:root {
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --primary-light: #3b82f6;
    --secondary-color: #64748b;
    --accent-color: #f59e0b;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-light: #94a3b8;
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #f1f5f9;
    --border-color: #e2e8f0;
    --border-light: #f1f5f9;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1);
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --transition-fast: 150ms ease;
    --transition-normal: 250ms ease;
    --container-max: 1200px;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
}

.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 24px;
}

.container-fluid {
    width: 100%;
    padding: 0 24px;
}

h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: 16px;
    color: var(--text-primary);
}

h1 {
    font-size: 2.5rem;
}

h2 {
    font-size: 2rem;
}

h3 {
    font-size: 1.5rem;
}

h4 {
    font-size: 1.25rem;
}

p {
    margin-bottom: 16px;
}

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--primary-dark);
}

img {
    max-width: 100%;
    height: auto;
}

.header {
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.navbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 72px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
}

.logo img {
    height: 40px;
    width: auto;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 8px;
}

.nav-link {
    padding: 8px 16px;
    color: var(--text-secondary);
    font-weight: 500;
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary-color);
    background-color: rgba(37, 99, 235, 0.05);
}

.dropdown {
    position: relative;
}

.dropdown-content {
    position: absolute;
    top: 100%;
    left: 0;
    min-width: 240px;
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    padding: 8px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all var(--transition-normal);
    z-index: 1000;
}

.dropdown:hover .dropdown-content {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-item {
    display: block;
    padding: 10px 14px;
    color: var(--text-secondary);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.dropdown-item:hover {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
}

.mobile-menu-btn {
    display: none;
    padding: 8px;
    font-size: 1.5rem;
    background: none;
    border: none;
    cursor: pointer;
}

.hero {
    padding: 80px 0;
    background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
}

.hero-content {
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 24px;
}

.hero p {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 32px;
}

.hero-tool {
    padding: 60px 0;
    background-color: var(--bg-secondary);
}

.hero-tool h1 {
    text-align: center;
    margin-bottom: 16px;
}

.hero-tool p {
    text-align: center;
    max-width: 700px;
    margin: 0 auto;
    color: var(--text-secondary);
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 24px;
    font-size: 1rem;
    font-weight: 600;
    border-radius: var(--radius-md);
    border: none;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background-color: var(--primary-dark);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
}

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

.btn-lg {
    padding: 16px 32px;
    font-size: 1.125rem;
}

.section {
    padding: 80px 0;
}

.section-title {
    text-align: center;
    margin-bottom: 48px;
}

.section-title h2 {
    margin-bottom: 12px;
}

.section-title p {
    color: var(--text-secondary);
    margin-bottom: 0;
}

.tool-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 24px;
}

.tool-card {
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 24px;
    transition: all var(--transition-normal);
}

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

.tool-card-icon {
    width: 48px;
    height: 48px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    color: white;
    margin-bottom: 16px;
}

.tool-card h3 {
    font-size: 1.125rem;
    margin-bottom: 8px;
}

.tool-card p {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    margin-bottom: 16px;
}

.tool-card-link {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    font-weight: 600;
    color: var(--primary-color);
}

.tool-card-link:hover {
    gap: 8px;
}

.tool-section {
    padding: 48px 0;
}

.tool-container {
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    padding: 32px;
    box-shadow: var(--shadow-md);
}

.content-grid {
    display: grid;
    grid-template-columns: 1fr 320px;
    gap: 48px;
}

.main-content {
    min-width: 0;
}

.sidebar {
    position: sticky;
    top: 100px;
    height: fit-content;
}

.sidebar-card {
    background-color: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: 24px;
    margin-bottom: 24px;
}

.sidebar-title {
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: 16px;
}

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

.sidebar-list li {
    margin-bottom: 8px;
}

.sidebar-list a {
    display: block;
    padding: 8px 12px;
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
}

.sidebar-list a:hover,
.sidebar-list a.active {
    background-color: var(--bg-primary);
    color: var(--primary-color);
}

.article {
    background-color: var(--bg-primary);
}

.article-header {
    margin-bottom: 32px;
}

.article-title {
    font-size: 2.5rem;
    margin-bottom: 16px;
}

.article-meta {
    display: flex;
    align-items: center;
    gap: 16px;
    color: var(--text-secondary);
    font-size: 0.9375rem;
}

.article-content {
    font-size: 1.125rem;
    line-height: 1.8;
}

.article-content h2 {
    margin-top: 40px;
    margin-bottom: 16px;
}

.article-content h3 {
    margin-top: 32px;
    margin-bottom: 12px;
}

.article-content ul,
.article-content ol {
    margin-bottom: 24px;
    padding-left: 24px;
}

.article-content li {
    margin-bottom: 8px;
}

.article-content blockquote {
    border-left: 4px solid var(--primary-color);
    padding-left: 20px;
    margin: 24px 0;
    color: var(--text-secondary);
    font-style: italic;
}

.faq-section {
    margin-top: 48px;
}

.faq-item {
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    margin-bottom: 16px;
    overflow: hidden;
}

.faq-question {
    padding: 20px;
    background-color: var(--bg-secondary);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-weight: 600;
}

.faq-answer {
    padding: 20px;
    border-top: 1px solid var(--border-color);
    display: none;
}

.faq-item.active .faq-answer {
    display: block;
}

.footer {
    background-color: var(--text-primary);
    color: var(--text-light);
    padding: 60px 0 32px;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 48px;
    margin-bottom: 48px;
}

.footer-brand p {
    margin-top: 16px;
    color: var(--text-light);
}

.footer-title {
    color: white;
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 20px;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 12px;
}

.footer-links a {
    color: var(--text-light);
    transition: color var(--transition-fast);
}

.footer-links a:hover {
    color: white;
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 32px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-social {
    display: flex;
    gap: 16px;
}

.footer-social a {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background-color: rgba(255, 255, 255, 0.1);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    transition: all var(--transition-fast);
}

.footer-social a:hover {
    background-color: var(--primary-color);
}

.lang-switcher {
    display: flex;
    align-items: center;
    gap: 8px;
    position: relative;
}

.lang-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 8px 16px;
    background-color: var(--bg-tertiary);
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    font-weight: 500;
}

.lang-dropdown {
    position: absolute;
    top: 100%;
    right: 0;
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    padding: 8px;
    min-width: 200px;
    display: none;
    z-index: 1000;
    margin-top: 0;
}

/* Add invisible bridge to maintain hover state */
.lang-dropdown::before {
    content: '';
    position: absolute;
    top: -8px;
    left: 0;
    right: 0;
    height: 8px;
}

.lang-switcher:hover .lang-dropdown,
.lang-dropdown:hover {
    display: block;
}

.lang-option {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 10px 14px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: background-color var(--transition-fast);
}

.lang-option:hover {
    background-color: var(--bg-tertiary);
}

.lang-option.active {
    background-color: rgba(37, 99, 235, 0.1);
    color: var(--primary-color);
}

.lang-flag {
    font-size: 1.5rem;
}

.breadcrumb {
    padding: 20px 0;
    background-color: var(--bg-secondary);
}

.breadcrumb-list {
    display: flex;
    align-items: center;
    gap: 8px;
    list-style: none;
    font-size: 0.9375rem;
}

.breadcrumb-list li {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-secondary);
}

.breadcrumb-list a {
    color: var(--text-secondary);
}

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

.breadcrumb-list .current {
    color: var(--text-primary);
    font-weight: 500;
}

.test-screen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 9999;
    display: none;
}

.test-screen.active {
    display: block;
}

.test-screen-exit {
    position: absolute;
    top: 20px;
    right: 20px;
    padding: 12px 24px;
    background-color: rgba(0, 0, 0, 0.7);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    font-weight: 600;
    z-index: 10000;
    transition: background-color var(--transition-fast);
}

.test-screen-exit:hover {
    background-color: rgba(0, 0, 0, 0.9);
}

.test-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 16px;
}

.test-item {
    background-color: var(--bg-secondary);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 20px;
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.test-item:hover {
    border-color: var(--primary-color);
    background-color: rgba(37, 99, 235, 0.05);
    transform: translateY(-2px);
}

.test-item-icon {
    width: 64px;
    height: 64px;
    margin: 0 auto 16px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    color: white;
}

.test-item h4 {
    font-size: 1rem;
    margin-bottom: 8px;
}

.test-item p {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 0;
}

@media (max-width: 1024px) {
    .content-grid {
        grid-template-columns: 1fr;
    }
    
    .sidebar {
        display: none;
    }
    
    .footer-grid {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 768px) {
    h1 {
        font-size: 2rem;
    }
    
    h2 {
        font-size: 1.5rem;
    }
    
    .hero {
        padding: 48px 0;
    }
    
    .hero h1 {
        font-size: 2.25rem;
    }
    
    .nav-links {
        display: none;
    }
    
    .mobile-menu-btn {
        display: block;
    }
    
    .tool-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-grid {
        grid-template-columns: 1fr;
        gap: 32px;
    }
    
    .footer-bottom {
        flex-direction: column;
        gap: 16px;
        text-align: center;
    }
    
    .section {
        padding: 48px 0;
    }
    
    .container {
        padding: 0 16px;
    }
}