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

body {
    font-family: 'Inter', sans-serif;
    background: linear-gradient(135deg, #121212, #1a1a1a);
    color: #e0e0e0;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    overflow-x: hidden;
    position: relative;
    padding: 20px;
    line-height: 1.6;
}

#particles-js {
    position: absolute;
    width: 100%;
    height: 100%;
    z-index: 0;
}

.hero-section {
    width: 100%;
    max-width: 1200px;
    margin: 50px 0 40px;
    position: relative;
    text-align: center;
    padding: 0 20px;
    z-index: 1;
}

.hero-content h1 {
    color: #4ECDC4;
    font-size: 2.5rem;
    margin-bottom: 15px;
    font-weight: 600;
}

.hero-description {
    color: #b0b0b0;
    max-width: 600px;
    margin: 0 auto 40px;
    font-size: 1.1rem;
}

.hero-description a {
    color: #4ECDC4;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    position: relative;
}

.hero-description a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 1px;
    background: #4ECDC4;
    transition: width 0.3s ease;
}

.hero-description a:hover {
    color: #3aa8a1;
}

.hero-description a:hover::after {
    width: 100%;
}

.download-grid {
    width: 90%;
    max-width: 1000px;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
    margin-bottom: 50px;
    z-index: 1;
    align-items: stretch;
}

.download-section {
    display: flex;
    flex-direction: column;
    gap: 20px;
    height: 100%;
}

.download-card {
    width: 100%;
    padding: 30px;
    background: rgba(30, 30, 30, 0.4);
    backdrop-filter: blur(15px);
    -webkit-backdrop-filter: blur(15px);
    border-radius: 16px;
    border: 1px solid rgba(78, 205, 196, 0.2);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.2);
    text-align: center;
    position: relative;
    overflow: hidden;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    height: 100%;
    display: flex;
    flex-direction: column;
}

.download-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.3);
}

.download-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle at 20% 80%, rgba(78, 205, 196, 0.05), transparent 70%);
    z-index: -1;
}

.section-title {
    color: #4ECDC4;
    font-size: 1.5rem;
    text-align: center;
    margin-bottom: 10px;
}

.card-icon {
    width: 70px;
    height: 70px;
    background: rgba(78, 205, 196, 0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    font-size: 1.8rem;
    color: #4ECDC4;
    transition: all 0.3s ease;
}

.teacher .card-icon {
    color: #4ECDC4;
}

.download-card:hover .card-icon {
    background: rgba(78, 205, 196, 0.2);
    transform: scale(1.1);
}

.version-title {
    color: #ffffff;
    font-size: 1.3rem;
    margin-bottom: 10px;
    font-weight: 600;
}

.card-description {
    color: #b0b0b0;
    margin-bottom: 25px;
    font-size: 0.95rem;
}

.version-selector {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-bottom: 20px;
}

.version-btn {
    padding: 8px 15px;
    border-radius: 6px;
    border: none;
    background: rgba(78, 205, 196, 0.1);
    color: #e0e0e0;
    font-family: 'Inter', sans-serif;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 6px;
}

.version-btn i {
    font-size: 1rem;
}

.version-btn.active {
    background: rgba(78, 205, 196, 0.3);
    color: #4ECDC4;
}

.version-btn:hover:not(.active) {
    background: rgba(78, 205, 196, 0.2);
}

.student .version-selector .version-btn {
    cursor: default;
    background: rgba(78, 205, 196, 0.3);
    color: #4ECDC4;
}

.student .version-selector .version-btn:hover {
    background: rgba(78, 205, 196, 0.3);
}

.download-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    background: linear-gradient(135deg, rgba(78, 205, 196, 0.8), rgba(58, 168, 161, 0.8));
    color: #ffffff;
    padding: 12px 25px;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    font-size: 0.95rem;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
    border: none;
    cursor: pointer;
    width: 100%;
    max-width: 180px;
    margin: 0 auto;
}

.android-download {
    background: linear-gradient(135deg, rgba(61, 220, 132, 0.8), rgba(46, 173, 103, 0.8));
}

.download-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.7s ease-in-out;
}

.download-btn:hover {
    background: linear-gradient(135deg, rgba(78, 205, 196, 1), rgba(58, 168, 161, 1));
    box-shadow: 0 0 20px rgba(78, 205, 196, 0.4);
}

.android-download:hover {
    background: linear-gradient(135deg, rgba(61, 220, 132, 1), rgba(46, 173, 103, 1));
    box-shadow: 0 0 20px rgba(61, 220, 132, 0.4);
}

.download-btn:hover::before {
    left: 100%;
}

@media (max-width: 900px) {
    .download-grid {
        grid-template-columns: 1fr;
        max-width: 600px;
    }
    
    .download-section {
        gap: 15px;
    }
}

@media (max-width: 768px) {
    .hero-content h1 {
        font-size: 2rem;
    }
    
    .hero-description {
        font-size: 1rem;
    }
    
    .section-title {
        font-size: 1.3rem;
    }
    
    .download-card {
        padding: 25px 20px;
    }
    
    .card-icon {
        width: 60px;
        height: 60px;
        font-size: 1.6rem;
    }
    
    .version-title {
        font-size: 1.2rem;
    }
    
    .version-selector {
        flex-direction: column;
        gap: 8px;
    }
    
    .version-btn {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .hero-content h1 {
        font-size: 1.8rem;
    }
    
    .hero-section {
        margin: 30px 0;
    }
    
    .download-card {
        padding: 20px 15px;
    }
    
    .download-btn {
        padding: 10px 20px;
        font-size: 0.9rem;
        max-width: 160px;
    }
}