* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Arial', sans-serif;
}

body {
    background: #f0f2f5;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

.calculator {
    background: white;
    padding: 25px;
    border-radius: 12px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    width: 100%;
    max-width: 500px;
}

h1 {
    color: #1a73e8;
    text-align: center;
    margin-bottom: 25px;
    font-size: 1.8rem;
}

.input-group {
    margin-bottom: 15px;
}

label {
    display: block;
    margin-bottom: 8px;
    color: #5f6368;
    font-weight: 500;
}

input {
    width: 100%;
    padding: 12px;
    border: 1px solid #dadce0;
    border-radius: 8px;
    font-size: 16px;
    transition: border-color 0.3s;
}

input:focus {
    outline: none;
    border-color: #1a73e8;
}

button {
    width: 100%;
    padding: 14px;
    background: #1a73e8;
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    cursor: pointer;
    margin-top: 10px;
    transition: background 0.3s;
}

button:hover {
    background: #1557b0;
}

.result-box {
    margin-top: 25px;
    padding: 20px;
    background: #f8f9fa;
    border-radius: 8px;
}

.result-item {
    display: flex;
    justify-content: space-between;
    margin: 10px 0;
    font-size: 16px;
}

.result-item span:first-child {
    color: #5f6368;
}

.error-msg {
    color: #dc3545;
    margin-top: 15px;
    text-align: center;
    display: none;
}

@media (max-width: 480px) {
    .calculator {
        padding: 15px;
    }
    
    h1 {
        font-size: 1.5rem;
    }
}