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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f5f5f5;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

header {
    background: white;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    margin-bottom: 20px;
}

header h1 {
    color: #2c3e50;
    margin-bottom: 10px;
}

nav {
    display: flex;
    gap: 20px;
}

nav a {
    text-decoration: none;
    color: #3498db;
    padding: 5px 10px;
    border-radius: 5px;
    transition: background-color 0.3s;
}

nav a:hover {
    background-color: #ecf0f1;
}

main {
    flex: 1;
}

footer {
    text-align: center;
    margin-top: 40px;
    padding: 20px;
    color: #7f8c8d;
}

/* Flash messages */
.flash-messages {
    margin-bottom: 20px;
}

.flash-message {
    padding: 15px;
    border-radius: 5px;
    margin-bottom: 10px;
    font-weight: bold;
}

.flash-message:contains("✅") {
    background-color: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.flash-message:contains("❌") {
    background-color: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

/* Welcome page */
.welcome {
    text-align: center;
    padding: 40px 20px;
}

.welcome h2 {
    color: #2c3e50;
    margin-bottom: 20px;
}

.welcome p {
    font-size: 1.1em;
    color: #7f8c8d;
    margin-bottom: 40px;
}

.feature-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    margin-top: 40px;
}

.card {
    background: white;
    padding: 30px;
    border-radius: 10px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    text-align: center;
    transition: transform 0.3s;
}

.card:hover {
    transform: translateY(-5px);
}

.card h3 {
    color: #2c3e50;
    margin-bottom: 15px;
}

.card p {
    color: #7f8c8d;
    margin-bottom: 20px;
}

/* Converter pages */
.converter {
    background: white;
    padding: 40px;
    border-radius: 10px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    max-width: 600px;
    margin: 0 auto;
}

.converter h2 {
    color: #2c3e50;
    margin-bottom: 10px;
    text-align: center;
}

.converter > p {
    color: #7f8c8d;
    text-align: center;
    margin-bottom: 30px;
}

.upload-form {
    margin-bottom: 30px;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: bold;
    color: #2c3e50;
}

.form-group input[type="file"] {
    width: 100%;
    padding: 10px;
    border: 2px dashed #bdc3c7;
    border-radius: 5px;
    background-color: #ecf0f1;
}

.form-group input[type="file"]:hover {
    border-color: #3498db;
}

/* Buttons */
.btn {
    display: inline-block;
    background-color: #3498db;
    color: white;
    padding: 12px 30px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 16px;
    text-decoration: none;
    transition: background-color 0.3s;
    width: 100%;
}

.btn:hover {
    background-color: #2980b9;
}

/* Instructions */
.instructions {
    background-color: #f8f9fa;
    padding: 20px;
    border-radius: 5px;
    border-left: 4px solid #3498db;
}

.instructions h3 {
    color: #2c3e50;
    margin-bottom: 10px;
}

.instructions ul {
    list-style-position: inside;
    color: #7f8c8d;
}

.instructions li {
    margin-bottom: 5px;
}

/* Responsive */
@media (max-width: 768px) {
    .container {
        padding: 10px;
    }
    
    .feature-cards {
        grid-template-columns: 1fr;
    }
    
    .converter {
        padding: 20px;
    }
    
    nav {
        flex-direction: column;
        gap: 10px;
    }
}