:root {
    /* Base Variables - Dark Mode Default */
    --bg-base: #0f172a;
    --bg-panel: #1e293b;
    --bg-surface: #334155;
    
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    
    --border: #334155;
    --border-light: rgba(148, 163, 184, 0.1);
    
    --primary: #3b82f6;
    --primary-hover: #2563eb;
    
    --accent: #8b5cf6;
    --error: #ef4444;
    --success: #10b981;
    
    --radius: 12px;
    --radius-sm: 8px;
    
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.5), 0 2px 4px -2px rgba(0, 0, 0, 0.5);
    
    /* Glassmorphism */
    --glass-bg: rgba(30, 41, 59, 0.7);
    --glass-border: rgba(255, 255, 255, 0.1);
}

[data-theme="light"] {
    --bg-base: #f1f5f9;
    --bg-panel: #ffffff;
    --bg-surface: #f8fafc;
    
    --text-main: #0f172a;
    --text-muted: #64748B;
    
    --border: #e2e8f0;
    --border-light: rgba(15, 23, 42, 0.05);
    
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
    
    --glass-bg: rgba(255, 255, 255, 0.7);
    --glass-border: rgba(0, 0, 0, 0.05);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    transition: background-color 0.3s ease, border-color 0.3s ease, color 0.3s ease;
}

body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    background-color: var(--bg-base);
    color: var(--text-main);
    line-height: 1.5;
    min-height: 100vh;
}

/* Layout */
.app-layout {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    max-width: 1400px;
    margin: 0 auto;
    padding: 1rem 2rem;
    gap: 1.5rem;
}

/* Header */
.app-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    padding: 1rem 1.5rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.brand {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo-box {
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--primary), var(--accent));
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
}
.logo-box i { width: 24px; height: 24px; }

.brand h1 {
    font-size: 1.25rem;
    font-weight: 700;
    letter-spacing: -0.025em;
    background: linear-gradient(135deg, var(--primary), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

/* Main Content area */
.main-content {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    flex: 1;
}

/* Base Panel */
.panel {
    background-color: var(--bg-panel);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

/* Toolbar */
.toolbar {
    display: flex;
    align-items: center;
    padding: 0.75rem 1.5rem;
    gap: 1rem;
    overflow-x: auto;
}
.toolbar::-webkit-scrollbar { height: 4px; }
.toolbar::-webkit-scrollbar-thumb { background: var(--border); border-radius: 4px; }

.toolbar-group {
    display: flex;
    gap: 0.5rem;
    align-items: center;
}
.toolbar-divider {
    width: 1px;
    height: 32px;
    background-color: var(--border);
}

.tool-btn {
    background: transparent;
    border: 1px solid transparent;
    border-radius: 6px;
    padding: 0.5rem;
    color: var(--text-main);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 44px;
    min-height: 44px;
    transition: all 0.2s;
    font-size: 1.1rem;
}
.tool-btn:hover {
    background-color: var(--bg-surface);
    border-color: var(--border);
    transform: translateY(-2px);
}
.tool-btn:active { transform: translateY(0); }
.tool-icon { display: flex; align-items: center; }
.tool-icon i { width: 20px; height: 20px; }
.tool-math { pointer-events: none; }

/* Workspace Grid */
.workspace {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
    flex: 1;
    min-height: 400px;
}

/* Editor & Preview Panels */
.input-panel, .preview-panel {
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

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

.panel-header h2 {
    font-size: 1rem;
    font-weight: 600;
}
.header-actions {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}
.shortcut-hint {
    font-size: 0.75rem;
    color: var(--text-muted);
    font-family: 'Fira Code', monospace;
    background: var(--bg-base);
    padding: 0.2rem 0.5rem;
    border-radius: 4px; border: 1px solid var(--border);
}

.editor-container {
    flex: 1;
    display: flex;
    position: relative;
    background-color: var(--bg-base);
}

.code-editor {
    width: 100%;
    height: 100%;
    min-height: 300px;
    padding: 1.5rem;
    background: transparent;
    border: none;
    color: var(--primary);
    font-family: 'Fira Code', monospace;
    font-size: 1rem;
    line-height: 1.6;
    resize: none;
    outline: none;
}
[data-theme="light"] .code-editor {
    color: var(--accent);
}

/* Preview Area */
.preview-container {
    flex: 1;
    display: flex;
    flex-direction: column;
    position: relative;
    background-color: var(--bg-panel);
    background-image: radial-gradient(var(--border) 1px, transparent 1px);
    background-size: 20px 20px;
}
.auto-render-toggle {
    position: absolute;
    top: 1rem; left: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    z-index: 10;
}
.toggle-switch {
    position: relative;
    display: inline-block;
    width: 36px;
    height: 20px;
}
.toggle-switch input { opacity: 0; width: 0; height: 0; }
.slider {
    position: absolute;
    cursor: pointer;
    top: 0; left: 0; right: 0; bottom: 0;
    background-color: var(--bg-surface);
    transition: .3s;
    border-radius: 20px;
    border: 1px solid var(--border);
}
.slider:before {
    position: absolute;
    content: "";
    height: 14px; width: 14px;
    left: 2px; bottom: 2px;
    background-color: var(--text-muted);
    transition: .3s;
    border-radius: 50%;
}
input:checked + .slider { background-color: var(--primary); border-color: var(--primary); }
input:checked + .slider:before { transform: translateX(16px); background-color: white; }
.toggle-label { font-size: 0.8rem; color: var(--text-muted); font-weight: 500; }

.zoom-controls {
    position: absolute;
    bottom: 1rem; right: 1.5rem;
    display: flex;
    align-items: center;
    background: var(--bg-surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 0.25rem;
    gap: 0.5rem;
    box-shadow: var(--shadow);
    z-index: 10;
}
#zoom-level {
    font-size: 0.8rem;
    font-family: 'Fira Code', monospace;
    color: var(--text-muted);
    min-width: 45px;
    text-align: center;
}

.render-area {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: auto;
    padding: 3rem;
}
#equation-output {
    transition: transform 0.2s ease;
    transform-origin: center center;
    /* This padding is to prevent clipping when exporting using html2canvas */
    padding: 1rem; 
}

.render-error {
    position: absolute;
    top: 3.5rem; left: 1.5rem; right: 1.5rem;
    background-color: rgba(239, 68, 68, 0.1);
    border: 1px solid var(--error);
    color: var(--error);
    padding: 0.75rem 1rem;
    border-radius: 6px;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.85rem;
    z-index: 10;
}
.render-error i { width: 18px; height: 18px; }

/* Buttons General */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    border-radius: 6px;
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    border: none;
    font-family: inherit;
    transition: all 0.2s;
}
.btn i { width: 16px; height: 16px; }

.btn-sm { padding: 0.35rem 0.75rem; font-size: 0.8rem; }
.btn-primary { background-color: var(--primary); color: white; }
.btn-primary:hover { background-color: var(--primary-hover); transform: translateY(-1px); }
.btn-outline { background-color: transparent; border: 1px solid var(--border); color: var(--text-main); }
.btn-outline:hover { background-color: var(--bg-surface); border-color: var(--text-muted); }
.btn-ghost { background-color: transparent; color: var(--text-muted); }
.btn-ghost:hover { background-color: var(--bg-surface); color: var(--text-main); }
.btn-icon { padding: 0.5rem; border-radius: 8px; background: transparent; color: var(--text-muted); border: 1px solid var(--border); }
.btn-icon:hover { background-color: var(--bg-surface); color: var(--text-main); }

/* Export Dropdown */
.export-dropdown { position: relative; }
.dropdown-menu {
    position: absolute;
    top: 100%; right: 0;
    margin-top: 0.5rem;
    background: var(--bg-panel);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow);
    list-style: none;
    min-width: 160px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all 0.2s;
    z-index: 100;
}
.export-dropdown.open .dropdown-menu {
    opacity: 1; visibility: visible; transform: translateY(0);
}
.dropdown-menu li button {
    width: 100%;
    text-align: left;
    background: transparent;
    border: none;
    padding: 0.75rem 1rem;
    color: var(--text-main);
    font-size: 0.85rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
.dropdown-menu li button:hover { background-color: var(--bg-surface); }
.dropdown-icon { transition: transform 0.2s; }
.export-dropdown.open .dropdown-icon { transform: rotate(180deg); }


/* Reference Footer */
.reference-panel {
    padding: 1.5rem;
}
.reference-title {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-main);
}
.reference-title i { width: 18px; height: 18px; color: var(--primary); }

.reference-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
}
.ref-col strong {
    display: block;
    margin-bottom: 0.5rem;
    font-size: 0.85rem;
    color: var(--text-muted);
}
.ref-col ul { list-style: none; }
.ref-col li {
    font-size: 0.85rem;
    margin-bottom: 0.4rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
.ref-col code {
    background-color: var(--bg-surface);
    border: 1px solid var(--border);
    padding: 0.1rem 0.4rem;
    border-radius: 4px;
    font-family: 'Fira Code', monospace;
    font-size: 0.75rem;
    color: var(--primary);
}

/* Toast */
.toast {
    position: fixed;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background: var(--text-main);
    color: var(--bg-base);
    padding: 0.75rem 1.5rem;
    border-radius: 30px;
    font-size: 0.9rem;
    font-weight: 600;
    box-shadow: 0 10px 25px rgba(0,0,0,0.5);
    opacity: 0;
    transition: all 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    z-index: 2000;
}
.toast.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

@media (max-width: 1024px) {
    .workspace {
        grid-template-columns: 1fr;
    }
    .input-panel {
        min-height: 250px;
    }
    .preview-panel {
        min-height: 350px;
    }
    .reference-grid {
        grid-template-columns: 1fr;
    }
}