:root {
    --primary-color: #4CAF50;
    --secondary-color: #2196F3;
    --accent-color: #FFC107;
    --text-dark: #333;
    --text-light: #666;
    --bg-light: #f8f9fa;
    --bg-white: #ffffff;
    --border-color: #e0e0e0;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --hero-overlay: rgba(0, 0, 0, 0.4);
}

/* Dark mode variables */
[data-theme="dark"] {
    --primary-color: #66BB6A;
    --secondary-color: #42A5F5;
    --accent-color: #FFD54F;
    --text-dark: #ffffff;
    --text-light: #b0b0b0;
    --bg-light: #2a2a2a;
    --bg-white: #1a1a1a;
    --border-color: #404040;
    --shadow-color: rgba(0, 0, 0, 0.3);
    --hero-overlay: rgba(0, 0, 0, 0.6);
}

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

/* Optimized font stack for Chinese users - no external fonts */
body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Source Han Sans SC', 'Noto Sans CJK SC', 'Microsoft YaHei', '微软雅黑', 'STHeitiSC-Light', 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--bg-white);
    /* Improve text rendering */
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    text-rendering: optimizeLegibility;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.section {
    padding: 80px 0;
    opacity: 0;
    transform: translateY(30px);
    animation: fadeInUp 0.8s ease-out forwards;
}

@keyframes fadeInUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    background-size: cover;
    background-position: center;
    color: var(--bg-white);
    text-align: center;
    min-height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--hero-overlay);
}

.hero-content {
    position: relative;
    z-index: 1;
}

.hero h1 {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 20px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
}

.hero p {
    font-size: 1.3rem;
    margin-bottom: 40px;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.cta-button {
    background-color: var(--accent-color);
    color: var(--text-dark);
    padding: 18px 40px;
    font-size: 1.2rem;
    font-weight: 600;
    border: none;
    border-radius: 50px;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-block;
}

.cta-button:hover {
    transform: scale(1.05);
    box-shadow: 0 8px 25px rgba(255, 193, 7, 0.3);
}

/* Problem & Solution Section */
.problem-solution {
    background-color: var(--bg-light);
    text-align: center;
}

.problem-solution h2 {
    font-size: 2.5rem;
    margin-bottom: 30px;
    color: var(--primary-color);
}

.problem-solution p {
    font-size: 1.1rem;
    max-width: 800px;
    margin: 0 auto;
    line-height: 1.8;
}

.icon-placeholder {
    font-size: 3rem;
    margin-bottom: 20px;
}

/* Secret Weapon Section */
.secret-weapon {
    text-align: center;
}

.secret-weapon h2 {
    font-size: 2.5rem;
    margin-bottom: 30px;
    color: var(--primary-color);
}

.secret-weapon > p {
    font-size: 1.1rem;
    line-height: 1.8;
    margin-bottom: 60px;
    max-width: 900px;
    margin-left: auto;
    margin-right: auto;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 40px;
    margin-top: 60px;
}

.feature-item {
    background: var(--bg-white);
    padding: 40px 30px;
    border-radius: 15px;
    box-shadow: 0 10px 30px var(--shadow-color);
    transition: transform 0.3s ease;
}

.feature-item:hover {
    transform: translateY(-10px);
}

.feature-item h3 {
    font-size: 1.5rem;
    margin-bottom: 20px;
    color: var(--secondary-color);
}

/* Testimonials Section */
.testimonials {
    background-color: var(--bg-light);
    text-align: center;
}

.testimonials h2 {
    font-size: 2.5rem;
    margin-bottom: 40px;
    color: var(--primary-color);
}

.testimonials > p {
    font-size: 1.1rem;
    line-height: 1.8;
    margin-bottom: 60px;
    max-width: 900px;
    margin-left: auto;
    margin-right: auto;
}

.testimonials-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 40px;
}

.testimonial-item {
    background: var(--bg-white);
    padding: 30px;
    border-radius: 15px;
    box-shadow: 0 10px 30px var(--shadow-color);
    transition: transform 0.3s ease;
}

.testimonial-item:hover {
    transform: translateY(-5px);
}

.testimonial-avatar {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    margin: 0 auto 20px;
    overflow: hidden;
}

.testimonial-avatar img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.testimonial-quote {
    font-style: italic;
    font-size: 1.1rem;
    line-height: 1.6;
    margin-bottom: 20px;
    color: var(--text-dark);
}

.testimonial-author {
    font-weight: 600;
    color: var(--secondary-color);
}

/* CTA Section */
.cta-section {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: var(--bg-white);
    text-align: center;
}

.cta-section h2 {
    font-size: 2.5rem;
    margin-bottom: 30px;
}

.cta-section p {
    font-size: 1.1rem;
    line-height: 1.8;
    margin-bottom: 40px;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.signup-form {
    background: var(--bg-white);
    padding: 40px;
    border-radius: 15px;
    max-width: 500px;
    margin: 0 auto;
    box-shadow: 0 15px 35px var(--shadow-color);
}

.form-group {
    margin-bottom: 20px;
    text-align: left;
}

.form-input {
    width: 100%;
    padding: 15px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    transition: all 0.3s ease;
    background-color: var(--bg-white);
    color: var(--text-dark);
}

.form-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 0.2rem rgba(76, 175, 80, 0.25);
}

.submit-button {
    width: 100%;
    background-color: var(--primary-color);
    color: var(--bg-white);
    padding: 15px;
    font-size: 1.1rem;
    font-weight: 600;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.submit-button:hover {
    background-color: #45a049;
}

.privacy-notice {
    font-size: 0.9rem;
    color: var(--text-light);
    margin-top: 20px;
}

/* FAQ Section */
.faq {
    background-color: var(--bg-light);
}

.faq h2 {
    font-size: 2.5rem;
    text-align: center;
    margin-bottom: 60px;
    color: var(--primary-color);
}

.faq-item {
    background: var(--bg-white);
    margin-bottom: 20px;
    border-radius: 10px;
    box-shadow: 0 5px 15px var(--shadow-color);
    overflow: hidden;
}

.faq-question {
    width: 100%;
    padding: 20px;
    background: none;
    border: none;
    text-align: left;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-dark);
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.faq-question:hover {
    background-color: var(--bg-light);
}

.faq-answer {
    padding: 0 20px 20px;
    color: var(--text-light);
    line-height: 1.6;
}

/* Share Section */
.share-section {
    background: var(--bg-light);
    padding: 40px 0;
    text-align: center;
}

.share-buttons {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-top: 20px;
    flex-wrap: wrap;
}

.share-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 20px;
    border: none;
    border-radius: 25px;
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    cursor: pointer;
    font-size: 14px;
}

.share-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}

.share-btn.wechat { background: #07C160; }
.share-btn.weibo { background: #E6162D; }
.share-btn.qq { background: #12B7F5; }
.share-btn.twitter { background: #1DA1F2; }
.share-btn.facebook { background: #4267B2; }
.share-btn.linkedin { background: #0077B5; }
.share-btn.copy { background: #6c757d; }

.share-icon {
    width: 18px;
    height: 18px;
}

/* Footer */
.footer {
    background-color: var(--text-dark);
    color: var(--bg-white);
    text-align: center;
    padding: 40px 0;
}

.footer p {
    margin-bottom: 20px;
}

.social-links {
    margin: 20px 0;
}

.social-links a {
    color: var(--bg-white);
    text-decoration: none;
    margin: 0 10px;
}

.social-links a:hover {
    color: var(--accent-color);
}

.footer-links a {
    color: var(--bg-white);
    text-decoration: none;
    margin: 0 10px;
}

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

/* Modal Styles */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    overflow-y: auto;
}

.modal-content {
    background-color: var(--bg-white);
    margin: 5% auto;
    padding: 0;
    border-radius: 15px;
    width: 90%;
    max-width: 800px;
    max-height: 90vh;
    overflow-y: auto;
    position: relative;
}

.modal-header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: var(--bg-white);
    padding: 20px 30px;
    border-radius: 15px 15px 0 0;
    position: sticky;
    top: 0;
    z-index: 1001;
}

.modal-header h2 {
    margin: 0;
    font-size: 1.8rem;
}

.close {
    position: absolute;
    right: 20px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--bg-white);
    font-size: 2rem;
    font-weight: bold;
    cursor: pointer;
    transition: opacity 0.3s ease;
}

.close:hover {
    opacity: 0.7;
}

.modal-body {
    padding: 30px;
    line-height: 1.6;
}

.modal-body h3 {
    color: var(--primary-color);
    margin: 30px 0 15px 0;
    font-size: 1.3rem;
}

.modal-body h3:first-child {
    margin-top: 0;
}

.modal-body p {
    margin-bottom: 15px;
    color: var(--text-dark);
}

.modal-body ul {
    margin: 15px 0;
    padding-left: 20px;
}

.modal-body li {
    margin-bottom: 8px;
    color: var(--text-dark);
}

.highlight-box {
    background-color: var(--bg-light);
    border-left: 4px solid var(--primary-color);
    padding: 20px;
    margin: 20px 0;
    border-radius: 0 8px 8px 0;
}

/* 复制成功提示 */
.copy-toast {
    position: fixed;
    top: 20px;
    right: 20px;
    background: #28a745;
    color: white;
    padding: 12px 20px;
    border-radius: 5px;
    z-index: 1000;
    opacity: 0;
    transform: translateX(100%);
    transition: all 0.3s ease;
}

.copy-toast.show {
    opacity: 1;
    transform: translateX(0);
}

/* 表单验证样式 */
.form-input.error {
    border-color: #dc3545;
    background-color: #fff5f5;
}

.form-input.success {
    border-color: #28a745;
    background-color: #f8fff8;
}

.error-message {
    color: #dc3545;
    font-size: 0.875rem;
    margin-top: 5px;
    display: none;
}

.error-message.show {
    display: block;
}

.form-input:focus.error {
    border-color: #dc3545;
    box-shadow: 0 0 0 0.2rem rgba(220, 53, 69, 0.25);
}

.form-input:focus.success {
    border-color: #28a745;
    box-shadow: 0 0 0 0.2rem rgba(40, 167, 69, 0.25);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 2.5rem;
    }

    .hero p {
        font-size: 1.1rem;
    }

    .section {
        padding: 60px 0;
    }

    h2 {
        font-size: 2rem !important;
    }

    .features-grid,
    .testimonials-grid {
        grid-template-columns: 1fr;
    }

    .container {
        padding: 0 15px;
    }

    .share-buttons {
        gap: 10px;
    }
    
    .share-btn {
        padding: 10px 16px;
        font-size: 13px;
    }
    
    .theme-toggle {
        top: 15px;
        right: 15px;
        padding: 8px 12px;
        font-size: 12px;
    }
    
    .theme-toggle-text {
        display: none;
    }
}

/* Dark Mode Toggle */
.theme-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 1000;
    background: var(--bg-white);
    border: 2px solid var(--border-color);
    border-radius: 50px;
    padding: 10px 15px;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px var(--shadow-color);
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 14px;
    font-weight: 500;
    color: var(--text-dark);
}

.theme-toggle:hover {
    transform: scale(1.05);
    box-shadow: 0 6px 20px var(--shadow-color);
}

.theme-toggle-icon {
    font-size: 16px;
    transition: transform 0.3s ease;
}

.theme-toggle:hover .theme-toggle-icon {
    transform: rotate(180deg);
}

/* Smooth theme transition */
* {
    transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 2rem;
    }

    .cta-button {
        padding: 15px 30px;
        font-size: 1rem;
    }

    .signup-form {
        padding: 30px 20px;
    }
    
    .theme-toggle {
        top: 10px;
        right: 10px;
        padding: 6px 10px;
        border-radius: 25px;
    }
    
    .theme-toggle-icon {
        font-size: 14px;
    }
}