* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: Arial, sans-serif;
    background: #f4f6f8;
    color: #1f2937;
}

.container {
    max-width: 900px;
    margin: 40px auto;
    padding: 0 20px 40px;
}

.container.narrow {
    max-width: 720px;
}

h1 {
    margin-bottom: 10px;
    font-size: 28px;
}

.subtitle {
    margin-bottom: 24px;
    color: #4b5563;
}

.card {
    background: #ffffff;
    border: 1px solid #dbe2ea;
    border-radius: 10px;
    padding: 20px;
    margin-bottom: 20px;
}

.result-box {
    min-height: 70px;
    padding: 14px;
    border: 1px solid #d1d5db;
    border-radius: 8px;
    background: #f9fafb;
    white-space: pre-wrap;
    word-break: break-word;
}

.button-group {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
}

button {
    padding: 12px 16px;
    border: none;
    border-radius: 8px;
    background: #2563eb;
    color: white;
    cursor: pointer;
    font-size: 14px;
}

button:hover {
    opacity: 0.92;
}

button.secondary {
    background: #6b7280;
}

a {
    color: #2563eb;
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}