#calculator {
    width: 500px;
}

#calculator #c-display {
    width: 100%;
    height: 125px;
    font-size: 48px;
    font-weight: bolder;
    text-align: right;
    border-radius: 0;
    background-color: #000;
    color: #fff;
    border: 1px solid #000;
    padding: 0 5px;
    margin: 0;
    outline: none;
}

#calculator #c-display:hover {
    outline: none;
}

#calculator .btn {
    margin:0;
}
#calculator .btn-calculator {
    width: 100%;
    height: 125px;
    font-size: 48px;
    font-weight: bolder;
    border-radius: 0;
    background-color: #fff;
    color: #000;
    border: 1px solid #000;
    margin: 0;
}

#calculator .btn-calculator:hover, #calculator #c-equal:hover, #calculator #c-percent:hover {
    outline: none;
    background-color: #000!important;
    color: #fff!important;
}

#calculator .c-operators {
    background-color: #ff6600;
    color: #fff;
}

#calculator .c-functions, #calculator #c-percent {
    background-color: #d9d9d9;
    color: #000;
}

#calculator .calculator-help {
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    border: 1px solid #dee2e6;
    border-radius: 12px;
    padding: 1.25rem;
    font-size: 0.9rem;
    color: #495057;
}

#calculator .calculator-help .help-header {
    display: flex;
    align-items: center;
    margin-bottom: 1rem;
    padding-bottom: 0.75rem;
    border-bottom: 1px solid #dee2e6;
    color: #212529;
}

#calculator .calculator-help .help-header i {
    color: #ff6600;
    font-size: 1.1rem;
}

#calculator .calculator-help .help-content {
    display: grid;
    grid-template-columns: repeat(auto-fit-fill, minmax(220px, 1fr));
    gap: 0.5rem 1.5rem;
}

#calculator .calculator-help .help-row {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

#calculator .calculator-help .help-label {
    color: #6c757d;
    font-size: 0.85rem;
    min-width: 80px;
}

#calculator .calculator-help .help-keys {
    display: flex;
    gap: 0.35rem;
    flex-wrap: wrap;
}

#calculator .calculator-help kbd {
    background-color: #fff;
    border: 1px solid #ced4da;
    border-radius: 4px;
    padding: 0.2rem 0.5rem;
    font-size: 0.8rem;
    font-family: 'Segoe UI', Roboto, sans-serif;
    color: #333;
    box-shadow: 0 1px 1px rgba(0,0,0,0.1);
    font-weight: 500;
}

#calculator .calculator-help kbd:hover {
    background-color: #ff6600;
    border-color: #ff6600;
    color: #fff;
}

@media (max-width: 576px) {
    #calculator .calculator-help .help-content {
        grid-template-columns: 1fr;
    }

    #calculator .calculator-help .help-row {
        justify-content: space-between;
    }
}