:root {
    --bg: #f5f7fa;
    --card: #ffffff;
    --primary: #4f46e5;
    --primary-light: #e0e7ff;
    --text: #111827;
    --muted: #6b7280;
    --radius: 10px;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.06);
    --transition: 0.22s ease;
}
body {
    font-family: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background: var(--bg);
    color: var(--text);
    margin: 0;
    padding: 3rem 1.5rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 100vh;
}
h1 {
    font-weight: 700;
    font-size: 2rem;
    margin: 0 0 2rem;
    letter-spacing: -0.5px;
}
form {
    background: var(--card);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 2rem;
    max-width: 420px;
    width: 100%;
}
table {
    width: 100%;
    border-collapse: collapse;
}
th, td {
    padding: 0.75rem 0.5rem;
    text-align: center;
    font-size: 1rem;
}
thead th {
    font-weight: 600;
    color: var(--muted);
    border-bottom: 2px solid var(--primary-light);
}
tbody th {
    font-weight: 600;
    text-align: left;
    padding-left: 0.75rem;
}
input[type="checkbox"] {
    width: 1.4rem;
    height: 1.4rem;
    border: 2px solid var(--muted);
    border-radius: 4px;
    cursor: pointer;
    transition: var(--transition);
    position: relative;
}
input[type="checkbox"]:checked {
    background: var(--primary);
    border-color: var(--primary);
}
input[type="checkbox"]:checked::after {
    content: "";
    position: absolute;
    top: 3px;
    left: 6px;
    width: 5px;
    height: 9px;
    border: solid #fff;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
}
#output {
    font-family: monospace;
    margin-top: 2rem;
    font-size: 1.5rem;
    font-weight: 700;
    background: var(--card);
    padding: 1rem 1.5rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    letter-spacing: 1px;
    min-width: 180px;
    text-align: center;
}
#presets {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-bottom: 2rem;
}

#presets button {
    padding: 0.5rem 1rem;
    border: 2px solid #e0e0e0;
    border-radius: 0.375rem;
    background-color: #ffffff;
    color: #333;
    font-weight: 600;
    font-size: 0.95rem;
    cursor: pointer;
    transition: all 0.2s ease;
}

#presets button:hover {
    border-color: #4a90e2;
    background-color: #f0f7ff;
    color: #4a90e2;
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(74, 144, 226, 0.15);
}