/* ========================================
   SciBoost 科技研发资金募集网站样式
   主色调：蓝色 + 白色
   风格：现代科技、专业可信、清爽简洁
   ======================================== */

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

:root {
    /* 主色调 */
    --primary-blue: #2563eb;
    --primary-blue-dark: #1d4ed8;
    --primary-blue-light: #3b82f6;
    --primary-blue-100: #dbeafe;
    --primary-blue-50: #eff6ff;
    
    /* 辅助色 */
    --secondary-blue: #0ea5e9;
    --accent-cyan: #06b6d4;
    --success-green: #10b981;
    --warning-orange: #f59e0b;
    --error-red: #ef4444;
    
    /* 中性色 */
    --white: #ffffff;
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    --black: #000000;
    
    /* 渐变 */
    --gradient-blue: linear-gradient(135deg, var(--primary-blue) 0%, var(--secondary-blue) 100%);
    --gradient-blue-light: linear-gradient(135deg, var(--primary-blue-light) 0%, var(--accent-cyan) 100%);
    --gradient-hero: linear-gradient(135deg, rgba(37, 99, 235, 0.9) 0%, rgba(14, 165, 233, 0.8) 100%);
    
    /* 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), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    
    /* 圆角 */
    --radius-sm: 0.25rem;
    --radius-md: 0.375rem;
    --radius-lg: 0.5rem;
    --radius-xl: 0.75rem;
    --radius-2xl: 1rem;
    
    /* 过渡动画 */
    --transition-fast: 0.15s ease-in-out;
    --transition-normal: 0.3s ease-in-out;
    --transition-slow: 0.5s ease-in-out;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--gray-800);
    background-color: var(--white);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* 容器 */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* 按钮样式 */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--radius-lg);
    font-weight: 500;
    font-size: 1rem;
    text-decoration: none;
    cursor: pointer;
    transition: all var(--transition-fast);
    outline: none;
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.3);
    transform: translate(-50%, -50%);
    transition: width var(--transition-normal), height var(--transition-normal);
}

.btn:active::before {
    width: 300px;
    height: 300px;
}

.btn-primary {
    background: var(--gradient-blue);
    color: var(--white);
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-primary:active {
    transform: translateY(0);
}

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

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

.btn-large {
    padding: 1rem 2rem;
    font-size: 1.125rem;
    font-weight: 600;
}

.btn-small {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

/* 导航栏 */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
    transition: all var(--transition-normal);
}

.navbar.scrolled {
    background: var(--white);
    box-shadow: var(--shadow-md);
}

.navbar .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 4rem;
}

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

.logo-text {
    font-size: 1.5rem;
    font-weight: 700;
    background: var(--gradient-blue);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

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

.nav-links a {
    text-decoration: none;
    color: var(--gray-700);
    font-weight: 500;
    transition: color var(--transition-fast);
    position: relative;
}

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

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -0.5rem;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-blue);
    transition: width var(--transition-fast);
}

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

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

.nav-links a.active::after {
    width: 100%;
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
    padding: 0.5rem;
}

.mobile-menu-toggle span {
    width: 24px;
    height: 2px;
    background: var(--gray-800);
    margin: 3px 0;
    transition: var(--transition-fast);
}

.mobile-menu-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.mobile-menu-toggle.active span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(7px, -6px);
}

/* 移动端菜单样式 */
@media (max-width: 768px) {
    .nav-links {
        position: fixed;
        top: 4rem;
        right: -100%;
        width: 100%;
        height: calc(100vh - 4rem);
        background: var(--white);
        flex-direction: column;
        padding: 2rem;
        gap: 1.5rem;
        transition: right var(--transition-normal);
        box-shadow: var(--shadow-lg);
        overflow-y: auto;
    }

    .nav-links.active {
        right: 0;
    }

    .nav-links a {
        font-size: 1.125rem;
        padding: 0.75rem 0;
        border-bottom: 1px solid var(--gray-200);
    }

    .nav-links a::after {
        display: none;
    }
}

/* Hero 区域 */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: url('https://images.unsplash.com/photo-1518770660439-4636190af475?w=1920&h=1080&fit=crop') center/cover no-repeat;
    overflow: hidden;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--gradient-hero);
}

.gradient-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(circle at 20% 30%, rgba(59, 130, 246, 0.3) 0%, transparent 50%),
                radial-gradient(circle at 80% 70%, rgba(14, 165, 233, 0.2) 0%, transparent 50%);
}

.hero-content {
    position: relative;
    text-align: center;
    color: var(--white);
    z-index: 2;
    max-width: 800px;
    padding: 0 1.5rem;
    animation: fadeInUp 1s ease-out;
}

.hero-title {
    font-size: 4rem;
    font-weight: 800;
    margin-bottom: 1rem;
    letter-spacing: -0.02em;
}

.gradient-text {
    background: linear-gradient(135deg, var(--white) 0%, var(--primary-blue-100) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.5rem;
    font-weight: 300;
    margin-bottom: 1.5rem;
    opacity: 0.9;
}

.hero-description {
    font-size: 1.125rem;
    margin-bottom: 2.5rem;
    opacity: 0.8;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

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

.scroll-indicator {
    position: absolute;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    animation: bounce 2s infinite;
}

.scroll-arrow {
    width: 30px;
    height: 50px;
    border: 2px solid rgba(255, 255, 255, 0.5);
    border-radius: 15px;
    position: relative;
}

.scroll-arrow::before {
    content: '';
    position: absolute;
    top: 10px;
    left: 50%;
    width: 6px;
    height: 10px;
    background: rgba(255, 255, 255, 0.8);
    border-radius: 3px;
    transform: translateX(-50%);
    animation: scroll 2s infinite;
}

/* 项目展示模块 */
.projects-section {
    padding: 6rem 0;
    background: var(--gray-50);
}

.section-header {
    text-align: center;
    margin-bottom: 4rem;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--gray-900);
    margin-bottom: 1rem;
    background: var(--gradient-blue);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

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

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
}

.project-card {
    background: var(--white);
    border-radius: var(--radius-xl);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
    border: 1px solid var(--gray-200);
}

.project-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
}

.project-image {
    position: relative;
    height: 200px;
    overflow: hidden;
}

.project-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-normal);
}

.project-card:hover .project-image img {
    transform: scale(1.05);
}

.project-category {
    position: absolute;
    top: 1rem;
    left: 1rem;
    background: var(--gradient-blue);
    color: var(--white);
    padding: 0.5rem 1rem;
    border-radius: var(--radius-lg);
    font-size: 0.875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.project-content {
    padding: 2rem;
}

.project-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: 1rem;
    line-height: 1.4;
}

.project-description {
    color: var(--gray-600);
    margin-bottom: 1.5rem;
    line-height: 1.6;
    font-size: 0.95rem;
}

.project-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1rem;
    margin-bottom: 1.5rem;
}

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

.stat-value {
    display: block;
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--gray-900);
}

.stat-value.overfunded {
    color: var(--success-green);
}

.stat-label {
    display: block;
    font-size: 0.75rem;
    color: var(--gray-500);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--gray-200);
    border-radius: 4px;
    overflow: hidden;
    margin-bottom: 1rem;
}

.progress-fill {
    height: 100%;
    background: var(--gradient-blue);
    border-radius: 4px;
    transition: width var(--transition-slow);
    width: 0;
}

.progress-fill.overfunded {
    background: var(--success-green);
}

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

.days-left {
    font-size: 0.875rem;
    color: var(--gray-500);
}

.project-status {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--success-green);
}

/* 参与方式模块 */
.participate-section {
    padding: 6rem 0;
    background: var(--white);
}

.steps-container {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.step-item {
    text-align: center;
    max-width: 200px;
    flex: 1;
    min-width: 150px;
}

.step-number {
    width: 48px;
    height: 48px;
    background: var(--gradient-blue);
    color: var(--white);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    font-weight: 700;
    margin: 0 auto 1rem;
}

.step-icon {
    color: var(--primary-blue);
    margin-bottom: 1rem;
}

.step-title {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: 0.5rem;
}

.step-description {
    font-size: 0.875rem;
    color: var(--gray-600);
    line-height: 1.5;
}

.step-arrow {
    color: var(--gray-400);
    align-self: center;
}

.participate-cta {
    text-align: center;
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

/* 关于我们模块 */
.about-section {
    padding: 6rem 0;
    background: var(--gray-50);
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: start;
}

.about-text {
    margin-bottom: 2rem;
}

.about-description {
    font-size: 1.125rem;
    color: var(--gray-600);
    line-height: 1.8;
    margin-bottom: 1.5rem;
}

.about-features {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.feature-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
}

.feature-icon {
    color: var(--primary-blue);
    flex-shrink: 0;
    margin-top: 0.25rem;
}

.feature-content h4 {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: 0.5rem;
}

.feature-content p {
    color: var(--gray-600);
    line-height: 1.6;
}

/* 联系我们模块 */
.contact-section {
    padding: 6rem 0;
    background: var(--white);
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
}

.contact-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    margin-bottom: 2rem;
}

.contact-icon {
    color: var(--primary-blue);
    margin-top: 0.25rem;
}

.contact-details h4 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: 0.25rem;
}

.contact-details p {
    color: var(--gray-600);
}

.social-links {
    display: flex;
    gap: 1rem;
    margin-top: 2rem;
}

.social-link {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: var(--gray-100);
    color: var(--gray-600);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

.social-link:hover {
    background: var(--primary-blue);
    color: var(--white);
}

.contact-form {
    background: var(--gray-50);
    padding: 2rem;
    border-radius: var(--radius-xl);
    border: 1px solid var(--gray-200);
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--gray-700);
    margin-bottom: 0.5rem;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--gray-300);
    border-radius: var(--radius-lg);
    font-size: 1rem;
    font-family: inherit;
    transition: border-color var(--transition-fast);
    background: var(--white);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-blue);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* 页脚 */
.footer {
    background: var(--gray-900);
    color: var(--gray-300);
    padding: 4rem 0 2rem;
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 3rem;
    margin-bottom: 3rem;
}

.footer-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--white);
    margin-bottom: 1rem;
}

.footer-description {
    color: var(--gray-400);
    line-height: 1.6;
    margin-bottom: 1.5rem;
}

.footer-subtitle {
    font-size: 1rem;
    font-weight: 600;
    color: var(--white);
    margin-bottom: 1rem;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 0.75rem;
}

.footer-links a {
    color: var(--gray-400);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

.footer-social {
    display: flex;
    gap: 1rem;
}

.footer-social .social-link {
    color: var(--gray-400);
}

.footer-social .social-link:hover {
    color: var(--primary-blue);
}

.footer-bottom {
    border-top: 1px solid var(--gray-700);
    padding-top: 2rem;
    text-align: center;
}

.footer-bottom p {
    color: var(--gray-500);
    font-size: 0.875rem;
}

/* 动画 */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% {
        transform: translateX(-50%) translateY(0);
    }
    40% {
        transform: translateX(-50%) translateY(-10px);
    }
    60% {
        transform: translateX(-50%) translateY(-5px);
    }
}

@keyframes scroll {
    0% {
        top: 10px;
        opacity: 1;
    }
    100% {
        top: 30px;
        opacity: 0;
    }
}

/* 响应式设计 */
@media (max-width: 1024px) {
    .about-content,
    .contact-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .footer-content {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 768px) {
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.25rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .projects-grid {
        grid-template-columns: 1fr;
    }
    
    .steps-container {
        flex-direction: column;
    }
    
    .step-arrow {
        transform: rotate(90deg);
    }
    
    .project-stats {
        grid-template-columns: 1fr;
        gap: 0.75rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        width: 100%;
    }
    
    .hero-buttons .btn {
        width: 100%;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .footer-section {
        margin-bottom: 2rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 1rem;
    }
    
    .hero-content {
        padding: 0 1rem;
    }
    
    .project-content {
        padding: 1.5rem;
    }
    
    .contact-form {
        padding: 1.5rem;
    }
}