/* Product Details Page - Clean Layout */
:root {
    --bg-dark: #0f0f0f;
    --bg-card: #1a1a1a;
    --bg-secondary: #141414;
    --bg-hover: #222222;
    --border-color: rgba(255, 255, 255, 0.08);
    --text-primary: #ffffff;
    --text-secondary: #a0a0a0;
    --text-muted: #666666;
    --primary: #4ADE80;
    --primary-dark: #22C55E;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Pretendard Variable', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg-dark);
    color: var(--text-primary);
    line-height: 1.5;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* Breadcrumb */
.breadcrumb-section {
    padding: 24px 0;
    border-bottom: 1px solid var(--border-color);
}

.breadcrumb {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 14px;
}

.breadcrumb-item {
    color: var(--text-muted);
    text-decoration: none;
    transition: color 0.2s;
}

.breadcrumb-item:hover {
    color: var(--primary);
}

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

.breadcrumb-separator {
    color: var(--text-muted);
    display: flex;
    align-items: center;
}

.breadcrumb-separator svg {
    width: 14px;
    height: 14px;
}

/* Main Content */
.main-content {
    padding: 48px 0 80px;
}

.content-grid {
    display: grid;
    grid-template-columns: 1fr 380px;
    gap: 48px;
    align-items: start;
}

/* Course Info Column */
.course-info-column {
    min-width: 0;
}

/* Course Header */
.course-header {
    margin-bottom: 32px;
}

.course-category {
    display: inline-block;
    padding: 6px 12px;
    background: rgba(74, 222, 128, 0.1);
    color: var(--primary);
    font-size: 13px;
    font-weight: 600;
    border-radius: 6px;
    margin-bottom: 16px;
}

.course-title {
    font-size: 32px;
    font-weight: 700;
    color: var(--text-primary);
    line-height: 1.3;
    margin-bottom: 16px;
}

.course-description {
    font-size: 16px;
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 24px;
}

.course-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
}

.meta-item {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-secondary);
    font-size: 14px;
}

.meta-item svg {
    stroke: var(--text-muted);
    flex-shrink: 0;
}

/* Tabs Section */
.tabs-section {
    background: var(--bg-card);
    border-radius: 16px;
    border: 1px solid var(--border-color);
    overflow: hidden;
}

.tabs-header {
    display: flex;
    border-bottom: 1px solid var(--border-color);
}

.tab-btn {
    flex: 1;
    padding: 16px 24px;
    background: transparent;
    border: none;
    color: var(--text-muted);
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    position: relative;
}

.tab-btn:hover {
    color: var(--text-secondary);
    background: var(--bg-hover);
}

.tab-btn.active {
    color: var(--primary);
}

.tab-btn.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--primary);
}

.tab-content {
    display: none;
    padding: 24px;
}

.tab-content.active {
    display: block;
}

/* Curriculum Tab */
.curriculum-summary {
    display: flex;
    gap: 32px;
    padding: 16px 20px;
    background: var(--bg-secondary);
    border-radius: 10px;
    margin-bottom: 20px;
}

.summary-item {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.summary-label {
    font-size: 12px;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.summary-value {
    font-size: 16px;
    font-weight: 600;
    color: var(--text-primary);
}

.curriculum-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.curriculum-section {
    background: var(--bg-secondary);
    border-radius: 12px;
    overflow: hidden;
}

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

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

.section-left {
    display: flex;
    align-items: center;
    gap: 16px;
}

.section-number {
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-card);
    border-radius: 8px;
    font-size: 14px;
    font-weight: 600;
    color: var(--primary);
}

.section-info {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.section-title {
    font-size: 15px;
    font-weight: 600;
    color: var(--text-primary);
}

.section-meta {
    font-size: 13px;
    color: var(--text-muted);
}

.section-header .chevron {
    stroke: var(--text-muted);
    transition: transform 0.2s;
    flex-shrink: 0;
}

.curriculum-section.open .chevron {
    transform: rotate(180deg);
}

.section-content {
    display: none;
    padding: 0 20px 16px;
}

.curriculum-section.open .section-content {
    display: block;
}

.lecture-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 16px;
    background: var(--bg-card);
    border-radius: 8px;
    margin-top: 8px;
}

.lecture-info {
    display: flex;
    align-items: center;
    gap: 12px;
}

.lecture-number {
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-secondary);
    border-radius: 6px;
    font-size: 12px;
    font-weight: 600;
    color: var(--text-muted);
}

.lecture-title {
    font-size: 14px;
    color: var(--text-primary);
}

.lecture-duration {
    font-size: 13px;
    color: var(--text-muted);
}

/* Overview Tab */
.overview-card {
    padding: 24px;
    background: var(--bg-secondary);
    border-radius: 12px;
    margin-bottom: 16px;
}

.overview-card:last-child {
    margin-bottom: 0;
}

.overview-title {
    font-size: 16px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 12px;
}

.overview-text {
    font-size: 15px;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* Instructor Tab */
.instructor-card {
    display: flex;
    gap: 24px;
    padding: 24px;
    background: var(--bg-secondary);
    border-radius: 12px;
}

.instructor-avatar {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    overflow: hidden;
    flex-shrink: 0;
    border: 2px solid var(--primary);
}

.instructor-avatar img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.instructor-details {
    flex: 1;
}

.instructor-name {
    font-size: 20px;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.instructor-role {
    font-size: 14px;
    color: var(--primary);
    margin-bottom: 12px;
}

.instructor-bio {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 20px;
}

.instructor-stats {
    display: flex;
    gap: 24px;
}

.stat-item {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 18px;
    font-weight: 700;
    color: var(--text-primary);
}

.stat-label {
    font-size: 12px;
    color: var(--text-muted);
}

/* Purchase Column */
.purchase-column {
    position: sticky;
    top: 100px;
}

.purchase-card {
    background: var(--bg-card);
    border-radius: 16px;
    border: 1px solid var(--border-color);
    overflow: hidden;
}

.card-thumbnail {
    position: relative;
    aspect-ratio: 16 / 9;
    overflow: hidden;
}

.card-thumbnail img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.3s;
}

.thumbnail-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.4);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: opacity 0.3s;
}

.card-thumbnail:hover .thumbnail-overlay {
    opacity: 1;
}

.card-thumbnail:hover img {
    transform: scale(1.05);
}

.preview-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 12px 24px;
    background: rgba(255, 255, 255, 0.15);
    backdrop-filter: blur(8px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 50px;
    color: white;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.preview-btn:hover {
    background: rgba(255, 255, 255, 0.25);
}

.preview-btn svg {
    width: 18px;
    height: 18px;
}

.card-body {
    padding: 24px;
}

.price-section {
    margin-bottom: 20px;
}

.price-current {
    font-size: 32px;
    font-weight: 700;
    color: var(--text-primary);
}

.price-original {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-top: 8px;
}

.original-amount {
    font-size: 16px;
    color: var(--text-muted);
    text-decoration: line-through;
}

.discount-rate {
    padding: 4px 10px;
    background: rgba(74, 222, 128, 0.15);
    color: var(--primary);
    font-size: 13px;
    font-weight: 600;
    border-radius: 6px;
}

.btn-purchase {
    width: 100%;
    padding: 16px;
    background: var(--primary);
    color: #000;
    border: none;
    border-radius: 12px;
    font-size: 16px;
    font-weight: 700;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    transition: all 0.2s;
}

.btn-purchase:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(74, 222, 128, 0.25);
}

.btn-purchase svg {
    stroke: #000;
}

.card-features {
    margin-top: 24px;
    padding-top: 24px;
    border-top: 1px solid var(--border-color);
}

.feature-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 10px 0;
    font-size: 14px;
    color: var(--text-secondary);
}

.feature-item svg {
    stroke: var(--primary);
    flex-shrink: 0;
}

/* Responsive */
@media (max-width: 1024px) {
    .content-grid {
        grid-template-columns: 1fr;
        gap: 32px;
    }

    .purchase-column {
        position: static;
        order: -1;
    }

    .purchase-card {
        max-width: 500px;
    }
}

@media (max-width: 768px) {
    .main-content {
        padding: 32px 0 60px;
    }

    .course-title {
        font-size: 26px;
    }

    .course-meta {
        gap: 12px;
    }

    .meta-item {
        font-size: 13px;
    }

    .tabs-header {
        overflow-x: auto;
    }

    .tab-btn {
        padding: 14px 16px;
        font-size: 14px;
        white-space: nowrap;
    }

    .tab-content {
        padding: 20px 16px;
    }

    .curriculum-summary {
        flex-wrap: wrap;
        gap: 16px;
    }

    .summary-item {
        min-width: calc(50% - 8px);
    }

    .instructor-card {
        flex-direction: column;
        align-items: center;
        text-align: center;
    }

    .instructor-stats {
        justify-content: center;
    }

    .purchase-card {
        max-width: 100%;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 16px;
    }

    .breadcrumb-section {
        padding: 16px 0;
    }

    .course-title {
        font-size: 22px;
    }

    .course-description {
        font-size: 15px;
    }

    .price-current {
        font-size: 28px;
    }

    .section-header {
        padding: 14px 16px;
    }

    .section-number {
        width: 28px;
        height: 28px;
        font-size: 13px;
    }

    .section-title {
        font-size: 14px;
    }

    .lecture-item {
        padding: 10px 12px;
    }

    .lecture-title {
        font-size: 13px;
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

.tab-btn:focus,
.btn-purchase:focus,
.preview-btn:focus,
.section-header:focus {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}