:root {
    --primary-color: #10a37f;  /* OpenAI 风格的主色调 */
    --accent-color: #0e906f;
    --text-color: #353740;
    --background-color: #ffffff;
    --section-padding: 4rem 0;
    --hero-bg: #000000;
    --hero-gradient: linear-gradient(to bottom, rgba(16, 163, 127, 0.1), rgba(0, 0, 0, 0));
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    line-height: 1.6;
    color: var(--text-color);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Navigation */
nav {
    background-color: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
    padding: 15px 0;
}

.nav-content {
    display: flex;
    align-items: center;
    gap: 2rem;
}

.nav-links {
    list-style: none;
    display: flex;
    align-items: center;
    gap: 2rem;
    margin: 0;
    padding: 0;
}

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

.logo {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-color);
    text-decoration: none;
    letter-spacing: -0.5px;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: color 0.3s ease;
}

.logo:hover {
    color: var(--accent-color);
}

.logo img {
    width: 32px;
    height: 32px;
    transition: transform 0.3s ease;
}

.logo:hover img {
    transform: scale(1.05);
}

.nav-links a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    padding: 8px 16px;
    border-radius: 20px;
    transition: all 0.3s ease;
}

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

.language-selector {
    margin-left: 1rem;
}

#language-select {
    padding: 0.5rem 2rem 0.5rem 1rem;
    border: 1px solid var(--primary-color);
    border-radius: 6px;
    background-color: white;
    color: var(--text-color);
    font-size: 0.9rem;
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22292.4%22%20height%3D%22292.4%22%3E%3Cpath%20fill%3D%22%23131313%22%20d%3D%22M287%2069.4a17.6%2017.6%200%200%200-13-5.4H18.4c-5%200-9.3%201.8-12.9%205.4A17.6%2017.6%200%200%200%200%2082.2c0%205%201.8%209.3%205.4%2012.9l128%20127.9c3.6%203.6%207.8%205.4%2012.8%205.4s9.2-1.8%2012.8-5.4L287%2095c3.5-3.5%205.4-7.8%205.4-12.8%200-5-1.9-9.2-5.5-12.8z%22%2F%3E%3C%2Fsvg%3E");
    background-repeat: no-repeat;
    background-position: right 0.7rem top 50%;
    background-size: 0.65rem auto;
}

#language-select:hover {
    border-color: var(--accent-color);
}

#language-select:focus {
    outline: none;
    box-shadow: 0 0 0 2px var(--primary-color);
}

#language-select option {
    padding: 0.5rem;
}

@media (max-width: 768px) {
    nav {
        padding: 10px 0;
    }
    
    .nav-content {
        flex-direction: column;
        gap: 1rem;
        align-items: flex-start;
    }
    
    .nav-links {
        display: none;
    }
    
    .logo {
        margin: 0;
        padding-left: 1rem;
        align-self: flex-start;
    }
    
    .language-selector {
        margin: 0;
    }
    
    #language-select {
        width: 100%;
        max-width: 200px;
    }
}

@media (max-width: 768px) {
    .nav-content {
        flex-direction: column;
        gap: 1rem;
        align-items: flex-start;
    }

    .logo {
        padding-left: 1rem;
        align-self: flex-start;
    }

    .nav-links {
        flex-direction: column;
        gap: 0.5rem;
        text-align: center;
        width: 100%;
        border-top: 1px solid rgba(0, 0, 0, 0.1);
        padding-top: 0.5rem;
    }
}

/* Hero Section */
#hero {
    background-color: var(--hero-bg);
    background-image: 
        var(--hero-gradient),
        radial-gradient(circle at 50% 50%, rgba(16, 163, 127, 0.1) 0%, transparent 50%),
        url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%2310a37f' fill-opacity='0.05'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
    color: white;
    text-align: center;
    padding: 8rem 0;
    position: relative;
    overflow: hidden;
}

#hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(45deg, rgba(16, 163, 127, 0.1) 0%, transparent 100%);
    pointer-events: none;
}

#hero h1 {
    font-size: 3.5rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    letter-spacing: -1px;
    line-height: 1.2;
    background: linear-gradient(to right, #ffffff, #e5e5e5);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    text-shadow: none;
}

.subtitle {
    font-size: 1.5rem;
    margin-bottom: 2rem;
    color: rgba(255, 255, 255, 0.9);
    font-weight: 400;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

/* Sections */
.section {
    padding: 80px 0;
}

.section h2 {
    text-align: center;
    margin-bottom: 40px;
    color: var(--primary-color);
}

/* Team Grid */
.team-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    text-align: center;
}

.team-member img {
    width: 150px;
    height: 150px;
    border-radius: 50%;
    margin-bottom: 1rem;
}

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

.goal-item {
    background: var(--background-color);
    padding: 2rem;
    border-radius: 8px;
    text-align: center;
}

/* Project Intro Section */
.intro-content {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
    background: #fff;
    border-radius: 16px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

.intro-content h3 {
    color: var(--primary-color);
    margin-top: 30px;
    margin-bottom: 15px;
    font-size: 1.5rem;
}

.intro-content p {
    margin-bottom: 20px;
    line-height: 1.8;
    color: #444;
}

.intro-content ul {
    list-style-type: none;
    padding-left: 20px;
    margin-bottom: 20px;
}

.intro-content ul li {
    position: relative;
    padding-left: 25px;
    margin-bottom: 10px;
    line-height: 1.6;
}

.intro-content ul li:before {
    content: "✓";
    color: var(--primary-color);
    position: absolute;
    left: 0;
    font-weight: bold;
}

.highlight-text {
    background: #f8f9fa;
    padding: 20px;
    border-left: 4px solid var(--primary-color);
    border-radius: 4px;
    font-style: italic;
    margin-top: 30px;
}

/* Video Section */
.video-container {
    position: relative;
    width: 100%;
    max-width: 393px;  
    margin: 0 auto;
    border-radius: 55px;  
    border: 14px solid #000; 
    background: #000;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
    overflow: hidden;
}

.video-container::before {
    content: '';
    display: block;
    padding-top: 217%; 
}

.video-container video {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 41px; 
}

/* Dynamic Island */
.video-container::after {
    content: '';
    position: absolute;
    top: 11px;
    left: 50%;
    transform: translateX(-50%);
    width: 134px; 
    height: 41px; 
    background: #000;
    border-radius: 20px;
    z-index: 2;
}

@media (max-width: 768px) {
    .video-container {
        max-width: 320px;
    }
}

/* Download Section */
.download-options {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2rem;
}

.download-button {
    display: inline-block;
    transition: transform 0.3s ease;
}

.download-button:hover {
    transform: scale(1.05);
}

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

.social-button {
    padding: 0.8rem 1.5rem;
    border-radius: 6px;
    text-decoration: none;
    color: white;
    font-weight: 500;
    transition: all 0.3s ease;
    border: 1px solid transparent;
}

.social-button.meme {
    background-color: var(--primary-color);
    border-color: var(--accent-color);
}

.social-button.twitter {
    background-color: #000000;
    border-color: rgba(255, 255, 255, 0.1);
}

.social-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

/* Footer */
footer {
    background: var(--background-color);
    padding: 20px 0;
    text-align: center;
}

/* Developer Section */
.developer-profile {
    text-align: center;
    padding: 2rem 0;
}

.developer-avatar {
    width: 120px;
    height: 120px;
    border-radius: 50%;
    margin-bottom: 1rem;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease;
}

.developer-avatar:hover {
    transform: scale(1.05);
}

.developer-name {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    color: var(--text-color);
}

.developer-bio {
    font-size: 1rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    #hero h1 {
        font-size: 2rem;
    }
    
    .section {
        padding: 40px 0;
    }
}

/* Mobile Responsive */
@media (max-width: 768px) {
    :root {
        --section-padding: 2rem 0;
    }

    .container {
        width: 95%;
        padding: 0 0.5rem;
    }

    nav {
        padding: 0.5rem 0;
    }

    .nav-content {
        flex-direction: column;
        gap: 1rem;
    }

    .nav-links {
        flex-direction: column;
        gap: 0.5rem;
        text-align: center;
        width: 100%;
    }

    .nav-links a {
        display: block;
        padding: 0.5rem;
    }

    .language-selector {
        margin: 0.5rem 0;
        width: 100%;
        display: flex;
        justify-content: center;
    }

    #language-select {
        width: 100%;
        max-width: 200px;
    }

    #hero {
        padding: 4rem 0;
    }

    #hero h1 {
        font-size: 2rem;
    }

    .subtitle {
        font-size: 1.2rem;
    }

    .description {
        font-size: 1rem;
    }

    .intro-content {
        padding: 0 1rem;
    }

    .goals-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }

    .goal-item {
        padding: 1.5rem;
    }

    .download-options {
        gap: 1.5rem;
    }

    .social-links {
        flex-direction: column;
        width: 100%;
        align-items: center;
    }

    .social-button {
        width: 100%;
        max-width: 200px;
        text-align: center;
    }
}

/* Small Mobile Devices */
@media (max-width: 480px) {
    .container {
        width: 100%;
    }

    #hero h1 {
        font-size: 1.8rem;
    }

    .subtitle {
        font-size: 1.1rem;
    }

    .goal-item {
        padding: 1rem;
    }
}

/* Print Styles */
@media print {
    nav {
        position: static;
    }

    main {
        padding-top: 0;
    }

    .video-container,
    .download-options,
    .language-selector {
        display: none;
    }
}