* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: #f4f7f6;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}

.calculator-container {
    background: #ffffff;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.1);
    width: 100%;
    max-width: 400px;
}

h1 {
    text-align: center;
    color: #333;
    margin-bottom: 25px;
    font-size: 24px;
}

.input-group {
    margin-bottom: 20px;
}

label {
    display: block;
    margin-bottom: 8px;
    color: #666;
    font-size: 14px;
    font-weight: 600;
}

input {
    width: 100%;
    padding: 12px;
    border: 1px solid #ccc;
    border-radius: 6px;
    font-size: 16px;
    outline: none;
    transition: border-color 0.2s;
}

input:focus {
    border-color: #4caf50;
}

button {
    width: 100%;
    background-color: #4caf50;
    color: white;
    border: none;
    padding: 14px;
    font-size: 16px;
    font-weight: bold;
    border-radius: 6px;
    cursor: pointer;
    transition: background 0.2s;
}

button:hover {
    background-color: #45a049;
}

.results-container {
    margin-top: 25px;
    background-color: #f9f9f9;
    padding: 15px;
    border-radius: 8px;
    border: 1px dashed #e0e0e0;
}

.result-row {
    display: flex;
    justify-content: space-between;
    margin-bottom: 10px;
    font-size: 15px;
    color: #444;
}

.result-row:last-child {
    margin-bottom: 0;
    font-weight: bold;
    color: #222;
}

#tip-amount, #total-amount {
    color: #4caf50;
    font-weight: bold;
}