:root {
    --gray-00: #ffffff;
    --gray-05: #f8f9fa;
    --gray-15: #dee2e6;
    --gray-75: #343a40;
    --gray-85: #212529;
    --gray-90: #121416;
    --blue-50: #4dabf7;
    --error: #e03131;
    --danger-color: #a61e4d;
    --danger-background: #ffe3e3;
    --accent-gradient: linear-gradient(135deg, #4dabf7, #228be6);
}

*,
::before,
::after {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}

body {
    font-family: "Inter", "Lato", Helvetica, Arial, sans-serif;
    font-size: 18px;
    background: radial-gradient(circle at top, var(--gray-85), var(--gray-90));
    color: var(--gray-05);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
}

main {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 20px;
    width: 100%;
}

h1 {
    margin: 20px auto 30px;
    font-weight: 700;
    letter-spacing: 0.5px;
    font-size: 2rem;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

form {
    width: 100%;
    max-width: 480px;
    text-align: center;
    padding: 20px;
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(12px);
    border-radius: 16px;
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.2);
}

h2 {
    margin-bottom: 20px;
}

fieldset {
    border: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 10px;
}

fieldset div {
    display: flex;
    justify-content: center;
    align-items: center;
}

.bracket,
.comma {
    font-size: 2rem;
    color: var(--gray-15);
}

select {
    font-family: inherit;
    font-size: 1rem;
    height: 40px;
    width: 55px;
    text-align: center;
    border-radius: 8px;
    border: 1px solid var(--gray-15);
    background: var(--gray-00);
    color: var(--gray-85);
    transition: all 0.2s ease-in-out;
}

select:hover {
    border-color: var(--blue-50);
    box-shadow: 0 0 0 3px rgba(77, 171, 247, 0.3);
}

select:focus-visible {
    outline: none;
    border-color: var(--blue-50);
    box-shadow: 0 0 0 3px rgba(77, 171, 247, 0.5);
}

button {
    cursor: pointer;
    margin-top: 20px;
    background: var(--accent-gradient);
    border: none;
    padding: 12px 18px;
    font-size: 1.1rem;
    width: 100%;
    color: white;
    border-radius: 10px;
    transition: all 0.25s ease-in-out;
    font-weight: 600;
    letter-spacing: 0.3px;
}

button:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 15px rgba(34, 139, 230, 0.4);
}

button:active {
    transform: translateY(0px);
    box-shadow: 0 6px 15px rgba(34, 139, 230, 0.4);
}

.output-container {
    width: 100%;
    max-width: 480px;
    margin-top: 25px;
    padding: 20px;
    border-radius: 16px;
    text-align: center;
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(10px);
    box-shadow: 0 4px 18px rgba(0, 0, 0, 0.15);
}

.output-array {
    display: flex;
    align-items: center;
    justify-content: space-evenly;
    gap: 10px;
}

.output-value {
    font-size: 1.6rem;
    font-weight: bold;
    color: var(--blue-50);
}

.alert {
    background-color: var(--danger-background);
    border: 2px solid var(--danger-color);
    color: var(--danger-color);
    border-radius: 10px;
    padding: 10px;
}

@media (max-width: 550px) {
    fieldset {
        justify-content: center;
    }
}