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

body {
    background-color: #f5f5f5;
    color: #333;
    line-height: 1.6;
}

.container {
    max-width: 600px;
    margin: 50px auto;
    padding: 20px;
    background-color: #fff;
    border-radius: 10px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

h1 {
    text-align: center;
    margin-bottom: 30px;
    color: #2c3e50;
}

.calculator {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 5px;
}

label {
    font-weight: 600;
    color: #555;
}

input {
    padding: 12px;
    border: 1px solid #ddd;
    border-radius: 5px;
    font-size: 16px;
    transition: border-color 0.3s;
}

input:focus {
    outline: none;
    border-color: #3498db;
}

.input-hint {
    font-size: 12px;
    color: #777;
    margin-top: 2px;
    font-style: italic;
}

.quick-distance {
    display: flex;
    flex-wrap: wrap;
    gap: 5px;
    margin-top: 8px;
}

.distance-btn {
    padding: 6px 10px;
    background-color: #f1f1f1;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 14px;
    cursor: pointer;
    transition: all 0.2s;
}

.distance-btn:hover {
    background-color: #e6e6e6;
}

.distance-btn.active {
    background-color: #3498db;
    color: white;
    border-color: #3498db;
}

.buttons {
    display: flex;
    gap: 10px;
    margin-top: 10px;
}

button {
    flex: 1;
    padding: 12px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    transition: background-color 0.3s;
}

#calculate {
    background-color: #3498db;
    color: white;
}

#calculate:hover {
    background-color: #2980b9;
}

#reset {
    background-color: #e74c3c;
    color: white;
}

#reset:hover {
    background-color: #c0392b;
}

.result {
    margin-top: 20px;
    padding: 15px;
    background-color: #f8f9fa;
    border-radius: 5px;
    font-weight: 500;
    text-align: center;
    min-height: 50px;
}