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

:root {
    --primary-color: #000000;
    --accent-color: #e74c3c;
    --text-color: #000000;
    --text-light: #666666;
    --text-lighter: #999999;
    --bg-white: #ffffff;
    --bg-light: #f8f8f8;
    --border-color: #e0e0e0;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-white);
    font-size: 16px;
    font-weight: 400;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 40px;
}

.header {
    background-color: var(--bg-white);
    border-bottom: 1px solid var(--border-color);
    padding: 24px 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

.header .container {
    position: relative;
}

.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 20px;
    font-weight: 600;
    color: var(--primary-color);
    text-decoration: none;
    letter-spacing: -0.3px;
}

.nav-menu {
    display: flex;
    gap: 48px;
    list-style: none;
    align-items: center;
}

.nav-menu a {
    color: var(--text-color);
    text-decoration: none;
    font-size: 15px;
    font-weight: 400;
    transition: color 0.2s;
}

.nav-menu a:hover {
    color: var(--accent-color);
}

.lang-switcher {
    display: flex;
    align-items: center;
    gap: 4px;
    padding: 6px 12px;
    background-color: var(--bg-light);
    border-radius: 4px;
}

.lang-link {
    font-size: 13px;
    font-weight: 600;
    color: var(--text-light);
    text-decoration: none;
    transition: all 0.2s;
    padding: 4px 8px;
    border-radius: 3px;
}

.lang-link:hover {
    color: var(--primary-color);
    background-color: rgba(0,0,0,0.05);
}

.lang-link.active {
    color: var(--bg-white);
    background-color: var(--primary-color);
    font-weight: 600;
}

.lang-separator {
    color: var(--text-lighter);
    font-size: 12px;
    font-weight: 300;
}

.main {
    min-height: calc(100vh - 200px);
}

.hero {
    background-color: var(--bg-white);
    padding: 120px 0 80px;
    text-align: center;
}

.hero-title {
    font-size: 64px;
    font-weight: 700;
    margin-bottom: 20px;
    letter-spacing: -1.5px;
    line-height: 1.1;
}

.hero-subtitle {
    font-size: 28px;
    font-weight: 400;
    margin-bottom: 32px;
    color: var(--text-light);
}

.hero-description {
    font-size: 18px;
    max-width: 640px;
    margin: 0 auto 60px;
    color: var(--text-light);
    line-height: 1.7;
}

.hero-stats {
    display: flex;
    gap: 80px;
    justify-content: center;
    margin-top: 60px;
}

.stat {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.stat-number {
    font-size: 56px;
    font-weight: 700;
    margin-bottom: 12px;
    letter-spacing: -1px;
}

.stat-label {
    font-size: 13px;
    color: var(--text-light);
    text-transform: uppercase;
    letter-spacing: 1.5px;
    font-weight: 500;
}

.categories {
    padding: 80px 0 100px;
    background-color: var(--bg-white);
}

.section-title {
    font-size: 40px;
    font-weight: 600;
    margin-bottom: 64px;
    text-align: center;
    color: var(--primary-color);
    letter-spacing: -0.8px;
}

.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: 40px;
    margin-top: 40px;
}

.category-card {
    background: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: 0;
    border-left: 4px solid var(--border-color);
    padding: 40px 36px;
    transition: all 0.3s ease;
    text-decoration: none;
    color: inherit;
    display: flex;
    flex-direction: column;
    min-height: 220px;
}

.category-card:hover {
    border-color: var(--border-color);
    box-shadow: 0 4px 20px rgba(0,0,0,0.08);
    transform: translateY(-4px);
}

.category-title {
    font-size: 24px;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--primary-color);
    letter-spacing: -0.3px;
    line-height: 1.3;
}

.category-description {
    color: var(--text-light);
    margin-bottom: 20px;
    font-size: 16px;
    flex-grow: 1;
    line-height: 1.7;
}

.category-count {
    display: inline-block;
    padding: 8px 14px;
    background-color: var(--bg-light);
    border-radius: 4px;
    font-size: 13px;
    color: var(--text-light);
    font-weight: 500;
    align-self: flex-start;
}

.cta {
    background-color: var(--bg-light);
    padding: 100px 0;
    text-align: center;
}

.cta h2 {
    font-size: 40px;
    margin-bottom: 20px;
    color: var(--primary-color);
    font-weight: 600;
    letter-spacing: -0.5px;
}

.cta p {
    color: var(--text-light);
    margin-bottom: 40px;
    font-size: 18px;
}

.btn {
    display: inline-block;
    padding: 16px 40px;
    border-radius: 0;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s;
    font-size: 15px;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
    border: 2px solid var(--primary-color);
}

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

.category-header {
    background-color: var(--bg-white);
    padding: 80px 0 60px;
    border-bottom: 4px solid var(--border-color);
}

.back-link {
    color: var(--text-light);
    text-decoration: none;
    display: inline-block;
    margin-bottom: 32px;
    font-weight: 400;
    font-size: 14px;
}

.back-link:hover {
    color: var(--primary-color);
}

.category-page-title {
    font-size: 56px;
    font-weight: 700;
    margin-bottom: 20px;
    letter-spacing: -1px;
    line-height: 1.1;
}

.category-page-description {
    font-size: 20px;
    color: var(--text-light);
    margin-bottom: 24px;
    line-height: 1.6;
    max-width: 800px;
}

.question-count-badge {
    display: inline-block;
    padding: 10px 18px;
    background-color: var(--bg-light);
    border-radius: 4px;
    font-size: 14px;
    color: var(--text-light);
    font-weight: 500;
}

.questions-list {
    padding: 80px 0;
}

.question-item {
    display: flex;
    align-items: flex-start;
    gap: 32px;
    padding: 32px;
    background: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: 0;
    margin-bottom: 20px;
    text-decoration: none;
    color: inherit;
    transition: all 0.3s;
}

.question-item:hover {
    box-shadow: 0 4px 16px rgba(0,0,0,0.08);
    transform: translateX(8px);
}

.question-number {
    font-weight: 600;
    color: var(--text-lighter);
    min-width: 60px;
    font-size: 14px;
}

.question-text {
    flex: 1;
    font-size: 18px;
    line-height: 1.6;
}

.arrow {
    color: var(--text-lighter);
    font-size: 24px;
    font-weight: 300;
}

.other-categories {
    padding: 80px 0;
    background-color: var(--bg-light);
}

.question-detail {
    padding: 80px 0;
}

.question-card-large {
    background: var(--bg-white);
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--border-color);
    border-radius: 0;
    padding: 80px 60px;
    margin: 60px 0;
}

.question-number-large {
    display: block;
    font-size: 13px;
    font-weight: 600;
    color: var(--text-lighter);
    margin-bottom: 24px;
    text-transform: uppercase;
    letter-spacing: 2px;
}

.question-text-large {
    font-size: 36px;
    font-weight: 600;
    line-height: 1.4;
    margin-bottom: 40px;
    color: var(--primary-color);
    letter-spacing: -0.8px;
}

.question-category-badge {
    display: inline-block;
    padding: 10px 18px;
    background-color: var(--bg-light);
    border-radius: 4px;
    font-size: 14px;
    font-weight: 500;
    color: var(--text-color);
}

.question-navigation {
    display: flex;
    gap: 20px;
    justify-content: center;
    margin: 60px 0;
    flex-wrap: wrap;
}

.nav-btn {
    padding: 16px 32px;
    border-radius: 0;
    background-color: var(--primary-color);
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s;
    font-size: 15px;
    border: 2px solid var(--primary-color);
}

.nav-btn:hover {
    background-color: transparent;
    color: var(--primary-color);
}

.nav-btn.disabled {
    background-color: var(--bg-light);
    color: var(--text-lighter);
    cursor: not-allowed;
    border-color: var(--bg-light);
}

.nav-btn.all-btn {
    background-color: transparent;
    color: var(--primary-color);
}

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

.question-tips {
    background-color: var(--bg-light);
    padding: 48px;
    border-radius: 0;
    margin-top: 80px;
}

.question-tips h3 {
    margin-bottom: 24px;
    color: var(--primary-color);
    font-size: 22px;
    font-weight: 600;
}

.question-tips ul {
    list-style-position: inside;
    color: var(--text-light);
}

.question-tips li {
    margin-bottom: 12px;
    line-height: 1.7;
    font-size: 16px;
}

.about-hero {
    background-color: var(--bg-white);
    padding: 120px 0 80px;
    text-align: center;
    border-bottom: 1px solid var(--border-color);
}

.about-hero h1 {
    font-size: 64px;
    margin-bottom: 20px;
    font-weight: 700;
    letter-spacing: -1.5px;
    line-height: 1.1;
}

.lead {
    font-size: 24px;
    color: var(--text-light);
}

.about-content {
    padding: 100px 0;
    max-width: 900px;
    margin: 0 auto;
}

.about-section {
    margin-bottom: 80px;
}

.about-section h2 {
    font-size: 36px;
    margin-bottom: 20px;
    color: var(--primary-color);
    font-weight: 600;
    letter-spacing: -0.5px;
}

.about-section p {
    color: var(--text-light);
    font-size: 18px;
    line-height: 1.8;
}

.steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 40px;
    margin-top: 48px;
}

.step {
    text-align: center;
    padding: 48px 40px;
    background: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: 0;
}

.step-number {
    display: inline-block;
    width: 64px;
    height: 64px;
    line-height: 64px;
    background-color: var(--primary-color);
    color: white;
    border-radius: 50%;
    font-size: 28px;
    font-weight: 600;
    margin-bottom: 24px;
}

.step h3 {
    margin-bottom: 16px;
    color: var(--primary-color);
    font-size: 22px;
    font-weight: 600;
}

.step p {
    color: var(--text-light);
    font-size: 16px;
    line-height: 1.7;
}

.category-list-simple {
    display: flex;
    flex-direction: column;
    gap: 28px;
    margin-top: 48px;
}

.category-list-item {
    display: flex;
    gap: 24px;
    align-items: start;
    padding: 32px;
    background: var(--bg-white);
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--border-color);
    border-radius: 0;
}

.category-color-dot {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    flex-shrink: 0;
    margin-top: 6px;
}

.category-list-item strong {
    display: block;
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 8px;
    letter-spacing: -0.2px;
}

.category-list-item p {
    margin: 0;
    font-size: 16px;
    line-height: 1.7;
}

.all-questions-header {
    background-color: var(--bg-white);
    padding: 80px 0 60px;
    border-bottom: 1px solid var(--border-color);
}

.all-questions-header h1 {
    font-size: 56px;
    margin-bottom: 16px;
    font-weight: 700;
    letter-spacing: -1px;
}

.all-questions-header p {
    font-size: 20px;
    color: var(--text-light);
}

.all-questions-list {
    padding: 80px 0;
}

.category-section {
    margin-bottom: 100px;
}

.category-section-header {
    padding: 40px;
    background: var(--bg-white);
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--border-color);
    border-radius: 0;
    margin-bottom: 32px;
}

.category-section-header h2 {
    font-size: 32px;
    margin-bottom: 12px;
    color: var(--primary-color);
    font-weight: 600;
    letter-spacing: -0.5px;
}

.category-section-header p {
    color: var(--text-light);
    font-size: 17px;
    line-height: 1.6;
}

.questions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: 20px;
}

.question-card-mini {
    display: flex;
    gap: 20px;
    padding: 28px;
    background: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: 0;
    text-decoration: none;
    color: inherit;
    transition: all 0.3s;
}

.question-card-mini:hover {
    box-shadow: 0 4px 16px rgba(0,0,0,0.08);
    transform: translateY(-4px);
}

.question-number-mini {
    font-weight: 600;
    color: var(--text-lighter);
    font-size: 13px;
    min-width: 45px;
}

.question-text-mini {
    flex: 1;
    font-size: 16px;
    line-height: 1.6;
}

.error-page {
    padding: 120px 0;
    text-align: center;
}

.error-title {
    font-size: 120px;
    font-weight: 700;
    color: var(--text-lighter);
    margin-bottom: 32px;
    letter-spacing: -2px;
}

.error-message {
    font-size: 28px;
    color: var(--text-light);
    margin-bottom: 48px;
}

.footer {
    background-color: var(--bg-white);
    border-top: 1px solid var(--border-color);
    color: var(--text-light);
    padding: 48px 0;
    text-align: center;
}

.footer p {
    margin: 10px 0;
    font-size: 14px;
}

.footer-tagline {
    color: var(--text-lighter);
    font-size: 14px;
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.mobile-menu-toggle span {
    display: block;
    width: 26px;
    height: 2px;
    background-color: var(--primary-color);
    transition: all 0.3s;
    border-radius: 2px;
}

.mobile-menu-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(6px, 6px);
}

.mobile-menu-toggle.active span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(7px, -7px);
}

@media (max-width: 1024px) {
    .container {
        padding: 0 32px;
    }
    
    .hero-title {
        font-size: 48px;
    }
    
    .hero-subtitle {
        font-size: 22px;
    }
    
    .category-page-title {
        font-size: 42px;
    }
    
    .category-grid {
        grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
        gap: 32px;
    }
}

@media (max-width: 768px) {
    .mobile-menu-toggle {
        display: flex;
    }
    
    .nav-menu {
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--bg-white);
        border-bottom: 1px solid var(--border-color);
        flex-direction: column;
        gap: 0;
        padding: 0;
        max-height: 0;
        overflow: hidden;
        transition: max-height 0.3s ease;
    }
    
    .nav-menu.active {
        max-height: 300px;
    }
    
    .nav-menu li {
        width: 100%;
        border-top: 1px solid var(--border-color);
    }
    
    .nav-menu a {
        display: block;
        padding: 18px 24px;
    }
    
    .container {
        padding: 0 20px;
    }
    
    .hero {
        padding: 80px 0 60px;
    }
    
    .hero-title {
        font-size: 40px;
    }
    
    .hero-subtitle {
        font-size: 20px;
    }
    
    .hero-description {
        font-size: 16px;
    }
    
    .hero-stats {
        gap: 48px;
    }
    
    .category-grid {
        grid-template-columns: 1fr;
        gap: 24px;
    }
    
    .category-card {
        padding: 32px 28px;
    }
    
    .question-navigation {
        flex-direction: column;
    }
    
    .steps {
        grid-template-columns: 1fr;
    }
    
    .question-card-large {
        padding: 48px 32px;
    }
    
    .question-text-large {
        font-size: 28px;
    }
    
    .about-hero h1 {
        font-size: 40px;
    }
    
    .questions-grid {
        grid-template-columns: 1fr;
    }
    
    .question-item {
        padding: 24px;
        gap: 20px;
    }
}