/* ============================================================
   MINH DUONG MATH — Chương Trình Học
   Dùng chung cho /chuong-trinh/ và các trang con lop-10/11/12
   ============================================================ */

/* ── Main Curriculum Overview ────────────────────────────────── */
.curriculum-intro {
    background: var(--white);
    padding: clamp(2.5rem, 8vw, 5rem) clamp(1rem, 4%, 2.5rem);
    text-align: center;
}

.grade-cards-section {
    background: var(--cream);
    padding: clamp(2.5rem, 8vw, 4rem) clamp(1rem, 4%, 2.5rem);
}

.grade-cards {
    display: grid;
    grid-template-columns: 1fr;
    gap: clamp(1rem, 3vw, 1.5rem);
    max-width: 960px;
    margin: clamp(1.5rem, 4vw, 2.5rem) auto 0;
}

@media (min-width: 640px) { .grade-cards { grid-template-columns: repeat(3, 1fr); } }

.grade-card {
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: clamp(1.5rem, 4%, 2rem);
    text-decoration: none;
    color: inherit;
    transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    position: relative;
    overflow: hidden;
}

.grade-card::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 4px;
    background: var(--primary-dark);
}

.grade-card:nth-child(2)::before { background: var(--primary-light); }
.grade-card:nth-child(3)::before { background: var(--gold); }

.grade-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-hover);
    border-color: var(--primary-light);
}

.grade-card__grade {
    font-size: clamp(0.75rem, 1.5vw, 0.8125rem);
    font-weight: 700;
    color: var(--primary-light);
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

.grade-card__name {
    font-family: 'Playfair Display', serif;
    font-size: clamp(1.1rem, 2.5vw, 1.375rem);
    font-weight: 700;
    color: var(--text-dark);
    line-height: 1.25;
}

.grade-card__meta {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.grade-card__stat {
    font-size: clamp(0.75rem, 1.5vw, 0.8125rem);
    color: var(--text-gray);
}

.grade-card__stat strong {
    color: var(--primary-dark);
    font-weight: 700;
}

.grade-card__arrow {
    margin-top: auto;
    font-size: 0.8125rem;
    color: var(--primary-light);
    font-weight: 500;
}

/* ── Grade Sub-nav ───────────────────────────────────────────── */
.grade-nav {
    background: var(--white);
    border-bottom: 1px solid var(--border);
    padding: 0 clamp(1rem, 4%, 2.5rem);
    display: flex;
    gap: 0;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
}

.grade-nav::-webkit-scrollbar { display: none; }

.grade-nav__link {
    padding: 0.875rem 1.25rem;
    text-decoration: none;
    color: var(--text-gray);
    font-size: clamp(0.8125rem, 1.6vw, 0.9375rem);
    font-weight: 500;
    border-bottom: 3px solid transparent;
    transition: color var(--transition), border-color var(--transition);
    white-space: nowrap;
    flex-shrink: 0;
}

.grade-nav__link:hover { color: var(--primary-dark); }

.grade-nav__link--active {
    color: var(--primary-dark);
    border-bottom-color: var(--primary-dark);
    font-weight: 600;
}

/* ── Stats Bar ───────────────────────────────────────────────── */
.stats-bar {
    background: var(--primary-pale);
    border-bottom: 1px solid var(--border);
    padding: 1rem clamp(1rem, 4%, 2.5rem);
    display: flex;
    gap: clamp(1.5rem, 5vw, 3.5rem);
    flex-wrap: wrap;
    align-items: center;
}

.stats-bar__item {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.stats-bar__value {
    font-family: 'Playfair Display', serif;
    font-size: clamp(1.25rem, 2.5vw, 1.625rem);
    font-weight: 700;
    color: var(--primary-dark);
    line-height: 1;
}

.stats-bar__label {
    font-size: clamp(0.6875rem, 1.2vw, 0.75rem);
    color: var(--text-gray);
    text-transform: uppercase;
    letter-spacing: 0.06em;
}

/* ── Chapter List ────────────────────────────────────────────── */
.chapter-section {
    background: var(--cream);
    padding: clamp(2rem, 6vw, 3.5rem) clamp(1rem, 4%, 2.5rem);
}

.chapter-section__title {
    font-family: 'Playfair Display', serif;
    font-size: clamp(1rem, 2vw, 1.125rem);
    color: var(--text-gray);
    margin-bottom: clamp(1.25rem, 3vw, 1.75rem);
    max-width: 960px;
    margin-left: auto;
    margin-right: auto;
}

.chapter-list {
    display: flex;
    flex-direction: column;
    gap: clamp(0.625rem, 1.5vw, 0.875rem);
    max-width: 960px;
    margin: 0 auto;
}

/* ── Chapter Card ────────────────────────────────────────────── */
.chapter-card {
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    overflow: hidden;
    transition: box-shadow var(--transition);
}

.chapter-card:hover { box-shadow: var(--shadow-card); }
.chapter-card--open { box-shadow: var(--shadow-card); }

.chapter-card__header {
    display: grid;
    grid-template-columns: auto 1fr auto auto;
    align-items: center;
    gap: clamp(0.625rem, 2vw, 1rem);
    padding: clamp(0.875rem, 3%, 1.125rem) clamp(1rem, 4%, 1.5rem);
    cursor: pointer;
    user-select: none;
    background: var(--white);
    transition: background var(--transition);
    -webkit-tap-highlight-color: transparent;
}

.chapter-card__header:hover { background: var(--primary-pale); }

.chapter-card--open .chapter-card__header { background: var(--primary-pale); }

.chapter-card__num {
    width: clamp(28px, 5vw, 34px);
    height: clamp(28px, 5vw, 34px);
    border-radius: 50%;
    background: var(--primary-dark);
    color: var(--white);
    font-size: clamp(0.6875rem, 1.4vw, 0.8125rem);
    font-weight: 700;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.chapter-card__name {
    font-size: clamp(0.8125rem, 1.7vw, 0.9375rem);
    font-weight: 600;
    color: var(--text-dark);
    line-height: 1.35;
}

.chapter-card__actions {
    display: flex;
    align-items: center;
    gap: 6px;
    flex-shrink: 0;
}

.chapter-card__badge {
    background: var(--primary-pale);
    color: var(--primary-dark);
    border-radius: var(--radius-pill);
    padding: 3px 10px;
    font-size: clamp(0.6875rem, 1.2vw, 0.75rem);
    font-weight: 700;
    white-space: nowrap;
    flex-shrink: 0;
}

.chapter-card__doc {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 3px 10px;
    border-radius: var(--radius-pill);
    font-size: clamp(0.6875rem, 1.2vw, 0.75rem);
    font-weight: 600;
    white-space: nowrap;
    text-decoration: none;
    flex-shrink: 0;
    transition: background var(--transition), color var(--transition), border-color var(--transition);
    border: 1.5px solid var(--border);
    color: var(--text-gray);
    background: var(--white);
    cursor: default;
    line-height: 1.4;
}

.chapter-card__doc--active {
    border-color: var(--primary-light);
    color: var(--primary-dark);
    cursor: pointer;
}

.chapter-card__doc--active:hover {
    background: var(--primary-dark);
    border-color: var(--primary-dark);
    color: var(--white);
}

.chapter-card__doc svg {
    width: 11px;
    height: 11px;
    flex-shrink: 0;
}

.chapter-card__chevron {
    width: 18px;
    height: 18px;
    color: var(--text-gray);
    transition: transform 0.3s ease;
    flex-shrink: 0;
}

.chapter-card--open .chapter-card__chevron { transform: rotate(180deg); }

/* ── Chapter Body ────────────────────────────────────────────── */
.chapter-card__body {
    display: none;
    border-top: 1px solid var(--border);
}

.chapter-card--open .chapter-card__body { display: block; }

/* ── Level Row ───────────────────────────────────────────────── */
.level-row {
    display: grid;
    grid-template-columns: clamp(110px, 18%, 150px) auto 1fr;
    gap: clamp(0.75rem, 2vw, 1.25rem);
    align-items: start;
    padding: clamp(0.875rem, 3%, 1.125rem) clamp(1rem, 4%, 1.5rem);
    border-bottom: 1px solid var(--border);
}

.level-row:last-child { border-bottom: none; }

@media (max-width: 599px) {
    .level-row { grid-template-columns: 1fr; gap: 0.375rem; }
    .level-row__sessions { align-self: auto; }
}

.level-row__name {
    font-size: clamp(0.6875rem, 1.3vw, 0.75rem);
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.07em;
    padding-top: 3px;
}

.level-row--nhan-biet  .level-row__name { color: #1f7a45; }
.level-row--thong-hieu .level-row__name { color: var(--primary-dark); }
.level-row--van-dung   .level-row__name { color: #8b5a00; }

.level-row__sessions {
    background: var(--cream-warm);
    border: 1px solid var(--border);
    border-radius: var(--radius-pill);
    padding: 2px 10px;
    font-size: clamp(0.6875rem, 1.2vw, 0.75rem);
    font-weight: 600;
    color: var(--text-gray);
    white-space: nowrap;
    align-self: start;
    margin-top: 1px;
}

.level-row__content {
    font-size: clamp(0.75rem, 1.4vw, 0.8125rem);
    color: var(--text-gray);
    line-height: 1.7;
}

/* ── Content Formatting ──────────────────────────────────────── */
.ct-topic {
    display: block;
    color: var(--text-dark);
    font-weight: 500;
    margin-top: 0.5rem;
    margin-bottom: 1px;
}

.ct-topic:first-child { margin-top: 0; }

.ct-exercise {
    display: block;
    padding-left: 1.125rem;
    position: relative;
    color: var(--text-gray);
    margin-bottom: 1px;
}

.ct-exercise::before {
    content: '→';
    position: absolute;
    left: 0;
    color: var(--primary-light);
    font-size: 0.65rem;
    top: 2px;
}

.ct-plain {
    display: block;
    color: var(--text-gray);
}

/* ── CTA Section ─────────────────────────────────────────────── */
.curriculum-cta {
    background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary-light) 100%);
    color: var(--white);
    padding: clamp(2.5rem, 8vw, 3.75rem) clamp(1rem, 4%, 2.5rem);
    text-align: center;
}

.curriculum-cta h2 { color: var(--white); margin-bottom: 0.75rem; }
.curriculum-cta p  { color: rgba(255,255,255,0.9); margin-bottom: clamp(1.25rem, 3vw, 1.75rem); font-size: clamp(0.9rem, 2vw, 1.05rem); }