:root {
    --bg-primary: #f8f9fb;
    --bg-surface: #ffffff;
    --bg-preview: #fdfdff;
    --bg-editor: #f8f9fb;
    --bg-symbols: #ffffff;
    --bg-template-btn: #f0f4f8;
    --bg-template-btn-hover: #e2e8f0;
    --bg-symbol-btn: #f7f8fa;
    --bg-symbol-btn-hover: #e8ecf1;
    --bg-tab-active: #ffffff;
    --bg-tab: #e8ecf1;
    --text-primary: #1a1a2e;
    --text-secondary: #555770;
    --text-editor: #000000;
    --text-editor-cursor: #000000;
    --text-placeholder: #999;
    --accent: #4f6ef7;
    --accent-light: #eef1ff;
    --accent-hover: #3b54d4;
    --danger: #e0556a;
    --danger-hover: #c94055;
    --success: #2ea87a;
    --border: #e0e4ea;
    --border-light: #eef0f4;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.12);
    --radius-sm: 6px;
    --radius: 10px;
    --radius-lg: 14px;
    --transition: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --font-mono: 'SF Mono', 'Cascadia Code', 'Consolas', 'Monaco', 'Courier New', monospace;
    --font-sans: 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
}

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

html {
    font-size: 15px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-sans);
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.5;
}

/* ========== 应用容器 ========== */
.app-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 16px 20px 32px;
    display: flex;
    flex-direction: column;
    gap: 16px;
    min-height: 100vh;
}

/* ========== 顶部标题栏 ========== */
.app-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 12px;
    padding: 14px 20px;
    background: var(--bg-surface);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
}

.copy-mode-selector {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    margin: 0 4px;
}

.app-title {
    font-size: 1.35rem;
    font-weight: 700;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 10px;
    letter-spacing: -0.01em;
}

.header-actions {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

/* ========== 按钮通用样式 ========== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 8px 15px;
    border-radius: var(--radius-sm);
    border: 1px solid transparent;
    cursor: pointer;
    font-size: 0.875rem;
    font-weight: 500;
    font-family: var(--font-sans);
    transition: all var(--transition);
    white-space: nowrap;
    user-select: none;
    -webkit-user-select: none;
}

.btn:active {
    transform: scale(0.97);
}

.btn-sm {
    padding: 6px 12px;
    font-size: 0.8rem;
}

.btn-outline {
    background: var(--bg-surface);
    border-color: var(--border);
    color: var(--text-secondary);
}

.btn-outline:hover {
    background: var(--bg-template-btn-hover);
    border-color: #c8cdd6;
    color: var(--text-primary);
}

.btn-outline:active {
    background: #dde3ea;
}

/* ========== 主体内容区 ========== */
.main-content {
    display: flex;
    flex-direction: column;
    gap: 14px;
}

/* ========== 区域标签 ========== */
.section-label {
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--text-secondary);
    margin-bottom: 8px;
    display: flex;
    align-items: center;
    gap: 8px;
}

/* ========== 预览区 ========== */
.preview-section {
    background: var(--bg-surface);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
    padding: 14px 18px;
}

.preview-wrapper {
    position: relative;
    min-height: 80px;
    max-height: 350px;
    background: var(--bg-preview);
    border-radius: var(--radius-sm);
    border: 2px dashed var(--border-light);
    display: flex;
    align-items: flex-start;
    justify-content: center;
    padding: 20px 24px;
    transition: border-color var(--transition);
    overflow: auto;
    word-break: break-word;
}

.preview-wrapper:has(.preview-area > *) {
    border-color: #d0d7e2;
    border-style: solid;
}

.preview-area {
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 60px;
    min-height: 50px;
    font-size: 1.3rem;
    word-break: break-all;
    text-align: center;
}

.preview-area .katex {
    font-size: 1.35rem;
}

.preview-placeholder {
    color: #c0c5ce;
    font-style: italic;
    font-size: 1rem;
    pointer-events: none;
}

.preview-error {
    background: #fff5f5;
    border: 1px solid #fecaca;
    border-radius: var(--radius-sm);
    padding: 10px 16px;
    color: var(--danger);
    font-size: 0.85rem;
    font-family: var(--font-mono);
    white-space: pre-wrap;
    word-break: break-all;
    margin-top: 8px;
    display: none;
}

.preview-error.visible {
    display: block;
}

/* 预览区控件 */
.preview-controls {
    font-size: 0.75rem;
    display: flex;
    align-items: center;
    gap: 4px;
}

.preview-controls label {
    cursor: pointer;
    user-select: none;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 4px;
}

.preview-controls input[type="checkbox"] {
    margin: 0;
    vertical-align: middle;
}

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

/* 自动换行模式下每行公式的容器 */
.formula-line {
    display: block;
    text-align: center;
    margin-bottom: 14px;
}

.formula-line:last-child {
    margin-bottom: 0;
}

.formula-error {
    color: var(--danger);
    font-size: 0.85rem;
    opacity: 0.9;
}

/* ========== 编辑区 ========== */
.editor-section {
    background: var(--bg-surface);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
    padding: 14px 18px;
}

.editor-textarea {
    width: 100%;
    min-height: 100px;
    max-height: 200px;
    background: var(--bg-editor);
    color: var(--text-editor);
    border: 2px solid #d0d7e2;
    border-radius: var(--radius-sm);
    padding: 14px 16px;
    font-family: var(--font-mono);
    font-size: 0.95rem;
    line-height: 1.7;
    resize: vertical;
    outline: none;
    caret-color: var(--text-editor-cursor);
    transition: border-color var(--transition);
    tab-size: 2;
}

.editor-textarea:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(79, 110, 247, 0.12);
}

.editor-textarea::placeholder {
    color: #666;
    font-style: italic;
}

.editor-textarea::-webkit-scrollbar {
    width: 6px;
}

.editor-textarea::-webkit-scrollbar-track {
    background: transparent;
}

.editor-textarea::-webkit-scrollbar-thumb {
    background: #444;
    border-radius: 3px;
}

/* ========== 结构模板区 ========== */
.templates-section {
    background: var(--bg-surface);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
    padding: 14px 18px;
}

.templates-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.template-btn {
    display: inline-flex;
    align-items: center;
    gap: 5px;
    padding: 7px 13px;
    background: var(--bg-template-btn);
    border: 1px solid var(--border-light);
    border-radius: 20px;
    cursor: pointer;
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--text-secondary);
    font-family: var(--font-sans);
    transition: all var(--transition);
    white-space: nowrap;
    user-select: none;
    -webkit-user-select: none;
}

.template-btn:hover {
    background: var(--bg-template-btn-hover);
    border-color: #c8cdd6;
    color: var(--text-primary);
    transform: translateY(-1px);
    box-shadow: var(--shadow-sm);
}

.template-btn:active {
    transform: scale(0.95);
    background: #dde3ea;
}

.template-icon {
    font-size: 1rem;
}

/* ========== 符号面板 ========== */
.symbols-section {
    background: var(--bg-surface);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
    padding: 14px 18px;
}

.symbols-tabs {
    display: flex;
    flex-wrap: wrap;
    gap: 4px;
    margin-bottom: 12px;
    border-bottom: 2px solid var(--border-light);
    padding-bottom: 10px;
}

.symbol-tab {
    padding: 7px 14px;
    background: var(--bg-tab);
    border: none;
    border-radius: 20px;
    cursor: pointer;
    font-size: 0.78rem;
    font-weight: 500;
    color: var(--text-secondary);
    font-family: var(--font-sans);
    transition: all var(--transition);
    white-space: nowrap;
    user-select: none;
    -webkit-user-select: none;
}

.symbol-tab:hover {
    background: #d5dbe3;
    color: var(--text-primary);
}

.symbol-tab.active {
    background: var(--accent);
    color: #fff;
    font-weight: 600;
    box-shadow: 0 2px 8px rgba(79, 110, 247, 0.3);
}

.symbols-panel {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    max-height: 220px;
    overflow-y: auto;
    padding: 2px;
}

.symbols-panel::-webkit-scrollbar {
    width: 5px;
}

.symbols-panel::-webkit-scrollbar-track {
    background: transparent;
}

.symbols-panel::-webkit-scrollbar-thumb {
    background: #d0d5dd;
    border-radius: 3px;
}

.symbol-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 42px;
    height: 38px;
    padding: 4px 10px;
    background: var(--bg-symbol-btn);
    border: 1px solid var(--border-light);
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 0.85rem;
    font-family: var(--font-mono);
    color: var(--text-primary);
    transition: all var(--transition);
    user-select: none;
    -webkit-user-select: none;
    white-space: nowrap;
}

.symbol-btn .katex {
    font-size: inherit !important;
    line-height: 1.2;
}

.symbol-btn:hover {
    background: var(--bg-symbol-btn-hover);
    border-color: #c0c7d2;
    color: #000;
    transform: translateY(-1px);
    box-shadow: var(--shadow-sm);
    z-index: 1;
}

.symbol-btn:active {
    transform: scale(0.92);
    background: #dde3ea;
}

.symbol-btn.latex-code {
    font-size: 0.75rem;
    min-width: 50px;
    color: var(--accent);
}

/* ========== 底部 ========== */
.toast-message {
    position: fixed;
    bottom: 24px;
    left: 50%;
    transform: translateX(-50%) translateY(20px);
    display: inline-block;
    padding: 10px 24px;
    background: var(--text-primary);
    color: #fff;
    border-radius: 30px;
    font-size: 0.85rem;
    font-weight: 500;
    white-space: nowrap;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.2);
    z-index: 1000;
    opacity: 0;
    transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
    pointer-events: none;
}

.toast-message.show {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

/* ========== 快捷公式面板 ========== */
.quick-formulas-section {
    background: var(--bg-surface);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
    padding: 14px 18px;
}

.quick-tabs {
    display: flex;
    gap: 6px;
    margin-bottom: 12px;
    border-bottom: 2px solid var(--border-light);
    padding-bottom: 10px;
}

.quick-tab {
    padding: 6px 14px;
    background: var(--bg-tab);
    border: none;
    border-radius: 20px;
    cursor: pointer;
    font-size: 0.78rem;
    font-weight: 500;
    color: var(--text-secondary);
    font-family: var(--font-sans);
    transition: all var(--transition);
    white-space: nowrap;
    user-select: none;
}

.quick-tab:hover {
    background: #d5dbe3;
    color: var(--text-primary);
}

.quick-tab.active {
    background: var(--accent);
    color: #fff;
    font-weight: 600;
    box-shadow: 0 2px 8px rgba(79, 110, 247, 0.3);
}

.quick-formulas-panel {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    max-height: 260px;
    overflow-y: auto;
    padding: 2px;
}

.quick-formula-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 70px;
    min-height: 42px;
    padding: 6px 14px;
    background: var(--bg-symbol-btn);
    border: 1px solid var(--border-light);
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 0.85rem;
    font-family: var(--font-sans);
    color: var(--text-primary);
    transition: all var(--transition);
    white-space: nowrap;
    user-select: none;
    gap: 6px;
}

.quick-formula-btn:hover {
    background: var(--bg-symbol-btn-hover);
    border-color: #c0c7d2;
    box-shadow: var(--shadow-sm);
    transform: translateY(-1px);
}

.quick-formula-btn .katex {
    font-size: 0.85rem !important;
    line-height: 1.2;
}

.quick-formula-btn .formula-label {
    font-size: 0.7rem;
    color: var(--text-secondary);
    margin-left: 2px;
}

/* ========== 格式工具栏 ========== */
.editor-toolbar {
    display: flex;
    flex-wrap: wrap;
    gap: 14px;
    align-items: center;
    margin-bottom: 10px;
    padding: 8px 0;
}

.toolbar-group {
    display: flex;
    align-items: center;
    gap: 6px;
}

.toolbar-label {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-secondary);
    white-space: nowrap;
}

.color-buttons {
    display: flex;
    gap: 4px;
    flex-wrap: wrap;
}

.color-btn {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    border: 1px solid rgba(0, 0, 0, 0.2);
    cursor: pointer;
    padding: 0;
    transition: transform 0.15s, box-shadow 0.15s;
    outline: none;
}

.color-btn:hover {
    transform: scale(1.25);
    box-shadow: 0 0 0 2px var(--accent);
}

.toolbar-select {
    padding: 4px 8px;
    font-size: 0.75rem;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    background: white;
    color: var(--text-primary);
    cursor: pointer;
    font-family: var(--font-sans);
}

.toolbar-select:focus {
    border-color: var(--accent);
    outline: none;
    box-shadow: 0 0 0 2px rgba(79, 110, 247, 0.15);
}

/* ========== 融合颜色组件 ========== */
.color-hex-fusion {
    display: inline-flex;
    align-items: center;
    gap: 0;
    border: 1px solid var(--border);
    border-radius: 20px;
    background: var(--bg-surface);
    padding: 0;
    height: 32px;
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
    transition: box-shadow 0.2s, border-color 0.2s;
    overflow: hidden;
}

.color-hex-fusion:hover {
    border-color: #a0aab5;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.08);
}

.color-preview-wrapper {
    position: relative;
    width: 28px;
    height: 28px;
    margin: 2px 4px 2px 4px;
    border-radius: 50%;
    flex-shrink: 0;
}

#customColorInput {
    position: absolute;
    top: 0;
    left: 0;
    background: transparent;
    width: 100%;
    height: 100%;
    padding: 0;
    border: none;
    border-radius: 50%;
    opacity: 0;
    cursor: pointer;
    z-index: 2;
}

.color-preview-circle {
    display: block;
    width: 100%;
    height: 100%;
    border-radius: 50%;
    border: 1px solid rgba(0, 0, 0, 0.15);
    box-sizing: border-box;
    pointer-events: none;
}

.hex-action-text {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0 12px;
    height: 100%;
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--text-secondary);
    cursor: pointer;
    user-select: none;
    transition: background 0.2s, color 0.2s;
    border-left: 1px solid var(--border-light);
}

.hex-action-text:hover {
    background: #f0f3f8;
    color: var(--accent);
}

/* ========== 说明区域样式 ========== */
.info-section {
    background: var(--bg-surface);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
    padding: 14px 18px;
}

.info-content {
    font-size: 0.85rem;
    line-height: 1.6;
    color: var(--text-secondary);
}

.info-content p {
    margin-bottom: 8px;
}

.info-content p:last-child {
    margin-bottom: 0;
}

/* ========== 响应式设计 ========== */
@media (max-width: 768px) {
    .app-container {
        padding: 10px 10px 24px;
        gap: 10px;
    }

    .app-header {
        padding: 10px 14px;
        gap: 8px;
    }

    .app-title {
        font-size: 1.1rem;
        gap: 6px;
    }

    .header-actions {
        gap: 4px;
    }

    .btn-sm {
        padding: 5px 10px;
        font-size: 0.72rem;
    }

    .preview-wrapper {
        min-height: 60px;
        padding: 14px 12px;
    }

    .preview-area .katex {
        font-size: 1.1rem;
    }

    .editor-textarea {
        min-height: 80px;
        font-size: 0.85rem;
    }

    .templates-grid {
        gap: 5px;
    }

    .template-btn {
        padding: 5px 10px;
        font-size: 0.72rem;
        gap: 3px;
    }

    .template-icon {
        font-size: 0.85rem;
    }

    .symbols-tabs {
        gap: 2px;
        padding-bottom: 8px;
    }

    .symbol-tab {
        padding: 5px 10px;
        font-size: 0.7rem;
    }

    .symbols-panel {
        gap: 4px;
        max-height: 160px;
    }

    .symbol-btn {
        min-width: 34px;
        height: 32px;
        font-size: 0.75rem;
        padding: 3px 7px;
    }

    .section-label {
        font-size: 0.7rem;
    }

    .editor-toolbar {
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
        padding: 8px 0;
    }

    .toolbar-group {
        width: 100%;
        gap: 8px;
        flex-wrap: wrap;
    }

    .toolbar-label {
        min-width: 40px;
    }

    .color-btn {
        width: 18px;
        height: 18px;
    }

    .color-buttons {
        flex-wrap: wrap;
        gap: 5px;
    }

    .color-hex-fusion {
        flex-shrink: 0;
        height: 28px;
    }

    .color-preview-wrapper {
        width: 24px;
        height: 24px;
        margin: 2px 2px;
    }

    .hex-action-text {
        padding: 0 8px;
        font-size: 0.7rem;
    }

    .toolbar-select {
        max-width: none;
        flex: 1;
    }

    .editor-textarea {
        font-size: 0.85rem;
        min-height: 80px;
    }

    .info-section {
        padding: 12px 16px;
    }

    .info-content {
        font-size: 0.8rem;
    }
}

@media (max-width: 480px) {
    .app-container {
        padding: 6px 6px 20px;
        gap: 8px;
    }

    .app-header {
        flex-direction: column;
        align-items: flex-start;
    }

    .header-actions {
        width: 100%;
        justify-content: flex-end;
    }

    .preview-wrapper {
        min-height: 50px;
        padding: 10px 8px;
    }

    .preview-area .katex {
        font-size: 0.95rem;
    }

    .editor-textarea {
        font-size: 0.78rem;
        padding: 10px 12px;
    }

    .templates-grid {
        gap: 4px;
    }

    .template-btn {
        padding: 4px 8px;
        font-size: 0.68rem;
        border-radius: 14px;
    }

    .symbol-tab {
        padding: 4px 8px;
        font-size: 0.65rem;
        border-radius: 14px;
    }

    .symbol-btn {
        min-width: 30px;
        height: 28px;
        font-size: 0.7rem;
        padding: 2px 6px;
    }

    .editor-toolbar {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
        padding: 6px 0;
    }

    .toolbar-group {
        width: 100%;
        gap: 6px;
        flex-wrap: wrap;
    }

    .toolbar-label {
        display: inline-block;
        font-size: 0.65rem;
        min-width: 36px;
    }


    .color-btn {
        width: 16px;
        height: 16px;
    }

    .color-hex-fusion {
        flex-shrink: 1;
        height: 26px;
    }

    .color-preview-wrapper {
        width: 20px;
        height: 20px;
        margin: 2px 1px;
    }

    .hex-action-text {
        padding: 0 6px;
        font-size: 0.65rem;
    }

    .toolbar-select {
        max-width: none;
        flex: 1;
    }

    .editor-textarea {
        font-size: 0.78rem;
        min-height: 70px;
        padding: 10px 12px;
    }

    .color-buttons {
        flex-wrap: wrap;
        gap: 3px;
    }

    .info-section {
        padding: 10px 14px;
    }

    .info-content {
        font-size: 0.75rem;
    }
}