/* 底线官网样式 */

/* 基础样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #4A90A4;
    --primary-dark: #3A7A8A;
    --secondary-color: #F5A623;
    --accent-color: #7ED321;
    --text-color: #333;
    --text-light: #666;
    --bg-color: #F8F9FA;
    --card-bg: #FFFFFF;
    --gradient-start: #4A90A4;
    --gradient-end: #7ED321;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
}

/* 导航栏 */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    z-index: 1000;
    padding: 1rem 0;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.logo-icon {
    font-size: 1.5rem;
}

.logo-text {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 2rem;
}

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

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

/* Hero 区域 */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 6rem 2rem 4rem;
    background: linear-gradient(135deg, #E8F4F8 0%, #F0F9F0 100%);
}

.hero-content {
    max-width: 600px;
    text-align: center;
}

.hero h1 {
    font-size: 4rem;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    letter-spacing: 0.1em;
}

.hero-subtitle {
    font-size: 1.8rem;
    color: var(--text-light);
    margin-bottom: 1rem;
}

.hero-desc {
    font-size: 1.2rem;
    color: var(--text-light);
    margin-bottom: 2rem;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

.btn {
    padding: 1rem 2rem;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 5px 20px rgba(74, 144, 164, 0.3);
}

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

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

/* 手机模型 */
.hero-visual {
    margin-left: 3rem;
}

.phone-mockup {
    width: 280px;
    height: 560px;
    background: #1a1a1a;
    border-radius: 40px;
    padding: 20px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

.phone-screen {
    width: 100%;
    height: 100%;
    background: white;
    border-radius: 30px;
    overflow: hidden;
}

.app-preview {
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 2rem 1rem;
    background: linear-gradient(180deg, #4A90A4 0%, #F8F9FA 30%);
}

.preview-header {
    color: white;
    font-size: 1rem;
    margin-bottom: 1rem;
}

.preview-score {
    text-align: center;
    margin-bottom: 1.5rem;
}

.score-value {
    font-size: 3rem;
    font-weight: 700;
    color: var(--primary-color);
}

.score-label {
    font-size: 0.8rem;
    color: var(--text-light);
}

.preview-chart {
    display: flex;
    gap: 0.5rem;
    height: 100px;
    align-items: flex-end;
    width: 80%;
}

.chart-bar {
    width: 20%;
    background: linear-gradient(180deg, var(--primary-color), var(--accent-color));
    border-radius: 4px 4px 0 0;
}

/* Section 通用 */
.section-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 4rem 2rem;
}

.section-title {
    font-size: 2.5rem;
    text-align: center;
    color: var(--primary-color);
    margin-bottom: 3rem;
}

/* 功能介绍 */
.features {
    background: white;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
}

.feature-card {
    padding: 2rem;
    border-radius: 20px;
    background: var(--bg-color);
    text-align: center;
    transition: all 0.3s;
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 10px 30px rgba(74, 144, 164, 0.1);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.feature-card h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

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

/* 科学依据 */
.science {
    background: linear-gradient(135deg, #4A90A4 0%, #3A7A8A 100%);
    color: white;
}

.science .section-title {
    color: white;
}

.science-content {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem;
}

.science-card {
    background: rgba(255, 255, 255, 0.1);
    padding: 2rem;
    border-radius: 20px;
}

.science-card h3 {
    margin-bottom: 1rem;
}

.bristol-scale {
    margin-top: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.bristol-item {
    display: flex;
    justify-content: space-between;
    padding: 0.5rem 1rem;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 8px;
}

.bristol-item.ideal {
    background: rgba(126, 211, 33, 0.3);
}

.score-algorithm {
    margin-top: 1.5rem;
    display: flex;
    justify-content: space-around;
}

.algo-item {
    text-align: center;
}

.algo-percent {
    font-size: 2rem;
    font-weight: 700;
    color: var(--secondary-color);
}

.algo-name {
    font-size: 0.9rem;
}

/* 社区功能 */
.community {
    background: var(--bg-color);
}

.community-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.5rem;
}

.community-item {
    text-align: center;
    padding: 1.5rem;
}

.community-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.community-item h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

.community-item p {
    color: var(--text-light);
    font-size: 0.85rem;
}

/* 下载区域 */
.download {
    background: white;
    text-align: center;
}

.download-desc {
    font-size: 1.2rem;
    color: var(--text-light);
    margin-bottom: 2rem;
}

.download-content {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 3rem;
    flex-wrap: wrap;
}

.qr-container {
    text-align: center;
}

.qr-code {
    width: 200px;
    height: 200px;
    background: white;
    border: 2px solid var(--primary-color);
    border-radius: 20px;
    padding: 1rem;
    display: flex;
    align-items: center;
    justify-content: center;
}

.qr-code img {
    width: 100%;
    height: 100%;
    object-fit: contain;
}

.qr-placeholder {
    color: var(--primary-color);
    font-weight: 600;
    text-align: center;
    line-height: 1.4;
}

.qr-tip {
    margin-top: 1rem;
    color: var(--text-light);
}

.download-info {
    text-align: left;
}

.download-info h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.download-features {
    list-style: none;
    margin-bottom: 1.5rem;
}

.download-features li {
    color: var(--text-light);
    margin-bottom: 0.5rem;
}

.download-stats {
    display: flex;
    gap: 2rem;
}

.stat-item {
    text-align: center;
}

.stat-value {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--primary-color);
}

.stat-label {
    font-size: 0.85rem;
    color: var(--text-light);
}

/* 页脚 */
.footer {
    background: #1a1a1a;
    color: white;
    padding: 3rem 2rem;
}

.footer-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 2rem;
}

.footer-brand {
    text-align: center;
}

.footer-logo {
    font-size: 1.5rem;
}

.footer-brand p {
    color: #999;
    margin-top: 0.5rem;
}

.footer-links {
    display: flex;
    gap: 2rem;
}

.footer-links a {
    color: #999;
    text-decoration: none;
    transition: color 0.3s;
}

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

.footer-copyright {
    color: #666;
    text-align: center;
}

/* 回到顶部 */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 50px;
    height: 50px;
    background: var(--primary-color);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    text-decoration: none;
    font-size: 1.5rem;
    opacity: 0;
    transition: all 0.3s;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.2);
}

.back-to-top.visible {
    opacity: 1;
}

.back-to-top:hover {
    background: var(--primary-dark);
    transform: translateY(-5px);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }

    .hero {
        flex-direction: column;
        text-align: center;
        padding: 5rem 1rem 3rem;
    }

    .hero h1 {
        font-size: 2.5rem;
    }

    .hero-subtitle {
        font-size: 1.2rem;
    }

    .hero-visual {
        margin-left: 0;
        margin-top: 2rem;
    }

    .phone-mockup {
        width: 200px;
        height: 400px;
    }

    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .science-content {
        grid-template-columns: 1fr;
    }

    .community-grid {
        grid-template-columns: repeat(2, 1fr);
    }

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

    .download-info {
        text-align: center;
    }

    .footer-container {
        flex-direction: column;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .features-grid {
        grid-template-columns: 1fr;
    }

    .community-grid {
        grid-template-columns: 1fr;
    }

    .hero-buttons {
        flex-direction: column;
    }
}