:root {
    --primary-blue: #003366;
    --secondary-blue: #0056b3;
    --accent-orange: #f39c12;
    --success-green: #28a745;
    --bg-light: #f4f7f9;
    --text-dark: #333;
    --white: #ffffff;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

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

body {
    background-color: var(--bg-light);
    color: var(--text-dark);
}

header {
    background-color: var(--primary-blue);
    color: var(--white);
    padding: 1rem 0;
    box-shadow: var(--shadow);
}

.navbar {
    width: 90%;
    max-width: 1100px;
    margin: 0 auto;
}

.logo {
    font-size: 1.8rem;
    font-weight: bold;
}

.tagline {
    font-size: 0.8rem;
    opacity: 0.8;
}

.container {
    max-width: 900px;
    margin: 3rem auto;
    padding: 0 1rem;
}

.calculator-card {
    background: var(--white);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: var(--shadow);
}

.card-header {
    text-align: center;
    margin-bottom: 2rem;
    border-bottom: 2px solid var(--bg-light);
    padding-bottom: 1rem;
}

.table-responsive {
    overflow-x: auto;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 2rem;
}

th {
    background-color: var(--primary-blue);
    color: var(--white);
    padding: 12px;
    text-align: left;
}

td {
    padding: 12px;
    border-bottom: 1px solid #ddd;
}

input[type="number"] {
    width: 80px;
    padding: 8px;
    border: 1px solid #ccc;
    border-radius: 4px;
}

.gp-display {
    font-weight: bold;
    color: var(--secondary-blue);
}

.action-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 1rem;
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-weight: 600;
    transition: 0.3s;
}

.btn-primary { background-color: var(--accent-orange); color: white; }
.btn-success { background-color: var(--success-green); color: white; }
.btn-secondary { background-color: #6c757d; color: white; }

.hidden { display: none; }

.result-card {
    margin-top: 2rem;
    padding: 1.5rem;
    background-color: #eef2f7;
    border-left: 5px solid var(--primary-blue);
    border-radius: 4px;
}

.result-grid {
    display: flex;
    justify-content: space-around;
    margin-top: 1rem;
}

.result-item strong { font-size: 1.5rem; color: var(--primary-blue); }

footer {
    text-align: center;
    padding: 2rem 0;
    color: #777;
    font-size: 0.9rem;
}

/* Print Styles */
@media print {
    header, .action-buttons, footer { display: none !important; }
    body { background-color: white; }
    .calculator-card { box-shadow: none; border: 1px solid #eee; }
    .container { margin: 0; max-width: 100%; }
    input { border: none !important; appearance: none; -moz-appearance: textfield; }
}