body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.6;
    margin: 0;
    padding: 0;
    color: #333;
    background-color: #f9f9f9;
}
header {
    background-color: #007aff;
    color: white;
    padding: 60px 20px;
    text-align: center;
}
header h1 { margin: 0; font-size: 2.5em; }
header p { font-size: 1.2em; opacity: 0.9; }
nav {
    background: white;
    padding: 15px;
    text-align: center;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}
nav a {
    color: #007aff;
    text-decoration: none;
    margin: 0 15px;
    font-weight: 600;
}
nav a:hover { text-decoration: underline; }
.container {
    max-width: 800px;
    margin: 40px auto;
    padding: 20px;
    background: white;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.features { display: flex; flex-wrap: wrap; gap: 20px; margin-top: 30px; }
.feature { flex: 1 1 calc(50% - 20px); background: #f1f1f1; padding: 20px; border-radius: 8px; }
.feature h3 { margin-top: 0; color: #007aff; }
footer { text-align: center; padding: 30px 20px; color: #666; font-size: 0.9em; }
.app-store-button {
    display: inline-block; background: #000; color: #fff; padding: 12px 24px;
    border-radius: 24px; text-decoration: none; font-weight: bold; margin-top: 20px;
}
.calc-form { display: flex; flex-direction: column; gap: 15px; }
.calc-form label { font-weight: bold; }
.calc-form input { padding: 10px; border: 1px solid #ccc; border-radius: 6px; font-size: 16px; }
.calc-form button { padding: 12px; background: #34c759; color: white; border: none; border-radius: 6px; font-size: 16px; font-weight: bold; cursor: pointer; }
.calc-form button:hover { background: #28a745; }
.result { margin-top: 20px; padding: 20px; background: #e5fbee; border-radius: 8px; border-left: 5px solid #34c759; }
.result h3 { margin-top: 0; color: #155724; }