:root {
    --primary-color: #000000;
    --primary-hover: #333333;
    --accent-color: #2563eb; /* Electric Blue */
    
    --text-primary: #111111;
    --text-secondary: #555555;
    --text-light: #888888;
    
    --bg-body: #ffffff;
    --bg-surface: #f9f9f9;
    --bg-card: #ffffff;
    
    --border-color: #e5e5e5;
    --border-dark: #000000;
    
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.05);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif, "PingFang SC", "Microsoft YaHei";
    line-height: 1.5;
    color: var(--text-primary);
    background-color: var(--bg-body);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

a {
    text-decoration: none;
    color: inherit;
    transition: color 0.2s ease;
}

ul {
    list-style: none;
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
}

/* Header */
.site-header {
    background: rgba(255,255,255,0.9);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
    padding: 1rem 0;
}

.site-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.25rem;
    font-weight: 800;
    color: var(--text-primary);
    letter-spacing: -0.03em;
    text-transform: uppercase;
}

.main-nav ul {
    display: flex;
    gap: 2.5rem;
    align-items: center;
}

.main-nav a {
    font-weight: 500;
    font-size: 0.9rem;
    color: var(--text-secondary);
    letter-spacing: -0.01em;
}

.main-nav a:hover {
    color: var(--text-primary);
}

.btn-nav {
    background-color: var(--primary-color);
    color: #ffffff !important;
    padding: 0.5rem 1rem;
    border-radius: 4px;
    font-weight: 600;
    font-size: 0.85rem;
    transition: all 0.2s ease;
}

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

/* Hero Section */
.hero-section {
    padding: 8rem 0 6rem;
    text-align: center;
    border-bottom: 1px solid var(--border-color);
    background: radial-gradient(circle at 50% 0%, #fafafa 0%, #ffffff 100%);
}

.hero-content {
    max-width: 760px;
    margin: 0 auto;
}

.hero-content h1 {
    font-size: 4.5rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
    line-height: 1.05;
    letter-spacing: -0.04em;
}

.hero-content h1 span {
    color: var(--accent-color);
    display: block;
}

.subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
    line-height: 1.6;
    letter-spacing: -0.01em;
}

.hero-actions {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 2rem;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.875rem 2rem;
    border-radius: 6px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    border: 1px solid transparent;
    font-size: 1rem;
    letter-spacing: -0.01em;
}

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

.btn-primary:hover {
    background-color: var(--primary-hover);
    transform: translateY(-1px);
}

.btn-outline {
    background-color: transparent;
    border-color: var(--border-color);
    color: var(--text-primary);
}

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

/* Feature Cards */
.features-section {
    padding: 6rem 0;
    border-bottom: 1px solid var(--border-color);
}

.section-title {
    text-align: center;
    font-size: 2rem;
    font-weight: 800;
    margin-bottom: 4rem;
    color: var(--text-primary);
    letter-spacing: -0.03em;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 2rem;
}

.feature-card {
    padding: 2rem;
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    transition: border-color 0.2s ease;
    text-align: left;
}

.feature-card:hover {
    border-color: var(--text-primary);
}

.feature-card .icon {
    font-size: 2rem;
    margin-bottom: 1.25rem;
    display: inline-block;
    color: var(--text-primary);
}

.feature-card h3 {
    font-size: 1.15rem;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
    font-weight: 700;
    letter-spacing: -0.02em;
}

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

/* Preview Section */
.preview-section {
    padding: 6rem 0;
    background-color: var(--bg-surface);
    border-bottom: 1px solid var(--border-color);
}

.preview-content {
    max-width: 1000px;
    margin: 0 auto;
}

.preview-content h2 {
    font-size: 2rem;
    font-weight: 800;
    color: var(--text-primary);
    margin-bottom: 3rem;
    text-align: center;
    letter-spacing: -0.03em;
}

.resource-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
}

.resource-card {
    background: #ffffff;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.5rem;
    transition: all 0.2s ease;
}

.resource-card:hover {
    border-color: var(--accent-color);
    box-shadow: 0 4px 12px rgba(0,0,0,0.05);
}

.card-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1.25rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.card-header .icon {
    font-size: 1.5rem;
}

.card-header h3 {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: -0.01em;
}

.file-list li {
    font-size: 0.9rem;
    color: var(--text-secondary);
    padding: 0.5rem 0;
    border-bottom: 1px dashed var(--border-color);
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.file-list li:last-child {
    border-bottom: none;
}

.file-list .type {
    font-size: 0.65rem;
    font-weight: 700;
    padding: 0.15rem 0.35rem;
    border-radius: 3px;
    background-color: var(--text-primary);
    color: #ffffff;
    min-width: 36px;
    text-align: center;
    text-transform: uppercase;
}

/* Reviews Section */
.reviews-section {
    padding: 6rem 0;
}

.reviews-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.review-card {
    background: var(--bg-surface);
    padding: 2rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.user-info {
    display: flex;
    align-items: center;
    margin-bottom: 1.25rem;
}

.avatar {
    width: 40px;
    height: 40px;
    background-color: var(--text-primary);
    color: #ffffff;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1rem;
    margin-right: 1rem;
}

.name {
    font-size: 1rem;
    font-weight: 700;
    color: var(--text-primary);
}

.role {
    font-size: 0.8rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.review-text {
    color: var(--text-primary);
    margin-bottom: 1rem;
    line-height: 1.6;
    font-size: 1rem;
}

.rating {
    color: var(--text-primary);
    font-size: 0.9rem;
    letter-spacing: 2px;
}

/* CTA Section */
.cta-section {
    padding: 6rem 0;
    text-align: center;
    background-color: var(--text-primary);
    color: #ffffff;
}

.cta-section h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    font-weight: 800;
    letter-spacing: -0.03em;
}

.cta-section p {
    font-size: 1.2rem;
    margin-bottom: 2.5rem;
    color: #aaaaaa;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.cta-section .btn {
    background: #ffffff;
    color: var(--text-primary);
}

.cta-section .btn:hover {
    background: #f0f0f0;
}

/* Footer */
.site-footer {
    padding: 2rem 0;
    background-color: #ffffff;
    border-top: 1px solid var(--border-color);
    color: var(--text-secondary);
    text-align: center;
}

.footer-keywords {
    margin-bottom: 2rem;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    align-items: center;
    gap: 0.75rem;
    padding-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
}

.keyword-label {
    font-size: 0.9rem;
    font-weight: 700;
    color: var(--text-primary);
}

.keyword-tag {
    font-size: 0.85rem;
    color: var(--text-secondary);
    background-color: var(--bg-surface);
    padding: 0.35rem 0.75rem;
    border-radius: 9999px;
    border: 1px solid var(--border-color);
    transition: all 0.2s ease;
    cursor: default;
}

.keyword-tag:hover {
    color: var(--text-primary);
    border-color: var(--text-primary);
    background-color: #ffffff;
}

.footer-links {
    margin-top: 1rem;
    display: flex;
    justify-content: center;
    gap: 2rem;
}

.footer-links a {
    font-size: 0.85rem;
    font-weight: 500;
}

.footer-links a:hover {
    color: var(--text-primary);
    text-decoration: underline;
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    overflow: auto;
    background-color: rgba(0,0,0,0.4);
    backdrop-filter: blur(4px);
    align-items: center;
    justify-content: center;
}

.modal-content {
    background-color: #ffffff;
    padding: 3rem;
    border-radius: 8px;
    width: 90%;
    max-width: 800px;
    text-align: center;
    position: relative;
    box-shadow: 0 10px 40px rgba(0,0,0,0.1);
    border: 1px solid var(--border-color);
    animation: modalSlideIn 0.3s ease-out;
}

@keyframes modalSlideIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.close-modal {
    position: absolute;
    top: 1.5rem;
    right: 1.5rem;
    color: var(--text-light);
    font-size: 1.5rem;
    cursor: pointer;
    transition: color 0.2s;
}

.close-modal:hover {
    color: var(--text-primary);
}

.modal h3 {
    margin-bottom: 0.5rem;
    font-size: 1.75rem;
    color: var(--text-primary);
    font-weight: 800;
    letter-spacing: -0.02em;
}

.modal-subtitle {
    color: var(--text-secondary);
    margin-bottom: 2.5rem;
    font-size: 1rem;
}

.download-options {
    display: flex;
    flex-direction: row;
    gap: 1.5rem;
    justify-content: center;
}

.download-option {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 2rem;
    transition: all 0.2s ease;
    flex: 1;
    min-width: 260px;
}

.download-option:hover {
    border-color: var(--accent-color);
    background: #ffffff;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.05);
}

.option-header {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    margin-bottom: 1.25rem;
}

.option-header .icon {
    font-size: 1.75rem;
}

.option-header .name {
    font-weight: 700;
    font-size: 1.1rem;
    color: var(--text-primary);
}

.qrcode-container {
    margin: 0 auto 1rem;
    display: flex;
    justify-content: center;
    padding: 0.5rem;
    background: #ffffff;
    border: 1px solid var(--border-color);
    border-radius: 4px;
}

.scan-text {
    font-size: 0.85rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.btn-baidu {
    background-color: #4e6ef2;
    color: white;
    display: block;
    width: 100%;
    padding: 0.875rem;
    border-radius: 4px;
    text-decoration: none;
    font-weight: 600;
    transition: background-color 0.2s;
}

.btn-baidu:hover {
    background-color: #3b5bdb;
}

.btn-quark {
    background-color: #008af5;
    color: white;
    display: block;
    width: 100%;
    padding: 0.875rem;
    border-radius: 4px;
    text-decoration: none;
    font-weight: 600;
    transition: background-color 0.2s;
}

.btn-quark:hover {
    background-color: #0070c9;
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .hero-content h1 {
        font-size: 2.75rem;
    }
    
    .hero-actions {
        flex-direction: column;
        gap: 0.75rem;
    }
    
    .main-nav {
        display: none; 
    }
    
    .site-header .container {
        justify-content: center;
    }

    .download-options {
        flex-direction: column;
    }

    .download-option {
        min-width: auto;
    }
    
    .features-grid, .reviews-grid, .resource-grid {
        grid-template-columns: 1fr;
    }
    
    .preview-content {
        padding: 0;
    }
    
    .modal-content {
        padding: 2rem;
        width: 95%;
    }
}