/* Base Styles */
:root {
    --primary-color: #3B82F6;
    --primary-dark: #2563EB;
    --secondary-color: #6366F1;
    --text-color: #1F2937;
    --light-text: #4B5563;
    --background: #F9FAFB;
    --card-bg: #FFFFFF;
    --border-color: #E5E7EB;
    --success-color: #10B981;
    --warning-color: #F59E0B;
    --danger-color: #EF4444;
}

body {
    font-family: 'Noto Sans SC', Tahoma, Arial, Roboto, "Droid Sans", "Helvetica Neue", "Droid Sans Fallback", "Heiti SC", "Hiragino Sans GB", Simsun, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
}

h1, h2, h3, h4, h5, h6 {
    font-family: 'Noto Serif SC', serif;
    font-weight: 600;
    line-height: 1.3;
}

/* Navigation */
.nav-link {
    position: relative;
    font-weight: 500;
    padding: 0.5rem 0;
    color: var(--light-text);
    transition: color 0.3s;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    transition: width 0.3s;
}

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

.nav-link:hover::after {
    width: 100%;
}

/* Buttons */
.btn-primary {
    display: inline-flex;
    align-items: center;
    padding: 0.75rem 1.5rem;
    background: var(--primary-color);
    color: white;
    font-weight: 500;
    border-radius: 0.5rem;
    transition: all 0.3s;
}

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 4px 6px rgba(59, 130, 246, 0.25);
}

.btn-secondary {
    display: inline-flex;
    align-items: center;
    padding: 0.75rem 1.5rem;
    background: white;
    color: var(--primary-color);
    font-weight: 500;
    border: 1px solid var(--primary-color);
    border-radius: 0.5rem;
    transition: all 0.3s;
}

.btn-secondary:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 4px 6px rgba(59, 130, 246, 0.15);
}

/* Sections */
.content-section {
    padding: 4rem 0;
    border-bottom: 1px solid var(--border-color);
}

.content-section:last-child {
    border-bottom: none;
}

.section-header {
    text-align: center;
    margin-bottom: 3rem;
}

.section-title {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-color);
    position: relative;
    display: inline-block;
    margin-bottom: 0.5rem;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -0.5rem;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 3px;
    background-color: var(--primary-color);
}

.section-subtitle {
    font-size: 1.125rem;
    color: var(--light-text);
    max-width: 600px;
    margin: 0 auto;
}

/* Cards */
.card {
    background: var(--card-bg);
    border-radius: 0.75rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    overflow: hidden;
    transition: transform 0.3s, box-shadow 0.3s;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 15px rgba(0, 0, 0, 0.05);
}

.card-header {
    padding: 1.25rem 1.5rem;
    background: linear-gradient(to right, #F9FAFB, #F3F4F6);
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.card-header h3 {
    margin: 0;
    font-size: 1.25rem;
    font-weight: 600;
}

.card-body {
    padding: 1.5rem;
}

/* Features */
.feature-box {
    padding: 1.5rem;
    background-color: #F9FAFB;
    border-radius: 0.5rem;
    height: 100%;
}

.feature-box i {
    font-size: 1.5rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
    display: block;
}

.feature-box h4 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
}

.feature-box ul {
    padding-left: 1.25rem;
    list-style-type: disc;
}

.feature-box ul li {
    margin-bottom: 0.375rem;
    font-size: 0.925rem;
}

/* Timeline */
.timeline {
    position: relative;
    padding: 1.5rem 0;
}

.timeline::before {
    content: '';
    position: absolute;
    top: 0;
    left: 1rem;
    height: 100%;
    width: 2px;
    background: var(--border-color);
}

.timeline-item {
    position: relative;
    padding-left: 3rem;
    margin-bottom: 2rem;
}

.timeline-item:last-child {
    margin-bottom: 0;
}

.timeline-marker {
    position: absolute;
    top: 0.25rem;
    left: 0.5rem;
    width: 1rem;
    height: 1rem;
    border-radius: 50%;
    background: var(--primary-color);
    border: 2px solid white;
    z-index: 1;
}

.timeline-content h4 {
    font-weight: 600;
    margin-bottom: 0.25rem;
    color: var(--primary-color);
}

/* Stats */
.stat-card {
    display: flex;
    align-items: center;
    padding: 1rem;
    background: white;
    border-radius: 0.5rem;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
}

.stat-icon {
    width: 3rem;
    height: 3rem;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    margin-right: 1rem;
}

.stat-title {
    font-size: 0.875rem;
    color: var(--light-text);
    margin-bottom: 0.25rem;
}

.stat-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-color);
    line-height: 1.2;
}

.stat-desc {
    font-size: 0.75rem;
    color: var(--light-text);
    margin-top: 0.25rem;
}

/* Comparison Table */
.comparison-table {
    width: 100%;
    border-collapse: collapse;
}

.comparison-table th,
.comparison-table td {
    padding: 0.75rem 1rem;
    text-align: center;
    border: 1px solid var(--border-color);
}

.comparison-table th {
    background-color: #F3F4F6;
    font-weight: 600;
}

.comparison-table tr:nth-child(even) td {
    background-color: #FAFAFA;
}

/* Feature Numbers */
.feature-number {
    flex-shrink: 0;
    width: 2rem;
    height: 2rem;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: 600;
    margin-right: 1rem;
    margin-top: 0.25rem;
}

/* Challenge Cards */
.challenge-card {
    padding: 1.5rem;
    background-color: white;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    height: 100%;
    transition: transform 0.3s;
}

.challenge-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 15px rgba(0, 0, 0, 0.05);
}

.challenge-icon {
    width: 3rem;
    height: 3rem;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    margin-bottom: 1rem;
}

.challenge-card h4 {
    font-weight: 600;
    margin-bottom: 1rem;
}

.challenge-card ul {
    padding-left: 1.25rem;
    list-style-type: disc;
}

.challenge-card ul li {
    margin-bottom: 0.375rem;
    font-size: 0.925rem;
}

/* Application Cards */
.application-card {
    padding: 1.5rem;
    border-radius: 0.5rem;
    height: 100%;
    position: relative;
    overflow: hidden;
    transition: transform 0.3s, box-shadow 0.3s;
}

.application-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 15px rgba(0, 0, 0, 0.05);
}

.application-icon {
    width: 3rem;
    height: 3rem;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.25rem;
    margin-bottom: 1rem;
}

.application-card h4 {
    font-weight: 600;
    margin-bottom: 1rem;
}

.application-card ul {
    padding-left: 1.25rem;
    list-style-type: disc;
}

.application-card ul li {
    margin-bottom: 0.375rem;
    font-size: 0.925rem;
}

/* Charts */
.chart-container {
    width: 100%;
    height: auto;
    margin: 1rem 0;
    border-radius: 0.5rem;
    overflow: hidden;
}

/* Responsive Adjustments */
@media (max-width: 768px) {
    .section-title {
        font-size: 1.75rem;
    }
    
    .timeline::before {
        left: 0.75rem;
    }
    
    .timeline-item {
        padding-left: 2.5rem;
    }
    
    .timeline-marker {
        left: 0.25rem;
        width: 0.875rem;
        height: 0.875rem;
    }
    
    .card-header {
        padding: 1rem 1.25rem;
    }
    
    .card-body {
        padding: 1.25rem;
    }
}

@media (max-width: 640px) {
    .stat-card {
        flex-direction: column;
        text-align: center;
        padding: 1.25rem;
    }
    
    .stat-icon {
        margin-right: 0;
        margin-bottom: 0.75rem;
    }
    
    .feature-number {
        width: 1.75rem;
        height: 1.75rem;
        font-size: 0.875rem;
    }
}