:root {
  --exercise-bg: #070808;
  --exercise-surface: #101212;
  --exercise-surface-strong: #151818;
  --exercise-border: rgba(255, 255, 255, .11);
  --exercise-border-accent: rgba(0, 229, 255, .48);
  --exercise-text: #f5f7f7;
  --exercise-muted: #a3aaad;
  --exercise-accent: #00e5ff;
  --exercise-radius: 14px;
  --exercise-shadow: 0 26px 70px rgba(0, 0, 0, .34);
}

.exercise-main {
  min-height: 72vh;
  padding: clamp(4rem, 6vw, 5.5rem) clamp(1rem, 3vw, 2rem) clamp(4.5rem, 8vw, 7rem);
  background: radial-gradient(circle at 78% 4%, rgba(0, 229, 255, .055), transparent 28rem), var(--exercise-bg);
  color: var(--exercise-text);
}

.exercise-shell { width: min(1240px, 100%); margin: 0 auto; }
.exercise-heading { max-width: 760px; margin-bottom: clamp(2rem, 5vw, 3.5rem); }
.exercise-heading h1 { margin-bottom: 1rem; font-size: clamp(2.7rem, 6vw, 5rem); line-height: .98; letter-spacing: -.035em; }
.exercise-heading p { color: var(--exercise-muted); font-size: clamp(1rem, 2vw, 1.17rem); line-height: 1.75; }
.exercise-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 290px), 1fr)); gap: 1.25rem; }
.exercise-card { display: flex; flex-direction: column; min-height: 100%; overflow: hidden; border: 1px solid var(--exercise-border); border-radius: var(--exercise-radius); background: var(--exercise-surface); transition: transform .2s ease, border-color .2s ease, box-shadow .2s ease; }
.exercise-card:hover { transform: translateY(-3px); border-color: var(--exercise-border-accent); box-shadow: 0 18px 44px rgba(0, 0, 0, .3); }
.exercise-card-media { aspect-ratio: 16 / 10; overflow: hidden; background: #050606; }
.exercise-card-media img { width: 100%; height: 100%; object-fit: cover; }
.exercise-card-body { display: flex; flex: 1; flex-direction: column; padding: 1.4rem; }
.exercise-card h2 { margin-bottom: .65rem; font-size: 1.4rem; line-height: 1.2; }
.exercise-card p { margin-bottom: 1.3rem; color: var(--exercise-muted); line-height: 1.65; }
.exercise-card-footer { display: flex; align-items: center; justify-content: space-between; gap: 1rem; margin-top: auto; }
.exercise-price { color: var(--exercise-accent); font-size: 1.12rem; font-weight: 800; }
.exercise-link { padding-bottom: .16rem; border-bottom: 1px solid var(--exercise-accent); color: #fff; text-decoration: none; }
.exercise-detail-page { min-width: 0; }
.exercise-back { display: inline-flex; align-items: center; gap: .45rem; min-height: 44px; margin-bottom: clamp(1.25rem, 3vw, 2rem); color: #b8bec1; text-decoration: none; transition: color .18s ease, transform .18s ease; }
.exercise-back-icon { width: 1.15rem; height: 1.15rem; flex: 0 0 auto; }
.exercise-back:hover { color: var(--exercise-accent); transform: translateX(-2px); }
.exercise-back:focus-visible, .exercise-buy:focus-visible, .exercise-slide-nav button:focus-visible, .exercise-resource-action:focus-visible, .exercise-secondary-link:focus-visible { outline: 2px solid var(--exercise-accent); outline-offset: 4px; }
.exercise-detail { display: grid; gap: clamp(2rem, 5vw, 4.5rem); align-items: center; }
.is-locked .exercise-detail { grid-template-columns: minmax(0, 1.08fr) minmax(320px, .92fr); }
.is-owned .exercise-detail { grid-template-columns: minmax(300px, .7fr) minmax(0, 1.3fr); align-items: start; }
.exercise-copy { min-width: 0; }
.exercise-copy h1 { max-width: 13ch; margin: 0 0 1.15rem; font-size: clamp(2.65rem, 5.4vw, 5.25rem); line-height: .96; letter-spacing: -.035em; text-wrap: balance; }
.exercise-copy .lead { max-width: 640px; color: #c8cdcf; font-size: clamp(1.08rem, 2vw, 1.25rem); line-height: 1.7; }
.exercise-long { color: var(--exercise-muted); line-height: 1.78; white-space: pre-line; }
.is-locked .exercise-long { margin: 1.45rem 0 0; }
.exercise-product-price { margin: clamp(1.8rem, 4vw, 2.8rem) 0 1.25rem; padding-top: 1.7rem; border-top: 1px solid var(--exercise-border); color: var(--exercise-accent); font-size: clamp(2rem, 4vw, 3rem); font-weight: 800; letter-spacing: -.025em; }
.exercise-buy { display: inline-flex; width: 100%; min-height: 56px; align-items: center; justify-content: center; padding: 1rem 1.4rem; border: 1px solid var(--exercise-accent); border-radius: 10px; background: var(--exercise-accent); box-shadow: 0 12px 36px rgba(0, 229, 255, .12); color: #001014; cursor: pointer; font: inherit; font-size: 1.05rem; font-weight: 850; text-decoration: none; transition: transform .18s ease, box-shadow .18s ease, background .18s ease; }
.exercise-buy:hover { transform: translateY(-2px); box-shadow: 0 16px 42px rgba(0, 229, 255, .2); background: #2feaff; }
.exercise-buy:disabled { opacity: .55; cursor: wait; transform: none; }
.exercise-purchase-note { display: grid; gap: .28rem; margin-top: 1rem; padding: 1rem 1.05rem 1rem 1.2rem; border-left: 2px solid rgba(0, 229, 255, .62); background: rgba(255, 255, 255, .025); color: var(--exercise-muted); font-size: .9rem; line-height: 1.55; }
.exercise-purchase-note strong { color: #e8ebec; font-weight: 600; }
.exercise-media { min-width: 0; }
.exercise-slides, .exercise-player-shell { position: relative; overflow: hidden; border: 1px solid var(--exercise-border); border-radius: var(--exercise-radius); background: #020303; box-shadow: var(--exercise-shadow); }
.exercise-slide { display: none; aspect-ratio: 16 / 10; place-items: center; background: #030404; }
.exercise-slide.active { display: grid; }
.exercise-slide img, .exercise-slide video, .exercise-youtube { display: block; width: 100%; height: 100%; border: 0; object-fit: contain; background: #020303; }
.exercise-slide-tabs img { filter: blur(2.5px); transform: scale(1.015); }
.exercise-slide-nav { display: flex; gap: .65rem; margin-top: .75rem; }
.exercise-slide-nav button { flex: 1; min-height: 44px; padding: .72rem 1rem; border: 1px solid var(--exercise-border); border-radius: 9px; background: #0e1010; color: var(--exercise-muted); cursor: pointer; font: inherit; transition: border-color .18s ease, color .18s ease, background .18s ease; }
.exercise-slide-nav button:hover, .exercise-slide-nav button.active { border-color: var(--exercise-border-accent); background: rgba(0, 229, 255, .045); color: var(--exercise-accent); }
.exercise-access-badge { display: inline-flex; align-items: center; gap: .6rem; margin-bottom: 1.4rem; color: var(--exercise-accent); font-size: .85rem; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; }
.exercise-access-dot { display: grid; width: 1.45rem; height: 1.45rem; place-items: center; border: 1px solid currentColor; border-radius: 50%; }
.exercise-access-dot svg { width: .9rem; height: .9rem; }
.exercise-section-heading { display: flex; align-items: center; gap: .8rem; margin-bottom: 1rem; }
.exercise-section-heading::after { width: 2rem; height: 1px; background: var(--exercise-accent); content: ''; }
.exercise-section-heading h2 { margin: 0; font-size: clamp(1.45rem, 2.6vw, 2rem); font-weight: 500; letter-spacing: .015em; }
.exercise-player-shell { display: grid; width: 100%; min-width: 0; place-items: stretch; overflow: hidden; border-radius: 12px; background: #000; }
.exercise-player-shell.is-youtube { aspect-ratio: 16 / 9; }
.exercise-player-shell .exercise-youtube { width: 100%; height: 100%; object-fit: contain; background: #000; }
.exercise-jf-player { width: 100%; min-width: 0; }
.exercise-slide.has-player { aspect-ratio: auto; }
.exercise-slide.has-player.active { display: block; }
.exercise-owned-content { display: grid; grid-template-columns: minmax(0, .85fr) minmax(360px, 1.15fr); gap: 1rem; margin-top: clamp(2rem, 4vw, 3.25rem); }
.exercise-description-panel, .exercise-materials { padding: clamp(1.35rem, 3vw, 2rem); border: 1px solid var(--exercise-border); border-radius: var(--exercise-radius); background: linear-gradient(145deg, rgba(255, 255, 255, .025), transparent), var(--exercise-surface); }
.exercise-resource { display: grid; grid-template-columns: auto minmax(0, 1fr) auto; gap: 1rem; align-items: center; padding: 1rem; border: 1px solid var(--exercise-border); border-radius: 10px; background: #0a0c0c; }
.exercise-resource-icon { display: grid; width: 48px; height: 48px; place-items: center; border: 1px solid rgba(0, 229, 255, .34); border-radius: 9px; color: var(--exercise-accent); font-size: .72rem; font-weight: 800; letter-spacing: .04em; }
.exercise-resource-copy h3 { margin: 0 0 .2rem; font-size: 1rem; }
.exercise-resource-copy p { margin: 0; color: var(--exercise-muted); font-size: .86rem; line-height: 1.5; }
.exercise-resource-action { display: inline-flex; min-height: 42px; align-items: center; justify-content: center; padding: .65rem .9rem; border: 1px solid var(--exercise-border-accent); border-radius: 8px; color: var(--exercise-accent); font-size: .88rem; font-weight: 700; text-decoration: none; transition: background .18s ease, transform .18s ease; }
.exercise-resource-action:hover { transform: translateY(-1px); background: rgba(0, 229, 255, .07); }
.purchase-panel { width: min(760px, 100%); margin: 0 auto; padding: clamp(1.5rem, 4vw, 3rem); border: 1px solid var(--exercise-border); border-radius: var(--exercise-radius); background: var(--exercise-surface); }
.purchase-panel h1 { margin: .6rem 0 .8rem; font-size: clamp(2.3rem, 5vw, 4rem); }
.purchase-panel .lead { color: var(--exercise-muted); font-size: 1.1rem; }
.purchase-actions { display: flex; gap: .8rem; flex-wrap: wrap; margin-top: 1.5rem; }
.purchase-actions .exercise-buy { width: auto; min-width: 190px; }
.exercise-secondary-link { display: inline-flex; min-height: 56px; align-items: center; justify-content: center; padding: .9rem 1.2rem; border: 1px solid var(--exercise-border); border-radius: 10px; color: #dce0e1; text-decoration: none; }
.exercise-state { padding: 3rem 0; color: var(--exercise-muted); }
.exercise-error { color: #ff8d8d; }

@media (max-width: 900px) {
  .is-locked .exercise-detail, .is-owned .exercise-detail { grid-template-columns: 1fr; }
  .is-locked .exercise-copy { order: -1; }
  .is-owned .exercise-copy h1 { max-width: 18ch; }
  .exercise-owned-content { grid-template-columns: 1fr; }
}

@media (max-width: 600px) {
  .exercise-main { padding: 4.2rem .9rem 4rem; }
  .exercise-heading h1 { font-size: 2.75rem; }
  .exercise-copy h1 { font-size: clamp(2.45rem, 14vw, 3.65rem); }
  .exercise-copy .lead { font-size: 1.03rem; }
  .exercise-back { margin-bottom: 1rem; }
  .exercise-slide-nav { flex-direction: column; }
  .exercise-resource { grid-template-columns: auto minmax(0, 1fr); }
  .exercise-resource-action { grid-column: 1 / -1; width: 100%; }
  .exercise-player-shell.is-youtube { aspect-ratio: 16 / 9; }
  .purchase-actions, .purchase-actions .exercise-buy, .exercise-secondary-link { width: 100%; }
}

@media (prefers-reduced-motion: reduce) {
  .exercise-card, .exercise-back, .exercise-buy, .exercise-resource-action { transition: none; }
}