/* ==========================================
   全局样式和设计系统
   ========================================== */

:root {
    /* 色彩系统 */
    --primary-blue: #2563EB;
    --success-green: #10B981;
    --background: #FFFFFF;
    --text-primary: #111827;
    --text-secondary: #4B5563;
    --text-light: #6B7280;
    --border-color: #E5E7EB;
    --light-bg: #F9FAFB;
    --blue-light: #EFF6FF;
    --green-light: #D1FAE5;
    --red-light: #FEE2E2;
    
    /* 字体 */
    --font-primary: 'Inter', 'HarmonyOS Sans', 'PingFang SC', -apple-system, BlinkMacSystemFont, sans-serif;
    
    /* 间距 */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    --spacing-3xl: 6rem;
    
    /* 圆角 */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    
    /* 阴影 */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-primary);
    color: var(--text-primary);
    background: var(--background);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

/* ==========================================
   导航栏
   ========================================== */

.navbar {
    position: sticky;
    top: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    padding: var(--spacing-sm) 0;
}

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

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
}

.nav-links {
    display: flex;
    gap: var(--spacing-xl);
}

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
}

.nav-links a:hover {
    color: var(--primary-blue);
}

/* 语言切换按钮 */
.lang-switcher {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    margin-left: var(--spacing-lg);
}

.lang-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    transition: all 0.3s;
}

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

.lang-btn.active {
    color: var(--primary-blue);
    font-weight: 600;
}

.lang-divider {
    color: var(--border-color);
    font-weight: 300;
}

/* ==========================================
   Hero 区域
   ========================================== */

.hero {
    padding: var(--spacing-3xl) 0;
    background: linear-gradient(180deg, var(--blue-light) 0%, var(--background) 100%);
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-3xl);
    align-items: center;
}

.hero-text h1 {
    font-size: 3.5rem;
    font-weight: 800;
    line-height: 1.1;
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
}

.hero-subheading {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
    line-height: 1.8;
}

.hero-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-lg);
    margin-top: var(--spacing-xl);
}

.stat-item {
    text-align: center;
    padding: var(--spacing-md);
    background: var(--background);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-blue);
    margin-bottom: var(--spacing-xs);
}

.stat-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

/* 手机模型 */
.phone-mockup {
    display: flex;
    justify-content: center;
    align-items: center;
}

.phone-frame {
    width: 320px;
    height: 650px;
    background: #1F2937;
    border-radius: 2.5rem;
    padding: 0.75rem;
    box-shadow: var(--shadow-xl);
    position: relative;
}

.phone-notch {
    position: absolute;
    top: 1rem;
    left: 50%;
    transform: translateX(-50%);
    width: 120px;
    height: 25px;
    background: #1F2937;
    border-radius: 0 0 1rem 1rem;
    z-index: 10;
}

.phone-screen {
    width: 100%;
    height: 100%;
    background: var(--background);
    border-radius: 2rem;
    overflow: hidden;
}

.chat-interface {
    height: 100%;
    display: flex;
    flex-direction: column;
    padding: 2.5rem 1rem 1rem;
}

.chat-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md);
    border-bottom: 1px solid var(--border-color);
}

.chat-title {
    font-weight: 600;
    color: var(--text-primary);
}

.chat-score {
    font-weight: 700;
    color: var(--primary-blue);
    font-size: 1.125rem;
}

.chat-messages {
    flex: 1;
    padding: var(--spacing-md);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.message {
    display: flex;
    flex-direction: column;
}

.message-bubble {
    background: var(--blue-light);
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
    font-size: 0.875rem;
    line-height: 1.6;
}

.message-bubble.highlight {
    background: var(--light-bg);
    border: 2px solid var(--border-color);
}

.feedback-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-xs) 0;
    font-size: 0.875rem;
}

.feedback-icon {
    width: 20px;
    height: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    font-size: 0.75rem;
    font-weight: 700;
}

.feedback-item .feedback-icon {
    background: var(--success-green);
    color: white;
}

.feedback-item.missing .feedback-icon {
    background: #DC2626;
    color: white;
}

/* ==========================================
   功能特色区域
   ========================================== */

.features {
    padding: var(--spacing-3xl) 0;
    background: var(--background);
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-3xl);
}

.section-header h2 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
}

.section-header p {
    font-size: 1.125rem;
    color: var(--text-secondary);
}

.feature-cards {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-xl);
}

.feature-card {
    background: var(--background);
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    transition: transform 0.3s, box-shadow 0.3s;
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.feature-icon {
    margin-bottom: var(--spacing-md);
}

.feature-card h3 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
}

.feature-card p {
    color: var(--text-secondary);
    line-height: 1.8;
}

/* ==========================================
   提分报告区域
   ========================================== */

.score-report {
    padding: var(--spacing-3xl) 0;
    background: var(--light-bg);
}

.report-visual {
    max-width: 1000px;
    margin: 0 auto;
}

.report-comparison {
    display: grid;
    grid-template-columns: 2fr auto 2fr;
    gap: var(--spacing-lg);
    align-items: center;
    margin-bottom: var(--spacing-xl);
    background: var(--background);
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
}

.report-before,
.report-after {
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
}

.report-label {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--spacing-sm);
}

.report-label.success {
    color: var(--success-green);
}

.score-display {
    font-size: 3rem;
    font-weight: 800;
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
}

.score-display.success {
    color: var(--success-green);
}

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

.breakdown-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm);
    background: var(--green-light);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
}

.breakdown-item.missing {
    background: var(--red-light);
    opacity: 0.6;
}

.breakdown-item.improved {
    background: var(--success-green);
    color: white;
    font-weight: 600;
}

.check,
.cross {
    width: 20px;
    height: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    font-size: 0.75rem;
    font-weight: 700;
}

.check {
    background: var(--success-green);
    color: white;
}

.cross {
    background: #DC2626;
    color: white;
}

.breakdown-item.improved .check {
    background: white;
    color: var(--success-green);
}

.report-arrow {
    display: flex;
    justify-content: center;
}

.report-insights {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-lg);
}

.insight-card {
    display: flex;
    gap: var(--spacing-md);
    padding: var(--spacing-lg);
    background: var(--background);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
}

.insight-icon {
    font-size: 2rem;
    flex-shrink: 0;
}

.insight-content h4 {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.insight-content p {
    color: var(--text-secondary);
    font-size: 0.875rem;
    line-height: 1.6;
}

/* ==========================================
   学习场景区域
   ========================================== */

.scenarios {
    padding: var(--spacing-3xl) 0;
    background: var(--background);
}

.scenario-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-xl);
}

.scenario-card {
    background: var(--light-bg);
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    transition: transform 0.3s, box-shadow 0.3s;
}

.scenario-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.scenario-illustration {
    display: flex;
    justify-content: center;
    align-items: center;
    margin-bottom: var(--spacing-md);
    padding: var(--spacing-lg);
}

.scenario-card h3 {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.scenario-card p {
    color: var(--text-secondary);
    line-height: 1.8;
}

/* ==========================================
   关于区域
   ========================================== */

.about {
    padding: var(--spacing-3xl) 0;
    background: var(--blue-light);
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-3xl);
    align-items: center;
}

.about-text h2 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
}

.mission-statement {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-blue);
    margin-bottom: var(--spacing-xl);
    line-height: 1.6;
}

.about-details {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
}

.about-details p {
    color: var(--text-secondary);
    line-height: 1.8;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-md);
}

.stat-box {
    background: var(--background);
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
    text-align: center;
    box-shadow: var(--shadow-sm);
}

.stat-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-blue);
    margin-bottom: var(--spacing-xs);
}

.stat-desc {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

/* Rubric 卡片 */
.rubric-card {
    background: var(--background);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    overflow: hidden;
}

.rubric-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md);
    background: var(--primary-blue);
    color: white;
}

.rubric-title {
    font-weight: 600;
    font-size: 1.125rem;
}

.rubric-total {
    font-weight: 700;
    font-size: 1.25rem;
}

.rubric-items {
    padding: var(--spacing-md);
}

.rubric-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-sm);
    border-radius: var(--radius-md);
    background: var(--light-bg);
}

.rubric-item.highlighted {
    background: #FEF3C7;
    border: 2px solid #F59E0B;
    position: relative;
}

.rubric-point {
    flex-shrink: 0;
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--primary-blue);
    color: white;
    border-radius: var(--radius-md);
    font-weight: 700;
}

.rubric-desc {
    flex: 1;
    color: var(--text-primary);
    font-weight: 500;
}

.rubric-note {
    position: absolute;
    top: -10px;
    right: var(--spacing-md);
    background: #F59E0B;
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.75rem;
    font-weight: 600;
}

/* ==========================================
   页脚
   ========================================== */

.footer {
    background: var(--text-primary);
    color: white;
    padding: var(--spacing-3xl) 0 var(--spacing-lg);
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 3fr;
    gap: var(--spacing-3xl);
    margin-bottom: var(--spacing-xl);
}

.footer-brand .logo {
    color: white;
    margin-bottom: var(--spacing-sm);
}

.footer-brand p {
    color: #9CA3AF;
}

.footer-links {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-xl);
}

.footer-column h4 {
    font-weight: 600;
    margin-bottom: var(--spacing-md);
}

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

.footer-column a {
    color: #9CA3AF;
    text-decoration: none;
    transition: color 0.3s;
}

.footer-column a:hover {
    color: white;
}

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-lg);
    border-top: 1px solid #374151;
    color: #9CA3AF;
}

/* ==========================================
   响应式设计
   ========================================== */

@media (max-width: 1024px) {
    .hero-content,
    .about-content {
        grid-template-columns: 1fr;
    }
    
    .phone-mockup {
        margin-top: var(--spacing-xl);
    }
    
    .feature-cards {
        grid-template-columns: 1fr;
    }
    
    .report-comparison {
        grid-template-columns: 1fr;
    }
    
    .report-arrow {
        transform: rotate(90deg);
    }
    
    .scenario-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    .lang-switcher {
        margin-left: auto;
    }
    
    .hero-text h1 {
        font-size: 2.5rem;
    }
    
    .hero-subheading {
        font-size: 1rem;
    }
    
    .hero-stats {
        grid-template-columns: 1fr;
    }
    
    .section-header h2 {
        font-size: 2rem;
    }
    
    .phone-frame {
        width: 280px;
        height: 570px;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
    
    .footer-links {
        grid-template-columns: 1fr;
    }
    
    .report-insights {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-md);
    }
    
    .hero {
        padding: var(--spacing-xl) 0;
    }
    
    .features,
    .score-report,
    .scenarios,
    .about {
        padding: var(--spacing-xl) 0;
    }
    
    .hero-text h1 {
        font-size: 2rem;
    }
    
    .stat-number {
        font-size: 2rem;
    }
    
    .phone-frame {
        width: 240px;
        height: 490px;
    }
}