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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f5f5f5;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
}

.container {
    background: white;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    padding: 30px;
    width: 100%;
    max-width: 600px;
}

header {
    text-align: center;
    margin-bottom: 30px;
}

h1 {
    color: #2c3e50;
    font-size: 1.8rem;
    margin-bottom: 10px;
}

.subtitle {
    color: #7f8c8d;
    font-size: 0.9rem;
}

.input-section,
.output-section {
    margin-bottom: 20px;
}

label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: #555;
}

textarea {
    width: 100%;
    padding: 12px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 1rem;
    font-family: inherit;
    resize: vertical;
    transition: border-color 0.3s;
}

textarea:focus {
    outline: none;
    border-color: #3498db;
}

textarea[readonly] {
    background-color: #f8f9fa;
}

.convert-btn,
.copy-btn {
    display: block;
    width: 100%;
    padding: 12px 20px;
    margin-top: 10px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
}

.convert-btn {
    background-color: #3498db;
    color: white;
}

.convert-btn:hover {
    background-color: #2980b9;
    transform: translateY(-1px);
}

.convert-btn:active {
    transform: translateY(0);
}

.copy-btn {
    background-color: #27ae60;
    color: white;
}

.copy-btn:hover:not(:disabled) {
    background-color: #229954;
    transform: translateY(-1px);
}

.copy-btn:active {
    transform: translateY(0);
}

.copy-btn:disabled {
    background-color: #95a5a6;
    cursor: not-allowed;
    opacity: 0.6;
}

.copy-btn.copied {
    background-color: #27ae60;
}

.options {
    margin-top: 20px;
    padding: 15px;
    background-color: #f8f9fa;
    border-radius: 8px;
}

.options label {
    display: flex;
    align-items: center;
    font-weight: normal;
    cursor: pointer;
}

.options input[type="checkbox"] {
    margin-right: 8px;
    cursor: pointer;
}

footer {
    text-align: center;
    margin-top: 30px;
    color: #7f8c8d;
    font-size: 0.9rem;
}

@media (max-width: 480px) {
    .container {
        padding: 20px;
    }
    
    h1 {
        font-size: 1.5rem;
    }
    
    textarea {
        font-size: 0.9rem;
    }
}