:root {
    --ui-black: #0b0b0b;
    --primary-color: var(--ui-black);
    --primary-hover: #111827;
    --accent-color: #06b6d4; /* teal */
    --accent-hover: #0ea5b5;
    --bg-color: #f8fafc;
    --panel-bg: #ffffff;
    --text-main: #0f172a;
    --text-muted: #6b7280;
    --border-color: #e6eef2;
    --border-focus: rgba(6, 182, 212, 0.12);
    --radius-sm: 6px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --shadow-sm: 0 1px 2px 0 rgba(0,0,0,0.06);
    --shadow-md: 0 6px 18px -6px rgba(11,11,11,0.12);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.5;
    height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
.app-header {
    background-color: var(--ui-black);
    border-bottom: 1px solid rgba(255,255,255,0.04);
    padding: 0 24px;
    height: 64px;
    flex-shrink: 0;
    color: #fff;
}

.header-container {
    max-width: 1400px;
    margin: 0 auto;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo-area {
    display: flex;
    align-items: center;
    gap: 12px;
}

.logo-icon {
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
}

.logo-area h1 {
    font-size: 1.25rem;
    font-weight: 600;
    letter-spacing: -0.025em;
    color: #fff;
}

.header-nav {
    display: flex;
    gap: 24px;
}

.header-nav a {
    text-decoration: none;
    color: rgba(255,255,255,0.72);
    font-size: 0.9rem;
    font-weight: 500;
    transition: color 0.2s;
}

.header-nav a:hover {
    color: #fff;
}

.header-nav a.active {
    color: var(--accent-color);
}

/* Main Workspace */
.app-main {
    flex: 1;
    padding: 24px;
    overflow: hidden;
}

.workspace {
    max-width: 1400px;
    margin: 0 auto;
    height: 100%;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
}

/* Panels */
.panel {
    background: var(--panel-bg);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    border-left: 4px solid transparent;
    transition: border-left-color 0.18s ease, box-shadow 0.18s ease;
}

.panel:hover {
    border-left-color: rgba(6,182,212,0.18);
    box-shadow: 0 10px 30px -10px rgba(11,11,11,0.12);
}

.panel-header {
    padding: 16px 24px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: rgba(11,11,11,0.02);
}

.panel-header h2 {
    font-size: 1.1rem;
    font-weight: 600;
}

.word-count, .editor-status {
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* Input Area */
.textarea-wrapper {
    flex: 1;
    padding: 24px;
    display: flex;
    flex-direction: column;
}

#source-text {
    flex: 1;
    width: 100%;
    resize: none;
    border: none;
    outline: none;
    font-family: inherit;
    font-size: 1rem;
    color: var(--text-main);
    line-height: 1.6;
}

#source-text::placeholder {
    color: #94a3b8;
}

/* Controls Section */
.controls-section {
    padding: 24px;
    border-top: 1px solid var(--border-color);
    background-color: rgba(11,11,11,0.01);
}

.controls-section h3 {
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-muted);
    margin-bottom: 16px;
}

.options-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    margin-bottom: 20px;
}

.option-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.option-group label {
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-main);
}

select {
    appearance: none;
    background-color: var(--panel-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: 10px 12px;
    font-size: 0.9rem;
    color: var(--text-main);
    cursor: pointer;
    outline: none;
    transition: border-color 0.2s;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
    padding-right: 36px;
}

select:focus {
    border-color: var(--accent-color);
    box-shadow: 0 0 0 4px var(--border-focus);
}

/* Extension Box */
.extension-box {
    background: linear-gradient(to right, rgba(6, 182, 212, 0.05), rgba(11,11,11,0.01));
    border: 1px solid rgba(6, 182, 212, 0.12);
    border-radius: var(--radius-md);
    padding: 16px;
    margin-bottom: 24px;
}

.extension-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 8px;
}

.extension-title {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 600;
    color: var(--text-main);
    font-size: 0.95rem;
}

.extension-desc {
    font-size: 0.85rem;
    color: var(--text-muted);
    line-height: 1.4;
}

/* Toggle Switch */
.toggle-switch {
    position: relative;
    display: inline-block;
    width: 44px;
    height: 24px;
}

.toggle-switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #cbd5e1;
    transition: .4s;
    border-radius: 24px;
}

.slider:before {
    position: absolute;
    content: "";
    height: 18px;
    width: 18px;
    left: 3px;
    bottom: 3px;
    background-color: white;
    transition: .4s;
    border-radius: 50%;
    box-shadow: 0 1px 2px rgba(0,0,0,0.1);
}

input:checked + .slider {
    background-color: var(--accent-color);
}

input:checked + .slider:before {
    transform: translateX(20px);
}

/* Buttons */
.action-buttons {
    display: flex;
    justify-content: flex-end;
    gap: 12px;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 10px 20px;
    border-radius: var(--radius-sm);
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
    border: none;
}

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

.btn-primary:hover {
    background-color: var(--primary-hover);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background-color: white;
    color: var(--text-main);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background-color: #f1f5f9;
}

.btn-icon {
    padding: 8px 12px;
    background-color: white;
    border: 1px solid var(--border-color);
    color: var(--text-main);
    font-size: 0.85rem;
}

.btn-icon:hover {
    background-color: #f1f5f9;
}

.btn-text {
    background: none;
    color: var(--text-muted);
    padding: 6px 12px;
}

.btn-text:hover {
    color: var(--text-main);
    background-color: #f1f5f9;
}

/* Editor Toolbar */
.editor-toolbar {
    padding: 12px 24px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: 8px;
    background-color: rgba(11,11,11,0.01);
}

.toolbar-group {
    display: flex;
    gap: 4px;
}

.format-btn {
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: none;
    border: 1px solid transparent;
    border-radius: 4px;
    color: var(--text-main);
    cursor: pointer;
    transition: all 0.2s;
}

.format-btn:hover {
    background-color: rgba(11,11,11,0.04);
}

.toolbar-divider {
    width: 1px;
    height: 20px;
    background-color: var(--border-color);
    margin: 0 8px;
}

.toolbar-spacer {
    flex: 1;
}

/* Editor Area */
.editor-wrapper {
    flex: 1;
    position: relative;
    display: flex;
    flex-direction: column;
}

.rich-editor {
    flex: 1;
    padding: 24px;
    outline: none;
    overflow-y: auto;
    font-size: 1rem;
    line-height: 1.7;
    color: var(--text-main);
}

.rich-editor p {
    margin-bottom: 1em;
}

.rich-editor ul, .rich-editor ol {
    margin-bottom: 1em;
    padding-left: 24px;
}

.placeholder-text {
    color: #98a5b3;
    pointer-events: none;
}

/* Loading Overlay */
.loading-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(255, 255, 255, 0.9);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 10;
    transition: opacity 0.3s;
}

.loading-overlay.hidden {
    opacity: 0;
    pointer-events: none;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid #e2e8f0;
    border-top-color: var(--accent-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: 16px;
}

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

#loading-text {
    font-weight: 500;
    color: var(--text-main);
}

/* Panel Footer */
.panel-footer {
    padding: 12px 24px;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: rgba(11,11,11,0.01);
}

/* Responsive */
@media (max-width: 1024px) {
    .workspace {
        grid-template-columns: 1fr;
        grid-template-rows: 1fr 1fr;
    }
    
    .app-main {
        overflow: auto;
    }
    
    .panel {
        min-height: 500px;
    }
}

@media (max-width: 640px) {
    .options-grid {
        grid-template-columns: 1fr;
    }
    
    .action-buttons {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
    }
}