/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    font-size: 1rem;
    line-height: 1.6;
    color: #212529;
    background-color: #FFFFFF;
}

/* Sidebar Navigation */
.sidebar {
    position: fixed;
    left: 0;
    top: 0;
    width: 250px;
    height: 100vh;
    background-color: #F8F9FA;
    overflow-y: auto;
    border-right: 1px solid #DEE2E6;
    z-index: 1000;
}

.logo-container {
    background-color: #F8F9FA;
    padding: 1.5rem;
    text-align: center;
    border-bottom: 1px solid #DEE2E6;
}

.logo {
    max-width: 100%;
    height: auto;
    margin-bottom: 0.75rem;
}

.logo-link {
    display: block;
    color: #0D6EFD;
    text-decoration: none;
    font-size: 0.875rem;
    margin-top: 0.5rem;
}

.logo-link:hover {
    text-decoration: underline;
}

.nav-menu {
    list-style: none;
    padding: 0;
    margin: 0;
}

.nav-item {
    height: 5rem;
    display: flex;
    align-items: center;
    padding: 0.75rem 1rem;
    border-left: 4px solid transparent;
    background-color: transparent;
    transition: background-color 0.2s ease;
    cursor: pointer;
    position: relative;
}

.nav-item:hover {
    background-color: #F8F9FA;
}

.nav-item.active {
    background-color: #F8F9FA;
    border-left-color: #0D6EFD;
}

.nav-icon {
    width: 16px;
    height: 16px;
    margin-right: 0.75rem;
    color: #212529;
    flex-shrink: 0;
}

.nav-item a {
    color: #212529;
    text-decoration: none;
    font-size: 1rem;
    font-weight: 400;
    flex: 1;
}

/* Main Content Area */
.main-content {
    margin-left: 250px;
    padding: 0;
    min-height: 100vh;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #0D6EFD 0%, #5DADE2 100%);
    border-radius: 1rem;
    margin: 2rem auto;
    max-width: 1000px;
    width: calc(100% - 4rem);
    min-height: 320px;
    padding: 60px 50px;
}

.hero-content {
    max-width: 100%;
}

.version-badge {
    color: #FFFFFF;
    font-size: 0.875rem;
    font-weight: 400;
    margin-bottom: 1rem;
    display: inline-block;
}

.hero-title {
    color: #FFFFFF;
    font-size: 2.5rem;
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 1rem;
}

.hero-subtitle {
    color: #FFFFFF;
    font-size: 1rem;
    line-height: 1.6;
    margin-bottom: 2rem;
    max-width: 800px;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
}

.btn {
    display: inline-block;
    padding: 0.5rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    text-decoration: none;
    border-radius: 0.375rem;
    transition: all 0.2s ease;
    cursor: pointer;
    border: none;
}

.btn-primary {
    background-color: #FFFFFF;
    color: #0D6EFD;
}

.btn-primary:hover {
    background-color: #F8F9FA;
    transform: scale(1.05);
}

.btn-secondary {
    background-color: transparent;
    color: #FFFFFF;
    border: 1px solid #FFFFFF;
}

.btn-secondary:hover {
    background-color: rgba(255, 255, 255, 0.1);
}

/* Content Section */
.content-section {
    max-width: 1000px;
    margin: 0 auto;
    padding: 2rem 3rem;
    background-color: #FFFFFF;
}

.section-title {
    color: #0D6EFD;
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
}

.subsection-title {
    color: #0D6EFD;
    font-size: 1.5rem;
    font-weight: 600;
    margin-top: 2rem;
    margin-bottom: 1rem;
}

.content-text {
    color: #212529;
    font-size: 1rem;
    line-height: 1.6;
    margin-bottom: 1.5rem;
}

.feature-list {
    list-style: none;
    padding-left: 0;
    margin-bottom: 2rem;
}

.feature-list li {
    color: #212529;
    font-size: 1rem;
    line-height: 1.6;
    margin-bottom: 0.75rem;
    padding-left: 1.5rem;
    position: relative;
}

.feature-list li:before {
    content: "•";
    color: #0D6EFD;
    font-weight: bold;
    position: absolute;
    left: 0;
}

.image-container {
    margin: 2rem 0;
}

.content-image {
    width: 100%;
    height: auto;
    border-radius: 0.5rem;
    border: 1px solid #DEE2E6;
    background-color: #E7F1FF;
}

.image-caption {
    color: #6C757D;
    font-size: 0.875rem;
    text-align: center;
    margin-top: 0.5rem;
}

/* Chapter Grid */
.chapter-grid {
    background-color: #F8F9FA;
    max-width: 1000px;
    margin: 3rem auto;
    padding: 40px;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}

.chapter-card {
    background-color: #FFFFFF;
    border: 2px dashed #198754;
    border-radius: 0.5rem;
    padding: 15px;
    height: 130px;
    cursor: pointer;
    transition: all 0.2s ease;
    position: relative;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.chapter-card:hover {
    background-color: #F8F9FA;
    box-shadow: 0 0.25rem 0.5rem rgba(0, 0, 0, 0.15);
}

.chapter-number {
    position: absolute;
    top: 10px;
    right: 10px;
    background-color: #198754;
    color: #FFFFFF;
    font-size: 0.75rem;
    font-weight: 600;
    padding: 4px 8px;
    border-radius: 4px;
}

.chapter-icon {
    width: 40px;
    height: 40px;
    margin-bottom: 10px;
}

.chapter-title {
    color: #212529;
    font-size: 1rem;
    font-weight: 700;
    text-align: center;
    line-height: 1.3;
}

/* Chapter Page Styles */
.page-header {
    max-width: 1000px;
    margin: 0 auto;
    padding: 2rem 3rem 1rem;
    border-bottom: 1px solid #DEE2E6;
}

.page-title {
    color: #0D6EFD;
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.page-subtitle {
    color: #6C757D;
    font-size: 0.875rem;
    margin-bottom: 1rem;
}

.section {
    max-width: 1000px;
    margin: 0 auto;
    padding: 2rem 3rem;
}

.section-header {
    color: #0D6EFD;
    font-size: 1.5rem;
    font-weight: 600;
    margin-top: 2rem;
    margin-bottom: 1rem;
}

/* Table Styles */
.data-table {
    width: 100%;
    border-collapse: collapse;
    margin: 2rem 0;
    background-color: #FFFFFF;
    border: 1px solid #DEE2E6;
}

.data-table thead {
    background-color: #F8F9FA;
}

.data-table th {
    color: #212529;
    font-size: 0.875rem;
    font-weight: 700;
    text-align: left;
    padding: 0.75rem 1rem;
    border: 1px solid #DEE2E6;
}

.data-table td {
    color: #212529;
    font-size: 1rem;
    padding: 0.75rem 1rem;
    border: 1px solid #DEE2E6;
    line-height: 1.6;
}

.data-table tbody tr {
    height: 2.5rem;
}

.data-table tbody tr:nth-child(even) {
    background-color: #F8F9FA;
}

/* Responsive Design */
@media (max-width: 1265px) {
    .chapter-grid {
        margin-left: 2rem;
        margin-right: 2rem;
    }
}

@media (max-width: 768px) {
    .sidebar {
        transform: translateX(-100%);
    }
    
    .main-content {
        margin-left: 0;
    }
    
    .hero {
        margin: 1rem;
        width: calc(100% - 2rem);
        padding: 40px 30px;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .chapter-grid {
        grid-template-columns: 1fr;
        padding: 20px;
        margin: 1rem;
    }
    
    .content-section,
    .page-header,
    .section {
        padding: 1.5rem;
    }
}