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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
}

.header {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: white;
    font-size: 1.5rem;
    font-weight: 700;
}

.logo-icon {
    width: 32px;
    height: 32px;
    background: linear-gradient(45deg, #ff6b6b, #4ecdc4);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: bold;
}

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

.nav a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: color 0.3s;
    font-weight: 500;
}

.nav a:hover {
    color: white;
}

.auth-buttons {
    display: flex;
    gap: 1rem;
}

.btn {
    padding: 0.5rem 1rem;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-weight: 500;
    transition: all 0.3s;
    text-decoration: none;
    display: inline-block;
}

.btn-outline {
    background: transparent;
    border: 1px solid rgba(255, 255, 255, 0.3);
    color: white;
}

.btn-primary {
    background: rgba(255, 255, 255, 0.2);
    color: white;
    backdrop-filter: blur(10px);
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
}

.main-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 4rem 2rem;
}

.hero {
    text-align: center;
    color: white;
    margin-bottom: 3rem;
}

.hero h1 {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    text-shadow: 0 2px 20px rgba(0, 0, 0, 0.3);
}

.hero p {
    font-size: 1.2rem;
    opacity: 0.9;
    margin-bottom: 2rem;
}

.converter-card {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    border-radius: 20px;
    padding: 3rem;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    margin-bottom: 4rem;
}

.format-selector {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
    align-items: center;
    flex-wrap: wrap;
}

.format-input {
    flex: 1;
    min-width: 200px;
}

.format-input select {
    width: 100%;
    padding: 1rem;
    border: 2px solid #e0e0e0;
    border-radius: 12px;
    font-size: 1rem;
    background: white;
    cursor: pointer;
}

.format-arrow {
    color: #667eea;
    font-size: 1.5rem;
    font-weight: bold;
}

.upload-area {
    border: 3px dashed #667eea;
    border-radius: 16px;
    padding: 3rem;
    text-align: center;
    background: rgba(102, 126, 234, 0.05);
    margin-bottom: 2rem;
    cursor: pointer;
    transition: all 0.3s;
}

.upload-area:hover {
    background: rgba(102, 126, 234, 0.1);
    border-color: #4c63d2;
}

.upload-icon {
    width: 64px;
    height: 64px;
    background: linear-gradient(45deg, #667eea, #764ba2);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1rem;
    color: white;
    font-size: 1.5rem;
}

.upload-text {
    font-size: 1.1rem;
    color: #333;
    margin-bottom: 0.5rem;
}

.upload-subtext {
    color: #666;
    font-size: 0.9rem;
}

.action-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-top: 2rem;
}

.btn-large {
    padding: 1rem 2rem;
    font-size: 1.1rem;
    border-radius: 12px;
}

.btn-convert {
    background: linear-gradient(45deg, #667eea, #764ba2);
    color: white;
    border: none;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-bottom: 4rem;
}

.feature-card {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border-radius: 16px;
    padding: 2rem;
    text-align: center;
    color: white;
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.feature-icon {
    width: 60px;
    height: 60px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1rem;
    font-size: 1.5rem;
}

.feature-card h3 {
    font-size: 1.3rem;
    margin-bottom: 1rem;
}

.feature-card p {
    opacity: 0.9;
    line-height: 1.6;
}

.formats-showcase {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border-radius: 16px;
    padding: 2rem;
    text-align: center;
    color: white;
    margin-bottom: 2rem;
}

.format-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    justify-content: center;
    margin-top: 1rem;
}

.format-tag {
    background: rgba(255, 255, 255, 0.2);
    padding: 0.5rem 1rem;
    border-radius: 20px;
    font-size: 0.9rem;
    backdrop-filter: blur(10px);
}

.footer {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    padding: 2rem;
    text-align: center;
    color: white;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.progress-bar {
    width: 100%;
    height: 4px;
    background: #e0e0e0;
    border-radius: 2px;
    overflow: hidden;
    margin: 1rem 0;
    display: none;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(45deg, #667eea, #764ba2);
    width: 0%;
    transition: width 0.3s;
}

.file-list {
    display: none;
    margin: 1rem 0;
}

.file-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem;
    background: #f5f5f5;
    border-radius: 8px;
    margin-bottom: 0.5rem;
}

.file-info {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.file-icon {
    width: 32px;
    height: 32px;
    background: #667eea;
    border-radius: 4px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 0.8rem;
    font-weight: bold;
}

/* Responsive Design */
/* Mobile Menu Styles */
.mobile-menu-btn {
    display: none;
    flex-direction: column;
    cursor: pointer;
    padding: 0.5rem;
    background: transparent;
    border: none;
    gap: 4px;
}

.mobile-menu-btn span {
    width: 25px;
    height: 2px;
    background: white;
    transition: all 0.3s;
    border-radius: 2px;
}

.mobile-menu-btn.active span:nth-child(1) {
    transform: rotate(45deg) translate(6px, 6px);
}

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

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

.mobile-nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    flex-direction: column;
    padding: 1rem 0;
    z-index: 1000;
}

.mobile-nav.active {
    display: flex;
}

.mobile-nav a {
    color: #333;
    text-decoration: none;
    padding: 1rem 2rem;
    font-weight: 500;
    transition: background 0.3s;
    border-bottom: 1px solid rgba(0, 0, 0, 0.1);
}

.mobile-nav a:hover {
    background: rgba(102, 126, 234, 0.1);
}

.mobile-nav a.active {
    background: rgba(102, 126, 234, 0.2);
    color: #667eea;
}

.mobile-auth {
    display: flex;
    gap: 1rem;
    padding: 1rem 2rem;
}

.mobile-auth .btn {
    flex: 1;
    text-align: center;
    padding: 0.75rem;
}

@media (max-width: 768px) {
    .hero h1 {
        font-size: 2.5rem;
    }
    
    .converter-card {
        padding: 2rem;
    }
    
    .format-selector {
        flex-direction: column;
    }
    
    .format-arrow {
        transform: rotate(90deg);
    }
    
    .nav {
        display: none;
    }
    
    .mobile-menu-btn {
        display: flex;
    }
    
    .header {
        padding: 1rem;
        position: relative;
    }
    
    .auth-buttons {
        display: none;
    }
    
    .main-container {
        padding: 2rem 1rem;
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 2rem;
    }
    
    .hero p {
        font-size: 1rem;
    }
    
    .converter-card {
        padding: 1.5rem;
    }
    
    .upload-area {
        padding: 2rem 1rem;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
}