body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: #f0f2f5;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}

.back-btn {
    position: fixed;
    top: 20px;
    left: 20px;
    padding: 10px 20px;
    background: #0066cc;
    color: white;
    text-decoration: none;
    border-radius: 8px;
    font-weight: 600;
    font-size: 0.9rem;
    box-shadow: 0 2px 8px rgba(0,102,204,0.2);
    transition: all 0.2s;
    z-index: 1000;
}
.back-btn:hover {
    background: #0052a3;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,102,204,0.3);
}

.calculator-card {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    width: 350px;
}

h2 { margin-top: 0; color: #1a1a1a; }

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

label {
    display: block;
    font-size: 0.9rem;
    color: #666;
    margin-bottom: 5px;
}

input {
    width: 100%;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 6px;
    font-size: 1rem;
    box-sizing: border-box;
}

button {
    width: 100%;
    padding: 12px;
    background-color: #0066cc; /* Corporate Blue */
    color: white;
    border: none;
    border-radius: 6px;
    font-size: 1rem;
    cursor: pointer;
    font-weight: 600;
    margin-top: 10px;
}

button:hover { background-color: #0052a3; }

.result-display {
    margin-top: 20px;
    padding-top: 20px;
    border-top: 1px solid #eee;
    text-align: center;
}

#total-output { color: #27ae60; margin: 0; }

.back-btn {
    position: fixed;
    top: 20px;
    left: 20px;
    padding: 10px 20px;
    background: #0066cc;
    color: white;
    text-decoration: none;
    border-radius: 8px;
    font-weight: 600;
    font-size: 0.9rem;
    box-shadow: 0 2px 8px rgba(0,102,204,0.2);
    transition: all 0.2s;
    z-index: 1000;
}
.back-btn:hover {
    background: #0052a3;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,102,204,0.3);
}