body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background-color: #f4f6f9;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    padding: 15px;
}

.calculator-card {
    background: #ffffff;
    padding: 25px;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.08);
    max-width: 450px;
    width: 100%;
}

h2 { margin-top: 0; color: #1a202c; }
.subtitle { font-size: 0.9em; color: #718096; margin-bottom: 20px; }

.input-group { margin-bottom: 15px; }
.input-group label { display: block; margin-bottom: 5px; font-weight: 600; font-size: 0.9em; color: #4a5568; }
.input-group input {
    width: 100%; padding: 10px; border: 1px solid #cbd5e0; border-radius: 6px; font-size: 1em; box-sizing: border-box;
}

button {
    width: 100%; padding: 12px; background: #2b6cb0; color: white; border: none; border-radius: 6px; font-weight: bold; cursor: pointer; transition: 0.2s;
}
button:hover { background: #2c5282; }

.result-box {
    margin-top: 20px; padding: 15px; background: #ebf8ff; border-radius: 8px; border: 1px solid #bee3f8;
}
.result-item { display: flex; justify-content: space-between; margin-bottom: 8px; color: #2d3748; }
.result-item.highlight strong { color: #2b6cb0; font-size: 1.3em; }

.cta-affiliate {
    margin-top: 15px; padding-top: 15px; border-top: 1px dashed #cbd5e0; text-align: center; font-size: 0.85em;
}
.btn-affiliate {
    display: inline-block; margin-top: 8px; padding: 8px 12px; background: #319795; color: white; text-decoration: none; border-radius: 4px; font-weight: bold;
}

.nav-back { margin-top: 20px; text-align: center; font-size: 0.85em; }
.nav-back a { color: #718096; text-decoration: none; }