/* Course detail, "Khối màu" — the 'new' arm of the course experiment.
 *
 * Loaded instead of page-course-detail.css. Every colour is stated outright:
 * design-system.css styles bare elements and claims anything left to inherit.
 * Prefixed .cd2- so it cannot collide with the old page's .cd- classes.
 *
 * House rules: radius 0, no shadow, no gradient, no translucency.
 */

body,.cd2-hero,.cd2-sec,.cd2-shop,.cd2-strip{
  --d2-ink:#0a0a0a; --d2-paper:#fff; --d2-dim:#6b7280; --d2-lab:#9aa1ab; --d2-hair:#e6e6e6;
  --d2-blue:#1a3aff; --d2-orange:#e8501e; --d2-green:#0f7a4a;
  --d2-font:'Be Vietnam Pro',system-ui,-apple-system,'Segoe UI',Roboto,sans-serif;
  --d2-pad:clamp(20px,5vw,72px);
}
.cd2-hero,.cd2-sec,.cd2-shop,.cd2-strip{font-family:var(--d2-font)}
.cd2-hero *,.cd2-sec *,.cd2-shop *,.cd2-strip *{box-sizing:border-box}
.cd2-in{max-width:1240px;margin:0 auto;padding-left:var(--d2-pad);padding-right:var(--d2-pad)}

.cd2-k{font-size:11px;letter-spacing:.2em;text-transform:uppercase;font-weight:700;
  color:var(--d2-blue);text-decoration:none;display:inline-block}
.cd2-k-dim{color:rgba(255,255,255,.6)}
.cd2-h2{font-size:clamp(26px,4vw,44px);line-height:1.08;letter-spacing:-.04em;font-weight:800;
  margin:12px 0 0;color:var(--d2-ink)}
.cd2-dark .cd2-h2{color:#fff}
.cd2-sub{font-size:clamp(14px,1.5vw,16.5px);line-height:1.55;color:var(--d2-dim);margin:12px 0 0;
  max-width:60ch}
.cd2-dark .cd2-sub{color:rgba(255,255,255,.7)}
.cd2-sec{padding:clamp(44px,6vw,84px) 0;background:var(--d2-paper)}
.cd2-dark{background:var(--d2-ink)}
.cd2-head{display:flex;align-items:flex-end;justify-content:space-between;gap:24px;
  flex-wrap:wrap;margin-bottom:clamp(24px,3.4vw,40px)}
.cd2-more{font-size:12.5px;font-weight:700;text-decoration:none;color:var(--d2-ink);
  border-bottom:2px solid currentColor;white-space:nowrap}

/* ── buttons ── */
.cd2-btn{display:inline-block;padding:15px 28px;font-weight:800;font-size:15px;text-decoration:none;
  border:2px solid var(--d2-ink);background:var(--d2-ink);color:#fff;border-radius:0;
  letter-spacing:-.01em;line-height:1.2;font-family:inherit;cursor:pointer}
.cd2-cta{display:flex;gap:12px;flex-wrap:wrap;margin-top:26px}
.cd2-hero .cd2-btn-on,.cd2-strip .cd2-btn-on{background:#fff;color:var(--d2-ink);border-color:#fff}
.cd2-hero .cd2-btn-on:hover,.cd2-strip .cd2-btn-on:hover{background:#f0f0f0;border-color:#f0f0f0}
.cd2-hero .cd2-btn-ghost{background:transparent;color:#fff;border-color:#fff}
.cd2-hero .cd2-btn-ghost:hover{background:#fff;color:var(--d2-ink)}

/* ── hero ── */
.cd2-hero{background:var(--d2-blue);color:#fff;padding:clamp(40px,6vw,80px) 0}
.cd2-hero .cd2-k{color:rgba(255,255,255,.92);border-bottom:1px solid rgba(255,255,255,.5)}
.cd2-hero .cd2-k:hover{color:#fff;border-bottom-color:#fff}
.cd2-h1{font-size:clamp(30px,5vw,60px);line-height:1.06;letter-spacing:-.045em;font-weight:800;
  margin:16px 0 0;max-width:20ch;color:#fff}
.cd2-lead{font-size:clamp(14.5px,1.6vw,18px);line-height:1.5;margin:16px 0 0;max-width:56ch;
  color:rgba(255,255,255,.88)}
.cd2-note{font-size:13px;line-height:1.5;color:rgba(255,255,255,.75);margin:14px 0 0;max-width:52ch}
.cd2-note a{color:#fff;font-weight:700;text-decoration:underline;text-underline-offset:3px}

.cd2-facts{display:flex;flex-wrap:wrap;gap:0;margin-top:28px;border-top:1px solid rgba(255,255,255,.3)}
.cd2-facts > div{padding:16px 26px 16px 0;margin-right:26px;
  border-right:1px solid rgba(255,255,255,.22)}
.cd2-facts > div:last-child{border-right:0;margin-right:0}
.cd2-facts b{display:block;font-size:clamp(24px,3vw,38px);font-weight:800;letter-spacing:-.045em;
  line-height:1;color:#fff;font-variant-numeric:tabular-nums}
.cd2-facts span{display:block;font-size:10.5px;letter-spacing:.14em;text-transform:uppercase;
  font-weight:700;color:rgba(255,255,255,.7);margin-top:7px}

.cd2-prog{margin-top:26px;max-width:560px}
.cd2-prog-top{display:flex;justify-content:space-between;gap:14px;flex-wrap:wrap;
  font-size:12.5px;font-weight:700;color:#fff;margin-bottom:8px}
.cd2-prog-top span:last-child{color:rgba(255,255,255,.7);font-weight:600}
.cd2-prog-bar{height:8px;background:rgba(255,255,255,.25)}
.cd2-prog-bar span{display:block;height:100%;background:#fff}

/* ── offline class ── */
.cd2-shop{background:var(--d2-green);color:#fff}
.cd2-shop-in{display:flex;align-items:center;justify-content:space-between;gap:20px;
  flex-wrap:wrap;padding-top:22px;padding-bottom:22px;text-decoration:none;color:#fff}
.cd2-shop-k{font-size:10px;letter-spacing:.18em;text-transform:uppercase;font-weight:700;
  color:rgba(255,255,255,.72)}
.cd2-shop-t{font-size:clamp(17px,2.2vw,25px);font-weight:800;letter-spacing:-.03em;margin-top:6px;
  line-height:1.2;color:#fff}
.cd2-shop-m{font-size:13px;color:rgba(255,255,255,.85);margin-top:6px}
.cd2-shop-go{font-size:14px;font-weight:800;white-space:nowrap;color:#fff}
.cd2-shop-in:hover .cd2-shop-t{text-decoration:underline;text-underline-offset:5px}

/* ── what you'll learn ── */
.cd2-learn{display:grid;grid-template-columns:1fr;border:2px solid var(--d2-ink)}
@media (min-width:700px){ .cd2-learn{grid-template-columns:1fr 1fr} }
.cd2-learn-i{display:flex;gap:13px;align-items:flex-start;padding:16px 18px;font-size:14.5px;
  line-height:1.45;font-weight:600;color:var(--d2-ink);
  border-bottom:1px solid var(--d2-hair);border-right:1px solid var(--d2-hair)}
.cd2-learn-i span{font-size:11px;font-weight:800;letter-spacing:.1em;color:var(--d2-lab);
  flex:0 0 auto;padding-top:3px;font-variant-numeric:tabular-nums}

/* ── curriculum ── */
.cd2-chapters{border:2px solid rgba(255,255,255,.3)}
.cd2-chapter{border-bottom:2px solid rgba(255,255,255,.3)}
.cd2-chapter:last-child{border-bottom:0}
.cd2-chapter-h{display:flex;align-items:baseline;gap:12px;padding:15px 18px;
  background:rgba(255,255,255,.06)}
.cd2-chapter-n{font-size:11px;font-weight:800;letter-spacing:.12em;color:rgba(255,255,255,.5);
  font-variant-numeric:tabular-nums}
.cd2-chapter-t{font-size:15px;font-weight:800;letter-spacing:-.025em;color:#fff;flex:1;
  min-width:0}
.cd2-chapter-c{font-size:10.5px;letter-spacing:.12em;text-transform:uppercase;font-weight:700;
  color:rgba(255,255,255,.5);white-space:nowrap}
.cd2-lesson{display:flex;align-items:center;justify-content:space-between;gap:14px;
  padding:12px 18px;border-top:1px solid rgba(255,255,255,.12);text-decoration:none;color:#fff}
.cd2-lesson:hover{background:rgba(255,255,255,.1)}
.cd2-lesson-t{font-size:14px;font-weight:600;line-height:1.4;color:#fff}
.cd2-lesson-go{font-size:13px;color:rgba(255,255,255,.45);flex:0 0 auto}
.cd2-lesson:hover .cd2-lesson-go{color:#fff}

.cd2-tests{margin-top:26px;border:2px solid rgba(255,255,255,.3)}
.cd2-tests-h{font-size:10px;letter-spacing:.18em;text-transform:uppercase;font-weight:700;
  color:rgba(255,255,255,.5);padding:13px 18px;border-bottom:1px solid rgba(255,255,255,.22)}
.cd2-test{display:flex;align-items:center;justify-content:space-between;gap:14px;padding:13px 18px;
  border-bottom:1px solid rgba(255,255,255,.12);text-decoration:none;color:#fff}
.cd2-test:last-child{border-bottom:0}
.cd2-test:hover{background:rgba(255,255,255,.1)}
.cd2-test-t{font-size:14px;font-weight:700;color:#fff}
.cd2-test-go{font-size:12px;font-weight:700;color:rgba(255,255,255,.6);white-space:nowrap}
.cd2-test:hover .cd2-test-go{color:#fff}

/* ── AI prompts ── */
.cd2-prompts{display:grid;grid-template-columns:1fr;border:2px solid var(--d2-ink)}
@media (min-width:820px){ .cd2-prompts{grid-template-columns:1fr 1fr} }
.cd2-prompt{display:block;width:100%;text-align:left;background:var(--d2-paper);border:0;
  border-bottom:2px solid var(--d2-ink);border-right:2px solid var(--d2-ink);border-radius:0;
  padding:18px 20px;cursor:pointer;font-family:inherit}
.cd2-prompt:hover{background:#fafafa}
.cd2-prompt.is-done{background:#f0fdf4}
.cd2-prompt-l{display:block;font-size:10px;letter-spacing:.16em;text-transform:uppercase;
  font-weight:700;color:var(--d2-lab)}
.cd2-prompt-t{display:block;font-size:13.5px;line-height:1.5;color:var(--d2-ink);margin-top:8px;
  font-weight:500}
.cd2-prompt-c{display:inline-block;font-size:11px;letter-spacing:.12em;text-transform:uppercase;
  font-weight:700;color:var(--d2-blue);margin-top:11px}

/* ── related ── */
.cd2-rel{display:grid;grid-template-columns:1fr;border:2px solid var(--d2-ink)}
@media (min-width:700px){ .cd2-rel{grid-template-columns:1fr 1fr} }
@media (min-width:1100px){ .cd2-rel{grid-template-columns:repeat(4,1fr)} }
.cd2-rel-i{display:block;padding:18px 18px 20px;text-decoration:none;color:var(--d2-ink);
  border-bottom:2px solid var(--d2-ink);border-right:2px solid var(--d2-ink)}
.cd2-rel-i:hover{background:var(--d2-ink)}
.cd2-rel-t{display:block;font-size:15.5px;font-weight:800;letter-spacing:-.028em;line-height:1.25;
  color:var(--d2-ink)}
.cd2-rel-m{display:block;font-size:11.5px;font-weight:600;color:var(--d2-lab);margin-top:8px}
.cd2-rel-i:hover .cd2-rel-t{color:#fff}
.cd2-rel-i:hover .cd2-rel-m{color:rgba(255,255,255,.66)}

/* ── closing strip ── */
.cd2-strip{background:var(--d2-orange);color:#fff;padding:clamp(30px,4vw,52px) 0}
.cd2-strip-in{display:flex;gap:24px;align-items:center;justify-content:space-between;flex-wrap:wrap}
.cd2-strip-t{font-size:clamp(19px,2.6vw,32px);font-weight:800;letter-spacing:-.032em;
  line-height:1.15;margin:0;color:#fff;max-width:26ch}
.cd2-strip-s{font-size:13.5px;line-height:1.55;color:rgba(255,255,255,.86);margin:8px 0 0;
  max-width:56ch}

/* ── defensive ─────────────────────────────────────────────────────────────
   design-system.css styles bare elements — a{color:var(--primary)} and a:hover
   at (0,1,1), which outranks a plain .cd2-lesson (0,1,0). Every rule below is
   (0,2,0) or more so it wins on specificity, not on load order. */
.cd2-layout a.cd2-lesson,.cd2-layout a.cd2-lesson:hover,
.cd2-layout a.cd2-test,.cd2-layout a.cd2-test:hover,
.cd2-layout a.cd2-shop-in,.cd2-layout a.cd2-shop-in:hover{color:#fff;text-decoration:none}
.cd2-layout a.cd2-rel-i,.cd2-layout a.cd2-rel-i:link,
.cd2-layout a.cd2-rel-i:visited{color:var(--d2-ink);text-decoration:none}
.cd2-layout a.cd2-rel-i:hover .cd2-rel-t{color:#fff}
.cd2-layout a.cd2-rel-i:hover .cd2-rel-m{color:rgba(255,255,255,.66)}
.cd2-layout a.cd2-more,.cd2-layout a.cd2-more:hover{color:var(--d2-ink)}
.cd2-layout .cd2-hero a.cd2-k{color:rgba(255,255,255,.92)}
.cd2-layout .cd2-hero a.cd2-k:hover{color:#fff}
.cd2-layout .cd2-note a,.cd2-layout .cd2-note a:hover{color:#fff}
.cd2-layout a.cd2-btn,.cd2-layout a.cd2-btn:hover{text-decoration:none}
.cd2-layout .cd2-hero a.cd2-btn-on,.cd2-layout .cd2-strip a.cd2-btn-on,
.cd2-layout .cd2-hero a.cd2-btn-on:hover,.cd2-layout .cd2-strip a.cd2-btn-on:hover{
  color:var(--d2-ink)}
.cd2-layout .cd2-hero a.cd2-btn-ghost{color:#fff}
.cd2-layout .cd2-hero a.cd2-btn-ghost:hover{color:var(--d2-ink)}
.cd2-layout .cd2-learn-i{color:var(--d2-ink)}
.cd2-layout .cd2-learn-i span{color:var(--d2-lab)}
.cd2-layout .cd2-prompt-t{color:var(--d2-ink)}
.cd2-layout .cd2-prompt-l{color:var(--d2-lab)}
.cd2-layout .cd2-prompt-c{color:var(--d2-blue)}
.cd2-layout .cd2-strip-t{color:#fff}
.cd2-layout .cd2-strip-s{color:rgba(255,255,255,.86)}