:root {
    --bg: #0f1724;
    --card: #0b1220;
    --accent: #7dd3fc;
    --muted: #94a3b8;
    --glass: rgba(255, 255, 255, 0.04)
}

* {
    box-sizing: border-box;
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial
}

body {
    min-height: 100vh;
    display: grid;
    place-items: center;
    background: linear-gradient(180deg, #071129 0%, #071022 100%);
    color: #e6eef6;
    margin: 0
}

.card {
    width: 360px;
    background: linear-gradient(180deg, rgba(255, 255, 255, 0.02), rgba(255, 255, 255, 0.01));
    border-radius: 14px;
    padding: 20px;
    border: 1px solid rgba(255, 255, 255, 0.04);
    box-shadow: 0 6px 30px rgba(2, 6, 23, 0.6)
}

h1 {
    font-size: 18px;
    margin: 0 0 12px;
    color: var(--accent)
}

.row {
    display: flex;
    gap: 10px;
    margin-bottom: 12px
}

label {
    font-size: 13px;
    color: var(--muted);
    display: block;
    margin-bottom: 6px
}

input[type=number] {
    width: 100%;
    padding: 10px;
    border-radius: 8px;
    border: 1px solid var(--glass);
    background: transparent;
    color: inherit;
    font-size: 15px
}

.buttons {
    display: flex;
    gap: 8px;
    margin-top: 6px
}

button.op {
    flex: 1;
    padding: 10px;
    border-radius: 10px;
    border: 0;
    background: linear-gradient(180deg, #0b6b8a, #065a72);
    color: white;
    font-weight: 600;
    font-size: 16px;
    cursor: pointer;
    transition: transform .08s ease
}

button.op:active {
    transform: scale(.98)
}

.result {
    margin-top: 14px;
    padding: 12px;
    border-radius: 10px;
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid rgba(255, 255, 255, 0.03);
    font-size: 16px
}

.muted {
    font-size: 13px;
    color: var(--muted);
    margin-top: 8px
}

footer {
    margin-top: 10px;
    text-align: center;
    font-size: 12px;
    color: var(--muted)
}