/* frontend/css/academia.css */
/* Version: 1.0.0 - একাডেমিয়া পেজের স্টাইল */

/* ===== একাডেমিয়া পেজ ===== */
#academiaPage {
    padding: 20px 30px;
    min-height: calc(100vh - 60px);
    background: var(--bg);
}

#academiaContent {
    max-width: 1200px;
    margin: 0 auto;
}

/* ===== ব্রেডক্রাম্ব ===== */
.academia-breadcrumb {
    padding: 12px 0 16px;
    margin-bottom: 20px;
    border-bottom: 2px solid var(--border);
    display: flex;
    align-items: center;
    gap: 6px;
    flex-wrap: wrap;
    font-size: 0.9rem;
}

.breadcrumb-item {
    color: var(--text-light);
}

.breadcrumb-item.active {
    color: var(--accent);
    font-weight: 600;
}

.breadcrumb-link {
    color: var(--accent);
    cursor: pointer;
    transition: all var(--transition);
    padding: 2px 8px;
    border-radius: 4px;
}

.breadcrumb-link:hover {
    background: rgba(33, 150, 243, 0.1);
    color: var(--accent-dark);
}

.breadcrumb-separator {
    color: var(--text-light);
    font-weight: 300;
}

/* ===== শ্রেণি গ্রিড ===== */
.class-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    padding: 10px 0;
}

.class-card {
    background: var(--card);
    border-radius: 16px;
    padding: 28px 20px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    border: 2px solid transparent;
    box-shadow: 0 2px 12px var(--shadow);
    position: relative;
    overflow: hidden;
}

.class-card::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--accent);
    transform: scaleX(0);
    transition: transform 0.3s ease;
}

.class-card:hover::after {
    transform: scaleX(1);
}

.class-card:hover {
    transform: translateY(-6px);
    border-color: var(--accent);
    box-shadow: 0 8px 30px var(--shadow);
}

.class-icon {
    font-size: 2.8rem;
    display: block;
    margin-bottom: 10px;
}

.class-name {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 4px;
}

.class-subjects {
    font-size: 0.82rem;
    color: var(--text-light);
    line-height: 1.4;
}

.class-badge {
    display: inline-block;
    margin-top: 10px;
    padding: 3px 14px;
    background: var(--accent);
    color: white;
    border-radius: 20px;
    font-size: 0.7rem;
    font-weight: 500;
}

/* ===== বিষয় গ্রিড ===== */
.subject-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 14px;
    padding: 10px 0;
}

.subject-card {
    background: var(--card);
    border-radius: 12px;
    padding: 16px 20px;
    display: flex;
    align-items: center;
    gap: 16px;
    cursor: pointer;
    transition: all 0.3s ease;
    border: 1px solid var(--border);
}

.subject-card:hover {
    transform: translateX(6px);
    border-color: var(--accent);
    box-shadow: 0 4px 16px var(--shadow);
}

.subject-icon {
    font-size: 2rem;
    flex-shrink: 0;
    width: 48px;
    text-align: center;
}

.subject-info {
    flex: 1;
}

.subject-name {
    font-size: 1rem;
    font-weight: 500;
    color: var(--text);
}

.subject-desc {
    font-size: 0.8rem;
    color: var(--text-light);
}

.subject-arrow {
    font-size: 1.2rem;
    color: var(--text-light);
    transition: transform 0.3s ease;
}

.subject-card:hover .subject-arrow {
    transform: translateX(4px);
    color: var(--accent);
}

/* ===== অধ্যায় লিস্ট ===== */
.chapter-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
    padding: 10px 0;
}

.chapter-card {
    background: var(--card);
    border-radius: 12px;
    overflow: hidden;
    border: 1px solid var(--border);
    transition: all 0.3s ease;
}

.chapter-card:hover {
    border-color: var(--accent);
}

.chapter-header {
    padding: 16px 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    transition: background 0.2s ease;
}

.chapter-header:hover {
    background: var(--bg);
}

.chapter-info {
    display: flex;
    align-items: center;
    gap: 14px;
    flex-wrap: wrap;
}

.chapter-number {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--accent);
    background: rgba(33, 150, 243, 0.1);
    padding: 2px 14px;
    border-radius: 20px;
}

.chapter-name {
    font-size: 1rem;
    color: var(--text);
    font-weight: 500;
}

.chapter-toggle {
    font-size: 0.8rem;
    color: var(--text-light);
    transition: transform 0.3s ease;
    padding: 4px 8px;
    border-radius: 4px;
}

.chapter-toggle:hover {
    background: var(--bg);
}

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

.chapter-body {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease;
    background: var(--bg);
}

.chapter-body.open {
    max-height: 800px;
}

/* ===== টপিক লিস্ট ===== */
.topic-list {
    padding: 12px 20px 20px;
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.topic-card {
    display: flex;
    align-items: center;
    gap: 14px;
    padding: 10px 16px;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.2s ease;
    border: 1px solid transparent;
    background: var(--card);
}

.topic-card:hover {
    background: var(--card);
    border-color: var(--accent);
    transform: translateX(4px);
    box-shadow: 0 2px 8px var(--shadow);
}

.topic-icon {
    font-size: 1.2rem;
    flex-shrink: 0;
}

.topic-name {
    flex: 1;
    font-size: 0.92rem;
    color: var(--text);
}

.topic-badge {
    font-size: 0.7rem;
    padding: 2px 12px;
    border-radius: 20px;
    font-weight: 500;
}

.topic-badge.note {
    background: rgba(33, 150, 243, 0.12);
    color: var(--accent);
}

.topic-badge.quiz {
    background: rgba(76, 175, 80, 0.12);
    color: var(--success);
}

/* ===== কন্টেন্ট ভিউয়ার ===== */
.content-viewer {
    background: var(--card);
    border-radius: 12px;
    border: 1px solid var(--border);
    overflow: hidden;
    margin-top: 10px;
}

.content-header {
    padding: 16px 20px;
    border-bottom: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--bg);
    flex-wrap: wrap;
    gap: 10px;
}

.content-title {
    font-size: 1.05rem;
    font-weight: 500;
    color: var(--text);
    display: flex;
    align-items: center;
    gap: 10px;
}

.content-actions {
    display: flex;
    gap: 10px;
}

.content-body {
    min-height: 200px;
}

/* ===== ডার্ক মোড ===== */
body.dark .class-card {
    background: #2d2d2d;
}

body.dark .subject-card {
    background: #2d2d2d;
}

body.dark .chapter-card {
    background: #2d2d2d;
}

body.dark .topic-card {
    background: #1a1a1a;
}

body.dark .topic-card:hover {
    background: #2d2d2d;
}

body.dark .content-viewer {
    background: #2d2d2d;
}

body.dark .content-header {
    background: #1a1a1a;
}

/* ===== রেসপনসিভ ===== */
@media (max-width: 768px) {
    #academiaPage {
        padding: 10px 15px;
    }
    
    .class-grid {
        grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
        gap: 14px;
    }
    
    .subject-grid {
        grid-template-columns: 1fr;
    }
    
    .chapter-header {
        padding: 14px 16px;
        flex-wrap: wrap;
        gap: 8px;
    }
    
    .chapter-info {
        flex-wrap: wrap;
    }
    
    .content-header {
        flex-direction: column;
        align-items: flex-start;
    }
}

@media (max-width: 480px) {
    .class-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 10px;
    }
    
    .class-card {
        padding: 16px 12px;
    }
    
    .class-icon {
        font-size: 2rem;
    }
    
    .class-name {
        font-size: 0.85rem;
    }
    
    .class-subjects {
        font-size: 0.7rem;
    }
    
    .topic-card {
        padding: 8px 12px;
    }
}

/* ============================================================
   ✅ Phase 2 Additions: Skeleton, Error States, Loading
   ============================================================ */

/* ===== Loading Skeleton ===== */
.content-skeleton {
    padding: 20px;
}

.skeleton-line {
    height: 16px;
    background: linear-gradient(
        90deg,
        var(--bg) 0%,
        var(--border) 50%,
        var(--bg) 100%
    );
    background-size: 200% 100%;
    animation: skeleton-shimmer 1.5s ease-in-out infinite;
    border-radius: 6px;
    margin-bottom: 12px;
}

.skeleton-title {
    height: 28px;
    width: 60%;
    margin-bottom: 20px;
}

.skeleton-short {
    width: 40%;
}

@keyframes skeleton-shimmer {
    0% { background-position: 200% 0; }
    100% { background-position: -200% 0; }
}

/* ===== Error State ===== */
.content-error {
    padding: 60px 20px;
    text-align: center;
    background: var(--card);
    border-radius: 12px;
    border: 2px solid var(--danger, #f44336);
    margin: 10px 0;
}

.content-error-icon {
    font-size: 4rem;
    margin-bottom: 16px;
}

.content-error-title {
    font-size: 1.3rem;
    color: var(--danger, #f44336);
    margin-bottom: 12px;
    font-weight: 700;
}

.content-error-message {
    color: var(--text);
    margin-bottom: 8px;
    font-size: 0.95rem;
    white-space: pre-wrap;
    word-break: break-word;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.content-error-hint {
    font-size: 0.85rem;
    color: var(--text-light);
    margin-bottom: 20px;
}

.content-error-hint code {
    background: var(--bg);
    padding: 3px 10px;
    border-radius: 4px;
    font-family: monospace;
    font-size: 0.85rem;
}

.content-error-actions {
    display: flex;
    gap: 12px;
    justify-content: center;
    flex-wrap: wrap;
}

/* ===== Buttons for content actions ===== */
.btn-secondary {
    background: var(--bg);
    color: var(--text);
    border: 1px solid var(--border);
    padding: 8px 16px;
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.85rem;
    transition: all 0.2s ease;
}

.btn-secondary:hover {
    border-color: var(--accent);
    color: var(--accent);
}

.btn-sm {
    padding: 6px 12px;
    font-size: 0.8rem;
}

/* ===== Math content scoping (styles_math_sol.css overrides) ===== */
.math-content {
    color: var(--text);
    line-height: 1.6;
}

.math-content .problem-card {
    background: var(--card);
    border-left: 4px solid var(--accent);
    border-radius: 12px;
    padding: 10px 1px 20px 1px;
    margin-bottom: 20px;
    box-shadow: 0 2px 8px var(--shadow);
}

.math-content .problem-title {
    color: var(--accent);
    font-size: 1.15rem;
    font-weight: 700;
    margin-bottom: 14px;
    padding: 4px 4px 4px 8px;
    border-bottom: 2px solid var(--border);
}

.math-content .step {
    padding: 8px 14px;
    margin: 8px 0;
    background: var(--bg);
    border-radius: 6px;
    font-size: 0.95rem;
    line-height: 1.7;
    font-family: 'Times New Roman', serif;
    overflow-x: auto;
}

.math-content .step-explain {
    padding: 8px 4px 8px 4px;
    margin: 6px 0;
    color: var(--text-light);
    font-size: 0.9rem;
    line-height: 1.6;
    border-left: 3px solid var(--border);
}

.math-content .katex {
    font-size: 1.05rem;
}

.math-content .katex-display {
    margin: 14px 0;
    overflow-x: auto;
    overflow-y: hidden;
    padding: 6px 0;
}

/* ===== Dark mode ===== */
body.dark .content-skeleton .skeleton-line {
    background: linear-gradient(
        90deg,
        #2d2d2d 0%,
        #404040 50%,
        #2d2d2d 100%
    );
    background-size: 200% 100%;
    animation: skeleton-shimmer 1.5s ease-in-out infinite;
}

body.dark .content-error {
    background: #2d2d2d;
}

body.dark .math-content .problem-card {
    background: #2d2d2d;
}

body.dark .math-content .step {
    background: #1a1a1a;
}

body.dark .math-content .step-explain {
    border-left-color: #404040;
}

body.dark .btn-secondary {
    background: #1a1a1a;
    color: var(--text);
    border-color: #404040;
}

body.dark .btn-secondary:hover {
    border-color: var(--accent);
    color: var(--accent);
}

/* ===== Responsive ===== */
@media (max-width: 600px) {
    .content-error {
        padding: 40px 16px;
    }

    .content-error-icon {
        font-size: 3rem;
    }

    .content-error-title {
        font-size: 1.1rem;
    }

    .content-error-actions {
        flex-direction: column;
    }

    .content-error-actions .btn {
        width: 100%;
    }

    .math-content .problem-card {
        padding: 16px;
    }

    .math-content .step {
        font-size: 0.85rem;
        padding: 6px 10px;
    }
}