:root {
    /* Light theme (default) */
    --primary-color: #3498db;
    --secondary-color: #2980b9;
    --accent-color: #e74c3c;
    --success-color: #2ecc71;
    --warning-color: #f39c12;
    --bg-color: #f5f5f5;
    --card-bg: #ffffff;
    --text-color: #333333;
    --text-secondary: #6c757d;
    --border-color: #dddddd;
    --input-bg: #ffffff;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --shadow: 0 2px 8px var(--shadow-color);
    --hover-bg: #f8f9fa;
    
    /* Improved accessibility */
    --focus-ring: 0 0 0 3px rgba(52, 152, 219, 0.5);
    --transition-speed: 0.3s;
    --border-radius: 6px;
    --large-border-radius: 12px;
}

body.dark-theme {
    /* Dark theme */
    --primary-color: #4dabf7;
    --secondary-color: #339af0;
    --accent-color: #ff6b6b;
    --success-color: #51cf66;
    --warning-color: #fcc419;
    --bg-color: #121212;
    --card-bg: #1e1e1e;
    --text-color: #e0e0e0;
    --text-secondary: #adb5bd;
    --border-color: #444444;
    --input-bg: #2c2c2c;
    --shadow-color: rgba(0, 0, 0, 0.3);
    --shadow: 0 2px 8px var(--shadow-color);
    --hover-bg: #2c2c2c;
    
    /* Dark theme focus ring needs higher contrast */
    --focus-ring: 0 0 0 3px rgba(77, 171, 247, 0.6);
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: 'Segoe UI', -apple-system, BlinkMacSystemFont, system-ui, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--bg-color);
    transition: background-color var(--transition-speed), color var(--transition-speed);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color 0.2s;
    position: relative;
}

a:hover {
    color: var(--secondary-color);
    text-decoration: underline;
}

a:focus {
    outline: none;
    box-shadow: var(--focus-ring);
    border-radius: 2px;
}

/* Layout */
.container {
    width: 100%;
    max-width: 1400px;
    margin: 0 auto;
    padding: 1rem;
    flex: 1;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
    padding-bottom: 0.75rem;
    border-bottom: 1px solid var(--border-color);
}

h1 {
    font-size: 1.6rem;
    color: var(--primary-color);
    font-weight: 600;
}

h2 {
    font-size: 1.25rem;
    color: var(--secondary-color);
    margin-bottom: 1rem;
    font-weight: 500;
}

h3 {
    font-size: 1rem;
    margin-bottom: 0.75rem;
    font-weight: 500;
}

/* Header controls */
.header-controls {
    display: flex;
    gap: 1rem;
    align-items: center;
}

.theme-toggle {
    margin-right: 0.5rem;
}

#themeToggle {
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: var(--border-radius);
    transition: background-color var(--transition-speed);
    display: flex;
    justify-content: center;
    align-items: center;
}

#themeToggle:hover {
    background-color: var(--hover-bg);
}

.light-icon, .dark-icon {
    font-size: 1.2rem;
}

body:not(.dark-theme) .dark-icon,
body.dark-theme .light-icon {
    display: none;
}

.language-selector {
    display: flex;
    gap: 0.5rem;
    border-radius: var(--border-radius);
    overflow: hidden;
}

.lang-btn {
    background: none;
    border: 1px solid var(--border-color);
    cursor: pointer;
    padding: 0.35rem 0.7rem;
    transition: all var(--transition-speed);
    font-size: 0.85rem;
    background-color: var(--input-bg);
}

.lang-btn.active {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
    font-weight: 500;
}

.lang-btn:hover:not(.active) {
    background-color: var(--hover-bg);
}

/* Main layout with flexbox for better responsiveness */
.main-content {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    margin-bottom: 2rem;
}

@media (min-width: 992px) {
    .main-content {
        flex-direction: row;
    }
    
    .tabs-vertical {
        width: 250px;
        flex-shrink: 0;
    }
    
    .conversion-panel {
        flex: 1;
    }
}

.tabs-vertical {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    padding: 1rem;
    background-color: var(--card-bg);
    border-radius: var(--large-border-radius);
    box-shadow: var(--shadow);
}

.tab-button {
    text-align: left;
    padding: 0.85rem 1rem;
    border: none;
    background-color: transparent;
    color: var(--text-color);
    cursor: pointer;
    border-radius: var(--border-radius);
    transition: all var(--transition-speed);
    font-size: 0.95rem;
    display: flex;
    align-items: center;
    font-weight: 500;
}

.tab-button:hover {
    background-color: var(--hover-bg);
}

.tab-button.active {
    background-color: var(--primary-color);
    color: white;
    font-weight: 600;
    position: relative;
}

.tab-button.active::after {
    content: "→";
    position: absolute;
    right: 1rem;
}

.recent-operations {
    margin-top: 1.5rem;
    border-top: 1px solid var(--border-color);
    padding-top: 1.5rem;
}

.recent-operations h3 {
    font-size: 0.95rem;
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
}

#recentOperations {
    list-style: none;
    max-height: calc(100vh - 350px);
    overflow-y: auto;
    margin-bottom: 0.5rem;
}

#recentOperations li {
    padding: 0.75rem;
    margin-bottom: 0.5rem;
    font-size: 0.85rem;
    cursor: pointer;
    border-radius: var(--border-radius);
    transition: all var(--transition-speed);
    background-color: var(--input-bg);
    border: 1px solid var(--border-color);
}

#recentOperations li:hover {
    background-color: var(--hover-bg);
    transform: translateY(-1px);
    border-color: var(--primary-color);
}

.operation-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.25rem;
}

.operation-mode {
    font-weight: 500;
    color: var(--primary-color);
}

.operation-time {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.operation-preview {
    color: var(--text-secondary);
    font-family: 'Consolas', 'Courier New', monospace;
    font-size: 0.8rem;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

/* Tab description styling */
.tab-description {
    background-color: var(--card-bg);
    padding: 1rem;
    border-radius: var(--border-radius);
    border-left: 4px solid var(--primary-color);
    margin-bottom: 1rem;
    box-shadow: var(--shadow);
}

.tab-description p {
    font-size: 0.95rem;
    margin-bottom: 0.75rem;
    color: var(--text-secondary);
}

.example-box {
    background-color: rgba(52, 152, 219, 0.05);
    border-radius: var(--border-radius);
    padding: 0.75rem;
    margin-top: 0.75rem;
}

.example-box p {
    font-size: 0.85rem;
    font-weight: 500;
    margin-bottom: 0.25rem;
}

.example-box pre {
    background-color: var(--card-bg);
    padding: 0.75rem;
    font-family: 'Consolas', 'Courier New', monospace;
    font-size: 0.9rem;
    overflow-x: auto;
    border-radius: var(--border-radius);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    margin-bottom: 0.75rem;
    line-height: 1.4;
}

/* Main content styling */
.conversion-panel {
    background-color: var(--card-bg);
    border-radius: var(--large-border-radius);
    box-shadow: var(--shadow);
    overflow: hidden;
}

@media (min-width: 768px) {
    .conversion-panel {
        display: flex;
        position: relative;
    }
    
    .input-section, .output-section {
        flex: 1;
        padding: 1.25rem;
        min-width: 200px;
        overflow: hidden;
    }
    
    /* Resizer Styles - Make it more visible */
    .resizer {
        width: 12px;
        background-color: #e0e0e0;
        cursor: col-resize;
        position: relative;
        transition: background-color 0.2s;
        display: flex;
        justify-content: center;
        align-items: center;
        z-index: 100;
        flex-shrink: 0;
        border-left: 1px solid #d0d0d0;
        border-right: 1px solid #d0d0d0;
    }
    
    .resizer:hover, .resizer.active {
        background-color: var(--primary-color);
    }
    
    .resizer-handle {
        width: 4px;
        height: 50px;
        background-color: #999;
        border-radius: 2px;
        opacity: 0.7;
    }
    
    .resizer:hover .resizer-handle, .resizer.active .resizer-handle {
        background-color: white;
        opacity: 1;
    }
}

@media (max-width: 767px) {
    .input-section, .output-section {
        padding: 1.25rem;
        border-bottom: 1px solid var(--border-color);
    }
    
    /* Hide resizer on mobile */
    .resizer {
        display: none;
    }
}

.input-section, .output-section {
    display: flex;
    flex-direction: column;
}

.input-method {
    display: flex;
    gap: 1.5rem;
    margin-bottom: 0.75rem;
}

.input-method label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
}

.input-method input[type="radio"] {
    margin-right: 0.25rem;
}

.input-actions {
    display: flex;
    gap: 0.75rem;
    margin: 0.5rem 0 1rem;
    flex-wrap: wrap;
}

textarea {
    resize: vertical;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    font-family: 'Consolas', 'Courier New', monospace;
    font-size: 0.9rem;
    background-color: var(--input-bg);
    color: var(--text-color);
    transition: border-color var(--transition-speed), box-shadow var(--transition-speed);
    min-height: 180px;
}

textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: var(--focus-ring);
}

.output-container {
    position: relative;
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}

#outputArea {
    flex-grow: 1;
    min-height: 180px;
    white-space: pre;
    overflow-x: auto;
    font-family: 'Consolas', 'Courier New', monospace;
    -webkit-font-smoothing: antialiased;
    tab-size: 4;
}

.router-output {
    border-top: 1px solid var(--border-color);
    padding-top: 1rem;
    margin-top: 1rem;
}

.options-panel {
    margin-top: 1rem;
    margin-bottom: 1rem;
    background-color: rgba(52, 152, 219, 0.05);
    padding: 1rem;
    border-radius: var(--border-radius);
}

.option-group {
    margin-bottom: 0.75rem;
}

.filter-options {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    margin: 0.5rem 0;
}

label {
    display: block;
    margin-bottom: 0.35rem;
    font-size: 0.95rem;
}

select, input[type="text"] {
    padding: 0.6rem 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 0.9rem;
    background-color: var(--input-bg);
    color: var(--text-color);
    transition: border-color var(--transition-speed), box-shadow var(--transition-speed);
    max-width: 100%;
}

select:focus, input[type="text"]:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: var(--focus-ring);
}

input[type="checkbox"], input[type="radio"] {
    margin-right: 0.5rem;
    transform: scale(1.1);
}

.router-specific-options {
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.info-text {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-top: 0.5rem;
    padding: 0.5rem;
    background-color: rgba(243, 156, 18, 0.1);
    border-radius: var(--border-radius);
}

.results-info {
    margin-bottom: 1rem;
    font-size: 0.9rem;
    padding: 0.5rem;
    background-color: rgba(46, 204, 113, 0.1);
    border-radius: var(--border-radius);
    border-left: 3px solid var(--success-color);
}

.primary-button, .secondary-button {
    padding: 0.75rem 1.25rem;
    border: none;
    border-radius: var(--border-radius);
    font-size: 0.95rem;
    cursor: pointer;
    transition: all var(--transition-speed);
    font-weight: 500;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

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

.primary-button:hover {
    background-color: var(--secondary-color);
    transform: translateY(-1px);
}

.secondary-button {
    background-color: var(--input-bg);
    color: var(--text-color);
    border: 1px solid var(--border-color);
}

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

.action-buttons {
    display: flex;
    gap: 0.75rem;
    margin-top: 1rem;
    flex-wrap: wrap;
}

/* Improved Dialog styling */
.dialog-container {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    padding: 1rem;
    backdrop-filter: blur(3px);
}

.dialog-content {
    background-color: var(--card-bg);
    padding: 2rem;
    border-radius: var(--large-border-radius);
    max-width: 500px;
    width: 100%;
    max-height: 80vh;
    overflow-y: auto;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.2);
    animation: dialogFadeIn 0.3s ease-out;
}

@keyframes dialogFadeIn {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.settings-section {
    margin-bottom: 2rem;
}

.setting-item {
    margin-bottom: 1rem;
}

.dialog-buttons {
    display: flex;
    justify-content: flex-end;
    gap: 1rem;
    margin-top: 2rem;
}

.templates-list {
    margin: 1rem 0;
    max-height: 300px;
    overflow-y: auto;
}

.template-item {
    padding: 1rem;
    margin-bottom: 0.75rem;
    background-color: var(--input-bg);
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: all var(--transition-speed);
    border: 1px solid var(--border-color);
}

.template-item:hover {
    transform: translateY(-2px);
}

.template-item h4 {
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

.template-item p {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.template-actions {
    display: flex;
    justify-content: flex-end;
    gap: 0.5rem;
    margin-top: 0.5rem;
}

/* Improved notifications */
.notification-container {
    position: fixed;
    top: 20px;
    right: 20px;
    max-width: 350px;
    background-color: var(--card-bg);
    color: var(--text-color);
    padding: 1rem;
    border-radius: var(--border-radius);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    z-index: 1000;
    display: none;
    border-left: 4px solid var(--primary-color);
    animation: notificationSlideIn 0.3s ease-out;
}

@keyframes notificationSlideIn {
    from {
        transform: translateX(100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

/* Footer */
footer {
    margin-top: auto;
    padding: 1rem;
    background-color: var(--card-bg);
    border-top: 1px solid var(--border-color);
    text-align: center;
}

.footer-content {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    margin-top: 0.75rem;
    flex-wrap: wrap;
}

/* For focus styles - accessibiity */
button:focus, a:focus, input:focus, select:focus, textarea:focus {
    outline: none;
    box-shadow: var(--focus-ring);
}

/* Loading indicator */
.loading-indicator {
    display: none;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    z-index: 10;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid rgba(52, 152, 219, 0.3);
    border-radius: 50%;
    border-top-color: var(--primary-color);
    animation: spin 1s ease-in-out infinite;
}

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

/* Mobile optimizations */
@media (max-width: 576px) {
    .header-controls {
        flex-direction: column;
        align-items: flex-end;
        gap: 0.5rem;
    }
    
    .input-actions, .action-buttons {
        flex-direction: column;
        width: 100%;
    }
    
    .input-actions button, .action-buttons button {
        width: 100%;
    }
    
    .conversion-panel {
        padding: 1rem;
    }
    
    .tabs-vertical {
        flex-direction: row;
        overflow-x: auto;
        white-space: nowrap;
        padding: 0.5rem;
    }
    
    .tab-button {
        padding: 0.6rem 1rem;
        font-size: 0.9rem;
    }
    
    .recent-operations {
        display: none;
    }
}

/* Keyboard navigation focus indicator */
.keyboard-focus button:focus,
.keyboard-focus a:focus,
.keyboard-focus input:focus,
.keyboard-focus select:focus,
.keyboard-focus textarea:focus {
    outline: 2px solid var(--primary-color);
    box-shadow: var(--focus-ring);
}

/* Tooltip styling */
.tooltip {
    position: relative;
    display: inline-block;
}

.tooltip .tooltip-text {
    visibility: hidden;
    width: 200px;
    background-color: var(--card-bg);
    color: var(--text-color);
    text-align: center;
    border-radius: var(--border-radius);
    padding: 0.5rem;
    position: absolute;
    z-index: 1;
    bottom: 125%;
    left: 50%;
    margin-left: -100px;
    opacity: 0;
    transition: opacity 0.3s;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
    font-size: 0.85rem;
}

.tooltip:hover .tooltip-text {
    visibility: visible;
    opacity: 1;
}

/* Progress indicator for file uploads or processing */
.progress-container {
    width: 100%;
    height: 8px;
    background-color: var(--border-color);
    border-radius: 4px;
    margin: 1rem 0;
    overflow: hidden;
    display: none;
}

.progress-bar {
    height: 100%;
    background-color: var(--primary-color);
    width: 0%;
    transition: width 0.3s;
}