:root {
    --bg: #FFFFFF;
    --fg: #000000;
    --muted: #666666;
    --accent: #000000;
    --card: #F5F5F5;
    --border: #E5E5E5;
    --user-bubble: #000000;
    --user-bubble-text: #FFFFFF;
    --separator: rgba(0,0,0,0.06);
    --input-bg: #FFFFFF;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.06);
    --shadow-md: 0 4px 20px rgba(0,0,0,0.08);
    --shadow-lg: 0 8px 40px rgba(0,0,0,0.12);
}

[data-theme="dark"] {
    --bg: #000000;
    --fg: #FFFFFF;
    --muted: #888888;
    --accent: #FFFFFF;
    --card: #111111;
    --border: #222222;
    --user-bubble: #FFFFFF;
    --user-bubble-text: #000000;
    --separator: rgba(255,255,255,0.08);
    --input-bg: #111111;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    -webkit-tap-highlight-color: transparent;
}

html, body {
    height: 100%;
    width: 100%;
    overflow: hidden;
    position: fixed;
    background: var(--bg);
    transition: background-color 0.4s ease;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    color: var(--fg);
    overscroll-behavior: none;
}

.chat-container {
    height: 100%;
    height: 100dvh;
    display: flex;
    flex-direction: column;
    width: 100%;
    overflow: hidden;
}

/* ========== Toast ========== */
.toast-container {
    position: fixed;
    top: max(20px, env(safe-area-inset-top));
    left: 50%;
    transform: translateX(-50%);
    z-index: 300;
    display: flex;
    flex-direction: column;
    gap: 8px;
    pointer-events: none;
}
.toast {
    background: var(--fg);
    color: var(--bg);
    padding: 10px 20px;
    border-radius: 20px;
    font-size: 14px;
    font-weight: 500;
    box-shadow: var(--shadow-lg);
    opacity: 0;
    transform: translateY(-10px);
    transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    pointer-events: auto;
    white-space: nowrap;
}
.toast.show {
    opacity: 1;
    transform: translateY(0);
}

/* ========== 侧边栏 ========== */
.sidebar-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.35);
    z-index: 199;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.35s ease, visibility 0.35s;
    backdrop-filter: blur(4px);
    -webkit-backdrop-filter: blur(4px);
}
.sidebar-overlay.active {
    opacity: 1;
    visibility: visible;
}

.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    width: 280px;
    height: 100%;
    height: 100dvh;
    background: var(--bg);
    border-right: 1px solid var(--border);
    z-index: 200;
    transform: translateX(-100%);
    transition: transform 0.45s cubic-bezier(0.16, 1, 0.3, 1);
    display: flex;
    flex-direction: column;
    box-shadow: var(--shadow-lg);
}
.sidebar.active {
    transform: translateX(0);
}

.sidebar-header {
    padding: 16px;
    padding-top: max(16px, env(safe-area-inset-top));
    border-bottom: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-shrink: 0;
}

.sidebar-title {
    font-size: 16px;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 8px;
}

.sidebar-close {
    width: 32px;
    height: 32px;
    border: none;
    background: transparent;
    color: var(--muted);
    cursor: pointer;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    transition: color 0.2s, background 0.2s;
}
.sidebar-close:active {
    background: var(--card);
    color: var(--fg);
}

.sidebar-content {
    flex: 1;
    overflow-y: auto;
    overflow-x: hidden;
    padding: 12px;
    -webkit-overflow-scrolling: touch;
}

.sidebar-empty {
    display: none;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 40px 20px;
    color: var(--muted);
    text-align: center;
}
.sidebar-empty i {
    font-size: 40px;
    margin-bottom: 12px;
    opacity: 0.4;
}
.sidebar-empty p {
    font-size: 14px;
    font-weight: 500;
    margin-bottom: 4px;
    color: var(--fg);
}
.sidebar-empty span {
    font-size: 12px;
    opacity: 0.7;
}

.sidebar-list {
    display: flex;
    flex-direction: column;
}

.sidebar-footer {
    padding: 12px 16px;
    padding-bottom: max(12px, env(safe-area-inset-bottom));
    border-top: 1px solid var(--border);
    flex-shrink: 0;
}

.ip-badge {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 12px;
    color: var(--muted);
    background: var(--card);
    padding: 8px 12px;
    border-radius: 20px;
}

/* ========== 历史对话项 ========== */
.history-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px;
    border-radius: 10px;
    cursor: pointer;
    margin-bottom: 4px;
    transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
    opacity: 0;
    transform: translateX(-8px);
    animation: slideInLeft 0.35s forwards;
    position: relative;
    overflow: hidden;
}
@keyframes slideInLeft {
    to { opacity: 1; transform: translateX(0); }
}
.history-item:hover {
    background: var(--card);
    transform: translateX(4px);
}
.history-item.active {
    background: var(--fg);
    color: var(--bg);
}
.history-item.active .history-time,
.history-item.active .history-btn {
    color: var(--bg);
    opacity: 0.7;
}

.history-icon {
    width: 32px;
    height: 32px;
    border-radius: 8px;
    background: var(--card);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--muted);
    font-size: 18px;
    flex-shrink: 0;
}
.history-item.active .history-icon {
    background: rgba(255,255,255,0.15);
    color: var(--bg);
}

.history-info {
    flex: 1;
    min-width: 0;
}

.history-title {
    font-size: 14px;
    font-weight: 500;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    margin-bottom: 2px;
}

.history-time {
    font-size: 11px;
    color: var(--muted);
    opacity: 0.8;
}

.history-actions {
    display: flex;
    gap: 4px;
    opacity: 0;
    transition: opacity 0.2s;
}
.history-item:hover .history-actions {
    opacity: 1;
}

.history-btn {
    width: 26px;
    height: 26px;
    border: none;
    background: transparent;
    color: var(--muted);
    cursor: pointer;
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    transition: all 0.15s;
}
.history-btn:hover {
    background: var(--separator);
    color: var(--fg);
}
.history-item.active .history-btn:hover {
    background: rgba(255,255,255,0.2);
    color: var(--bg);
}

/* ========== 头部 ========== */
.header {
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    padding: 16px;
    padding-top: max(16px, env(safe-area-inset-top));
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-shrink: 0;
    position: sticky;
    top: 0;
    z-index: 50;
    transition: background-color 0.4s ease, border-color 0.4s ease;
}

@supports (backdrop-filter: blur(20px)) {
    .header {
        background: rgba(255,255,255,0.85);
        backdrop-filter: blur(20px) saturate(180%);
        -webkit-backdrop-filter: blur(20px) saturate(180%);
    }
    [data-theme="dark"] .header {
        background: rgba(0,0,0,0.85);
    }
}

.header-title {
    font-size: 17px;
    font-weight: 600;
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    letter-spacing: -0.3px;
}

.header-btn {
    width: 32px;
    height: 32px;
    background: transparent;
    border: none;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    border-radius: 50%;
    color: var(--muted);
    font-size: 20px;
    position: relative;
    z-index: 51;
    transition: color 0.2s ease, transform 0.15s ease;
}
.header-btn:active {
    transform: scale(0.88);
}

@media (hover: hover) {
    .header-btn:hover { color: var(--fg); }
}

/* ========== 消息区域 & 滚动条 ========== */
.messages-area {
    flex: 1;
    overflow-y: auto;
    overflow-x: hidden;
    position: relative;
    -webkit-overflow-scrolling: touch;
    padding: 24px 0;
}

.messages-area::-webkit-scrollbar {
    width: 4px;
}
.messages-area::-webkit-scrollbar-track {
    background: transparent;
}
.messages-area::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 4px;
}
.messages-area::-webkit-scrollbar-thumb:hover {
    background: var(--muted);
}

/* ========== 欢迎界面 ========== */
.welcome-screen {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 20px;
    opacity: 0;
    animation: fadeIn 0.6s 0.1s cubic-bezier(0.16, 1, 0.3, 1) forwards;
    z-index: 1;
    pointer-events: none;
}
.welcome-screen > * { pointer-events: auto; }

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

.welcome-time {
    font-size: 15px;
    color: var(--muted);
    margin-bottom: 8px;
    font-weight: 500;
    opacity: 0;
    animation: fadeIn 0.5s 0.2s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

.welcome-title {
    font-size: 32px;
    font-weight: 700;
    color: var(--fg);
    margin-bottom: 24px;
    letter-spacing: -0.5px;
    opacity: 0;
    animation: fadeIn 0.5s 0.35s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

.welcome-suggestion {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 14px 20px;
    font-size: 14px;
    color: var(--muted);
    display: inline-block;
    transition: border-color 0.3s, transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    opacity: 0;
    animation: fadeIn 0.5s 0.5s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}
@media (hover: hover) {
    .welcome-suggestion:hover {
        border-color: var(--muted);
        transform: translateY(-1px);
    }
}

/* ========== 消息动画 ========== */
@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(16px) scale(0.96); }
    to { opacity: 1; transform: translateY(0) scale(1); }
}

.message-wrapper {
    margin-bottom: 20px;
    animation: fadeInUp 0.45s cubic-bezier(0.16, 1, 0.3, 1) both;
    position: relative;
    padding: 0 16px;
    width: 100%;
}

.message-wrapper.user {
    display: flex;
    justify-content: flex-end;
}

.user-bubble {
    background: var(--user-bubble);
    color: var(--user-bubble-text);
    padding: 12px 16px;
    border-radius: 18px;
    border-bottom-right-radius: 4px;
    font-size: 15px;
    line-height: 1.5;
    max-width: 85%;
    word-wrap: break-word;
    display: inline-block;
    box-shadow: var(--shadow-sm);
    transition: transform 0.2s, box-shadow 0.2s;
}
.user-bubble:active {
    transform: scale(0.98);
}

.message-wrapper.ai {
    position: relative;
}
.message-wrapper.ai::before {
    content: '';
    position: absolute;
    left: 0;
    top: 5px;
    bottom: 5px;
    width: 2px;
    background: var(--border);
    border-radius: 2px;
}

.ai-header {
    font-size: 13px;
    font-weight: 600;
    color: var(--muted);
    margin-bottom: 6px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.ai-content {
    font-size: 15px;
    line-height: 1.6;
    color: var(--fg);
    max-width: 100%;
    word-wrap: break-word;
    overflow-wrap: break-word;
}

/* 复制按钮 */
.copy-btn {
    background: none;
    border: none;
    padding: 4px;
    cursor: pointer;
    color: var(--muted);
    opacity: 0.5;
    transition: opacity 0.2s, color 0.2s;
    display: flex;
    align-items: center;
    gap: 4px;
    font-size: 12px;
    font-family: inherit;
}
@media (hover: hover) {
    .copy-btn:hover { opacity: 1; }
}
.copy-btn.copied {
    color: var(--fg);
    opacity: 1;
}

/* 统计信息 */
.message-stats {
    margin-top: 8px;
    font-size: 11px;
    color: var(--muted);
    background: var(--separator);
    padding: 6px 10px;
    border-radius: 8px;
    display: flex;
    flex-wrap: wrap;
    gap: 8px 16px;
    opacity: 0;
    transform: translateY(-4px);
    transition: opacity 0.3s ease, transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}
.message-stats.visible {
    opacity: 1;
    transform: translateY(0);
}

.stat-item {
    display: flex;
    align-items: center;
    gap: 4px;
}
.stat-value {
    font-weight: 600;
    color: var(--fg);
}

/* 加载动画 */
.loading-dots {
    display: flex;
    align-items: center;
    gap: 4px;
    padding: 4px 0;
    height: 24px;
}
.loading-dots span {
    width: 6px;
    height: 6px;
    background: var(--muted);
    border-radius: 50%;
    animation: bounce 1.4s infinite ease-in-out both;
}
.loading-dots span:nth-child(1) { animation-delay: -0.32s; }
.loading-dots span:nth-child(2) { animation-delay: -0.16s; }
@keyframes bounce {
    0%, 80%, 100% { transform: scale(0.6); opacity: 0.4; }
    40% { transform: scale(1); opacity: 1; }
}

/* Markdown */
.ai-content p { margin: 0 0 10px 0; }
.ai-content p:last-child { margin-bottom: 0; }
.ai-content code {
    background: var(--separator);
    padding: 2px 5px;
    border-radius: 4px;
    font-family: 'SF Mono', Monaco, monospace;
    font-size: 13px;
    white-space: pre-wrap;
}
.ai-content pre {
    background: #000000;
    color: #FFFFFF;
    padding: 12px;
    border-radius: 8px;
    overflow-x: auto;
    margin: 10px 0;
    font-size: 13px;
    width: 100%;
    max-width: 100%;
}
[data-theme="dark"] .ai-content pre {
    background: #1a1a1a;
    color: #FFFFFF;
}
.ai-content pre code {
    background: none;
    padding: 0;
    color: inherit;
    white-space: pre;
}
.ai-content ul, .ai-content ol {
    margin: 10px 0;
    padding-left: 20px;
}
.ai-content li { margin: 4px 0; }

/* 提示栏 */
.disclaimer-bar {
    padding: 6px 16px;
    text-align: center;
    font-size: 11px;
    color: var(--muted);
    background: var(--bg);
    border-top: 1px solid var(--border);
    opacity: 0.6;
    flex-shrink: 0;
    transition: background 0.4s, border-color 0.4s;
}

/* 弹窗 */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.4);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 100;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s;
}
.modal-overlay.active {
    opacity: 1;
    visibility: visible;
}
.modal-content {
    background: var(--card);
    width: 280px;
    border-radius: 14px;
    overflow: hidden;
    transform: scale(0.9) translateY(10px);
    transition: transform 0.35s cubic-bezier(0.16, 1, 0.3, 1);
}
.modal-overlay.active .modal-content {
    transform: scale(1) translateY(0);
}
.modal-body {
    padding: 24px 16px;
    text-align: center;
}
.modal-title {
    font-size: 17px;
    font-weight: 600;
    margin-bottom: 8px;
}
.modal-text {
    font-size: 13px;
    color: var(--muted);
    line-height: 1.4;
}
.modal-actions {
    display: flex;
    border-top: 1px solid var(--border);
}
.modal-btn {
    flex: 1;
    padding: 12px;
    font-size: 17px;
    font-family: inherit;
    background: transparent;
    border: none;
    cursor: pointer;
    color: var(--fg);
    transition: background 0.15s;
}
@media (hover: hover) {
    .modal-btn:hover { background: var(--separator); }
}
.modal-btn.cancel {
    border-right: 1px solid var(--border);
}
.modal-btn.confirm {
    font-weight: 600;
}

/* 输入区域 */
.input-container {
    background: var(--card);
    border-top: 1px solid var(--border);
    padding: 12px;
    padding-bottom: max(12px, calc(env(safe-area-inset-bottom) + 12px));
    flex-shrink: 0;
    transition: background-color 0.4s ease, border-color 0.4s ease;
}
.input-row {
    display: flex;
    align-items: flex-end;
    gap: 8px;
    max-width: 100%;
}
.input-field {
    flex: 1;
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: 20px;
    padding: 10px 16px;
    font-size: 15px;
    font-family: inherit;
    resize: none;
    max-height: 100px;
    min-height: 42px;
    outline: none;
    line-height: 1.4;
    color: var(--fg);
    transition: border-color 0.2s, background-color 0.4s, box-shadow 0.2s;
}
.input-field:focus {
    border-color: var(--fg);
    box-shadow: 0 0 0 3px var(--separator);
}
.send-button, .stop-button {
    width: 42px;
    height: 42px;
    border: none;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    flex-shrink: 0;
    color: var(--user-bubble-text);
    font-size: 20px;
    transition: opacity 0.2s, transform 0.15s;
}
.send-button:active, .stop-button:active {
    transform: scale(0.9);
}
.send-button {
    background: var(--fg);
}
.stop-button {
    background: var(--fg);
}
.hidden {
    display: none !important;
}

/* ========== 响应式 ========== */
@media (max-width: 480px) {
    .sidebar { width: 260px; }
    .history-actions { opacity: 1; }
}