body {
    margin: 0;
    font-family: system-ui, Segoe UI, Roboto, Arial, sans-serif;
    background: #111827;
    color: #f3f4f6;
    display: grid;
    place-items: center;
    min-height: 100vh
}

.shell {
    width: min(680px, 92vw)
}

h1,h3 {
    text-align: center;
    margin: 18px 0
}

.panel {
    background: #1f2937;
    border-radius: 18px;
    padding: 20px;
    box-shadow: 0 8px 30px rgba(0, 0, 0, .35)
}

label {
    display: block;
    margin: 10px 0
}

input[type=number] {
    width: 100%;
    padding: 10px;
    border-radius: 10px;
    border: 1px solid #374151;
    background: #111827;
    color: #f9fafb
}

.tips {
    border: 1px dashed #374151;
    border-radius: 12px;
    padding: 10px;
    margin: 12px 0;
    display: flex;
    gap: 16px;
    justify-content: center
}

button {
    width: 100%;
    padding: 12px;
    border: none;
    border-radius: 12px;
    background: #2563eb;
    color: #fff;
    font-weight: 600;
    cursor: pointer
}

.results {
    margin-top: 14px;
    font-size: 18px
}