:root {
    --primary: #2196F3;
    --secondary: #607D8B;
    --success: #4CAF50;
    --danger: #F44336;
    --text: #37474F;
    --light: #CFD8DC;
    --dark: #000000;
    --shadow: 0 4px 6px rgba(0,0,0,0.1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', system-ui;
}

body {
    background: #ECEFF1;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    line-height: 1.6;
}

/* Header Styles */
.header {
    background: linear-gradient(135deg, var(--primary), #1976D2);
    color: white;
    padding: 1rem 2rem;
    box-shadow: var(--shadow);
}

.nav-container {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.brand h1 {
    font-size: 2rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

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

.nav-link {
    color: white;
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: 5px;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* Main Content */
.converter-container {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 1rem;
}

.upload-section {
    background: white;
    border-radius: 15px;
    padding: 2rem;
    box-shadow: var(--shadow);
}

.drop-zone {
    border: 2px dashed var(--primary);
    border-radius: 12px;
    padding: 2rem;
    margin: 1.5rem 0;
    cursor: pointer;
    transition: all 0.3s ease;
}

.upload-content {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    text-align: center;
}

.browse-btn {
    background: var(--primary);
    color: white;
    border: none;
    padding: 1rem 2rem;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s;
}

.preview-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    gap: 1rem;
    margin: 1rem 0;
}

.preview-image {
    width: 100%;
    height: 120px;
    object-fit: cover;
    border-radius: 8px;
    box-shadow: var(--shadow);
}

.controls {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin: 2rem 0;
    flex-wrap: wrap;
}

.btn-convert {
    background: var(--primary);
    color: white;
    padding: 1rem 2rem;
    border-radius: 8px;
    border: none;
    cursor: pointer;
}

.btn-clear {
    background: var(--danger);
    color: white;
    padding: 1rem 2rem;
    border-radius: 8px;
    border: none;
    cursor: pointer;
}

.btn-download {
    background: var(--success);
    color: white;
    padding: 1rem 2rem;
    border-radius: 8px;
    border: none;
    cursor: pointer;
}

.btn-download:disabled {
    background: #78909C;
    cursor: not-allowed;
}

/* Description Section */
.description-box {
    margin-top: 3rem;
    padding: 2rem;
    background: #f8f9fa;
    border-radius: 12px;
}

.features-list {
    display: grid;
    gap: 1.5rem;
    margin-top: 1.5rem;
}

.feature-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1.5rem;
    background: white;
    border-radius: 8px;
    box-shadow: var(--shadow);
}

.feature-icon {
    font-size: 2rem;
    min-width: 50px;
    text-align: center;
}

/* Footer Styles */
.footer {
    background: var(--dark);
    color: white;
    padding: 2rem;
    margin-top: auto;
}

.footer-content {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 2rem;
}

.footer-links {
    display: flex;
    gap: 1.5rem;
}

.footer-link {
    color: #CFD8DC;
    text-decoration: none;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-container {
        flex-direction: column;
        gap: 1rem;
    }
    
    .controls {
        flex-direction: column;
    }
    
    .btn-convert, .btn-clear, .btn-download {
        width: 100%;
    }
    
    .feature-item {
        flex-direction: column;
        text-align: center;
    }
}