:root {
    --bg: #0f172a;
    --panel: #1e293b;
    --panel-dark: #0f172a;
    --text: #e2e8f0;
    --text-muted: #94a3b8;
    --text-subtle: #64748b;
    --border: #334155;
    --border-faint: #1e293b;
    --accent: #38bdf8;
    --accent-bg: #0ea5e9;
    --accent-light: #7dd3fc;
    --accent-soft: rgba(56, 189, 248, 0.1);
    --accent-border: rgba(56, 189, 248, 0.3);
    --warning-bg: rgba(245, 158, 11, 0.15);
    --warning-text: #fbbf24;
    --warning-border: rgba(245, 158, 11, 0.3);
    --info-bg: rgba(59, 130, 246, 0.15);
    --info-text: #60a5fa;
    --info-border: rgba(59, 130, 246, 0.3);
    --danger-bg: rgba(239, 68, 68, 0.15);
    --danger-text: #f87171;
    --danger-border: rgba(239, 68, 68, 0.3);
    --success-text: #34d399;
}

/* ----------------------------- Root Container ----------------------------- */
.lesson-slider {
    display: grid;
    grid-template-rows: 1fr auto auto;
    gap: 0.75rem;
    padding: 0.5rem;
    height: 100vh;
    min-height: 500px;
    max-height: 900px;
    background: var(--bg);
    color: var(--text);
    font-family: 'Noto Sans', sans-serif;
    box-sizing: border-box;
}

/* --------------------------------- Stage ---------------------------------- */
.lesson-slider__stage {
    position: relative;
    min-height: 0;
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: 0.75rem;
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    overflow: hidden;
    display: grid;
    grid-template-rows: auto 1fr;
}

.lesson-slider__progress-track {
    height: 0.375rem;
    background: var(--panel-dark);
    border-bottom: 1px solid var(--border-faint);
}

.lesson-slider__progress {
    height: 100%;
    background: var(--accent);
    width: 0;
}

.lesson-slider__slides {
    position: relative;
    min-height: 0;
    overflow: hidden;
}

.lesson-slider__slide {
    position: absolute;
    inset: 0;
    padding: 1rem;
    overflow-y: auto;
    background: var(--panel-dark);
}

/* --------------------------------- Nav ------------------------------------ */
.lesson-slider__nav {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    align-items: center;
    gap: 0.75rem;
}

.lesson-slider__nav-button {
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    border: 1px solid var(--border);
    background: var(--panel);
    color: var(--text);
    transition: opacity 0.2s;
}

.lesson-slider__nav-button--prev {
    justify-self: start;
}

.lesson-slider__nav-button--next {
    justify-self: end;
    background: var(--accent-bg);
    color: #fff;
    border-color: transparent;
}

.lesson-slider__nav-button:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}

.lesson-slider__page-indicator {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-muted);
}

/* --------------------------------- Dots ----------------------------------- */
.lesson-slider__dots {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(1.75rem, auto));
    gap: 0.5rem;
    justify-content: center;
}

.lesson-slider__dot {
    width: 1.75rem;
    height: 1.75rem;
    border-radius: 9999px;
    font-size: 0.75rem;
    font-weight: 600;
    border: 1px solid var(--border);
    cursor: pointer;
    background: var(--panel-dark);
    color: var(--text-muted);
    transition: transform 0.2s;
}

.lesson-slider__dot--active {
    background: var(--accent);
    border-color: transparent;
    color: var(--bg);
}

/* --------------------------- Common Slide Content ------------------------- */
.lesson-slider__slide-content {
    display: grid;
    grid-auto-flow: row;
    align-content: center;
    height: 100%;
    justify-content: center;
    align-items: center;
}

.lesson-slider__badge {
    display: inline-block;
    align-self: start;
    padding: 0.375rem 0.75rem;
    border-radius: 9999px;
    border: 1px solid;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 1rem;
}

/* Badge variants */
.lesson-slider__badge--title,
.lesson-slider__badge--objectives,
.lesson-slider__badge--controlled,
.lesson-slider__badge--freer,
.lesson-slider__badge--speaking,
.lesson-slider__badge--wrapup {
    background: var(--accent-soft);
    color: var(--accent-light);
    border-color: var(--accent-border);
}

.lesson-slider__badge--warmup {
    background: var(--warning-bg);
    color: var(--warning-text);
    border-color: var(--warning-border);
}

.lesson-slider__badge--presentation,
.lesson-slider__badge--clarification,
.lesson-slider__badge--listening,
.lesson-slider__badge--homework {
    background: var(--info-bg);
    color: var(--info-text);
    border-color: var(--info-border);
}

.lesson-slider__badge--feedback {
    background: var(--danger-bg);
    color: var(--danger-text);
    border-color: var(--danger-border);
}

.lesson-slider__heading {
    font-weight: 700;
    color: var(--text);
    margin-top: 0.5rem;
    margin-bottom: 0.75rem;
}

h1.lesson-slider__heading {
    font-size: clamp(1.5rem, 4vw, 2.25rem);
}

h2.lesson-slider__heading {
    font-size: clamp(1.25rem, 3.5vw, 1.875rem);
}

.lesson-slider__level {
    font-size: 1rem;
    color: var(--text-muted);
    margin-bottom: 0.75rem;
}

.lesson-slider__meta {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(max-content, auto));
    justify-content: center;
    align-items: center;
    gap: 0.5rem;
    color: var(--text);
}

.lesson-slider__meta-item {
    background: var(--panel);
    padding: 0.375rem 0.75rem;
    border-radius: 9999px;
    font-size: 0.75rem;
    border: 1px solid var(--border);
}

.lesson-slider__emoji {
    margin-top: 1.5rem;
    font-size: 2.5rem;
}

/* -------------------------------- Images & Lists ------------------------- */
.lesson-slider__image {
    background: var(--panel-dark);
    border: 1px solid var(--border-faint);
    border-radius: 0.75rem;
    padding: 1rem;
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.lesson-slider__list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.lesson-slider__list-item {
    margin-bottom: 0.375rem;
    color: var(--text);
    font-size: 0.875rem;
}

.lesson-slider__questions,
.lesson-slider__exercises,
.lesson-slider__activities,
.lesson-slider__instructions,
.lesson-slider__review-questions,
.lesson-slider__homework-tasks {
    display: grid;
    grid-auto-flow: row;
    gap: 0.5rem;
}

/* ------------------------------- Objectives ------------------------------- */
.lesson-slider__objectives {
    display: grid;
    gap: 0.5rem;
}

.lesson-slider__objective {
    background: var(--accent-soft);
    border-left: 4px solid var(--accent);
    padding: 0.75rem;
    border-radius: 0 0.5rem 0.5rem 0;
    color: var(--text);
    font-size: 0.875rem;
}

.lesson-slider__objective-text {
    color: var(--text);
}

/* ------------------------------ Presentation ------------------------------ */
.lesson-slider__dialogue {
    background: var(--panel-dark);
    border: 1px solid var(--border-faint);
    border-radius: 0.75rem;
    padding: 1rem;
    color: var(--text);
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
}

.lesson-slider__dialogue-line {
    display: grid;
    grid-template-columns: auto 1fr;
    align-items: baseline;
    gap: 0.25rem;
    margin: 0.25rem 0;
}

.lesson-slider__speaker {
    font-weight: 700;
    color: var(--text);
}

.lesson-slider__dialogue-text--highlight {
    background: var(--warning-bg);
    color: var(--warning-text);
    border: 1px solid var(--warning-border);
    padding: 0 0.25rem;
    border-radius: 0.25rem;
}

.lesson-slider__target-language {
    margin-top: 0.75rem;
    font-size: 0.75rem;
    color: var(--text-muted);
}

/* ------------------------------ Clarification ----------------------------- */
.lesson-slider__sections {
    display: grid;
    grid-template-columns: 1fr;
    gap: 0.75rem;
}

.lesson-slider__section-card {
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: 0.75rem;
    padding: 0.75rem;
}

.lesson-slider__section-title {
    font-weight: 700;
    margin-bottom: 0.375rem;
    font-size: 0.875rem;
    color: var(--text);
}

.lesson-slider__section-content {
    color: var(--text);
    font-size: 0.75rem;
    line-height: 1.5;
}

/* ------------------------------ Controlled -------------------------------- */
.lesson-slider__exercise,
.lesson-slider__activity,
.lesson-slider__instruction,
.lesson-slider__review-question,
.lesson-slider__homework-task {
    color: var(--text);
    font-size: 0.875rem;
    margin: 0;
}

.lesson-slider__extra {
    margin-top: 1rem;
}

.lesson-slider__extra-block {
    margin-bottom: 0.75rem;
}

.lesson-slider__extra-heading {
    font-weight: 700;
    font-size: 0.875rem;
    color: var(--text);
    margin-bottom: 0.25rem;
}

.lesson-slider__extra-paragraph {
    color: var(--text);
    font-size: 0.75rem;
    line-height: 1.5;
    margin: 0;
}

/* --------------------------------- Freer ----------------------------------- */
.lesson-slider__cards {
    display: grid;
    grid-template-columns: 1fr;
    gap: 0.75rem;
}

.lesson-slider__role-card {
    border-radius: 0.75rem;
    padding: 0.75rem;
    border: 1px solid var(--border);
    background: var(--panel);
}

.lesson-slider__card-title {
    font-weight: 700;
    font-size: 0.875rem;
    color: var(--text);
}

.lesson-slider__card-text {
    color: var(--text);
    font-size: 0.75rem;
    margin-top: 0.375rem;
}

/* ------------------------------ Speaking / Prod ---------------------------- */
.lesson-slider__success-criteria {
    margin-top: 1rem;
    background: var(--accent-soft);
    border: 1px solid var(--accent-border);
    border-radius: 0.75rem;
    padding: 0.75rem;
}

.lesson-slider__success-title {
    font-weight: 700;
    font-size: 0.75rem;
    color: var(--accent-light);
}

.lesson-slider__success-text {
    color: var(--text);
    font-size: 0.75rem;
    margin-top: 0.25rem;
}

/* -------------------------------- Feedback -------------------------------- */
.lesson-slider__mistakes {
    display: grid;
    grid-auto-flow: row;
    gap: 0.5rem;
}

.lesson-slider__mistake {
    display: grid;
    grid-template-columns: auto auto 1fr;
    align-items: center;
    gap: 0.5rem;
    background: var(--danger-bg);
    border: 1px solid var(--danger-border);
    border-radius: 0.5rem;
    padding: 0.625rem 0.75rem;
    color: var(--danger-text);
    font-size: 0.75rem;
}

.lesson-slider__mistake-wrong {
    color: var(--danger-text);
}

.lesson-slider__mistake-arrow {
    color: var(--text-subtle);
}

.lesson-slider__mistake-right {
    font-weight: 600;
    color: var(--success-text);
}

.lesson-slider__praise {
    margin-top: 0.75rem;
    font-size: 0.875rem;
    color: var(--text);
}

.lesson-slider__self-correct {
    margin-top: 0.375rem;
    font-size: 0.75rem;
    color: var(--text-muted);
}

/* -------------------------------- Wrap-up --------------------------------- */
.lesson-slider__vocab {
    margin-top: 0.75rem;
    background: var(--panel-dark);
    border: 1px solid var(--border-faint);
    border-radius: 0.75rem;
    padding: 0.75rem;
}

.lesson-slider__vocab-title {
    font-weight: 600;
    color: var(--text);
    margin-bottom: 0.375rem;
    font-size: 0.75rem;
}

.lesson-slider__vocab-text {
    color: var(--text);
    font-size: 0.875rem;
}

.lesson-slider__quiz {
    margin-top: 0.75rem;
    background: var(--accent-soft);
    border: 1px solid var(--accent-border);
    border-radius: 0.75rem;
    padding: 0.75rem;
}

.lesson-slider__quiz-title {
    font-weight: 600;
    color: var(--accent-light);
    margin-bottom: 0.375rem;
    font-size: 0.75rem;
}

.lesson-slider__quiz-content {
    color: var(--text);
    font-size: 0.875rem;
}

/* ----------------------------- Rich Text Helpers -------------------------- */
.lesson-slider__slide-content strong {
    font-weight: 700;
}

.lesson-slider__slide-content em {
    font-style: italic;
}

.lesson-slider__slide-content a {
    color: var(--accent-light);
    text-decoration: underline;
}

/* ----------------------------- Responsive -------------------------------- */
@media (min-width: 640px) {
    .lesson-slider__sections,
    .lesson-slider__cards {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .lesson-slider__slide {
        padding: 1.25rem;
    }
}