden; }
.p-card-head {
    font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.14em; text-transform: uppercase;
    color: var(--faint); padding: 0.75rem 1rem; border-bottom: 1px solid var(--line-soft);
    display: flex; justify-content: space-between; align-items: center;
}
.p-dot { color: var(--green); }
.p-card-body { padding: 1.15rem 1rem 1.25rem; }

/* ---------- next-token + LoRA ---------- */
.toks { display: flex; flex-wrap: wrap; gap: 0.35rem; font-family: var(--mono); font-size: 0.86rem; margin-bottom: 1.1rem; }
.tok { padding: 0.28rem 0.5rem; border: 1px solid var(--line); border-radius: 2px; color: var(--muted); background: var(--panel-2); }
.tok.pred { border-color: var(--green); color: var(--green); background: var(--green-dim); }
.tok.slot { border-style: dashed; color: var(--faint); }
.dist { display: grid; gap: 0.45rem; }
.dist-row { display: grid; grid-template-columns: 8.5em 1fr 3em; align-items: center; gap: 0.6rem; font-family: var(--mono); font-size: 0.78rem; }
.dist-row .lbl { color: var(--muted); text-align: right; }
.dist-row.top .lbl { color: var(--green); }
.bar { height: 8px; background: var(--line); border-radius: 6px; overflow: hidden; }
.bar > span { display: block; height: 100%; background: linear-gradient(90deg, #1f6b12, var(--green)); border-radius: 6px; }
.dist-row .pct { color: var(--faint); text-align: right; }
.dist-row.top .pct { color: var(--green); }
.lora-formula { font-family: var(--mono); display: flex; align-items: center; justify-content: center; gap: 0.6rem; font-size: 1.5rem; padding: 1.4rem 0 1rem; flex-wrap: wrap; }
.lora-formula .frozen { color: var(--faint); }
.lora-formula .train { color: var(--green); }
.lora-formula .op { color: var(--muted); }
.lora-legend { display: flex; justify-content: center; gap: 1.4rem; font-family: var(--mono); font-size: 0.72rem; color: var(--faint); }
.lora-legend .k-frozen::before, .lora-legend .k-train::before { content: "■ "; }
.lora-legend .k-frozen { color: var(--faint); }
.lora-legend .k-train { color: var(--green); }

/* ---------- pipeline flow ---------- */
.p-flow-section { padding: 3.5rem 0; border-bottom: 1px solid var(--line); }
.p-flow { display: flex; align-items: stretch; gap: 0; overflow-x: auto; padding-bottom: 0.5rem; }
.flow-node { flex: 1 0 auto; min-width: 120px; text-align: center; position: relative; padding: 0 0.25rem; }
.flow-node .n { font-family: var(--mono); font-size: 0.68rem; color: var(--faint); }
.flow-node .t { font-family: var(--mono); font-size: 0.82rem; color: var(--text); margin-top: 0.5rem; padding: 0.55rem 0.4rem; border: 1px solid var(--line); border-radius: 3px; background: var(--panel); display: block; }
.flow-node:not(:last-child)::after { content: "→"; position: absolute; right: -0.35em; top: 2.35em; color: var(--green); font-family: var(--mono); }

/* ---------- pensum layout: rail + modules ---------- */
.p-layout { display: grid; grid-template-columns: 240px 1fr; gap: 3.5rem; padding: 3.5rem 0 5rem; align-items: start; }
.p-rail { position: sticky; top: 6rem; }
.rail-title { font-family: var(--mono); font-size: 0.7rem; letter-spacing: 0.18em; text-transform: uppercase; color: var(--faint); margin-bottom: 1rem; }
.rail-list { list-style: none; margin: 0; padding: 0; }
.rail-list a { display: flex; gap: 0.7rem; font-family: var(--mono); font-size: 0.8rem; color: var(--muted); padding: 0.32rem 0; border-left: 2px solid transparent; padding-left: 0.8rem; transition: color 0.2s, border-color 0.2s; }
.rail-list a .rn { color: var(--faint); }
.rail-list a:hover { color: var(--text); }
.rail-list a.active { color: var(--green); border-left-color: var(--green); }
.rail-list a.active .rn { color: var(--green); }
.rail-sep { height: 1px; background: var(--line-soft); margin: 0.7rem 0 0.7rem 0.8rem; }

.p-modules { position: relative; }
.module { padding: 0 0 3rem 2rem; position: relative; border-left: 1px solid var(--line); }
.module:last-child { border-left-color: transparent; }
.module::before { content: ""; position: absolute; left: -6px; top: 0.35rem; width: 11px; height: 11px; border-radius: 50%; background: var(--bg); border: 2px solid var(--green); }
.mod-num { font-family: var(--mono); font-size: 0.75rem; letter-spacing: 0.1em; color: var(--green); display: block; margin-bottom: 0.35rem; }
.module h3 { font-size: 1.4rem; margin-bottom: 0.5rem; letter-spacing: -0.01em; }
.mod-goal { font-family: var(--mono); font-size: 0.82rem; color: var(--muted); border-left: 2px solid var(--green); padding: 0.15rem 0 0.15rem 0.8rem; margin: 0.9rem 0 1.1rem; background: var(--green-faint); }
.mod-goal b { color: var(--green); font-weight: 500; }
.module p { color: var(--muted); font-size: 0.95rem; }

/* "Estudiar módulo" link on pensum index */
.study-link {
    display: inline-flex; align-items: center; gap: 0.5rem;
    font-family: var(--mono); font-size: 0.8rem; color: var(--green);
    border: 1px solid var(--line); border-radius: 3px; padding: 0.5rem 0.9rem;
    margin-top: 1.2rem; background: var(--panel); transition: background 0.2s, border-color 0.2s;
}
.study-link:hover { background: var(--green-dim); border-color: var(--green); color: var(--green); }
.study-link .arw { transition: transform 0.2s; }
.study-link:hover .arw { transform: translateX(3px); }

/* ---------- chips / labels / code ---------- */
.chips { display: flex; flex-wrap: wrap; gap: 0.4rem; margin: 0.9rem 0 0.4rem; }
.chip { font-family: var(--mono); font-size: 0.72rem; color: var(--muted); border: 1px solid var(--line); border-radius: 2px; padding: 0.28rem 0.55rem; background: var(--panel-2); }
.chip:hover { border-color: var(--green); color: var(--green); }
.mod-label { font-family: var(--mono); font-size: 0.68rem; letter-spacing: 0.14em; text-transform: uppercase; color: var(--faint); margin: 1.3rem 0 0.5rem; }

pre.code { font-family: var(--mono); font-size: 0.8rem; line-height: 1.6; background: var(--panel-2); border: 1px solid var(--line); border-radius: 4px; padding: 1rem 1.1rem; overflow-x: auto; color: #cfd6cf; margin: 0.6rem 0 0; }
pre.code .c { color: var(--faint); }
pre.code .g { color: var(--green); }
pre.code .s { color: var(--amber); }
pre.code .k { color: #7fb3ff; }

.callout { display: flex; gap: 0.75rem; font-size: 0.9rem; color: var(--muted); background: var(--panel); border: 1px solid var(--line); border-left: 3px solid var(--amber); border-radius: 3px; padding: 0.9rem 1rem; margin-top: 1rem; }
.callout b { color: var(--amber); font-weight: 500; }

/* ---------- loss patterns ---------- */
.p-panel-section { padding: 1rem 0 3.5rem 2rem; border-left: 1px solid var(--line); position: relative; }
.p-panel-section::before { content: ""; position: absolute; left: -6px; top: 0.35rem; width: 11px; height: 11px; border-radius: 50%; background: var(--bg); border: 2px solid var(--amber); }
.loss-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; margin-top: 1rem; }
.loss-card { background: var(--panel); border: 1px solid var(--line); border-radius: 4px; padding: 1rem; }
.loss-card .dx { font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--amber); margin-bottom: 0.7rem; }
.spark { height: 44px; display: block; width: 100%; margin-bottom: 0.6rem; }
.loss-card p { font-size: 0.82rem; margin: 0; color: var(--muted); }

/* ---------- etapas / stages ---------- */
.p-stages { padding: 4rem 0; border-top: 1px solid var(--line); }
.stages-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; margin-top: 2rem; }
.stage { background: var(--panel); border: 1px solid var(--line); border-radius: 4px; padding: 1.3rem 1.2rem; position: relative; }
.stage .en { font-family: var(--mono); font-size: 2.4rem; font-weight: 700; color: var(--green-dim); line-height: 1; }
.stage h4 { font-size: 1.05rem; margin: 0.4rem 0 0.6rem; }
.stage p { font-size: 0.85rem; margin: 0 0 0.8rem; color: var(--muted); }
.stage .deliver { font-family: var(--mono); font-size: 0.72rem; color: var(--green); border-top: 1px solid var(--line-soft); padding-top: 0.6rem; }
.stage .deliver span { color: var(--faint); }

/* ---------- stack + ignore ---------- */
.p-bottom { display: grid; grid-template-columns: 1.2fr 1fr; gap: 2.5rem; padding: 1rem 0 5rem; }
.stack-list { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-top: 1.2rem; }
.stack-item { font-family: var(--mono); font-size: 0.82rem; color: var(--text); border: 1px solid var(--line); border-radius: 2px; padding: 0.45rem 0.7rem; background: var(--panel); }
.stack-item small { color: var(--faint); }
.ignore-list { list-style: none; margin: 1.2rem 0 0; padding: 0; }
.ignore-list li { font-family: var(--mono); font-size: 0.82rem; color: var(--faint); padding: 0.35rem 0; border-bottom: 1px solid var(--line-soft); display: flex; gap: 0.6rem; }
.ignore-list li::before { content: "—"; color: #444; }

/* ---------- footer ---------- */
.p-footer { border-top: 1px solid var(--line); padding: 2.5rem 0; text-align: center; }
.p-footer p { font-family: var(--mono); font-size: 0.78rem; color: var(--faint); margin: 0; }
.p-footer a { color: var(--green); }

/* ============================================================
   LECCIONES (m00–m11)
   ============================================================ */
.breadcrumb { font-family: var(--mono); font-size: 0.78rem; color: var(--faint); padding-top: 7.5rem; letter-spacing: 0.03em; }
.breadcrumb a { color: var(--faint); }
.breadcrumb a:hover { color: var(--green); }
.breadcrumb .sep { color: #333; margin: 0 0.5rem; }
.breadcrumb .cur { color: var(--muted); }

.lesson-hero { padding: 1.5rem 0 2rem; border-bottom: 1px solid var(--line); margin-bottom: 2.5rem; }
.lesson-kicker { font-family: var(--mono); font-size: 0.75rem; letter-spacing: 0.18em; text-transform: uppercase; color: var(--green); margin-bottom: 0.8rem; }
.lesson-hero h1 { font-size: clamp(1.9rem, 4vw, 2.8rem); line-height: 1.08; letter-spacing: -0.02em; margin-bottom: 1rem; }
.lesson-intro { font-size: 1.08rem; color: var(--muted); line-height: 1.7; max-width: 68ch; }
.lesson-metabar { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-top: 1.5rem; font-family: var(--mono); font-size: 0.76rem; }

/* objetivos "al terminar sabrás" */
.objectives { background: var(--panel); border: 1px solid var(--line); border-left: 3px solid var(--green); border-radius: 4px; padding: 1.2rem 1.3rem; margin: 0 0 2.5rem; }
.objectives h2 { font-family: var(--mono); font-size: 0.74rem; letter-spacing: 0.14em; text-transform: uppercase; color: var(--green); margin-bottom: 0.8rem; }
.objectives ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 0.5rem; }
.objectives li { color: var(--muted); font-size: 0.92rem; padding-left: 1.5rem; position: relative; }
.objectives li::before { content: "→"; position: absolute; left: 0; color: var(--green); font-family: var(--mono); }

/* prose body */
.lesson-body { max-width: 760px; }
.lesson-body h2 { font-size: 1.5rem; letter-spacing: -0.01em; margin: 2.8rem 0 1rem; padding-top: 0.5rem; }
.lesson-body h2 .hn { font-family: var(--mono); font-size: 0.8rem; color: var(--green); margin-right: 0.6rem; vertical-align: middle; }
.lesson-body h3 { font-size: 1.15rem; margin: 1.8rem 0 0.7rem; color: var(--text); }
.lesson-body p { color: var(--muted); font-size: 1rem; line-height: 1.75; margin-bottom: 1.1rem; }
.lesson-body p b, .lesson-body li b { color: var(--text); font-weight: 600; }
.lesson-body a { color: var(--green); text-decoration: underline; text-decoration-color: rgba(57,255,20,0.35); text-underline-offset: 3px; }
.lesson-body ul, .lesson-body ol { color: var(--muted); margin: 0 0 1.3rem 0; padding-left: 1.4rem; line-height: 1.7; }
.lesson-body li { margin-bottom: 0.5rem; }
.lesson-body code { font-family: var(--mono); font-size: 0.86em; background: var(--panel-2); border: 1px solid var(--line-soft); border-radius: 3px; padding: 0.1em 0.4em; color: var(--green); }
.lesson-body pre.code code { background: none; border: none; padding: 0; color: inherit; }
.lesson-body .mod-label { margin-top: 1.8rem; }

.figure { margin: 1.5rem 0; }
.figure figcaption { font-family: var(--mono); font-size: 0.74rem; color: var(--faint); margin-top: 0.6rem; text-align: center; }

/* note / warn / exercise / keypoints blocks */
.note, .warn, .exercise, .keypoints { border-radius: 4px; padding: 1.15rem 1.3rem; margin: 1.6rem 0; }
.note { background: var(--panel); border: 1px solid var(--line); border-left: 3px solid var(--green); }
.warn { background: rgba(255,107,94,0.05); border: 1px solid rgba(255,107,94,0.25); border-left: 3px solid var(--red); }
.note .tag, .warn .tag, .exercise .tag { font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.12em; text-transform: uppercase; display: block; margin-bottom: 0.5rem; }
.note .tag { color: var(--green); }
.warn .tag { color: var(--red); }
.note p, .warn p { margin: 0; font-size: 0.94rem; }
.warn p { color: #d8b3ae; }

.exercise { background: var(--panel); border: 1px solid var(--line); border-left: 3px solid var(--amber); }
.exercise .tag { color: var(--amber); }
.exercise h4 { font-size: 1.05rem; margin: 0 0 0.6rem; }
.exercise p { font-size: 0.94rem; margin-bottom: 0.8rem; }
.exercise .expect { font-family: var(--mono); font-size: 0.78rem; color: var(--faint); border-top: 1px solid var(--line-soft); padding-top: 0.7rem; margin-top: 0.4rem; }
.exercise .expect b { color: var(--amber); font-weight: 500; }

.keypoints { background: var(--green-faint); border: 1px solid var(--line); border-left: 3px solid var(--green); }
.keypoints .tag { font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.12em; text-transform: uppercase; color: var(--green); display: block; margin-bottom: 0.7rem; }
.keypoints ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 0.55rem; }
.keypoints li { color: var(--muted); font-size: 0.92rem; padding-left: 1.6rem; position: relative; }
.keypoints li::before { content: "✓"; position: absolute; left: 0; color: var(--green); font-family: var(--mono); font-size: 0.85rem; }

/* comparison table */
.l-table { width: 100%; border-collapse: collapse; margin: 1.4rem 0; font-size: 0.9rem; }
.l-table th, .l-table td { text-align: left; padding: 0.7rem 0.9rem; border-bottom: 1px solid var(--line); vertical-align: top; }
.l-table th { font-family: var(--mono); font-size: 0.74rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--green); }
.l-table td { color: var(--muted); }
.l-table tr:last-child td { border-bottom: none; }
.l-table-wrap { overflow-x: auto; }

/* Cómo practicar — pasos numerados */
.practice { background: var(--panel); border: 1px solid var(--line); border-left: 3px solid var(--green); border-radius: 4px; padding: 1.2rem 1.3rem 1.3rem; margin: 1.8rem 0; }
.practice .tag { font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.12em; text-transform: uppercase; color: var(--green); display: block; margin-bottom: 0.9rem; }
.practice ol { counter-reset: pstep; list-style: none; margin: 0; padding: 0; display: grid; gap: 0.85rem; }
.practice ol li { position: relative; padding-left: 2.3rem; color: var(--muted); font-size: 0.95rem; line-height: 1.6; }
.practice ol li::before { counter-increment: pstep; content: counter(pstep); position: absolute; left: 0; top: -0.1rem; width: 1.55rem; height: 1.55rem; border: 1px solid var(--green); color: var(--green); border-radius: 50%; font-family: var(--mono); font-size: 0.78rem; display: grid; place-items: center; }
.practice ol li b { color: var(--text); font-weight: 600; }
.practice .tools { margin-top: 1.1rem; padding-top: 0.9rem; border-top: 1px solid var(--line-soft); font-family: var(--mono); font-size: 0.76rem; color: var(--faint); }
.practice .tools b { color: var(--muted); font-weight: 500; }

/* Rust · on-device */
.rustbox { background: linear-gradient(180deg, rgba(224,138,90,0.07), rgba(224,138,90,0)); border: 1px solid rgba(224,138,90,0.3); border-left: 3px solid #e08a5a; border-radius: 4px; padding: 1.2rem 1.3rem 1.3rem; margin: 1.8rem 0; }
.rustbox .tag { font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.12em; text-transform: uppercase; color: #e08a5a; display: block; margin-bottom: 0.6rem; }
.rustbox p { color: var(--muted); font-size: 0.93rem; line-height: 1.65; margin-bottom: 0.7rem; }
.rustbox p:last-child { margin-bottom: 0; }
.rustbox b { color: #f0b48f; font-weight: 600; }
.rustbox code { font-family: var(--mono); font-size: 0.85em; background: rgba(224,138,90,0.1); border: 1px solid rgba(224,138,90,0.2); border-radius: 3px; padding: 0.1em 0.4em; color: #f0b48f; }
.rustbox pre.code { margin-top: 0.8rem; }
.rustbox .crates { display: flex; flex-wrap: wrap; gap: 0.4rem; margin-top: 0.9rem; }
.rustbox .crate { font-family: var(--mono); font-size: 0.72rem; color: #e8a882; border: 1px solid rgba(224,138,90,0.3); border-radius: 2px; padding: 0.28rem 0.5rem; background: rgba(224,138,90,0.05); }
.rustbox a.crate:hover { border-color: #e08a5a; color: #f0b48f; }

/* En el teléfono — nota de enfoque on-device */
.ondevice { background: rgba(92,200,232,0.05); border: 1px solid rgba(92,200,232,0.22); border-left: 3px solid #5cc8e8; border-radius: 4px; padding: 1rem 1.2rem; margin: 1.6rem 0; }
.ondevice .tag { font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.12em; text-transform: uppercase; color: #5cc8e8; display: block; margin-bottom: 0.45rem; }
.ondevice p { color: #b8cdd6; font-size: 0.92rem; line-height: 1.6; margin: 0; }
.ondevice p b { color: #d3e7ef; }

/* readings: tipo por color de badge */
.reading .rk.doc { color: #5cc8e8; }
.reading .rk.video { color: #e08a5a; }
.reading .rk.repo { color: #a98bf0; }

/* KaTeX display equations */
.math-block { margin: 1.4rem 0; padding: 1rem 1.1rem; background: var(--panel-2); border: 1px solid var(--line); border-left: 3px solid var(--green); border-radius: 4px; overflow-x: auto; }
.math-block .katex-display { margin: 0; }
.math-block .katex { color: #e6ede6; font-size: 1.05em; }
.math-note { font-family: var(--mono); font-size: 0.74rem; color: var(--faint); margin-top: 0.6rem; }
.lesson-body .katex { color: #e6ede6; }

/* lecturas / PDFs */
.readings { margin: 1.4rem 0; display: grid; gap: 0.6rem; }
.reading {
    display: flex; align-items: baseline; gap: 0.8rem;
    padding: 0.8rem 1rem; background: var(--panel); border: 1px solid var(--line);
    border-radius: 4px; transition: border-color 0.2s, background 0.2s;
}
.reading:hover { border-color: var(--green); background: var(--green-dim); }
.reading .rk { font-family: var(--mono); font-size: 0.68rem; letter-spacing: 0.06em; text-transform: uppercase; color: var(--green); border: 1px solid var(--line); border-radius: 2px; padding: 0.2rem 0.45rem; flex: 0 0 auto; }
.reading .rt { color: var(--text); font-weight: 500; font-size: 0.92rem; text-decoration: none; }
.reading:hover .rt { color: var(--green); }
.reading .rmeta { font-family: var(--mono); font-size: 0.72rem; color: var(--faint); margin-left: auto; flex: 0 0 auto; }

/* prev/next nav */
.lesson-nav { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin: 4rem 0 3rem; border-top: 1px solid var(--line); padding-top: 2rem; }
.lesson-nav a { display: flex; flex-direction: column; gap: 0.3rem; padding: 1rem 1.2rem; border: 1px solid var(--line); border-radius: 4px; background: var(--panel); transition: border-color 0.2s, background 0.2s; }
.lesson-nav a:hover { border-color: var(--green); background: var(--green-dim); }
.lesson-nav .dir { font-family: var(--mono); font-size: 0.72rem; color: var(--faint); letter-spacing: 0.08em; }
.lesson-nav .ttl { color: var(--text); font-weight: 500; font-size: 0.95rem; }
.lesson-nav a:hover .ttl { color: var(--green); }
.lesson-nav .next { text-align: right; }
.lesson-nav .disabled { opacity: 0.35; pointer-events: none; }

/* progress dots (which module) */
.lesson-progress { display: flex; flex-wrap: wrap; gap: 0.3rem; margin-top: 1.3rem; }
.lesson-progress span { width: 10px; height: 10px; border-radius: 50%; border: 1px solid var(--line); background: var(--panel-2); font-size: 0; }
.lesson-progress span.done { background: var(--green-dim); border-color: var(--green); }
.lesson-progress span.cur { background: var(--green); border-color: var(--green); }

@media (max-width: 900px) {
    .p-signature { grid-template-columns: 1fr; }
    .p-layout { grid-template-columns: 1fr; gap: 1.5rem; }
    .p-rail { display: none; }
    .loss-grid, .stages-grid { grid-template-columns: 1fr; }
    .p-bottom { grid-template-columns: 1fr; }
    .lesson-nav { grid-template-columns: 1fr; }
}
@media (max-width: 560px) {
    .p-hero { padding: 6.5rem 0 2rem; }
    .dist-row { grid-template-columns: 6.5em 1fr 2.5em; }
    .breadcrumb { padding-top: 6.5rem; }
}
@media (prefers-reduced-motion: reduce) {
    * { animation: none !important; transition: none !important; scroll-behavior: auto !important; }
}