:root {
    --primary-color: #3B82F6;
    --secondary-color: #10B981;
    --accent-color: #8B5CF6;
    --text-color: #111827;
    --text-secondary: #4B5563;
    --text-tertiary: #6B7280;
    --bg-primary: #FFFFFF;
    --bg-secondary: #F9FAFB;
    --bg-tertiary: #F3F4F6;
    --border-color: #E5E7EB;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --radius-base: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;    
    --radius-2xl: 1.5rem;
    
    --gray-100: #F3F4F6;
    --gray-200: #E5E7EB;
    --gray-300: #D1D5DB;
    --gray-400: #9CA3AF;
    
    --danger-color: #EF4444;
    --danger-light: #FCA5A5;
    --success-color: #10B981;
    --warning-color: #F59E0B;

    --brand-primary: var(--primary-color);
    --brand-secondary: var(--secondary-color);
    --text-primary: var(--text-color);
}

[data-theme="dark"] {
    --text-color: #F9FAFB;
    --text-secondary: #D1D5DB;
    --text-tertiary: #9CA3AF;
    --bg-primary: #111827;
    --bg-secondary: #1F2937;
    --bg-tertiary: #374151;
    --border-color: #374151;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.2);
}

body {
    background: var(--bg-primary);
}

[data-theme="dark"] body {
    background: var(--bg-primary);
}

.tool-hero {
    margin-top: 0;
    padding: 120px 0 80px;
    position: relative;
    z-index: 2;
    background:  linear-gradient(135deg, var(--bg-primary) 0%, rgba(59, 130, 246, 0.1) 30%, rgba(16, 185, 129, 0.1) 70%, var(--bg-primary) 100%);
    overflow: hidden;
}

.tool-hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        radial-gradient(circle at 20% 80%, rgba(59, 130, 246, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(16, 185, 129, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 40% 40%, rgba(139, 92, 246, 0.05) 0%, transparent 50%);
    animation: heroBackgroundPulse 8s ease-in-out infinite;
}

.hero-content {
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
    position: relative;
    z-index: 3;
}

.hero-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100px;
    height: 100px;
    margin: 0 auto 30px auto;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 50%, var(--accent-color) 100%);
    border-radius: 50%;
    box-shadow: 
        0 15px 35px rgba(59, 130, 246, 0.4),
        0 0 0 10px rgba(59, 130, 246, 0.1),
        0 0 0 20px rgba(59, 130, 246, 0.05);
    animation: heroIconFloat 3s ease-in-out infinite;
}

.hero-icon i {
    font-size: 2.5rem;
    color: white;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

@keyframes heroIconFloat {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-10px); }
}

@keyframes heroBackgroundPulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.8; }
}

.hero-content h1 {
    font-size: 3.5rem;
    font-weight: 800;
    margin: 0 0 1.5rem 0;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 50%, var(--accent-color) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1.1;
}

.hero-content p {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin: 0;
    line-height: 1.6;
}

.calculator-main {
    padding: 4rem 0;
}

.calculator-container {
    max-width: 1400px;
    margin: 0 auto;
}

.calculator-card {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-2xl);
    box-shadow: var(--shadow-lg);
    overflow: hidden;
}

/* Editor Controls */
.editor-controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 2rem;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    flex-wrap: wrap;
    gap: 1rem;
}

.controls-left {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.theme-selector {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.theme-selector label {
    font-weight: 500;
    color: var(--text-color);
    font-size: 0.9rem;
    white-space: nowrap;
}

.theme-selector select {
    padding: 0.5rem 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-base);
    background: var(--bg-primary);
    color: var(--text-color);
    font-size: 0.9rem;
    min-width: 120px;
}

.controls-right {
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.control-button {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1rem;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: var(--radius-base);
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 0.9rem;
}

.control-button:hover {
    background: var(--accent-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

/* Toolbar */
.toolbar {
    display: flex;
    gap: 0.5rem;
    padding: 1rem 2rem;
    background: var(--bg-tertiary);
    border-bottom: 1px solid var(--border-color);
    flex-wrap: wrap;
    align-items: center;
}

.toolbar-button {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-base);
    cursor: pointer;
    transition: all 0.3s ease;
    color: var(--text-color);
}

.toolbar-button:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow-sm);
}

.toolbar-separator {
    width: 1px;
    height: 30px;
    background: var(--border-color);
    margin: 0 0.5rem;
}

/* Editor Layout */
.editor-layout {
    display: grid;
    grid-template-columns: 1fr 1fr;
    min-height: 600px;
}

.editor-pane,
.preview-pane {
    display: flex;
    flex-direction: column;
    border-right: 1px solid var(--border-color);
}

.preview-pane {
    border-right: none;
}

.pane-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 1.5rem;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
}

.pane-header h3 {
    margin: 0;
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-color);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.toggle-toc {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 0.75rem;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: var(--radius-base);
    font-size: 0.85rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.toggle-toc:hover {
    background: var(--accent-color);
}

/* Editor Textarea */
#markdownEditor {
    flex: 1;
    padding: 1.5rem;
    border: none;
    outline: none;
    resize: none;
    font-family: 'Courier New', monospace;
    font-size: 0.95rem;
    line-height: 1.6;
    background: var(--bg-primary);
    color: var(--text-color);
    tab-size: 2;
}

#markdownEditor::placeholder {
    color: var(--text-tertiary);
    opacity: 0.8;
}

/* Status Bar */
.status-bar {
    display: flex;
    gap: 1.5rem;
    padding: 0.75rem 1.5rem;
    background: var(--bg-tertiary);
    border-top: 1px solid var(--border-color);
    font-size: 0.85rem;
    color: var(--text-secondary);
    flex-wrap: wrap;
}

.status-item {
    white-space: nowrap;
}

/* Table of Contents */
.toc-container {
    position: absolute;
    top: 60px;
    right: 1rem;
    width: 280px;
    max-height: 400px;
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    z-index: 10;
    display: none;
    overflow: hidden;
}

.toc-container.active {
    display: block;
    animation: slideInFromRight 0.3s ease;
}

@keyframes slideInFromRight {
    from {
        opacity: 0;
        transform: translateX(20px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.toc-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
}

.toc-header h4 {
    margin: 0;
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-color);
}

.toc-close {
    background: none;
    border: none;
    cursor: pointer;
    color: var(--text-secondary);
    padding: 0.25rem;
    border-radius: var(--radius-base);
    transition: all 0.3s ease;
}

.toc-close:hover {
    background: var(--border-color);
    color: var(--text-color);
}

.toc-content {
    max-height: 320px;
    overflow-y: auto;
    padding: 0.5rem;
}

.toc-item {
    display: block;
    padding: 0.5rem 0.75rem;
    color: var(--text-color);
    text-decoration: none;
    border-radius: var(--radius-base);
    transition: all 0.3s ease;
    font-size: 0.85rem;
    margin-bottom: 0.25rem;
}

.toc-item:hover {
    background: var(--bg-secondary);
    color: var(--primary-color);
}

.toc-item.level-1 {
    font-weight: 600;
    margin-left: 0;
}

.toc-item.level-2 {
    margin-left: 1rem;
    font-weight: 500;
}

.toc-item.level-3 {
    margin-left: 2rem;
    font-weight: normal;
}

/* Preview Content */
.preview-pane {
    position: relative;
}

.preview-content {
    flex: 1;
    padding: 1.5rem;
    overflow-y: auto;
    font-family: 'Inter', sans-serif;
    line-height: 1.7;
    color: var(--text-color);
}

/* Preview Themes */
.preview-content.theme-modern {
    font-family: 'Inter', sans-serif;
}

.preview-content.theme-academic {
    font-family: 'Times New Roman', serif;
}

.preview-content.theme-dark {
    background: #1a1a1a;
    color: #e0e0e0;
}

/* Markdown Styling */
.preview-content h1,
.preview-content h2,
.preview-content h3,
.preview-content h4,
.preview-content h5,
.preview-content h6 {
    margin-top: 2rem;
    margin-bottom: 1rem;
    font-weight: 600;
    line-height: 1.3;
    color: var(--text-color);
}

.preview-content h1:first-child,
.preview-content h2:first-child,
.preview-content h3:first-child {
    margin-top: 0;
}

.preview-content h1 {
    font-size: 2.25rem;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 0.5rem;
}

.preview-content h2 {
    font-size: 1.875rem;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 0.25rem;
}

.preview-content h3 {
    font-size: 1.5rem;
}

.preview-content h4 {
    font-size: 1.25rem;
}

.preview-content h5 {
    font-size: 1.125rem;
}

.preview-content h6 {
    font-size: 1rem;
}

.preview-content p {
    margin-bottom: 1rem;
    color: var(--text-color);
}

.preview-content strong {
    font-weight: 600;
}

.preview-content em {
    font-style: italic;
}

.preview-content code {
    background: var(--bg-tertiary);
    padding: 0.2rem 0.4rem;
    border-radius: var(--radius-base);
    font-family: 'Courier New', monospace;
    font-size: 0.9em;
    color: var(--primary-color);
}

.preview-content pre {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 1rem;
    overflow-x: auto;
    margin: 1rem 0;
}

.preview-content pre code {
    background: none;
    padding: 0;
    color: var(--text-color);
}

.preview-content blockquote {
    border-left: 4px solid var(--primary-color);
    padding-left: 1rem;
    margin: 1rem 0;
    background: var(--bg-secondary);
    border-radius: 0 var(--radius-base) var(--radius-base) 0;
    color: var(--text-secondary);
    font-style: italic;
}

.preview-content ul,
.preview-content ol {
    margin: 1rem 0;
    padding-left: 2rem;
}

.preview-content li {
    margin-bottom: 0.5rem;
}

.preview-content a {
    color: var(--primary-color);
    text-decoration: underline;
    transition: color 0.3s ease;
}

.preview-content a:hover {
    color: var(--accent-color);
}

.preview-content img {
    max-width: 100%;
    height: auto;
    border-radius: var(--radius-lg);
    margin: 1rem 0;
}

.preview-content table {
    width: 100%;
    border-collapse: collapse;
    margin: 1rem 0;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    overflow: hidden;
}

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

.preview-content th {
    background: var(--bg-secondary);
    font-weight: 600;
}

.preview-content hr {
    border: none;
    height: 2px;
    background: var(--border-color);
    margin: 2rem 0;
    border-radius: 1px;
}

/* Mermaid Diagrams */
.preview-content .mermaid {
    text-align: center;
    margin: 1.5rem 0;
}

.mermaid-container {
    text-align: center;
    margin: 1.5rem 0;
    padding: 1rem;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
}

.mermaid-container {
    text-align: center;
    margin: 1.5rem 0;
    padding: 1rem;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
}

.mermaid-error {
    text-align: left;
    margin: 1.5rem 0;
    padding: 1rem;
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid var(--danger-color);
    border-radius: var(--radius-lg);
    color: var(--danger-color);
    font-family: 'Inter', sans-serif;
    font-size: 0.9rem;
}

.mermaid-error strong {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.mermaid-error details {
    margin-top: 0.5rem;
}

.mermaid-error summary {
    cursor: pointer;
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.mermaid-error pre {
    background: rgba(0, 0, 0, 0.1);
    padding: 0.5rem;
    border-radius: var(--radius-base);
    font-family: 'Courier New', monospace;
    font-size: 0.8rem;
    overflow-x: auto;
    margin-top: 0.5rem;
}

/* Presentation Mode */
.presentation-modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.95);
    z-index: 1000;
    display: none;
    align-items: center;
    justify-content: center;
}

.presentation-modal.active {
    display: flex;
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.presentation-content {
    width: 90%;
    height: 90%;
    max-width: 1200px;
    background: var(--bg-primary);
    border-radius: var(--radius-2xl);
    position: relative;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.presentation-controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
}

.presentation-nav {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 1.2rem;
}

.presentation-nav:hover {
    background: var(--accent-color);
    transform: scale(1.1);
}

.presentation-nav:disabled {
    background: var(--gray-300);
    cursor: not-allowed;
    transform: none;
}

.slide-counter {
    font-weight: 600;
    color: var(--text-color);
    font-size: 1.1rem;
}

.presentation-close {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    background: var(--danger-color);
    color: white;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 1.2rem;
}

.presentation-close:hover {
    background: #DC2626;
    transform: scale(1.1);
}

.presentation-slide {
    flex: 1;
    padding: 3rem;
    overflow-y: auto;
    font-size: 1.2rem;
    line-height: 1.8;
}

.presentation-slide h1,
.presentation-slide h2 {
    text-align: center;
    margin-bottom: 2rem;
}

.presentation-slide h1 {
    font-size: 3rem;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.presentation-slide h2 {
    font-size: 2.5rem;
    color: var(--accent-color);
}

/* Responsive Design */
@media (max-width: 1024px) {
    .editor-layout {
        grid-template-columns: 1fr;
        grid-template-rows: 1fr 1fr;
    }
    
    .editor-pane {
        border-right: none;
        border-bottom: 1px solid var(--border-color);
    }
    
    .toc-container {
        position: fixed;
        top: 50%;
        left: 50%;
        transform: translate(-50%, -50%);
        width: 90%;
        max-width: 400px;
    }
}

@media (max-width: 768px) {
    .hero-content h1 {
        font-size: 2.5rem;
    }
    
    .hero-content p {
        font-size: 1.1rem;
    }
    
    .editor-controls {
        flex-direction: column;
        align-items: stretch;
    }
    
    .controls-left,
    .controls-right {
        justify-content: center;
    }
    
    .toolbar {
        justify-content: center;
    }
    
    .status-bar {
        justify-content: center;
        text-align: center;
    }
    
    .presentation-slide {
        padding: 2rem 1.5rem;
        font-size: 1.1rem;
    }
    
    .presentation-slide h1 {
        font-size: 2.5rem;
    }
    
    .presentation-slide h2 {
        font-size: 2rem;
    }
}

@media (max-width: 640px) {
    .calculator-card {
        margin: 0 1rem;
        border-radius: var(--radius-xl);
    }
    
    .editor-controls {
        padding: 1rem;
    }
    
    .toolbar {
        padding: 0.75rem 1rem;
        gap: 0.25rem;
    }
    
    .toolbar-button {
        width: 36px;
        height: 36px;
        font-size: 0.9rem;
    }
    
    #markdownEditor {
        padding: 1rem;
        font-size: 0.9rem;
    }
    
    .preview-content {
        padding: 1rem;
    }
    
    .status-bar {
        padding: 0.5rem 1rem;
        gap: 1rem;
    }
}

/* Popup Modal for Clear Confirmation */
.markdown-popup-overlay {
    position: fixed;
    top: 0; left: 0; right: 0; bottom: 0;
    background: rgba(0,0,0,0.35);
    z-index: 10000;
    display: flex;
    align-items: center;
    justify-content: center;
}
.markdown-popup {
    background: var(--bg-primary, #fff);
    color: var(--text-color, #111827);
    border-radius: var(--radius-lg, 0.75rem);
    box-shadow: var(--shadow-lg, 0 10px 15px -3px rgba(0,0,0,0.1));
    padding: 2rem 2.5rem;
    min-width: 320px;
    max-width: 90vw;
    text-align: center;
    font-size: 1.1rem;
    animation: popup-fade-in 0.2s;
}
.markdown-popup-buttons {
    margin-top: 1.5rem;
    display: flex;
    gap: 1rem;
    justify-content: center;
}
.markdown-popup-btn {
    padding: 0.5rem 1.5rem;
    border-radius: var(--radius-base, 0.5rem);
    border: none;
    font-size: 1rem;
    cursor: pointer;
    background: var(--primary-color, #3B82F6);
    color: #fff;
    transition: background 0.15s;
}
.markdown-popup-btn.cancel {
    background: var(--bg-secondary);
    color: var(--text-color, #111827);
}
@keyframes popup-fade-in {
    from { opacity: 0; transform: scale(0.97); }
    to { opacity: 1; transform: scale(1); }
}