:root {
    /* Color Palette */
    --color-text: #343a40;
    --color-background: #f8f9fa;
    --color-surface: #ffffff;
    --color-primary: #337ab7;
    --color-primary-hover: #286090;
    --color-success: #5cb85c;
    --color-success-hover: #4cae4c;
    --color-warning: #f0ad4e;
    --color-warning-hover: #ec971f;
    --color-secondary: #6c757d;
    --color-secondary-hover: #5a6268;
    --color-border: #dee2e6;
    --color-muted: #6c757d;
    --color-header-bg: #212529;
    --color-header-text: #ffffff;
    --color-code-bg: #e9ecef;
    --color-highlight-bg: rgba(255, 220, 0, 0.5);
    --color-reveal-bg: rgba(100, 100, 255, 0.2);
    --color-reveal-border: rgba(100, 100, 255, 0.4);
    --color-active-bg: #d1e7dd;
    --color-active-border: #a2c9b7;
    
    /* Options Panel Dark Theme Colors */
    --options-bg: #1a1a2e;
    --options-surface: #16213e;
    --options-border: #2c3e50;
    --options-text: #ffffff;
    --options-checkbox-bg: #ffffff;
    --options-checkbox-checked: #2196f3;
    --options-tag-bg: #e0e0e0;
    --options-tag-text: #ffffff;
    --options-tag-active-bg: #4caf50;
    --options-tag-active-text: #ffffff;

    /* Typography */
    --font-family-sans-serif: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-family-monospace: 'SF Mono', 'Monaco', 'Inconsolata', 'Roboto Mono', 'Source Code Pro', monospace;
    --font-size-base: 1rem;
    --font-size-lg: 1.25rem;
    --font-size-sm: 0.875rem;
    --font-size-h1: 2rem;
    --font-size-h2: 1.5rem;
    --font-weight-normal: 400;
    --font-weight-bold: 700;
    --line-height-base: 1.6;

    /* Spacing */
    --spacing-1: 0.25rem;
    --spacing-2: 0.5rem;
    --spacing-3: 1rem;
    --spacing-4: 1.5rem;
    --spacing-5: 2rem;

    /* Borders */
    --border-width: 1px;
    --border-radius: 0.375rem;
    --border-radius-sm: 0.25rem;
}

body {
    font-family: var(--font-family-sans-serif);
    line-height: var(--line-height-base);
    margin: 0;
    padding: 0;
    background-color: var(--color-background);
    color: var(--color-text);
}

header {
    background: var(--color-warning);
    padding: var(--spacing-3) var(--spacing-5);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-4);
}

#header-logo {
    max-height: 60px;
    width: auto;
}

.header-logo-link {
    text-decoration: none;
    border: none;
    outline: none;
    transition: transform 0.2s ease, opacity 0.2s ease;
}

.header-logo-link:hover {
    transform: scale(1.05);
    opacity: 0.8;
}

.header-logo-link:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.header-text {
    text-align: left;
}

header h1 {
    margin: 0;
    font-size: var(--font-size-h1);
    color: #1a1a1a;
}

header p {
    font-size: var(--font-size-sm);
    color: #333333;
    margin: 0;
}

.theme-toggle-btn {
    background: transparent;
    border: 2px solid #1a1a1a;
    border-radius: 50%;
    width: 44px;
    height: 44px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    transition: transform 0.2s ease;
    flex-shrink: 0;
}

.theme-toggle-btn:hover {
    transform: scale(1.1);
}

.theme-icon-dark {
    display: none;
}

body.dark-mode .theme-icon-light {
    display: none;
}

body.dark-mode .theme-icon-dark {
    display: inline;
}

body.dark-mode .theme-toggle-btn {
    border-color: var(--color-text);
}

main {
    padding: var(--spacing-3);
}

.container {
    max-width: 1200px;
    margin: auto;
    overflow: hidden;
    padding: 0 var(--spacing-5);
    display: grid;
    grid-template-columns: 1fr;
    grid-template-rows: auto auto auto;
    gap: var(--spacing-4);
}

#input-section {
    grid-row: 1;
}

#output-section {
    grid-row: 2;
}

#options-section {
    grid-row: 3;
}

#input-section, #output-section, #options-section {
    background: var(--color-surface);
    padding: var(--spacing-4);
    border-radius: var(--border-radius);
    box-shadow: 0 0 10px rgba(0,0,0,0.05);
}

h2 {
    color: var(--color-text);
    margin-top: 0;
    font-size: var(--font-size-h2);
    font-weight: var(--font-weight-normal);
}

/* --- Textarea & Highlighting --- */

.input-area-wrapper, .output-area-wrapper {
    position: relative;
    width: 100%;
    margin-bottom: var(--spacing-3);
}

textarea {
    width: 100%;
    min-height: 150px;
    padding: var(--spacing-2);
    border: var(--border-width) solid var(--color-border);
    border-radius: var(--border-radius);
    margin-bottom: 0;
    font-family: var(--font-family-monospace);
    box-sizing: border-box;
    resize: vertical;
    background-color: transparent;
    color: var(--color-text);
    position: relative;
    z-index: 2;
}

#outputText {
    min-height: 300px;
}

#highlightContainer, #outputHighlightContainer {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 1;
    font-family: var(--font-family-monospace);
    font-size: inherit;
    line-height: inherit;
    color: transparent;
    padding: var(--spacing-2);
    border: var(--border-width) solid transparent;
    border-radius: var(--border-radius);
    box-sizing: border-box;
    white-space: pre-wrap;
    word-wrap: break-word;
    overflow: hidden;
    pointer-events: none;
}

#highlightContainer.reveal-mode-active,
#outputHighlightContainer.reveal-mode-active {
    color: var(--color-text);
    font-family: 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    font-size: 14px;
    line-height: 1.6;
}


.highlighted-char {
    background-color: var(--color-highlight-bg);
    border-radius: var(--border-radius-sm);
}

.revealed-code {
    background-color: var(--color-reveal-bg);
    color: #1a1a2e;
    font-weight: var(--font-weight-bold);
    padding: 0 var(--spacing-1);
    border-radius: var(--border-radius-sm);
    border: var(--border-width) solid var(--color-reveal-border);
}

#inputText.reveal-mode-active,
#outputText.reveal-mode-active {
    color: transparent;
    caret-color: var(--color-text);
    background-color: transparent !important;
}

/* --- Options Panel --- */

#options-panel {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-4);
    background-color: var(--options-surface);
    border: 2px solid var(--options-border);
    border-radius: var(--border-radius);
    padding: var(--spacing-4);
    margin-top: var(--spacing-3);
}

#options-panel fieldset {
    border: 1px solid var(--options-border);
    padding: var(--spacing-3);
    border-radius: var(--border-radius);
    background-color: rgba(15, 52, 96, 0.3);
    margin-bottom: var(--spacing-3);
    break-inside: avoid;
}

#options-panel legend {
    font-weight: var(--font-weight-bold);
    color: var(--options-text);
    padding: 0 var(--spacing-2);
    font-size: var(--font-size-lg);
    border-bottom: 1px solid var(--options-border);
    margin-bottom: var(--spacing-2);
    padding-bottom: var(--spacing-2);
}

#options-panel label {
    display: flex;
    align-items: center;
    margin-bottom: var(--spacing-2);
    font-size: var(--font-size-base);
    color: var(--options-text);
    cursor: pointer;
    transition: all 0.2s ease;
}

#options-panel label span {
    flex-grow: 1;
    margin-left: var(--spacing-2);
    color: #cccccc;
}

#options-panel code {
    background-color: #333333;
    border: 1px solid #333333;
    padding: var(--spacing-1) var(--spacing-2);
    border-radius: var(--border-radius-sm);
    font-family: var(--font-family-monospace);
    font-size: var(--font-size-sm);
    color: #cccccc;
    font-weight: var(--font-weight-bold);
    flex-shrink: 0;
    min-width: 60px;
    text-align: center;
    transition: all 0.2s ease;
}

#options-panel label input[type="checkbox"]:checked + span + code,
#options-panel label input[type="radio"]:checked + span + code {
    background-color: #333333;
    border-color: #333333;
    color: #cccccc;
    border-color: var(--options-tag-active-bg);
    color: var(--options-tag-active-text);
}

/* Custom Checkbox Styling for Options Panel */
#options-panel input[type="checkbox"],
#options-panel input[type="radio"] {
    appearance: none;
    width: 18px;
    height: 18px;
    border: 2px solid var(--options-checkbox-bg);
    border-radius: 3px;
    background-color: transparent;
    cursor: pointer;
    position: relative;
    transition: all 0.2s ease;
    flex-shrink: 0;
}

#options-panel input[type="checkbox"]:checked,
#options-panel input[type="radio"]:checked {
    background-color: var(--options-checkbox-checked);
    border-color: var(--options-checkbox-checked);
}

#options-panel input[type="checkbox"]:checked::after,
#options-panel input[type="radio"]:checked::after {
    content: '✓';
    position: absolute;
    top: -2px;
    left: 2px;
    color: white;
    font-size: 14px;
    font-weight: bold;
}

#options-panel input[type="radio"] {
    border-radius: 50%;
}

#options-panel input[type="radio"]:checked::after {
    content: '';
    width: 6px;
    height: 6px;
    background-color: white;
    border-radius: 50%;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

.options-buttons {
    grid-column: 1 / -1;
    margin-top: var(--spacing-3);
    padding-top: var(--spacing-3);
    border-top: var(--border-width) solid var(--color-border);
}

/* --- Buttons & Status --- */

.action-buttons {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: var(--spacing-2);
    margin-bottom: var(--spacing-3);
}

#statusMessage {
    margin-left: auto;
    padding: var(--spacing-2) var(--spacing-3);
    background-color: var(--color-code-bg);
    border-radius: var(--border-radius-sm);
    font-size: var(--font-size-sm);
    color: var(--color-text);
    min-width: 150px;
    text-align: center;
}

.input-stats,
.output-stats {
    margin-bottom: var(--spacing-3);
}

.input-stats p,
.output-stats p {
    font-size: var(--font-size-sm);
    color: var(--color-muted);
    margin: 0;
}

.warning-text {
    color: var(--color-warning-hover);
    font-weight: var(--font-weight-bold);
}

.button {
    display: inline-block;
    padding: var(--spacing-2) var(--spacing-3);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-normal);
    cursor: pointer;
    border: none;
    border-radius: var(--border-radius);
    margin-right: var(--spacing-2);
    margin-bottom: var(--spacing-2);
    text-align: center;
    vertical-align: middle;
    transition: background-color 0.15s ease-in-out;
}

.button-primary {
    background-color: var(--color-primary);
    color: var(--color-header-text);
}
.button-primary:hover {
    background-color: var(--color-primary-hover);
}

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

.button-warning {
    background-color: var(--color-warning);
    color: #1a1a1a;
}
.button-warning:hover {
    background-color: var(--color-warning-hover);
    color: #1a1a1a;
}

.button-secondary {
    background-color: #e0e0e0;
    color: #333333;
    border: 1px solid #cccccc;
}
.button-secondary:hover {
    background-color: #d0d0d0;
    color: #333333;
}

/* --- Help Section Styles */
#help-section {
    /* background-color: var(--background-color-light); /* Removed to blend with parent */
    padding: 25px 20px; /* Vertical padding retained, 20px horizontal padding added */
    margin-top: 40px; /* More space above the help section */
    /* border-top: 1px solid var(--border-color); /* Removed */
    /* border-radius: var(--border-radius); /* Removed as parent provides rounding */
}

#help-section h2 {
    color: var(--color-primary);
    text-align: center;
    margin-bottom: 30px;
    font-size: 2em;
}

.help-article {
    background-color: var(--color-surface);
    padding: 20px;
    margin-bottom: 25px;
    border-radius: var(--border-radius);
    box-shadow: 0 3px 6px rgba(0,0,0,0.07);
}

.help-article:last-child {
    margin-bottom: 0; /* No margin for the last article */
}

.help-article h3 {
    color: var(--color-primary-hover);
    margin-top: 0;
    margin-bottom: 15px;
    font-size: 1.5em;
    border-bottom: 1px solid var(--color-border);
    padding-bottom: 8px;
}

.help-article p,
.help-article ul,
.help-article ol {
    line-height: 1.75;
    color: var(--color-muted);
    margin-bottom: 15px;
}

.help-article ul,
.help-article ol {
    padding-left: 30px; /* More indentation for lists */
}

.help-article li {
    margin-bottom: 10px; /* More space between list items */
}

.help-article strong {
    color: var(--color-text);
    font-weight: 600;
}

/* --- Footer --- */

footer {
    text-align: center;
    padding: var(--spacing-4) 0;
    margin-top: var(--spacing-4);
    border-top: var(--border-width) solid var(--color-border);
}

.privacy-statement {
    font-size: var(--font-size-sm);
    color: var(--color-muted);
    margin: 0;
}

.footer-stats {
    font-size: 0.75rem;
    color: var(--color-muted);
    margin-top: var(--spacing-2);
    opacity: 0.7;
}

.build-date {
    text-align: center;
    font-size: 0.8em;
    color: #666;
    margin-top: 10px;
    opacity: 0.6;
}

/* --- Media Queries --- */

@media (max-width: 768px) {
    .container {
        grid-template-columns: 1fr;
        grid-template-rows: auto auto auto;
        gap: var(--spacing-3);
    }
    
    /* Reduce padding on smaller screens */
    #input-section, #output-section, #options-section {
        padding: var(--spacing-3);
    }
    
    /* Make options panel more compact on mobile */
    #options-panel {
        column-count: 1;
    }
    
    .options-column {
        margin-bottom: var(--spacing-3);
    }
    
    /* Mobile-specific adjustments */
    header {
        padding: var(--spacing-2);
    }
    
    header h1 {
        font-size: 1.25rem;
    }
    
    header p {
        font-size: 0.875rem;
    }
    
    .theme-toggle-btn {
        width: 36px;
        height: 36px;
        font-size: 1rem;
    }
    
    /* Stack action buttons vertically on mobile */
    .action-buttons {
        display: flex;
        flex-direction: column;
        gap: var(--spacing-2);
    }
    
    .action-buttons button {
        width: 100%;
        margin: 0;
    }
    
    /* Make buttons more touch-friendly */
    .button {
        padding: var(--spacing-2) var(--spacing-3);
        min-height: 44px; /* Touch target size */
        font-size: 0.875rem;
    }
    
    /* Adjust textarea sizes for mobile */
    textarea {
        min-height: 120px;
        font-size: 0.875rem;
    }
    
    #outputText {
        min-height: 200px;
    }
    
    /* Compact stats display */
    .input-stats, .output-stats {
        font-size: 0.75rem;
    }
    
    /* Reduce spacing in help section */
    .help-article {
        margin-bottom: var(--spacing-3);
    }
    
    .help-article h3 {
        font-size: 1.125rem;
    }
    
    .help-article h4 {
        font-size: 1rem;
    }
}

@media (min-width: 992px) {
    #options-panel {
        column-count: 2;
        column-gap: var(--spacing-4);
    }
}

/* --- Dark Mode Support --- */

/* Auto dark mode (OS preference) - only when no manual override */
@media (prefers-color-scheme: dark) {
    body:not(.light-mode) {
        --color-text: #e9ecef;
        --color-background: #1a1a2e;
        --color-surface: #16213e;
        --color-primary: #4dabf7;
        --color-primary-hover: #74c0fc;
        --color-success: #69db7c;
        --color-success-hover: #8ce99a;
        --color-warning: #ffd43b;
        --color-warning-hover: #ffe066;
        --color-secondary: #868e96;
        --color-secondary-hover: #adb5bd;
        --color-border: #495057;
        --color-muted: #adb5bd;
        --color-header-bg: #0f0f23;
        --color-header-text: #e9ecef;
        --color-code-bg: #2d3748;
        --color-highlight-bg: rgba(255, 220, 0, 0.3);
        --color-reveal-bg: rgba(100, 100, 255, 0.3);
        --color-reveal-border: rgba(100, 100, 255, 0.5);
        --color-active-bg: #1e4d3d;
        --color-active-border: #2d6a4f;
    }

    body:not(.light-mode) textarea {
        background-color: var(--color-surface);
        color: var(--color-text);
        border-color: var(--color-border);
    }

    body:not(.light-mode) textarea::placeholder {
        color: var(--color-muted);
    }

    body:not(.light-mode) header h1 {
        color: #1a1a1a;
    }

    body:not(.light-mode) header p {
        color: #333333;
    }
}

/* Manual dark mode override */
body.dark-mode {
    --color-text: #e9ecef;
    --color-background: #1a1a2e;
    --color-surface: #16213e;
    --color-primary: #4dabf7;
    --color-primary-hover: #74c0fc;
    --color-success: #69db7c;
    --color-success-hover: #8ce99a;
    --color-warning: #ffd43b;
    --color-warning-hover: #ffe066;
    --color-secondary: #868e96;
    --color-secondary-hover: #adb5bd;
    --color-border: #495057;
    --color-muted: #adb5bd;
    --color-header-bg: #0f0f23;
    --color-header-text: #e9ecef;
    --color-code-bg: #2d3748;
    --color-highlight-bg: rgba(255, 220, 0, 0.3);
    --color-reveal-bg: rgba(100, 100, 255, 0.3);
    --color-reveal-border: rgba(100, 100, 255, 0.5);
    --color-active-bg: #1e4d3d;
    --color-active-border: #2d6a4f;
}

body.dark-mode textarea {
    background-color: var(--color-surface);
    color: var(--color-text);
    border-color: var(--color-border);
}

body.dark-mode .revealed-code,
body:not(.light-mode) .revealed-code {
    background-color: rgba(180, 180, 255, 0.95);
    color: #1a1a2e;
    border-color: rgba(150, 150, 255, 0.8);
}

body.dark-mode #highlightContainer.reveal-mode-active,
body.dark-mode #outputHighlightContainer.reveal-mode-active,
body:not(.light-mode) #highlightContainer.reveal-mode-active,
body:not(.light-mode) #outputHighlightContainer.reveal-mode-active {
    background-color: var(--color-surface);
    border-color: var(--color-border);
}

body.dark-mode .build-date,
body:not(.light-mode) .build-date {
    color: var(--color-muted);
}

body.dark-mode textarea::placeholder {
    color: var(--color-muted);
}

body.dark-mode header h1 {
    color: #1a1a1a;
}

body.dark-mode header p {
    color: #333333;
}

/* AI Fingerprint Analysis Styling */
.ai-fingerprint-summary {
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    padding: var(--spacing-3);
    margin: var(--spacing-4) 0;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

body.dark-mode .ai-fingerprint-summary {
    background: linear-gradient(135deg, #2d3748 0%, #1a202c 100%);
    border-color: var(--color-border);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.ai-fingerprint-summary h4 {
    margin-top: 0;
    margin-bottom: var(--spacing-2);
    color: var(--color-primary);
    font-weight: var(--font-weight-bold);
}

.ai-fingerprint-summary p {
    margin: var(--spacing-1) 0;
    font-size: var(--font-size-sm);
}

.help-article h4 {
    color: var(--color-primary);
    padding-bottom: var(--spacing-1);
    margin-top: var(--spacing-4);
    margin-bottom: var(--spacing-2);
    font-weight: var(--font-weight-normal);
}

.help-article ul li strong {
    color: var(--color-text);
    font-weight: var(--font-weight-bold);
}

.help-article ul li em {
    color: var(--color-muted);
    font-style: italic;
}

body.dark-mode .help-article h4 {
    color: #63b3ed;
}

body.dark-mode .help-article ul li strong {
    color: #e2e8f0;
}

body.dark-mode .help-article ul li em {
    color: #a0aec0;
}

/* Support Section Styling */
.support-section {
    margin-top: var(--spacing-4);
    text-align: center;
    padding-top: var(--spacing-3);
    border-top: 1px solid var(--color-border);
}

.support-text {
    color: var(--color-muted);
    font-size: var(--font-size-sm);
    margin: 0;
}

.coffee-button {
    display: inline-block;
    background: linear-gradient(135deg, #ff8c00 0%, #ff6b00 100%);
    color: white !important;
    text-decoration: none !important;
    padding: var(--spacing-2) var(--spacing-4);
    border-radius: var(--border-radius);
    font-weight: var(--font-weight-bold);
    font-size: var(--font-size-sm);
    transition: all 0.3s ease;
    box-shadow: 0 2px 4px rgba(255, 140, 0, 0.2);
    border: none;
    margin-left: var(--spacing-2);
}

.coffee-button:hover {
    background: linear-gradient(135deg, #ff6b00 0%, #ff5400 100%);
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(255, 140, 0, 0.3);
    text-decoration: none !important;
}

.coffee-button:active {
    transform: translateY(0);
    box-shadow: 0 2px 4px rgba(255, 140, 0, 0.2);
}

body.dark-mode .support-section {
    border-top-color: #4a5568;
}

body.dark-mode .support-text {
    color: #a0aec0;
}

body.dark-mode .coffee-button {
    background: linear-gradient(135deg, #ff8c00 0%, #ff6b00 100%);
    box-shadow: 0 2px 4px rgba(255, 140, 0, 0.3);
}

body.dark-mode .coffee-button:hover {
    background: linear-gradient(135deg, #ff6b00 0%, #ff5400 100%);
    box-shadow: 0 4px 8px rgba(255, 140, 0, 0.4);
}

/* Header Actions Container */
.header-actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    flex-shrink: 0;
}

/* Header Coffee Button - Compact Version */
.coffee-button-header {
    padding: var(--spacing-1) var(--spacing-2) !important;
    font-size: 1.5rem !important;
    min-width: auto !important;
    border-radius: 50% !important;
    width: 40px;
    height: 40px;
    display: flex !important;
    align-items: center;
    justify-content: center;
    text-decoration: none !important;
    margin: 0 !important;
}

.coffee-button-header:hover {
    transform: scale(1.1) !important;
    text-decoration: none !important;
}

.coffee-button-header:active {
    transform: scale(1.05) !important;
}

/* Responsive Header */
@media (max-width: 768px) {
    .header-actions {
        gap: var(--spacing-1);
    }
    
    .coffee-button-header {
        width: 36px;
        height: 36px;
        font-size: 1.25rem !important;
    }
    
    .theme-toggle-btn {
        width: 36px;
        height: 36px;
        font-size: 1rem;
    }
}