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

body {
    background-color: #f4f7f6;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
}

.calculator-container {
    background: #fff;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 8px 24px rgba(0,0,0,0.1);
    width: 100%;
    max-width: 500px;
}

h2, h3 {
    color: #333;
    text-align: center;
}

.step {
    display: none;
    animation: fadeIn 0.4s ease-in-out;
}

.step.active {
    display: block;
}

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

.input-group label {
    display: block;
    margin-bottom: 8px;
    color: #555;
    font-weight: 600;
}

.input-group input[type="text"],
.input-group input[type="number"] {
    width: 100%;
    padding: 12px;
    border: 1px solid #ddd;
    border-radius: 6px;
    font-size: 16px;
}

.checkbox-group {
    display: flex;
    align-items: center;
    gap: 10px;
}

.checkbox-group input {
    width: 20px;
    height: 20px;
}

.btn-group {
    display: flex;
    justify-content: space-between;
    gap: 10px;
}

.btn {
    flex: 1;
    padding: 12px;
    background-color: #0066cc;
    color: white;
    border: none;
    border-radius: 6px;
    font-size: 16px;
    cursor: pointer;
    transition: background-color 0.3s;
}

.btn:hover {
    background-color: #0052a3;
}

.prev-btn {
    background-color: #e0e0e0;
    color: #333;
}

.prev-btn:hover {
    background-color: #ccc;
}

.hidden {
    display: none !important;
}

/* Loading Animation */
#loading-state {
    text-align: center;
    padding: 40px 0;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 5px solid #f3f3f3;
    border-top: 5px solid #0066cc;
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 20px auto;
}

.result-box {
    background: #e8f4fd;
    padding: 20px;
    border-radius: 8px;
    font-size: 24px;
    font-weight: bold;
    color: #0066cc;
    text-align: center;
    margin-bottom: 20px;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}