:root {
    --primary: #4361ee;
    --primary-dark: #3a56d4;
    --secondary: #7209b7;
    --success: #4cc9f0;
    --light: #f8f9fa;
    --dark: #212529;
    --gray: #6c757d;
    --gray-light: #e9ecef;
    --border-radius: 8px;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

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

body {
    background-color: #f5f7fb;
    color: var(--dark);
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

header {
    text-align: center;
    margin-bottom: 30px;
    padding: 20px;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
}

header p {
    font-size: 1.1rem;
    opacity: 0.9;
}

.app-container {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 20px;
}

@media (max-width: 768px) {
    .app-container {
        grid-template-columns: 1fr;
    }
}

.control-panel {
    background: white;
    padding: 25px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.data-preview {
    background: white;
    padding: 25px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    display: flex;
    flex-direction: column;
}

.section-title {
    font-size: 1.3rem;
    margin-bottom: 20px;
    color: var(--primary);
    border-bottom: 2px solid var(--gray-light);
    padding-bottom: 10px;
}

.form-group {
    margin-bottom: 20px;
}

label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--dark);
}

select, input, button {
    width: 100%;
    padding: 12px 15px;
    border: 1px solid var(--gray-light);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
}

select:focus, input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(67, 97, 238, 0.2);
}

button {
    background-color: var(--primary);
    color: white;
    border: none;
    cursor: pointer;
    font-weight: 600;
    margin-top: 10px;
}

button:hover {
    background-color: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

button.secondary {
    background-color: var(--gray);
}

button.secondary:hover {
    background-color: #5a6268;
}

button.success {
    background-color: var(--success);
}

button.success:hover {
    background-color: #3bb4d8;
}

.button-group {
    display: flex;
    gap: 10px;
}

.button-group button {
    flex: 1;
}

.preview-area {
    flex: 1;
    background-color: var(--light);
    border-radius: var(--border-radius);
    padding: 15px;
    overflow: auto;
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    border: 1px solid var(--gray-light);
    min-height: 300px;
    white-space: pre-wrap;
}

.stats {
    display: flex;
    justify-content: space-between;
    margin-top: 15px;
    padding-top: 15px;
    border-top: 1px solid var(--gray-light);
    font-size: 0.9rem;
    color: var(--gray);
}

.tabs {
    display: flex;
    margin-bottom: 20px;
    border-bottom: 1px solid var(--gray-light);
}

.tab {
    padding: 10px 20px;
    cursor: pointer;
    border-bottom: 3px solid transparent;
    transition: var(--transition);
}

.tab.active {
    border-bottom-color: var(--primary);
    color: var(--primary);
    font-weight: 600;
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

.options-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px;
}

.option-item {
    display: flex;
    align-items: center;
    gap: 8px;
}

.option-item input[type="checkbox"] {
    width: auto;
}

.history-item {
    padding: 10px;
    border-bottom: 1px solid var(--gray-light);
    cursor: pointer;
    transition: var(--transition);
}

.history-item:hover {
    background-color: var(--gray-light);
}

.history-item:last-child {
    border-bottom: none;
}

.toast {
    position: fixed;
    bottom: 20px;
    right: 20px;
    padding: 15px 25px;
    background-color: var(--success);
    color: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    transform: translateY(100px);
    opacity: 0;
    transition: var(--transition);
    z-index: 1000;
}

.toast.show {
    transform: translateY(0);
    opacity: 1;
}

footer {
    text-align: center;
    margin-top: 40px;
    padding: 20px;
    color: var(--gray);
    font-size: 0.9rem;
}

.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255,255,255,.3);
    border-radius: 50%;
    border-top-color: #fff;
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}