/* 基础重置 */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --color-bg: #faf8f5;
    --color-ink: #2d3b2d;
    --color-green: #3d5a3d;
    --color-green-light: #5a7a5a;
    --color-apricot: #e8a87c;
    --color-apricot-light: #f4d4b8;
    --color-border: #e5e0d8;
    --color-text: #4a4a4a;
    --color-text-light: #6b6b6b;
    
    --font-serif: "Noto Serif SC", "Source Han Serif SC", "Songti SC", serif;
    --font-sans: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
    
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 6rem;
    
    --max-width: 1200px;
    --transition: 0.3s ease;
}

html {
    scroll-behavior: smooth;
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

body {
    font-family: var(--font-sans);
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.7;
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
}

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

/* 导航 */
.site-header {
    position: sticky;
    top: 0;
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    z-index: 100;
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: var(--spacing-sm) var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-family: var(--font-serif);
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--color-green);
    text-decoration: none;
}

.nav-menu {
    display: flex;
    gap: var(--spacing-md);
    list-style: none;
    align-items: center;
}

.nav-menu a {
    color: var(--color-text);
    text-decoration: none;
    font-size: 0.95rem;
    transition: color var(--transition);
}

.nav-menu a:hover,
.nav-menu a:focus {
    color: var(--color-green);
}

.nav-cta {
    background-color: var(--color-green);
    color: white !important;
    padding: 0.5rem 1.25rem;
    border-radius: 6px;
    transition: background-color var(--transition);
}

.nav-cta:hover,
.nav-cta:focus {
    background-color: var(--color-green-light);
}

.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.menu-toggle span {
    width: 24px;
    height: 2px;
    background-color: var(--color-ink);
    transition: all var(--transition);
}

.menu-toggle:focus {
    outline: 2px solid var(--color-green);
    outline-offset: 2px;
}

/* 首屏 */
.hero {
    padding: var(--spacing-xl) 0;
    max-width: var(--max-width);
    margin: 0 auto;
    padding-left: var(--spacing-md);
    padding-right: var(--spacing-md);
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-lg);
    align-items: center;
}

.hero-title {
    font-family: var(--font-serif);
    font-size: 3.5rem;
    font-weight: 600;
    color: var(--color-ink);
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
}

.hero-desc {
    font-size: 1.1rem;
    color: var(--color-text-light);
    margin-bottom: var(--spacing-md);
    max-width: 500px;
}

.hero-actions {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.btn {
    display: inline-block;
    padding: 0.875rem 2rem;
    border-radius: 6px;
    text-decoration: none;
    font-weight: 500;
    transition: all var(--transition);
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

.btn:focus {
    outline: 2px solid var(--color-green);
    outline-offset: 2px;
}

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

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

.btn-secondary {
    background-color: transparent;
    color: var(--color-green);
    border: 2px solid var(--color-green);
}

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

.hero-visual {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.code-card {
    background-color: #2d3b2d;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
}

.code-header {
    background-color: #1a241a;
    padding: 0.75rem 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
}

.dot.red { background-color: #ff5f56; }
.dot.yellow { background-color: #ffbd2e; }
.dot.green { background-color: #27c93f; }

.code-title {
    color: #a0a0a0;
    font-size: 0.85rem;
    margin-left: auto;
}

.code-body {
    padding: 1.5rem;
    color: #e0e0e0;
    font-family: "Fira Code", "Consolas", monospace;
    font-size: 0.9rem;
    line-height: 1.6;
    overflow-x: auto;
}

.keyword { color: #ff79c6; }
.string { color: #f1fa8c; }
.comment { color: #a7b9b0; }
.function { color: #50fa7b; }
.number { color: #bd93f9; }

.project-card {
    background-color: white;
    border: 2px solid var(--color-border);
    border-radius: 8px;
    padding: 1.5rem;
    text-align: center;
}

.project-icon {
    font-size: 3rem;
    margin-bottom: 0.5rem;
}

.project-card h3 {
    font-family: var(--font-serif);
    color: var(--color-ink);
    margin-bottom: 0.5rem;
}

.project-card p {
    color: var(--color-text-light);
    font-size: 0.95rem;
}

/* 通用区块 */
section {
    padding: var(--spacing-xl) 0;
}

.section-title {
    font-family: var(--font-serif);
    font-size: 2.5rem;
    font-weight: 600;
    color: var(--color-ink);
    text-align: center;
    margin-bottom: var(--spacing-sm);
}

.section-desc {
    text-align: center;
    color: var(--color-text-light);
    max-width: 600px;
    margin: 0 auto var(--spacing-lg);
    font-size: 1.05rem;
}

/* 课程方向 */
.directions {
    background-color: white;
    border-top: 1px solid var(--color-border);
    border-bottom: 1px solid var(--color-border);
}

.direction-switcher {
    display: flex;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
    flex-wrap: wrap;
}

.switch-btn {
    background-color: transparent;
    border: 2px solid var(--color-border);
    padding: 0.75rem 1.5rem;
    border-radius: 6px;
    cursor: pointer;
    font-size: 1rem;
    color: var(--color-text);
    transition: all var(--transition);
}

.switch-btn:hover {
    border-color: var(--color-green);
    color: var(--color-green);
}

.switch-btn:focus {
    outline: 2px solid var(--color-green);
    outline-offset: 2px;
}

.switch-btn.active {
    background-color: var(--color-green);
    border-color: var(--color-green);
    color: white;
}

.direction-panels {
    position: relative;
}

.direction-panel {
    display: none;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-lg);
    align-items: center;
}

.direction-panel.active {
    display: grid;
}

.panel-content h3 {
    font-family: var(--font-serif);
    font-size: 1.75rem;
    color: var(--color-ink);
    margin-bottom: var(--spacing-sm);
}

.panel-content p {
    color: var(--color-text-light);
    margin-bottom: var(--spacing-md);
    font-size: 1.05rem;
}

.feature-list {
    list-style: none;
    margin-bottom: var(--spacing-md);
}

.feature-list li {
    padding: 0.5rem 0;
    padding-left: 1.5rem;
    position: relative;
    color: var(--color-text);
}

.feature-list li::before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--color-green);
    font-weight: bold;
}

.panel-visual {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.concept-card {
    background-color: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: 1.25rem;
}

.concept-label {
    font-size: 0.85rem;
    color: var(--color-text-light);
    margin-bottom: 0.5rem;
}

.concept-code {
    font-family: "Fira Code", "Consolas", monospace;
    color: var(--color-green);
    font-size: 1rem;
}

.level-badge {
    background-color: var(--color-apricot-light);
    color: var(--color-ink);
    padding: 1rem;
    border-radius: 8px;
    text-align: center;
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

.exam-card {
    background-color: white;
    border: 2px solid var(--color-green);
    border-radius: 8px;
    padding: 1.5rem;
    text-align: center;
}

.exam-title {
    font-family: var(--font-serif);
    font-size: 1.25rem;
    color: var(--color-ink);
    margin-bottom: 0.5rem;
}

.exam-topics {
    color: var(--color-text-light);
    font-size: 0.95rem;
}

.project-idea,
.project-result {
    background-color: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: 1.5rem;
    display: flex;
    align-items: center;
    gap: 1rem;
}

.idea-icon,
.result-icon {
    font-size: 2.5rem;
}

.idea-text,
.result-text {
    font-size: 1.1rem;
    color: var(--color-ink);
    font-weight: 500;
}

.project-arrow {
    text-align: center;
    font-size: 2rem;
    color: var(--color-apricot);
    padding: 0.5rem 0;
}

/* 学习路径 */
.path-steps {
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
    justify-content: center;
}

.path-step {
    display: flex;
    gap: var(--spacing-sm);
    align-items: flex-start;
    flex: 1;
    min-width: 200px;
    max-width: 250px;
}

.step-number {
    width: 40px;
    height: 40px;
    background-color: var(--color-green);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    flex-shrink: 0;
}

.step-content h3 {
    font-family: var(--font-serif);
    color: var(--color-ink);
    margin-bottom: 0.25rem;
    font-size: 1.1rem;
}

.step-content p {
    color: var(--color-text-light);
    font-size: 0.95rem;
}

.path-connector {
    width: 40px;
    height: 2px;
    background-color: var(--color-border);
    margin-top: 20px;
    flex-shrink: 0;
}

/* 示例项目 */
.sample-projects {
    background-color: white;
    border-top: 1px solid var(--color-border);
    border-bottom: 1px solid var(--color-border);
}

.project-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.project-item {
    background-color: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: 1.5rem;
    transition: transform var(--transition), box-shadow var(--transition);
}

.project-item:hover {
    transform: translateY(-4px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.project-item-icon {
    font-size: 2.5rem;
    margin-bottom: 0.75rem;
}

.project-item h3 {
    font-family: var(--font-serif);
    color: var(--color-ink);
    margin-bottom: 0.5rem;
    font-size: 1.2rem;
}

.project-item p {
    color: var(--color-text-light);
    font-size: 0.95rem;
    margin-bottom: 1rem;
}

.project-tag {
    display: inline-block;
    background-color: var(--color-apricot-light);
    color: var(--color-ink);
    padding: 0.25rem 0.75rem;
    border-radius: 4px;
    font-size: 0.85rem;
}

.note {
    text-align: center;
    color: var(--color-text-light);
    font-size: 0.9rem;
    font-style: italic;
}

/* FAQ */
.faq-list {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    border-bottom: 1px solid var(--color-border);
}

.faq-question {
    width: 100%;
    background: none;
    border: none;
    padding: 1.5rem 0;
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    text-align: left;
    font-size: 1.1rem;
    color: var(--color-ink);
    font-weight: 500;
    transition: color var(--transition);
}

.faq-question:hover {
    color: var(--color-green);
}

.faq-question:focus {
    outline: 2px solid var(--color-green);
    outline-offset: 2px;
}

.faq-icon {
    width: 20px;
    height: 20px;
    position: relative;
    flex-shrink: 0;
    margin-left: 1rem;
}

.faq-icon::before,
.faq-icon::after {
    content: '';
    position: absolute;
    background-color: var(--color-green);
    transition: transform var(--transition);
}

.faq-icon::before {
    width: 20px;
    height: 2px;
    top: 9px;
    left: 0;
}

.faq-icon::after {
    width: 2px;
    height: 20px;
    top: 0;
    left: 9px;
}

.faq-question[aria-expanded="true"] .faq-icon::after {
    transform: rotate(90deg);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition);
}

.faq-answer p {
    padding: 0 0 1.5rem 0;
    color: var(--color-text-light);
    line-height: 1.8;
}

.faq-answer a {
    color: var(--color-green);
    text-decoration: underline;
}

.faq-item.open .faq-answer {
    max-height: 500px;
}

/* 页脚 */
.site-footer {
    background-color: var(--color-ink);
    color: white;
    padding: var(--spacing-lg) 0 var(--spacing-md);
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: var(--spacing-md);
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.footer-brand h3 {
    font-family: var(--font-serif);
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}

.footer-brand p {
    color: #b0b0b0;
}

.footer-links {
    display: flex;
    gap: var(--spacing-md);
}

.footer-links a {
    color: white;
    text-decoration: none;
    transition: color var(--transition);
}

.footer-links a:hover {
    color: var(--color-apricot);
}

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-md);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: #c8d4c8;
    font-size: 0.9rem;
}

/* 响应式 */
@media (max-width: 768px) {
    .menu-toggle {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        top: 60px;
        left: 0;
        right: 0;
        background-color: var(--color-bg);
        flex-direction: column;
        padding: var(--spacing-md);
        border-bottom: 1px solid var(--color-border);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        pointer-events: none;
        transition: all var(--transition);
    }
    
    .nav-menu.open {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
        pointer-events: all;
    }
    
    .hero {
        grid-template-columns: 1fr;
        padding: var(--spacing-lg) var(--spacing-md);
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-visual {
        order: 0;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .direction-panel {
        grid-template-columns: 1fr;
    }
    
    .path-steps {
        flex-direction: column;
        align-items: stretch;
    }
    
    .path-connector {
        width: 2px;
        height: 30px;
        margin: 0 auto;
    }
    
    .footer-content {
        flex-direction: column;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .section-title {
        font-size: 1.75rem;
    }
    
    .direction-switcher {
        flex-direction: column;
    }
    
    .switch-btn {
        width: 100%;
    }
}