:root {
    --lw-navbar-h: 72px;
    --lw-rail-w: 360px;
    --lw-rail-min: 240px;
    --lw-resizer-w: 8px;
}

#lecture-detail.lecture-detail-workspace {
    position: fixed;
    top: var(--lw-navbar-h);
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 10;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.lw-host {
    display: flex;
    flex-direction: column;
    min-height: 0;
    overflow: hidden;
    background:
        radial-gradient(ellipse 60% 40% at 50% -10%, rgba(16, 185, 129, 0.04), transparent 60%),
        var(--color-bg-primary);
}

/* Top bar */
.lw-topbar {
    display: grid;
    grid-template-columns: auto 1fr auto auto;
    align-items: center;
    gap: 1.25rem;
    padding: 0.85rem 1.5rem;
    background: rgba(17, 24, 39, 0.78);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--color-border-subtle);
    position: sticky;
    top: 0;
    z-index: 50;
    flex-shrink: 0;
}

.lw-back { display: flex; align-items: center; gap: 0.4rem; }

.lw-topbar-title {
    display: flex;
    align-items: baseline;
    gap: 0.5rem;
    min-width: 0;
    overflow: hidden;
    white-space: nowrap;
    text-overflow: ellipsis;
}
.lw-topbar-num {
    font-size: 0.72rem;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--color-accent);
}
.lw-topbar-sep { color: var(--color-text-muted); opacity: 0.5; }
.lw-topbar-lec {
    font-size: 0.92rem;
    font-weight: 600;
    color: var(--color-text-primary);
}

.lw-topbar-progress {
    display: flex;
    align-items: center;
    gap: 0.7rem;
    min-width: 180px;
}
.lw-topbar-bar {
    flex: 1;
    height: 5px;
    background: var(--color-border-soft);
    border-radius: 100px;
    overflow: hidden;
    position: relative;
}
.lw-topbar-bar span {
    position: absolute;
    inset: 0 auto 0 0;
    background: linear-gradient(90deg, var(--color-accent), var(--color-accent-hover));
    border-radius: 100px;
    transition: width 0.35s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: 0 0 8px rgba(16, 185, 129, 0.4);
}
.lw-topbar-count {
    font-size: 0.72rem;
    font-weight: 700;
    color: var(--color-text-secondary);
    font-variant-numeric: tabular-nums;
    min-width: 36px;
    text-align: right;
}

.lw-topbar-actions {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* Launch buttons */
.lw-launch-group {
    display: inline-flex;
    align-items: stretch;
    border-radius: var(--radius-md);
    background: linear-gradient(180deg, rgba(16, 185, 129, 0.08), rgba(16, 185, 129, 0.02));
    border: 1px solid var(--color-accent-30);
    overflow: hidden;
    box-shadow:
        inset 0 1px 0 rgba(255, 255, 255, 0.04),
        0 6px 16px rgba(0, 0, 0, 0.25);
}
.lw-launch-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.45rem 0.85rem;
    font-size: 0.78rem;
    font-weight: 600;
    border: none;
    border-radius: 0;
    box-shadow: none;
    white-space: nowrap;
    transition: background var(--transition-fast), color var(--transition-fast);
}
.lw-launch-btn + .lw-launch-btn { border-left: 1px solid var(--color-accent-30); }
.lw-launch-desktop {
    background: linear-gradient(180deg, var(--color-accent), #0ea271);
    color: #04140d;
}
.lw-launch-desktop:hover {
    background: linear-gradient(180deg, var(--color-accent-hover), var(--color-accent));
    color: #04140d;
}
.lw-launch-terminal { background: transparent; color: var(--color-accent); }
.lw-launch-terminal:hover { background: rgba(16, 185, 129, 0.12); color: var(--color-accent-hover); }
.lw-launch-btn svg { flex-shrink: 0; }

@media (max-width: 720px) {
    .lw-launch-btn span { display: none; }
    .lw-launch-btn      { padding: 0.45rem 0.65rem; }
}

/* Grid + resizer */
.lw-grid {
    display: grid;
    grid-template-columns: var(--lw-rail-w) var(--lw-resizer-w) minmax(0, 1fr);
    grid-template-rows: minmax(0, 1fr);
    flex: 1;
    min-height: 0;
    overflow: hidden;
}
.lw-grid-compact {
    --lw-rail-w: 280px;
    --lw-rail-min: 200px;
}

.lw-resizer {
    position: relative;
    cursor: col-resize;
    background: transparent;
    z-index: 5;
    touch-action: none;
    user-select: none;
}
.lw-resizer::before {
    content: '';
    position: absolute;
    top: 0;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 2px;
    background: var(--color-border-soft);
    transition: background 0.15s ease, box-shadow 0.15s ease;
    pointer-events: none;
}
.lw-resizer::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 4px;
    height: 36px;
    transform: translate(-50%, -50%);
    background: rgba(156, 163, 175, 0.25);
    border-radius: 2px;
    transition: background 0.15s ease;
    pointer-events: none;
}
.lw-resizer:hover::before,
.lw-resizer.is-dragging::before {
    background: var(--color-accent);
    box-shadow: 0 0 8px rgba(16, 185, 129, 0.5);
}
.lw-resizer:hover::after,
.lw-resizer.is-dragging::after { background: var(--color-accent); }

body.lw-resizing,
body.lw-resizing * {
    cursor: col-resize !important;
    user-select: none !important;
}
body.lw-resizing iframe { pointer-events: none; }

/* Rail */
.lw-rail {
    background: rgba(10, 15, 26, 0.6);
    border-right: 1px solid var(--color-border-subtle);
    overflow-y: auto;
    overflow-x: hidden;
    min-height: 0;
    padding: 1.5rem 1rem 2rem;
    position: relative;
}
.lw-rail::-webkit-scrollbar       { width: 6px; }
.lw-rail::-webkit-scrollbar-track { background: transparent; }
.lw-rail::-webkit-scrollbar-thumb { background: var(--color-border-soft); border-radius: 100px; }
.lw-rail::after {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    width: 1px;
    background: linear-gradient(180deg, transparent, rgba(16, 185, 129, 0.08) 30%, rgba(16, 185, 129, 0.08) 70%, transparent);
    pointer-events: none;
}

.lw-rail-top {
    padding: 0 0.5rem 1.25rem;
    border-bottom: 1px solid var(--color-border-subtle);
    margin-bottom: 1rem;
}
.lw-rail-eyebrow {
    display: block;
    font-size: 0.62rem;
    font-weight: 700;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--color-accent);
    margin-bottom: 0.45rem;
}
.lw-rail-title {
    font-size: 1rem;
    font-weight: 700;
    color: var(--color-text-primary);
    margin: 0 0 0.5rem;
    letter-spacing: -0.01em;
    line-height: 1.3;
}

.lw-rail-nav {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

/* Chapter */
.lw-chapter { position: relative; padding: 0.4rem 0 0.55rem; }
.lw-chapter + .lw-chapter {
    border-top: 1px solid rgba(255, 255, 255, 0.04);
    margin-top: 0.25rem;
    padding-top: 0.85rem;
}

.lw-ch-head {
    display: grid;
    grid-template-columns: 36px 1fr auto;
    align-items: center;
    gap: 0.6rem;
    padding: 0.4rem 0.55rem;
    margin-bottom: 0.2rem;
    border-radius: var(--radius-sm);
    user-select: none;
    transition: background 0.18s ease;
}
.lw-ch-head-jump,
.lw-ch-head-toggle           { cursor: pointer; }
.lw-ch-head-jump:hover,
.lw-ch-head-toggle:hover     { background: rgba(255, 255, 255, 0.03); }
.lw-ch-head-jump:focus-visible,
.lw-ch-head-toggle:focus-visible {
    outline: 2px solid rgba(16, 185, 129, 0.4);
    outline-offset: 1px;
}

.lw-chapter.is-active .lw-ch-head        { background: rgba(16, 185, 129, 0.06); }
.lw-chapter-collapsible .lw-ch-head      { grid-template-columns: 36px 1fr auto auto; }

.lw-ch-toggle {
    width: 20px;
    height: 20px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text-muted);
    transition: color 0.2s ease;
    margin-left: 0.25rem;
}
.lw-ch-toggle svg {
    width: 12px;
    height: 12px;
    transform: rotate(90deg);
    transition: transform 0.25s ease;
}
.lw-chapter.is-collapsed .lw-ch-toggle svg { transform: rotate(0deg); }
.lw-chapter.is-active    .lw-ch-toggle      { color: var(--color-accent); }

.lw-ch-body { overflow: hidden; transition: max-height 0.3s cubic-bezier(0.4, 0, 0.2, 1); }
.lw-chapter-reading .lw-ch-body { display: none; }

.lw-ch-ring {
    --ring-deg: 0deg;
    width: 32px;
    height: 32px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.72rem;
    font-weight: 700;
    color: var(--color-text-secondary);
    background: conic-gradient(var(--color-accent) var(--ring-deg), var(--color-border-soft) 0deg);
    position: relative;
    font-variant-numeric: tabular-nums;
}
.lw-ch-ring::before {
    content: '';
    position: absolute;
    inset: 3px;
    background: var(--color-bg-primary);
    border-radius: 50%;
    z-index: 0;
}
.lw-ch-ring > *  { position: relative; z-index: 1; }
.lw-ch-ring svg  { color: var(--color-accent); }
.lw-ch-ring-read {
    background: rgba(75, 85, 99, 0.15);
    color: var(--color-text-muted);
    font-size: 0.68rem;
}
.lw-ch-ring-read::before { display: none; }

.lw-ch-head-text {
    min-width: 0;
    display: flex;
    flex-direction: column;
    gap: 0.1rem;
}
.lw-ch-eyebrow {
    font-size: 0.58rem;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--color-text-muted);
}
.lw-chapter.is-active .lw-ch-eyebrow { color: var(--color-accent); }

.lw-ch-title {
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--color-text-primary);
    margin: 0;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    line-height: 1.3;
}

.lw-ch-stats {
    font-size: 0.68rem;
    font-weight: 700;
    color: var(--color-text-muted);
    font-variant-numeric: tabular-nums;
    padding: 0.15rem 0.45rem;
    background: rgba(75, 85, 99, 0.2);
    border-radius: 100px;
    white-space: nowrap;
}
.lw-ch-stats-read {
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
}
.lw-ch-stats-read svg { opacity: 0.7; }

/* Track-coloured group / chip / marker:
   Each group sets the track palette via custom properties; group, chip, and
   marker selectors all read from the same vars so we don't repeat the trio. */
.lw-group {
    --track-color: var(--color-accent);
    --track-soft:  var(--color-accent-10);
    --track-edge:  var(--color-accent-30);
    --track-glow:  rgba(16, 185, 129, 0.4);
    margin-top: 0.75rem;
    padding-left: 0.4rem;
    border-left: 2px solid var(--track-edge);
}
.lw-group:first-child { margin-top: 0.3rem; }

.lw-group-semi-guided {
    --track-color: var(--color-info-soft);
    --track-soft:  var(--color-info-10);
    --track-edge:  var(--color-info-30);
    --track-glow:  rgba(59, 130, 246, 0.4);
}
.lw-group-challenge {
    --track-color: var(--color-purple-soft);
    --track-soft:  var(--color-purple-10);
    --track-edge:  var(--color-purple-30);
    --track-glow:  rgba(139, 92, 246, 0.4);
}

.lw-group-header {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.25rem 0.5rem 0.4rem;
}
.lw-group-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--track-color);
    box-shadow: 0 0 8px var(--track-glow);
    flex-shrink: 0;
}
.lw-group-title {
    flex: 1;
    font-size: 0.62rem;
    font-weight: 700;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--track-color);
}
.lw-group-count {
    font-size: 0.62rem;
    font-weight: 700;
    color: var(--color-text-muted);
    font-variant-numeric: tabular-nums;
    padding: 0.1rem 0.4rem;
    background: rgba(75, 85, 99, 0.2);
    border-radius: 100px;
}

/* Step list */
.lw-step-list {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    gap: 0.15rem;
}
.lw-step-item {
    display: grid;
    grid-template-columns: 28px 1fr auto;
    align-items: center;
    gap: 0.65rem;
    padding: 0.5rem 0.65rem;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: background 0.15s ease;
    position: relative;
}
.lw-step-item:hover            { background: rgba(255, 255, 255, 0.03); }
.lw-step-item.is-active {
    background: rgba(16, 185, 129, 0.09);
    box-shadow: inset 2px 0 0 var(--color-accent);
}

.lw-step-marker {
    width: 30px;
    height: 24px;
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.68rem;
    font-weight: 700;
    font-family: var(--font-mono);
    letter-spacing: 0.04em;
    font-variant-numeric: tabular-nums;
    background: rgba(75, 85, 99, 0.18);
    color: var(--color-text-muted);
    border: 1px solid rgba(75, 85, 99, 0.28);
    transition: all 0.2s ease;
    flex-shrink: 0;
}
.lw-step-marker-ex {
    background: var(--track-soft);
    color: var(--track-color);
    border-color: var(--track-edge);
}
.lw-step-marker-read {
    width: 24px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.04);
}

.lw-step-item.is-active .lw-step-marker {
    color: var(--color-accent);
    border-color: var(--color-accent);
    background: rgba(16, 185, 129, 0.14);
    box-shadow: 0 0 0 1px var(--color-accent-20), 0 0 12px rgba(16, 185, 129, 0.18);
}
.lw-step-item.is-done .lw-step-marker {
    background: var(--color-accent);
    color: #fff;
    border-color: var(--color-accent);
}

.lw-step-text {
    display: flex;
    flex-direction: column;
    gap: 0.1rem;
    min-width: 0;
}
.lw-step-title {
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--color-text-secondary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    line-height: 1.3;
}
.lw-step-item.is-active .lw-step-title {
    color: var(--color-text-primary);
    font-weight: 600;
}

.lw-step-check {
    width: 18px;
    height: 18px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-accent);
    opacity: 0;
    transform: scale(0.6);
    transition: opacity 0.2s ease, transform 0.2s ease;
}
.lw-step-item.is-done .lw-step-check { opacity: 1; transform: scale(1); }

.lw-step-item.is-locked {
    opacity: 0.4;
    cursor: not-allowed;
    pointer-events: none;
}
.lw-step-item.is-locked .lw-step-marker {
    background: rgba(75, 85, 99, 0.12);
    color: rgba(156, 163, 175, 0.6);
    border-color: rgba(75, 85, 99, 0.2);
}

/* ---------- Stage ---------- */
.lw-stage {
    display: flex;
    flex-direction: column;
    min-width: 0;
    min-height: 0;
    position: relative;
    background: var(--color-bg-primary);
}
.lw-stage-inner {
    flex: 1;
    display: flex;
    flex-direction: column;
    min-height: 0;
}
.lw-stage-header {
    padding: 2rem 3rem 1.5rem;
    border-bottom: 1px solid rgba(75, 85, 99, 0.12);
    background: radial-gradient(ellipse 60% 100% at 0% 0%, rgba(16, 185, 129, 0.04), transparent 50%);
    flex-shrink: 0;
}

.lw-stage-crumb {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.7rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--color-text-muted);
    margin-bottom: 0.85rem;
}
.lw-crumb-chapter { color: var(--color-accent); }
.lw-crumb-sep     { opacity: 0.4; font-weight: 400; }
.lw-crumb-pos     { font-variant-numeric: tabular-nums; }

.lw-stage-chips {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1rem;
}
.lw-chip {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0.25rem 0.7rem;
    font-size: 0.7rem;
    font-weight: 700;
    letter-spacing: 0.04em;
    border-radius: 100px;
    border: 1px solid transparent;
    white-space: nowrap;
}
.lw-chip-read {
    background: rgba(255, 255, 255, 0.04);
    color: var(--color-text-secondary);
    border-color: rgba(75, 85, 99, 0.25);
}
.lw-chip-letter {
    background: rgba(17, 24, 39, 0.6);
    color: var(--color-text-secondary);
    border-color: var(--color-border-soft);
    font-family: var(--font-mono);
    font-variant-numeric: tabular-nums;
    letter-spacing: 0.04em;
}
.lw-chip-dim    { color: var(--color-text-muted); font-weight: 500; margin-left: 0.1rem; }
.lw-chip-track  { text-transform: uppercase; letter-spacing: 0.1em; font-size: 0.62rem; }

.lw-chip-guided      { background: var(--color-accent-10); color: var(--color-accent-hover); border-color: var(--color-accent-30); }
.lw-chip-semi-guided { background: var(--color-info-10);   color: var(--color-info-soft);    border-color: var(--color-info-30); }
.lw-chip-challenge   { background: var(--color-purple-10); color: var(--color-purple-soft);  border-color: var(--color-purple-30); }

.lw-stage-title {
    font-size: 2rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    margin: 0;
    line-height: 1.15;
    background: linear-gradient(135deg, #ffffff 0%, #d1d5db 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}
.lw-stage-sub {
    font-size: 1rem;
    color: var(--color-text-secondary);
    margin: 0.6rem 0 0;
    line-height: 1.55;
}

.lw-stage-body {
    flex: 1;
    overflow-y: auto;
    padding: 2rem 3rem;
    scroll-behavior: smooth;
}
.lw-stage-body::-webkit-scrollbar       { width: 8px; }
.lw-stage-body::-webkit-scrollbar-track { background: transparent; }
.lw-stage-body::-webkit-scrollbar-thumb { background: var(--color-border-soft); border-radius: 100px; }

.lw-stage-body > *:first-child { margin-top: 0; }
.lw-stage-body > *:last-child  { margin-bottom: 0; }

.lw-stage-body p {
    font-size: 1rem;
    line-height: 1.75;
    color: var(--color-text-secondary);
    margin: 0 0 1rem;
    max-width: 760px;
}
.lw-stage-body h2 { font-size: 1.5rem;  font-weight: 700; color: var(--color-text-primary); margin: 1.5rem 0 1rem;    letter-spacing: -0.01em; }
.lw-stage-body h3 { font-size: 1.15rem; font-weight: 700; color: var(--color-text-primary); margin: 1.25rem 0 0.6rem; }
.lw-stage-body h4 { font-size: 0.98rem; font-weight: 700; color: var(--color-text-primary); margin: 1rem 0 0.5rem; }

.lw-stage-body ul, .lw-stage-body ol {
    padding-left: 1.25rem;
    margin: 0 0 1rem;
    max-width: 760px;
}
.lw-stage-body li {
    font-size: 1rem;
    line-height: 1.7;
    color: var(--color-text-secondary);
    margin-bottom: 0.35rem;
}

/* ---------- Exercise body ---------- */
.lw-ex {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    max-width: 860px;
}
.lw-ex-explain {
    font-size: 1rem;
    line-height: 1.7;
    color: var(--color-text-secondary);
    padding: 1.25rem 1.5rem;
    background: rgba(17, 24, 39, 0.5);
    border-left: 3px solid var(--color-accent);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
}
.lw-ex-explain code,
.lw-theory-body code {
    background: var(--color-accent-10);
    color: var(--color-accent);
    padding: 0.15rem 0.4rem;
    border-radius: 3px;
    font-size: 0.88em;
}

.lw-theory {
    position: relative;
    padding: 1.35rem 1.5rem 1.4rem;
    background:
        radial-gradient(ellipse 80% 60% at 0% 0%, rgba(16, 185, 129, 0.06), transparent 60%),
        rgba(17, 24, 39, 0.55);
    border: 1px solid var(--color-border-subtle);
    border-left: 3px solid var(--color-accent);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.02);
}
.lw-theory-head {
    display: flex;
    align-items: center;
    gap: 0.55rem;
    margin-bottom: 0.65rem;
}
.lw-theory-mark {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 22px;
    height: 22px;
    border-radius: 6px;
    background: var(--color-accent-muted);
    color: var(--color-accent);
    border: 1px solid var(--color-accent-30);
    flex-shrink: 0;
}
.lw-theory-label {
    font-size: 0.7rem;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--color-accent);
    line-height: 1;
}
.lw-theory-body {
    margin: 0;
    font-size: 1rem;
    line-height: 1.7;
    color: var(--color-text-secondary);
}

/* ---------- Footer ---------- */
.lw-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    padding: 1rem 3rem;
    border-top: 1px solid var(--color-border-subtle);
    background: rgba(10, 15, 26, 0.5);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    flex-shrink: 0;
}
.lw-prev, .lw-next {
    display: inline-flex;
    align-items: center;
    gap: 0.45rem;
    font-weight: 600;
}

/* ---------- Inline context blocks ---------- */
.lw-inline-context {
    margin-top: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}
.lw-inline-context:empty { display: none; }

.lw-inline-block {
    padding: 1rem 1.15rem;
    background: rgba(17, 24, 39, 0.5);
    border: 1px solid var(--color-border-subtle);
    border-radius: var(--radius-md);
}
.lw-inline-eyebrow {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    font-size: 0.6rem;
    font-weight: 700;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--color-accent);
    margin-bottom: 0.5rem;
}
.lw-inline-block p {
    font-size: 0.88rem;
    color: var(--color-text-secondary);
    line-height: 1.55;
    margin: 0;
}

.lw-inline-objective { border-left: 3px solid var(--color-accent); }
.lw-inline-output    { border-left: 3px solid var(--color-info); }
.lw-inline-tip       { border-left: 3px solid var(--color-purple); }

.lw-inline-check {
    border-left: 3px solid var(--color-warning);
    background: linear-gradient(180deg, rgba(245, 158, 11, 0.04) 0%, rgba(17, 24, 39, 0.5) 60%);
}
.lw-inline-check .lw-inline-eyebrow { color: var(--color-warning-soft); }

.lw-inline-check-q {
    font-size: 0.92rem;
    color: var(--color-text-primary);
    line-height: 1.55;
    margin: 0 0 0.6rem;
    font-weight: 500;
}
.lw-inline-check-q code,
.lw-inline-check-answer code {
    background: var(--color-warning-10);
    color: var(--color-warning-soft);
    border: 1px solid rgba(245, 158, 11, 0.25);
    border-radius: 4px;
    padding: 0.05rem 0.35rem;
    font-family: var(--font-mono);
    font-size: 0.85em;
}

.lw-inline-check-reveal {
    border-radius: var(--radius-sm);
    background: rgba(17, 24, 39, 0.55);
    border: 1px dashed rgba(245, 158, 11, 0.3);
    overflow: hidden;
    transition: border-color 0.15s ease;
}
.lw-inline-check-reveal[open] {
    border-style: solid;
    border-color: rgba(245, 158, 11, 0.45);
}
.lw-inline-check-reveal summary {
    list-style: none;
    cursor: pointer;
    padding: 0.5rem 0.75rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0.5rem;
    font-size: 0.7rem;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--color-warning-soft);
    user-select: none;
    transition: background 0.15s ease;
}
.lw-inline-check-reveal summary::-webkit-details-marker { display: none; }
.lw-inline-check-reveal summary:hover                   { background: rgba(245, 158, 11, 0.06); }
.lw-inline-check-reveal summary svg                     { transition: transform 0.2s ease; opacity: 0.65; }
.lw-inline-check-reveal[open] summary svg               { transform: rotate(90deg); }

.lw-inline-check-answer {
    padding: 0.65rem 0.75rem;
    border-top: 1px solid rgba(245, 158, 11, 0.2);
    font-family: var(--font-mono);
    font-size: 0.84rem;
    color: var(--color-text-primary);
    background: rgba(0, 0, 0, 0.18);
    word-break: break-all;
}

.lw-inline-output pre {
    background: var(--color-bg-primary);
    border: 1px solid var(--color-border-soft);
    border-radius: var(--radius-sm);
    padding: 0.7rem;
    overflow-x: auto;
    font-size: 0.76rem;
    line-height: 1.55;
    max-height: 180px;
    overflow-y: auto;
}
.lw-inline-output code {
    color: var(--color-text-secondary);
    font-family: var(--font-mono);
    white-space: pre;
}

/* ---------- Responsive ---------- */
@media (max-width: 1200px) { .lw-grid { --lw-rail-w: 320px; } }

@media (max-width: 900px) {
    .lw-grid,
    .lw-grid-compact {
        grid-template-columns: 1fr;
        grid-template-rows: auto minmax(0, 1fr);
    }
    .lw-rail {
        max-height: 200px;
        min-height: 0;
        border-right: none;
        border-bottom: 1px solid var(--color-border-subtle);
    }
    .lw-resizer       { display: none; }
    .lw-stage-header  { padding: 1rem 1rem 0.75rem; }
    .lw-stage-body    { padding: 1rem; }
    .lw-footer        { padding: 0.75rem 1rem; gap: 0.75rem; }
    .lw-stage-title   { font-size: 1.35rem; }
    .lw-topbar        { grid-template-columns: auto 1fr auto; gap: 0.75rem; padding: 0.65rem 0.75rem; }
    .lw-topbar-title  { display: none; }
    .lw-topbar-progress { min-width: 100px; }
}

/* ---------- Compact (split-view) overrides ---------- */
.split-panel-lecture .lw-host         { height: 100%; }
.split-panel-lecture .lw-stage-header { padding: 1rem 1.25rem 0.75rem; }
.split-panel-lecture .lw-stage-body   { padding: 1rem 1.25rem; }
.split-panel-lecture .lw-stage-title  { font-size: 1.25rem; }
.split-panel-lecture .lw-footer       { padding: 0.6rem 1rem; gap: 0.75rem; justify-content: space-between; }
.split-panel-lecture .lw-rail         { padding: 0.75rem 0.6rem 1rem; min-width: 0; }
.split-panel-lecture .lw-rail-title   { font-size: 0.88rem; }
.split-panel-lecture .lw-ch-title,
.split-panel-lecture .lw-step-title   { white-space: normal; }
.split-panel-lecture .lw-grid-compact { --lw-rail-w: 260px; --lw-rail-min: 190px; }
.split-panel-lecture .lw-prev,
.split-panel-lecture .lw-next         { font-size: 0.82rem; padding: 0.4rem 0.75rem; }