* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary: #2c3e50;
    --secondary: #3498db;
    --accent: #e74c3c;
    --light: #ecf0f1;
    --dark: #2c3e50;
    --success: #2ecc71;
    --text: #333;
    --text-light: #777;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
    --border-radius: 8px;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text);
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    min-height: 100vh;
    padding: 0;
    margin: 0;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

/* Header Styles */
.header {
    background: var(--primary);
    color: white;
    padding: 1.5rem 0;
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.8rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.logo i {
    color: var(--accent);
}

/* Navigation */
.nav {
    background: white;
    padding: 1rem 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

.nav a {
    margin-right: 2rem;
    text-decoration: none;
    font-weight: 600;
    color: var(--primary);
    transition: var(--transition);
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
}

.nav a:hover {
    background: var(--secondary);
    color: white;
}

/* Card Styles */
.card {
    background: white;
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

.card-header {
    padding: 1.5rem 2rem;
    background: linear-gradient(to right, var(--secondary), var(--primary));
    color: white;
}

.card-title {
    font-size: 1.8rem;
    margin: 0;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
}

.card-body {
    padding: 2rem;
}

/* Form Styles */
.form-group {
    margin-bottom: 1.5rem;
}

.form-label {
    display: block;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--dark);
}

.form-control {
    width: 100%;
    padding: 0.8rem;
    border: 1px solid #ddd;
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
    font-family: inherit;
}

.form-control:focus {
    outline: none;
    border-color: var(--secondary);
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.2);
}

textarea.form-control {
    min-height: 120px;
    resize: vertical;
}

/* Button Styles */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    background: var(--secondary);
    color: white;
    padding: 0.7rem 1.5rem;
    border-radius: var(--border-radius);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    border: none;
    cursor: pointer;
    font-family: inherit;
    font-size: 1rem;
}

.btn:hover {
    background: var(--primary);
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.15);
}

.btn-accent {
    background: var(--accent);
}

.btn-accent:hover {
    background: #c0392b;
}

.btn-success {
    background: var(--success);
}

.btn-success:hover {
    background: #27ae60;
}

/* Table Styles */
.table {
    width: 100%;
    border-collapse: collapse;
    background: white;
    box-shadow: var(--shadow);
    border-radius: var(--border-radius);
    overflow: hidden;
    margin-bottom: 2rem;
}

.table th,
.table td {
    border: 1px solid #ddd;
    padding: 0.75rem;
    text-align: left;
}

.table th {
    background: var(--primary);
    color: white;
    font-weight: 500;
}

.table tr:nth-child(even) {
    background-color: #f9f9f9;
}

.table tr:hover {
    background-color: #f1f1f1;
}

/* Pre and Code Styles */
pre {
    background-color: #f8f9fa;
    padding: 1rem;
    border-radius: var(--border-radius);
    border: 1px solid #e9ecef;
    overflow-x: auto;
    margin: 1rem 0;
    font-family: 'Consolas', 'Monaco', monospace;
    font-size: 0.9rem;
    line-height: 1.4;
}

.export-result {
    background: #f8f9fa;
    border: 1px solid #e9ecef;
    padding: 1rem;
    border-radius: var(--border-radius);
    margin-top: 1rem;
    white-space: pre-wrap;
    font-family: 'Consolas', 'Monaco', monospace;
    font-size: 0.9rem;
    line-height: 1.4;
}

/* Utility Classes */
.text-center {
    text-align: center;
}

.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }

.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }

.hidden {
    display: none;
}

/* Radio and Checkbox Styles */
.radio-group {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

.radio-label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
    padding: 0.5rem 1rem;
    background: #f8f9fa;
    border-radius: var(--border-radius);
    transition: var(--transition);
}

.radio-label:hover {
    background: #e9ecef;
}

.radio-label input[type="radio"] {
    margin: 0;
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }

    .nav {
        padding: 1rem;
    }

    .nav a {
        margin-right: 1rem;
        margin-bottom: 0.5rem;
        display: inline-block;
    }

    .card-header {
        padding: 1rem;
    }

    .card-title {
        font-size: 1.5rem;
    }

    .card-body {
        padding: 1rem;
    }

    .radio-group {
        flex-direction: column;
        gap: 0.5rem;
    }

    .table {
        font-size: 0.9rem;
    }

    .table th,
    .table td {
        padding: 0.5rem;
    }
}

@media (max-width: 480px) {
    .header-content {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }

    .nav a {
        display: block;
        margin-right: 0;
        margin-bottom: 0.5rem;
        text-align: center;
    }

    .btn {
        width: 100%;
        justify-content: center;
    }
}