:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --background-color: #f5f7fa;
    --text-color: #2c3e50;
    --border-color: #ddd;
    --error-color: #e74c3c;
    --success-color: #2ecc71;
    --warning-color: #f39c12;
    --card-bg: #ffffff;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

[data-theme="dark"] {
    --primary-color: #3498db;
    --secondary-color: #2ecc71;
    --background-color: #1a1a2e;
    --text-color: #f0f0f0;
    --border-color: #444;
    --card-bg: #16213e;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--background-color);
    transition: var(--transition);
    padding: 20px;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

h1, h2, h3 {
    color: var(--primary-color);
}

main {
    max-width: 1200px;
    margin: 0 auto;
}

section {
    background: var(--card-bg);
    border-radius: 8px;
    box-shadow: var(--shadow);
    padding: 1.5rem;
    margin-bottom: 2rem;
}

/* Input Section */
.input-section {
    margin-bottom: 2rem;
}

.paste-container {
    margin: 1rem 0;
}

textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    resize: vertical;
    min-height: 150px;
    font-family: monospace;
    background-color: var(--card-bg);
    color: var(--text-color);
}

/* Buttons */
.button-group {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
}

.primary-btn, .secondary-btn {
    padding: 0.5rem 1rem;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-weight: 500;
    transition: var(--transition);
}

.primary-btn {
    background-color: var(--primary-color);
    color: white;
}

.primary-btn:hover {
    opacity: 0.9;
}

.secondary-btn {
    background-color: transparent;
    border: 1px solid var(--primary-color);
    color: var(--primary-color);
}

.secondary-btn:hover {
    background-color: rgba(52, 152, 219, 0.1);
}

/* Table Styles */
.table-container {
    overflow-x: auto;
    margin-top: 1rem;
}

.data-table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 1rem;
}

.data-table th, .data-table td {
    padding: 0.75rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

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

.data-table tr:hover {
    background-color: rgba(52, 152, 219, 0.05);
}

/* Chart Section */
.chart-container {
    position: relative;
    height: 400px;
    margin-top: 1rem;
}

.chart-controls {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin: 1rem 0;
    align-items: center;
}

.form-group {
    display: flex;
    flex-direction: column;
    min-width: 150px;
}

.form-group label {
    margin-bottom: 0.25rem;
    font-size: 0.9rem;
}

.form-control {
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    background-color: var(--card-bg);
    color: var(--text-color);
}

/* Toast Notifications */
.toast {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background-color: var(--card-bg);
    border-left: 4px solid var(--error-color);
    padding: 1rem;
    border-radius: 4px;
    box-shadow: var(--shadow);
    max-width: 350px;
    z-index: 1000;
    display: flex;
    align-items: center;
    transform: translateX(120%);
    transition: transform 0.3s ease;
}

.toast.show {
    transform: translateX(0);
}

.toast.success {
    border-left-color: var(--success-color);
}

.toast.warning {
    border-left-color: var(--warning-color);
}

.close-toast {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    margin-left: 1rem;
    color: var(--text-color);
}

/* File Input Styling */
.file-input-container {
    margin-bottom: 1rem;
}

.file-input-label {
    display: inline-block;
    padding: 0.5rem 1rem;
    background-color: var(--primary-color);
    color: white;
    border-radius: 4px;
    cursor: pointer;
    transition: var(--transition);
}

.file-input-label:hover {
    opacity: 0.9;
}

#fileInput {
    display: none;
}

/* Theme Toggle */
.theme-toggle button {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-color);
}

/* Accessibility */
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Responsive Design */
@media (max-width: 768px) {
    .chart-controls {
        flex-direction: column;
        align-items: stretch;
    }
    
    .form-group {
        width: 100%;
    }
    
    .button-group {
        flex-direction: column;
    }
    
    .primary-btn, .secondary-btn {
        width: 100%;
    }
}

/* Focus styles for accessibility */
:focus-visible {
    outline: 3px solid var(--primary-color);
    outline-offset: 2px;
}

/* Skip to main content link */
.skip-to-content {
    position: absolute;
    left: -9999px;
    z-index: 999;
    padding: 1em;
    background-color: var(--card-bg);
    color: var(--primary-color);
    opacity: 0;
}

.skip-to-content:focus {
    left: 50%;
    transform: translateX(-50%);
    opacity: 1;
}