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

:root {
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --accent-color: #3b82f6;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --bg-light: #f9fafb;
    --bg-white: #ffffff;
    --border-color: #e5e7eb;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --danger-color: #ef4444;
    --sidebar-width: 280px;
    --header-height: 70px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-light);
}

/* Header */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background-color: var(--bg-white);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    padding: 0 2rem;
    z-index: 100;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.header-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.header-title .logo {
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: bold;
    font-size: 1.2rem;
}

/* Sidebar Navigation */
.sidebar {
    position: fixed;
    top: var(--header-height);
    left: 0;
    width: var(--sidebar-width);
    height: calc(100vh - var(--header-height));
    background-color: var(--bg-white);
    border-right: 1px solid var(--border-color);
    overflow-y: auto;
    z-index: 50;
    padding: 1.5rem 0;
}

.sidebar-nav {
    list-style: none;
}

.sidebar-nav li {
    margin-bottom: 0.25rem;
}

.sidebar-nav a {
    display: flex;
    align-items: center;
    padding: 0.75rem 1.5rem;
    color: var(--text-secondary);
    text-decoration: none;
    transition: all 0.2s ease;
    font-size: 0.95rem;
    border-left: 3px solid transparent;
}

.sidebar-nav a:hover {
    background-color: var(--bg-light);
    color: var(--primary-color);
}

.sidebar-nav a.active {
    background-color: #eff6ff;
    color: var(--primary-color);
    font-weight: 600;
    border-left-color: var(--primary-color);
}

.sidebar-nav .nav-number {
    display: inline-block;
    min-width: 1.5rem;
    margin-right: 0.75rem;
    font-weight: 600;
}

/* Main Content */
.main-content {
    margin-left: var(--sidebar-width);
    margin-top: var(--header-height);
    padding: 3rem;
    max-width: 1400px;
}

.page-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 1rem;
}

.page-title .title-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 3rem;
    height: 3rem;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    color: white;
    border-radius: 12px;
    font-size: 1.5rem;
}

.page-subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 2.5rem;
    line-height: 1.7;
}

.section {
    background-color: var(--bg-white);
    border-radius: 12px;
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.section-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.section-title .icon {
    width: 2rem;
    height: 2rem;
    background-color: #eff6ff;
    color: var(--primary-color);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
}

.step-list {
    list-style: none;
    counter-reset: step-counter;
}

.step-item {
    counter-increment: step-counter;
    margin-bottom: 2rem;
    padding-left: 3.5rem;
    position: relative;
}

.step-item::before {
    content: counter(step-counter);
    position: absolute;
    left: 0;
    top: 0;
    width: 2.5rem;
    height: 2.5rem;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    font-size: 1.125rem;
}

.step-content {
    margin-top: 0.5rem;
}

.step-text {
    font-size: 1rem;
    color: var(--text-primary);
    margin-bottom: 1rem;
    line-height: 1.7;
}

.step-image {
    width: 100%;
    max-width: 700px;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    margin-top: 1rem;
}

.info-box {
    background-color: #eff6ff;
    border-left: 4px solid var(--primary-color);
    padding: 1rem 1.5rem;
    border-radius: 8px;
    margin: 1.5rem 0;
}

.info-box.warning {
    background-color: #fef3c7;
    border-left-color: var(--warning-color);
}

.info-box.success {
    background-color: #d1fae5;
    border-left-color: var(--success-color);
}

.info-box.danger {
    background-color: #fee2e2;
    border-left-color: var(--danger-color);
}

.info-box-title {
    font-weight: 600;
    margin-bottom: 0.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.grid-2 {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem;
    margin: 2rem 0;
}

.grid-3 {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
    margin: 2rem 0;
}

.card {
    background-color: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.5rem;
    transition: all 0.3s ease;
}

.card:hover {
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    transform: translateY(-2px);
}

.card-title {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.card-text {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
}

.card-image {
    width: 100%;
    border-radius: 6px;
    margin-bottom: 1rem;
}

.highlight {
    background-color: #fef3c7;
    padding: 0.125rem 0.375rem;
    border-radius: 4px;
    font-weight: 500;
}

.code {
    background-color: #f3f4f6;
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    color: #dc2626;
}

.nav-buttons {
    display: flex;
    justify-content: space-between;
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
}

.nav-button {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    background-color: var(--primary-color);
    color: white;
    text-decoration: none;
    border-radius: 8px;
    font-weight: 500;
    transition: all 0.2s ease;
}

.nav-button:hover {
    background-color: var(--secondary-color);
    transform: translateX(4px);
}

.nav-button.prev:hover {
    transform: translateX(-4px);
}

.nav-button.disabled {
    opacity: 0.5;
    pointer-events: none;
}

/* Responsive */
@media (max-width: 1024px) {
    .sidebar {
        transform: translateX(-100%);
        transition: transform 0.3s ease;
    }

    .sidebar.active {
        transform: translateX(0);
    }

    .main-content {
        margin-left: 0;
        padding: 2rem 1.5rem;
    }

    .grid-2, .grid-3 {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .page-title {
        font-size: 2rem;
    }

    .main-content {
        padding: 1.5rem 1rem;
    }
}