/* =============================================
   Playground - 在线练习场样式
   复用 style.css 的 CSS 变量
   ============================================= */

/* 当前页面导航高亮 */
.nav-link-active {
    color: var(--primary) !important;
}

.nav-link-active::after {
    width: 100% !important;
}

/* ---------- 主布局 ---------- */
.playground-main {
    margin-top: var(--navbar-height);
    height: calc(100vh - var(--navbar-height));
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

/* 禁止 playground 页面整页滚动 */
body.playground-page {
    overflow: hidden;
}

/* ---------- 工具栏 ---------- */
.playground-toolbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    gap: var(--spacing-md);
    flex-shrink: 0;
}

.toolbar-left,
.toolbar-right {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.problem-select {
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 0.9rem;
    font-family: var(--font-sans);
    min-width: 240px;
    cursor: pointer;
}

.problem-select:focus {
    outline: none;
    border-color: var(--primary);
}

.nav-problem-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 28px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.nav-problem-btn:hover {
    color: var(--text-primary);
    border-color: var(--border-hover);
    background: var(--bg-card-hover);
}

.nav-problem-btn:disabled {
    opacity: 0.3;
    cursor: not-allowed;
}

/* Pyodide 状态 */
.pyodide-status {
    font-size: 0.8rem;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    white-space: nowrap;
}

.pyodide-status.loading {
    color: var(--medium);
    background: rgba(255, 192, 30, 0.12);
}

.pyodide-status.ready {
    color: var(--easy);
    background: rgba(0, 184, 163, 0.12);
}

.pyodide-status.error {
    color: var(--hard);
    background: rgba(255, 55, 95, 0.12);
}

/* 按钮 */
.btn-run {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    background: linear-gradient(135deg, var(--easy), #00d4aa);
    color: #000;
    border: none;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.btn-run:hover:not(:disabled) {
    transform: translateY(-1px);
    box-shadow: 0 4px 16px rgba(0, 184, 163, 0.4);
}

.btn-run:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-reset {
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 0.85rem;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.btn-reset:hover {
    border-color: var(--border-hover);
    color: var(--text-primary);
}

/* ---------- 两栏布局 ---------- */
.playground-layout {
    flex: 1;
    display: flex;
    overflow: hidden;
}

.panel {
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.panel-left {
    width: 35%;
    min-width: 280px;
    border-right: 1px solid var(--border-color);
    position: relative;
    transition: width 0.25s cubic-bezier(0.4, 0, 0.2, 1),
                min-width 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

body.left-collapsed .panel-left {
    width: 0;
    min-width: 0;
    border-right: none;
    overflow: hidden;
}

.panel-center {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    min-width: 0;
}

.panel-center {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    min-width: 0;
}

.panel-editor {
    flex: 1;
    min-height: 0;
}

.panel-output {
    height: 35%;
    min-height: 120px;
    border-top: 1px solid var(--border-color);
    transition: height 0.25s cubic-bezier(0.4, 0, 0.2, 1),
                min-height 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

/* 面板头 */
.panel-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 44px;
    box-sizing: border-box;
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-tertiary);
    border-bottom: 1px solid var(--border-color);
    flex-shrink: 0;
}

.panel-title {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.panel-hint {
    font-size: 0.75rem;
    color: var(--text-muted);
    font-family: var(--font-mono);
}

/* 面板内容 */
.panel-body {
    flex: 1;
    overflow-y: auto;
    padding: var(--spacing-md);
    background: var(--bg-primary);
}

/* ---------- 题目描述样式 ---------- */
#problem-description h3 {
    font-size: 1.2rem;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

#problem-description h4 {
    font-size: 0.95rem;
    margin-top: var(--spacing-lg);
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

#problem-description p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: var(--spacing-sm);
}

#problem-description code {
    background: var(--bg-tertiary);
    padding: 2px 6px;
    border-radius: 4px;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--primary-light);
}

#problem-description pre {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: var(--spacing-md);
    font-family: var(--font-mono);
    font-size: 0.85rem;
    line-height: 1.6;
    overflow-x: auto;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

#problem-description ul {
    padding-left: var(--spacing-lg);
    margin-bottom: var(--spacing-sm);
}

#problem-description li {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
}

.difficulty-tag {
    font-size: 0.75rem;
    padding: 2px 8px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    vertical-align: middle;
}

.difficulty-tag.easy {
    background: rgba(0, 184, 163, 0.15);
    color: var(--easy);
}

.difficulty-tag.medium {
    background: rgba(255, 192, 30, 0.15);
    color: var(--medium);
}

.difficulty-tag.hard {
    background: rgba(255, 55, 95, 0.15);
    color: var(--hard);
}

/* 题目面板底部固定栏 */
.panel-footer {
    flex-shrink: 0;
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-tertiary);
    border-top: 1px solid var(--border-color);
}

.solution-btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    background: linear-gradient(135deg, var(--primary), var(--accent));
    border-radius: var(--radius-md);
    color: white !important;
    font-size: 0.85rem;
    font-weight: 600;
    transition: all var(--transition-fast);
}

.solution-btn:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-glow);
}

.leetcode-btn {
    background: linear-gradient(135deg, #ffa116, #ff6b00);
    margin-left: var(--spacing-sm);
}

.blog-btn {
    background: linear-gradient(135deg, #ff6b6b, #ee5a24);
    margin-left: var(--spacing-sm);
}

/* ---------- CodeMirror 覆盖 ---------- */
.editor-body {
    padding: 0 !important;
}

.editor-body .CodeMirror {
    height: 100%;
    font-family: var(--font-mono);
    font-size: 14px;
    line-height: 1.6;
}

/* CodeMirror 自动补全下拉样式 */
.CodeMirror-hints {
    background: var(--bg-secondary) !important;
    border: 1px solid var(--border-color) !important;
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-md);
    font-family: var(--font-mono);
    font-size: 13px;
    z-index: 1100;
}

.CodeMirror-hint {
    color: var(--text-primary) !important;
    padding: 4px 8px !important;
    border-radius: 3px;
}

.CodeMirror-hint-active {
    background: var(--primary) !important;
    color: white !important;
}

/* ---------- 测试结果 ---------- */
.output-header {
    cursor: pointer;
    user-select: none;
}

.output-header:hover {
    background: var(--bg-card-hover);
}

.output-toggle-icon {
    margin-left: auto;
    transition: transform 0.2s ease;
    color: var(--text-muted);
}

.panel-output.collapsed .output-toggle-icon {
    transform: rotate(180deg);
}

.panel-output.collapsed {
    height: auto;
    min-height: 0;
}

.panel-output.collapsed .output-body {
    display: none;
}

.result-summary {
    font-size: 0.8rem;
    font-weight: 600;
    padding: 2px 8px;
    border-radius: var(--radius-sm);
}

.result-summary.all-pass {
    color: var(--easy);
    background: rgba(0, 184, 163, 0.15);
}

.result-summary.has-fail {
    color: var(--hard);
    background: rgba(255, 55, 95, 0.15);
}

.output-placeholder {
    color: var(--text-muted);
    font-size: 0.9rem;
    text-align: center;
    padding: var(--spacing-xl);
}

.test-case {
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    margin-bottom: var(--spacing-sm);
    overflow: hidden;
}

.test-case.pass {
    border-color: rgba(0, 184, 163, 0.3);
}

.test-case.fail,
.test-case.error {
    border-color: rgba(255, 55, 95, 0.3);
}

.test-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-tertiary);
}

.test-icon {
    font-size: 0.9rem;
}

.test-case.pass .test-icon {
    color: var(--easy);
}

.test-case.fail .test-icon,
.test-case.error .test-icon {
    color: var(--hard);
}

.test-label {
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-primary);
}

.test-time {
    margin-left: auto;
    font-size: 0.75rem;
    font-family: var(--font-mono);
    color: var(--text-muted);
}

.test-status {
    margin-left: 0;
    font-size: 0.75rem;
    font-weight: 600;
    padding: 1px 6px;
    border-radius: var(--radius-sm);
}

.test-status.pass {
    color: var(--easy);
    background: rgba(0, 184, 163, 0.12);
}

.test-status.fail {
    color: var(--hard);
    background: rgba(255, 55, 95, 0.12);
}

.test-detail {
    padding: var(--spacing-sm) var(--spacing-md);
}

.test-row {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: 4px;
    font-size: 0.85rem;
    align-items: baseline;
}

.test-key {
    color: var(--text-muted);
    white-space: nowrap;
    min-width: 40px;
}

.test-row code {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--text-primary);
    word-break: break-all;
}

.test-row.error-msg code {
    color: var(--hard);
}

/* =============================================
   AI 刷题助手样式
   ============================================= */

/* ---------- 浮动按钮 (FAB) ---------- */
.ai-fab {
    position: fixed;
    bottom: 24px;
    right: 24px;
    width: 56px;
    height: 56px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--accent));
    border: none;
    cursor: pointer;
    color: #fff;
    z-index: 1100;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 20px var(--primary-glow);
    transition: right 0.3s cubic-bezier(0.4, 0, 0.2, 1),
                bottom var(--transition-base),
                transform var(--transition-base),
                box-shadow var(--transition-base);
}

/* AI 面板展开时，FAB 左移到中间列下方，不遮挡内容 */
body.ai-open .ai-fab {
    right: calc(28% + 16px);
}

.ai-fab:hover {
    transform: translateY(-3px) scale(1.05);
    box-shadow: 0 8px 30px var(--primary-glow);
}

.ai-fab.active {
    transform: rotate(180deg) scale(0.9);
    opacity: 0.6;
}

.ai-fab-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    line-height: 1;
}

.ai-brand-icon {
    display: block;
}

.ai-panel-title-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-light);
}

.ai-fab-pulse {
    position: absolute;
    inset: -4px;
    border-radius: 50%;
    border: 2px solid var(--primary);
    animation: ai-pulse 2s ease-in-out infinite;
}

@keyframes ai-pulse {
    0%, 100% { opacity: 0; transform: scale(0.95); }
    50% { opacity: 0.6; transform: scale(1.1); }
}

.ai-fab.active .ai-fab-pulse {
    display: none;
}

/* ---------- 遥罩 ---------- */
.ai-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.4);
    backdrop-filter: blur(2px);
    z-index: 1200;
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition-base);
    /* 桌面端隐藏，移动端在 @media 中恢复 */
    display: none;
}

.ai-overlay.visible {
    opacity: 1;
    pointer-events: auto;
}

/* ---------- AI 面板：内嵌侧边栏（桌面端） ---------- */
.ai-panel {
    /* 内嵌到 playground-layout flex 容器中，作为第三列 */
    width: 0;
    min-width: 0;
    overflow: hidden;
    flex-shrink: 0;
    display: flex;
    flex-direction: column;
    background: var(--bg-secondary);
    border-left: 1px solid var(--border-color);
    transition: width 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.ai-panel.open {
    width: 28%;
}

/* 面板头部 */
.ai-panel-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 44px;
    box-sizing: border-box;
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-tertiary);
    border-bottom: 1px solid var(--border-color);
    flex-shrink: 0;
}

.ai-panel-title {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-secondary);
    letter-spacing: 0.5px;
}

.ai-panel-actions {
    display: flex;
    align-items: center;
    gap: 4px;
}

.ai-icon-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 26px;
    height: 26px;
    border-radius: var(--radius-sm);
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.ai-icon-btn:hover {
    background: var(--bg-card-hover);
    color: var(--text-primary);
}

/* ---------- 消息列表 ---------- */
.ai-messages {
    flex: 1;
    overflow-y: auto;
    padding: var(--spacing-md);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

/* 欢迎界面 */
.ai-welcome {
    text-align: center;
    padding: var(--spacing-2xl) var(--spacing-md);
    color: var(--text-secondary);
}

.ai-welcome-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-md);
    color: var(--primary-light);
}

.ai-brand-icon-large {
    width: 64px;
    height: 64px;
}

.ai-welcome h3 {
    font-size: 1.1rem;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.ai-welcome p {
    font-size: 0.85rem;
    line-height: 1.6;
}

.ai-welcome-hint {
    margin-top: var(--spacing-md);
    color: var(--text-muted);
    font-size: 0.8rem !important;
}

/* 消息气泡 */
.ai-msg {
    display: flex;
    gap: var(--spacing-sm);
    max-width: 100%;
}

.ai-msg-user {
    flex-direction: row-reverse;
}

.ai-msg-avatar {
    flex-shrink: 0;
    font-size: 1.2rem;
    width: 28px;
    height: 28px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-light);
}

.ai-msg-bubble {
    max-width: 85%;
    border-radius: var(--radius-md);
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 0.88rem;
    line-height: 1.65;
}

.ai-msg-user .ai-msg-bubble {
    background: linear-gradient(135deg, var(--primary), hsl(var(--primary-hue), 80%, 55%));
    color: white;
    border-bottom-right-radius: 4px;
}

.ai-msg-assistant .ai-msg-bubble {
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    border-bottom-left-radius: 4px;
}

/* 系统消息 */
.ai-msg-system {
    justify-content: center;
}

.ai-msg-system-text {
    font-size: 0.8rem;
    color: var(--text-muted);
    padding: var(--spacing-xs) var(--spacing-md);
    background: var(--bg-tertiary);
    border-radius: var(--radius-xl);
}

/* AI 消息中的 Markdown 内容 */
.ai-msg-content {
    word-break: break-word;
}

.ai-msg-loading .ai-msg-bubble {
    min-width: 64px;
}

.ai-typing {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    min-height: 20px;
}

.ai-typing-dot {
    width: 7px;
    height: 7px;
    border-radius: 50%;
    background: var(--text-muted);
    opacity: 0.35;
    animation: ai-typing-bounce 1s ease-in-out infinite;
}

.ai-typing-dot:nth-child(2) {
    animation-delay: 0.15s;
}

.ai-typing-dot:nth-child(3) {
    animation-delay: 0.3s;
}

.ai-msg-content p {
    margin-bottom: 0.5em;
}

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

.ai-msg-content code {
    background: rgba(255, 255, 255, 0.08);
    padding: 1px 5px;
    border-radius: 3px;
    font-family: var(--font-mono);
    font-size: 0.82em;
}

.ai-msg-content pre {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    margin: var(--spacing-sm) 0;
    overflow-x: auto;
    font-size: 0.82rem;
    line-height: 1.5;
}

.ai-msg-content pre code {
    background: none;
    padding: 0;
    font-size: inherit;
}

.ai-msg-content ul,
.ai-msg-content ol {
    padding-left: 1.2em;
    margin: 0.4em 0;
}

.ai-msg-content li {
    margin-bottom: 0.2em;
}

.ai-msg-content strong {
    color: var(--primary-light);
}

.ai-msg-content h1,
.ai-msg-content h2,
.ai-msg-content h3,
.ai-msg-content h4 {
    margin: 0.6em 0 0.3em;
    color: var(--text-primary);
}

.ai-msg-content h3 { font-size: 0.95rem; }
.ai-msg-content h4 { font-size: 0.9rem; }

/* 错误信息 */
.ai-error {
    margin-top: var(--spacing-sm);
    padding: var(--spacing-sm);
    background: rgba(255, 55, 95, 0.1);
    border-radius: var(--radius-sm);
    color: var(--hard);
    font-size: 0.82rem;
}

/* 加载动画 */
.ai-spinner {
    display: inline-block;
    width: 16px;
    height: 16px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-top-color: white;
    border-radius: 50%;
    animation: ai-spin 0.6s linear infinite;
}

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

@keyframes ai-typing-bounce {
    0%, 80%, 100% {
        transform: translateY(0);
        opacity: 0.35;
    }
    40% {
        transform: translateY(-3px);
        opacity: 1;
    }
}

/* ---------- 快捷操作 ---------- */
.ai-quick-actions {
    padding: var(--spacing-sm) var(--spacing-md);
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    border-top: 1px solid var(--border-color);
    background: var(--bg-secondary);
    flex-shrink: 0;
}

.ai-quick-btn {
    padding: 4px 10px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    color: var(--text-secondary);
    font-size: 0.75rem;
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
}

.ai-quick-btn:hover {
    border-color: var(--primary);
    color: var(--primary-light);
    background: rgba(var(--primary-hue), 100%, 65%, 0.08);
}

/* ---------- 输入区域 ---------- */
.ai-input-area {
    display: flex;
    align-items: flex-end;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    border-top: 1px solid var(--border-color);
    background: var(--bg-tertiary);
    flex-shrink: 0;
}

.ai-input {
    flex: 1;
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 0.88rem;
    font-family: var(--font-sans);
    resize: none;
    line-height: 1.5;
    max-height: 120px;
    outline: none;
    transition: border-color var(--transition-fast);
}

.ai-input:focus {
    border-color: var(--primary);
}

.ai-input::placeholder {
    color: var(--text-muted);
}

.ai-send-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: var(--radius-md);
    background: linear-gradient(135deg, var(--primary), var(--accent));
    border: none;
    color: white;
    cursor: pointer;
    flex-shrink: 0;
    transition: all var(--transition-fast);
}

.ai-send-btn:hover:not(:disabled) {
    transform: translateY(-1px);
    box-shadow: 0 4px 12px var(--primary-glow);
}

.ai-send-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* ---------- 配置弹窗 ---------- */
.ai-config-modal {
    position: fixed;
    inset: 0;
    z-index: 1400;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition-base);
}

.ai-config-modal.open {
    opacity: 1;
    pointer-events: auto;
}

.ai-config-content {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    width: 380px;
    max-width: 90vw;
    box-shadow: var(--shadow-lg);
}

.ai-config-content h3 {
    font-size: 1.1rem;
    margin-bottom: var(--spacing-xs);
}

.ai-config-desc {
    font-size: 0.82rem;
    color: var(--text-muted);
    margin-bottom: var(--spacing-lg);
}

.ai-config-field {
    margin-bottom: var(--spacing-md);
}

.ai-config-field label {
    display: block;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.ai-config-field input {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 0.88rem;
    font-family: var(--font-mono);
    outline: none;
    transition: border-color var(--transition-fast);
}

.ai-config-field input:focus {
    border-color: var(--primary);
}

.ai-config-field input::placeholder {
    color: var(--text-muted);
    font-family: var(--font-mono);
}

.ai-config-actions {
    display: flex;
    justify-content: flex-end;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-lg);
}

.ai-config-btn {
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    font-size: 0.88rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    border: none;
}

.ai-config-btn-cancel {
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
}

.ai-config-btn-cancel:hover {
    color: var(--text-primary);
    border-color: var(--border-hover);
}

.ai-config-btn-save {
    background: linear-gradient(135deg, var(--primary), var(--accent));
    color: white;
}

.ai-config-btn-save:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 12px var(--primary-glow);
}

/* ---------- 响应式 ---------- */
@media (max-width: 768px) {
    .playground-layout {
        flex-direction: column;
    }

    .panel-problem {
        width: 100%;
        min-width: unset;
        height: 35%;
        border-right: none;
        border-bottom: 1px solid var(--border-color);
    }

    .panel-right {
        height: 65%;
    }

    .playground-toolbar {
        flex-wrap: wrap;
    }

    .toolbar-left {
        width: 100%;
    }

    .problem-select {
        width: 100%;
        min-width: unset;
    }

    /* 移动端：AI 面板恢复浮窗行为 */
    .ai-overlay {
        display: block;
    }

    .ai-panel {
        position: fixed;
        top: 0;
        right: 0;
        width: 90vw !important; /* 覆盖 desktop width:0 */
        max-width: 90vw;
        height: 100vh;
        overflow: visible;
        z-index: 1300;
        box-shadow: -8px 0 32px rgba(0, 0, 0, 0.5);
        border-left: 1px solid var(--border-color);
        /* 用 transform 动画替代 width 动画 */
        transform: translateX(100%);
        transition: transform var(--transition-base);
    }

    .ai-panel.open {
        transform: translateX(0);
    }

    .ai-fab {
        bottom: 16px;
        right: 16px;
        width: 48px;
        height: 48px;
    }

    .ai-fab-icon {
        font-size: 1.3rem;
    }
}

/* =============================================
   Toolbar Buttons
   ============================================= */

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

.panel-collapse-btn {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    height: 28px;
    padding: 0 10px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-size: 0.8rem;
    font-weight: 500;
}

.panel-collapse-btn .collapse-label {
    white-space: nowrap;
}

.panel-collapse-btn:hover {
    color: var(--text-primary);
    border-color: var(--border-hover);
}

body.left-collapsed #left-collapse-btn svg {
    transform: rotate(180deg);
}

body.cph-collapsed #cph-toggle-btn svg {
    transform: rotate(180deg);
}

/* =============================================
   Left Panel Collapse Handle
   ============================================= */

.panel-collapse-handle {
    position: absolute;
    right: -20px;
    top: 50%;
    transform: translateY(-50%);
    width: 20px;
    height: 48px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-left: none;
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    cursor: pointer;
    z-index: 10;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1px;
    color: var(--text-muted);
    transition: all var(--transition-fast);
}

.panel-collapse-handle:hover {
    background: var(--bg-card-hover);
    color: var(--text-primary);
}

body.left-collapsed .panel-collapse-handle {
    right: -20px;
    border-left: none;
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

body.left-collapsed .panel-collapse-handle svg {
    transform: rotate(180deg);
}

/* =============================================
   CPH Panel (Right Side)
   ============================================= */

.cph-panel {
    width: 30%;
    min-width: 260px;
    max-width: 420px;
    border-left: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    position: relative;
    transition: width 0.25s cubic-bezier(0.4, 0, 0.2, 1),
                min-width 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

body.cph-collapsed .cph-panel {
    width: 0;
    min-width: 0;
    border-left: none;
    overflow: hidden;
}

.cph-content {
    display: flex;
    flex-direction: column;
    flex: 1;
    overflow: hidden;
    min-height: 0;
}

.cph-subpanel {
    display: flex;
    flex-direction: column;
    overflow: hidden;
    min-height: 0;
}

.cph-subpanel + .cph-subpanel {
    border-top: 1px solid var(--border-color);
}

.cph-subpanel-input { flex: 1; }
.cph-subpanel-output { flex: 1; }
.cph-subpanel-expected { flex: 0.6; min-height: 50px; }

/* CPH Collapse Handle (left side of panel) */
.cph-collapse-handle {
    position: absolute;
    left: -20px;
    top: 50%;
    transform: translateY(-50%);
    width: 20px;
    height: 48px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-right: none;
    border-radius: var(--radius-sm) 0 0 var(--radius-sm);
    cursor: pointer;
    z-index: 10;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1px;
    color: var(--text-muted);
    transition: all var(--transition-fast);
}

.cph-collapse-handle:hover {
    background: var(--bg-card-hover);
    color: var(--text-primary);
}

body.cph-collapsed .cph-collapse-handle {
    left: -20px;
    border-right: none;
    border-radius: var(--radius-sm) 0 0 var(--radius-sm);
}

body.cph-collapsed .cph-collapse-handle svg {
    transform: rotate(180deg);
}

/* =============================================
   IO Shared Styles
   ============================================= */

.io-body {
    flex: 1;
    overflow: hidden;
    padding: var(--spacing-sm) !important;
    display: flex;
}

.io-textarea {
    width: 100%;
    height: 100%;
    background: var(--bg-primary);
    color: var(--text-primary);
    border: none;
    resize: none;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    line-height: 1.5;
    padding: var(--spacing-sm);
    outline: none;
}

.io-output {
    width: 100%;
    height: 100%;
    background: var(--bg-primary);
    color: var(--text-primary);
    font-family: var(--font-mono);
    font-size: 0.85rem;
    line-height: 1.5;
    padding: var(--spacing-sm);
    overflow: auto;
    white-space: pre-wrap;
    word-break: break-all;
    margin: 0;
}

.io-output.placeholder-text {
    color: var(--text-muted);
    font-style: italic;
}

.panel-action-btn {
    padding: 2px var(--spacing-sm);
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-secondary);
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.panel-action-btn:hover {
    opacity: 0.8;
}

/* Run Status */
.run-status {
    font-size: 0.75rem;
    font-weight: 600;
    padding: 2px var(--spacing-sm);
    border-radius: var(--radius-sm);
}

.run-status.accepted {
    color: var(--easy);
    background: rgba(0, 184, 163, 0.12);
}

.run-status.wrong {
    color: var(--hard);
    background: rgba(255, 55, 95, 0.12);
}

.run-status.error {
    color: var(--medium);
    background: rgba(255, 192, 30, 0.12);
}

/* Diff Result */
.diff-result {
    font-size: 0.75rem;
    font-weight: 600;
    padding: 2px var(--spacing-sm);
    border-radius: var(--radius-sm);
}

.diff-result.accepted {
    color: var(--easy);
    background: rgba(0, 184, 163, 0.12);
}

.diff-result.wrong {
    color: var(--hard);
    background: rgba(255, 55, 95, 0.12);
}

/* =============================================
   Debug Panel (inside CPH)
   ============================================= */

.debug-panel {
    display: none;
    flex-direction: column;
    border-top: 1px solid var(--border-color);
}

.debug-panel.open {
    display: flex;
}

.debug-controls {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-xs) var(--spacing-sm);
    background: var(--bg-tertiary);
    border-bottom: 1px solid var(--border-color);
}

.debug-step-btn {
    padding: 2px var(--spacing-sm);
    font-size: 0.75rem;
    color: var(--text-secondary);
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.debug-step-btn:hover {
    color: var(--text-primary);
    border-color: var(--primary);
}

.debug-info {
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-left: auto;
}

.debug-body {
    max-height: 200px;
    overflow-y: auto;
    padding: var(--spacing-sm);
}

.debug-vars-header {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.debug-var {
    display: flex;
    align-items: baseline;
    gap: var(--spacing-sm);
    padding: 2px 0;
    font-family: var(--font-mono);
    font-size: 0.8rem;
}

.debug-var-name {
    color: var(--primary);
    font-weight: 600;
}

.debug-var-value {
    color: var(--text-primary);
}

.debug-var-value.changed {
    background: rgba(255, 192, 30, 0.15);
    padding: 0 2px;
    border-radius: 2px;
}

/* Breakpoint gutter */
.breakpoint-marker {
    color: var(--hard);
    font-size: 14px;
    line-height: 1;
}

/* =============================================
   Mobile Responsive Updates
   ============================================= */

@media (max-width: 768px) {
    .panel-left {
        width: 100%;
        min-width: unset;
        height: 35%;
        border-right: none;
        border-bottom: 1px solid var(--border-color);
        transition: height 0.25s cubic-bezier(0.4, 0, 0.2, 1);
    }

    body.left-collapsed .panel-left {
        width: 100%;
        height: 0;
    }

    .cph-panel {
        position: absolute;
        right: 0;
        top: 0;
        bottom: 0;
        width: 85%;
        max-width: none;
        z-index: 20;
        box-shadow: -4px 0 16px rgba(0,0,0,0.2);
    }

    body.cph-collapsed .cph-panel {
        width: 0;
    }

    .panel-collapse-handle,
    .cph-collapse-handle {
        display: none;
    }
}