:root {
    --whatsapp-green: #25D366;
    --whatsapp-dark-green: #128C7E;
    --background-color: #f0f2f5;
    --card-background: #ffffff;
    --text-primary: #111b21;
    --text-secondary: #667781;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--background-color);
    color: var(--text-primary);
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
}

.container {
    background-color: var(--card-background);
    padding: 2.5rem;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    width: 100%;
    max-width: 450px;
    text-align: center;
}

h1 {
    margin-bottom: 0.5rem;
    color: var(--whatsapp-dark-green);
    font-size: 1.75rem;
}

p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
    line-height: 1.5;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-bottom: 2rem;
}

input[type="text"] {
    padding: 12px 16px;
    border: 1px solid #d1d7db;
    border-radius: 8px;
    font-size: 1rem;
    outline: none;
    transition: border-color 0.2s;
}

input[type="text"]:focus {
    border-color: var(--whatsapp-green);
    box-shadow: 0 0 0 2px rgba(37, 211, 102, 0.1);
}

button {
    background-color: var(--whatsapp-green);
    color: white;
    border: none;
    border-radius: 8px;
    padding: 12px 24px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s, transform 0.1s;
}

button:hover {
    background-color: var(--whatsapp-dark-green);
}

button:active {
    transform: scale(0.98);
}

.result-container {
    margin-top: 1.5rem;
    min-height: 60px;
}

.result-box {
    padding: 1.5rem;
    background-color: #f8f9fa;
    border-radius: 8px;
    border: 1px dashed var(--whatsapp-green);
    animation: fadeIn 0.3s ease-out;
}

.wa-link {
    display: block;
    margin: 1rem 0;
    color: var(--whatsapp-dark-green);
    text-decoration: none;
    font-weight: 500;
    word-break: break-all;
    font-size: 1.1rem;
}

.wa-link:hover {
    text-decoration: underline;
}

.copy-btn {
    padding: 8px 16px;
    font-size: 0.9rem;
    background-color: var(--text-secondary);
}

.error {
    color: #d32f2f;
    font-size: 0.9rem;
    margin: 0;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}