/* ===== 基础重置 ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    -webkit-tap-highlight-color: transparent;
}

/* ===== Dark Token System: Night Watch ===== */
:root {
    /* Background layers — progressively deeper */
    --bg-deepest: #050A14;     /* page body */
    --bg-deep: #0C1525;        /* header */
    --bg-card: #111B2E;        /* cards */
    --bg-card-hover: #152035;
    --bg-elevated: #1A2740;    /* inputs, selects */
    --bg-input-focus: #1E2D48;
    --bg-overlay: rgba(5, 10, 20, 0.7);

    /* Borders */
    --border-subtle: #1E2D48;
    --border-mid: #2A3F5F;
    --border-active: #3B5A8A;

    /* Text */
    --text-primary: #E8EDF4;
    --text-secondary: #9BA8BE;
    --text-muted: #5E6E88;
    --text-inverse: #0C1525;

    /* Brand */
    --primary: #3B82F6;
    --primary-dim: #2563EB;
    --primary-glow: rgba(59, 130, 246, 0.15);
    --primary-subtle: rgba(59, 130, 246, 0.08);

    /* Semantic */
    --danger: #EF4444;
    --danger-dim: #DC2626;
    --danger-bg: rgba(239, 68, 68, 0.1);
    --danger-border: rgba(239, 68, 68, 0.3);
    --success: #22C55E;
    --success-bg: rgba(34, 197, 94, 0.1);
    --success-border: rgba(34, 197, 94, 0.3);
    --warning: #F59E0B;
    --warning-bg: rgba(245, 158, 11, 0.1);
    --warning-border: rgba(245, 158, 11, 0.3);
    --ai-gradient-start: #8B5CF6;
    --ai-gradient-end: #6366F1;

    /* Structure */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;

    /* Animation */
    --speed-fast: 0.12s;
    --speed-normal: 0.2s;
    --speed-slow: 0.35s;
    --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
    --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
    --ease-smooth: cubic-bezier(0.4, 0, 0.2, 1);

    /* Layout */
    --max-width: 1120px;
    --header-height: 56px;
    --nav-height: 48px;
    --footer-height: 40px;
}

body {
    background: var(--bg-deepest);
    color: var(--text-primary);
    min-height: 100vh;
}

/* ===== 滚动条美化 ===== */
::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}
::-webkit-scrollbar-track {
    background: transparent;
}
::-webkit-scrollbar-thumb {
    background: var(--border-mid);
    border-radius: 3px;
}
::-webkit-scrollbar-thumb:hover {
    background: var(--border-active);
}

/* ===== 加载遮罩 ===== */
.loader-container {
    position: fixed;
    inset: 0;
    background: var(--bg-deepest);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    z-index: 9999;
}
.loader-container.fade-out {
    animation: loaderFadeOut 0.5s ease-out forwards;
}
@keyframes loaderFadeOut {
    to { opacity: 0; }
}
.loader-title {
    font-size: 18px;
    color: var(--text-secondary);
    margin-bottom: 28px;
    font-weight: 600;
    letter-spacing: 0.03em;
    animation: loaderPulse 1.5s ease-in-out infinite;
}
@keyframes loaderPulse {
    0%, 100% { opacity: 0.6; }
    50% { opacity: 1; }
}

/* ===== 头部 ===== */
.global-header {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: var(--bg-deep);
    border-bottom: 1px solid var(--border-subtle);
    padding: 0;
    width: 100%;
}
.header-content {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 20px;
}
.header-top {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 8px;
    padding: 12px 0 8px;
}
.title-group {
    flex: 1;
    min-width: 0;
}
.header-title {
    font-size: 16px;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 1px;
    line-height: 1.3;
    letter-spacing: 0.01em;
}
.header-sub {
    font-size: 11px;
    color: var(--text-muted);
    font-weight: 400;
}
.univ-brand {
    font-size: 14px;
    font-weight: 600;
    letter-spacing: 0.04em;
    color: var(--primary);
    white-space: nowrap;
    text-decoration: none;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 8px 16px;
    border-radius: var(--radius-md);
    background: transparent;
    border: none;
    transition: all var(--speed-fast) var(--ease-smooth);
}
.univ-brand:hover {
    background: var(--primary-subtle);
    color: var(--primary-dim);
}
.univ-brand:active {
    transform: scale(0.97);
}

/* ===== 导航 ===== */
.nav-wrapper {
    position: relative;
    border-top: 1px solid var(--border-subtle);
}
.nav {
    display: flex;
    gap: 0;
    flex-wrap: nowrap;
    overflow-x: auto;
    padding-bottom: 0;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
}
.nav::-webkit-scrollbar {
    display: none;
}
.nav-btn {
    padding: 10px 16px;
    background: transparent;
    border: none;
    border-radius: 0;
    color: var(--text-muted);
    cursor: pointer;
    font-size: 13px;
    font-weight: 500;
    white-space: nowrap;
    min-height: 44px;
    transition: color var(--speed-fast) var(--ease-smooth),
                background var(--speed-fast) var(--ease-smooth);
    position: relative;
}
.nav-btn:hover {
    color: var(--text-secondary);
    background: var(--bg-card);
}
.nav-btn.active {
    color: var(--primary);
    font-weight: 600;
    background: var(--bg-card);
}
.nav-btn.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 16px;
    right: 16px;
    height: 2px;
    background: var(--primary);
    border-radius: 1px 1px 0 0;
    animation: navLineIn 0.25s var(--ease-spring) forwards;
}
@keyframes navLineIn {
    from { transform: scaleX(0); }
    to { transform: scaleX(1); }
}
.nav-underline {
    display: none;
}

/* ===== 页面切换 ===== */
.page {
    visibility: hidden;
    width: 100%;
    min-height: calc(100vh - var(--header-height) - var(--nav-height) - var(--footer-height) - 20px);
    position: absolute;
    left: 0;
    right: 0;
    top: 0;
    pointer-events: none;
}
.page.active {
    visibility: visible;
    position: relative;
    pointer-events: auto;
    animation: pageSlideIn 0.35s var(--ease-out) forwards;
}
@keyframes pageSlideIn {
    from {
        opacity: 0;
        transform: translateY(12px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ===== 布局 ===== */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 20px 20px 60px;
}

/* ===== 卡片 ===== */
.page-content {
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-subtle);
    padding: 28px 32px;
    margin-bottom: 20px;
    position: relative;
    overflow: hidden;
}
/* 顶部装饰线 */
.page-content::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--primary), var(--ai-gradient-end));
    opacity: 0.6;
}
.page-title {
    font-size: 17px;
    color: var(--text-primary);
    padding-bottom: 10px;
    border-bottom: 1px solid var(--border-subtle);
    margin-bottom: 24px;
    font-weight: 700;
    width: fit-content;
    letter-spacing: 0.01em;
}

/* ===== 分区标题（档案标签风格） ===== */
.section-title {
    font-size: 11px;
    font-weight: 700;
    color: var(--text-secondary);
    margin: 28px 0 14px;
    padding: 5px 10px;
    background: var(--bg-elevated);
    border-left: 3px solid var(--primary);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    display: flex;
    align-items: center;
    gap: 8px;
    animation: sectionSlideIn 0.3s var(--ease-out) forwards;
    opacity: 0;
    transform: translateX(-4px);
}
.section-title::before {
    content: '';
    display: inline-block;
    width: 14px;
    height: 14px;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%239BA8BE' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M22 19a2 2 0 0 1-2 2H4a2 2 0 0 1-2-2V5a2 2 0 0 1 2-2h5l2 3h9a2 2 0 0 1 2 2z'/%3E%3C/svg%3E");
    background-size: contain;
    background-repeat: no-repeat;
    background-position: center;
    filter: saturate(0.3);
}
.section-title:first-of-type {
    margin-top: 0;
}
/* 交错入场动画 */
.page-content .section-title:nth-of-type(1) { animation-delay: 0.1s; }
.page-content .section-title:nth-of-type(2) { animation-delay: 0.15s; }
.page-content .section-title:nth-of-type(3) { animation-delay: 0.2s; }
.page-content .section-title:nth-of-type(4) { animation-delay: 0.25s; }
@keyframes sectionSlideIn {
    from { opacity: 0; transform: translateX(-4px); }
    to { opacity: 1; transform: translateX(0); }
}

/* ===== 通知/提示 ===== */
.notice {
    background: var(--warning-bg);
    border: 1px solid var(--warning-border);
    border-left: 3px solid var(--warning);
    padding: 10px 14px;
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    margin: 0 0 18px;
    font-size: 13px;
    color: var(--text-secondary);
    line-height: 1.6;
    animation: noticePop 0.3s var(--ease-spring) forwards;
}
@keyframes noticePop {
    from { opacity: 0; transform: scale(0.97); }
    to { opacity: 1; transform: scale(1); }
}
.tip {
    font-size: 12px;
    color: var(--text-muted);
    margin: 6px 0 12px;
    line-height: 1.5;
}
.loading-tip {
    color: var(--primary);
    margin: 10px 0;
    font-size: 13px;
    display: flex;
    align-items: center;
    gap: 8px;
}
.loading-spin {
    width: 14px;
    height: 14px;
    border: 2px solid var(--primary);
    border-top-color: transparent;
    border-radius: 50%;
    animation: spin 0.7s linear infinite;
    display: inline-block;
}
@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

/* ===== 结果框 ===== */
.result-box {
    background: var(--bg-elevated);
    padding: 0;
    border-radius: var(--radius-md);
    white-space: pre-line;
    line-height: 1.7;
    margin: 16px 0;
    border: 1px solid var(--border-subtle);
    display: grid;
    grid-template-rows: 0fr;
    transition: grid-template-rows var(--speed-slow) var(--ease-smooth);
}
.result-box.show {
    grid-template-rows: 1fr;
}
.result-box > * {
    overflow: hidden;
}
.result-box.show > * {
    padding: 14px 16px;
    overflow-y: auto;
}

/* ===== 表单 ===== */
.form-group {
    margin-bottom: 16px;
    animation: formGroupIn 0.3s var(--ease-out) forwards;
    opacity: 0;
    transform: translateY(4px);
}
@keyframes formGroupIn {
    to { opacity: 1; transform: translateY(0); }
}
.form-group:nth-child(1) { animation-delay: 0.05s; }
.form-group:nth-child(2) { animation-delay: 0.08s; }
.form-group:nth-child(3) { animation-delay: 0.11s; }
.form-group:nth-child(4) { animation-delay: 0.14s; }
.form-group:nth-child(n+5) { animation-delay: 0.17s; }

.form-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 5px;
    font-size: 13px;
    color: var(--text-primary);
    letter-spacing: 0.01em;
}
.form-group label .required-star {
    color: var(--danger);
    margin-left: 2px;
}
.form-group label .optional-tag {
    color: var(--text-muted);
    font-weight: 400;
    font-size: 11px;
    margin-left: 4px;
    background: var(--bg-elevated);
    padding: 1px 6px;
    border-radius: 10px;
    border: 1px solid var(--border-subtle);
}
.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 9px 12px;
    border: 1px solid var(--border-mid);
    border-radius: var(--radius-md);
    font-size: 14px;
    transition: border-color var(--speed-fast) var(--ease-smooth),
                box-shadow var(--speed-fast) var(--ease-smooth),
                background var(--speed-fast) var(--ease-smooth);
    background: var(--bg-elevated);
    color: var(--text-primary);
}
.form-group input::placeholder,
.form-group textarea::placeholder {
    color: var(--text-muted);
}
.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
    border-color: var(--primary);
    outline: none;
    box-shadow: 0 0 0 3px var(--primary-glow);
    background: var(--bg-input-focus);
}
.form-group.valid input,
.form-group.valid textarea {
    border-color: var(--success);
    box-shadow: 0 0 0 3px rgba(34, 197, 94, 0.1);
}
.error-message {
    color: var(--danger);
    font-size: 12px;
    margin-top: 4px;
    display: none;
    font-weight: 500;
    animation: errorMsgIn 0.2s var(--ease-spring) forwards;
}
@keyframes errorMsgIn {
    from { opacity: 0; transform: translateY(-2px); }
    to { opacity: 1; transform: translateY(0); }
}
.form-group.error input,
.form-group.error textarea,
.form-group.error select {
    border-color: var(--danger);
    background: var(--danger-bg);
}
.form-group.error .error-message {
    display: block;
}

/* ===== 按钮 ===== */
.btn {
    padding: 9px 18px;
    border: 1px solid transparent;
    border-radius: var(--radius-md);
    font-size: 14px;
    cursor: pointer;
    font-weight: 600;
    min-height: 40px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    transition: all var(--speed-fast) var(--ease-smooth);
    letter-spacing: 0.01em;
    position: relative;
    overflow: hidden;
}
/* 按钮涟漪效果 */
.btn::after {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(circle at var(--ripple-x, 50%) var(--ripple-y, 50%), rgba(255,255,255,0.15) 0%, transparent 70%);
    opacity: 0;
    transition: opacity var(--speed-fast);
}
.btn:hover::after {
    opacity: 1;
}
.btn:hover {
    transform: translateY(-1px);
    box-shadow: 0 2px 8px rgba(0,0,0,0.2);
}
.btn:active {
    transform: translateY(0) scale(0.98);
    box-shadow: none;
}
.btn-primary {
    background: var(--primary);
    color: var(--text-inverse);
    border-color: var(--primary);
}
.btn-primary:hover {
    background: var(--primary-dim);
    border-color: var(--primary-dim);
    box-shadow: 0 2px 12px var(--primary-glow);
}
.btn-default {
    background: var(--bg-elevated);
    color: var(--text-secondary);
    border-color: var(--border-mid);
}
.btn-default:hover {
    background: var(--bg-card-hover);
    border-color: var(--border-active);
    color: var(--text-primary);
}
.btn-success {
    background: var(--success);
    color: var(--text-inverse);
    border-color: var(--success);
}
.btn-success:hover {
    box-shadow: 0 2px 12px var(--success-bg);
}
.btn-export {
    background: var(--primary-dim);
    color: var(--text-inverse);
    border-color: var(--primary-dim);
}
.btn-pdf {
    background: var(--bg-elevated);
    color: var(--text-secondary);
    border-color: var(--border-mid);
}
.btn-pdf:hover {
    background: var(--bg-card-hover);
    border-color: var(--border-active);
    color: var(--text-primary);
}
.btn-deep {
    background: linear-gradient(135deg, var(--ai-gradient-start), var(--ai-gradient-end));
    color: var(--text-inverse);
    border-color: transparent;
}
.btn-deep:hover {
    filter: brightness(1.15);
    box-shadow: 0 4px 16px rgba(139, 92, 246, 0.25);
}

/* 按钮组 */
.btn-group {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin: 16px 0;
}
.btn-group .btn {
    animation: btnIn 0.3s var(--ease-out) forwards;
    opacity: 0;
    transform: translateY(4px);
}
.btn-group .btn:nth-child(1) { animation-delay: 0.05s; }
.btn-group .btn:nth-child(2) { animation-delay: 0.08s; }
.btn-group .btn:nth-child(3) { animation-delay: 0.11s; }
.btn-group .btn:nth-child(4) { animation-delay: 0.14s; }
@keyframes btnIn {
    to { opacity: 1; transform: translateY(0); }
}

/* ===== 上传区域 ===== */
.upload-area {
    border: 1px dashed var(--border-mid);
    border-radius: var(--radius-md);
    padding: 20px;
    text-align: center;
    cursor: pointer;
    margin: 14px 0;
    background: var(--bg-elevated);
    transition: all var(--speed-normal) var(--ease-smooth);
    font-size: 13px;
    color: var(--text-secondary);
}
.upload-area:hover {
    border-color: var(--primary);
    background: var(--primary-subtle);
    transform: translateY(-1px);
}
.upload-area.dragover {
    border-color: var(--primary);
    background: var(--primary-glow);
    box-shadow: 0 0 0 3px var(--primary-glow);
}
.upload-area input {
    display: none;
}

/* ===== 预览缩略图 ===== */
.preview {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin: 14px 0;
}
.preview-item {
    width: 80px;
    height: 80px;
    border-radius: var(--radius-md);
    overflow: hidden;
    border: 1px solid var(--border-subtle);
    position: relative;
    animation: thumbIn 0.25s var(--ease-spring) forwards;
    opacity: 0;
    transform: scale(0.9);
}
@keyframes thumbIn {
    to { opacity: 1; transform: scale(1); }
}
.preview-item img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--speed-normal) var(--ease-smooth);
}
.preview-item:hover img {
    transform: scale(1.05);
}
.preview-del {
    position: absolute;
    top: 2px;
    right: 2px;
    width: 18px;
    height: 18px;
    background: var(--danger);
    color: var(--white);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 11px;
    cursor: pointer;
    opacity: 0;
    transition: opacity var(--speed-fast), transform var(--speed-fast) var(--ease-spring);
    transform: scale(0.8);
}
.preview-item:hover .preview-del {
    opacity: 1;
    transform: scale(1);
}

/* ===== 语料按钮 ===== */
.corpus-btns {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    margin: 12px 0;
}
.corpus-btn {
    padding: 5px 12px;
    border: 1px solid var(--border-mid);
    border-radius: var(--radius-sm);
    background: var(--bg-elevated);
    cursor: pointer;
    font-size: 13px;
    color: var(--text-secondary);
    transition: all var(--speed-fast) var(--ease-smooth);
}
.corpus-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
    background: var(--primary-subtle);
}
.corpus-btn.active {
    background: var(--primary);
    color: var(--text-inverse);
    border-color: var(--primary);
    box-shadow: 0 0 0 3px var(--primary-glow);
}

/* ===== 开关 ===== */
.switch {
    display: flex;
    align-items: center;
    gap: 8px;
    margin: 12px 0;
    cursor: pointer;
    width: fit-content;
}
.switch input[type="checkbox"] {
    width: auto;
    margin: 0;
    accent-color: var(--primary);
    cursor: pointer;
}
.switch label {
    font-size: 13px;
    color: var(--text-secondary);
    cursor: pointer;
}

/* ===== 首页快捷按钮 ===== */
.home-btns {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 12px;
    margin-top: 32px;
}
.home-btns .btn {
    min-width: 180px;
    animation: btnIn 0.3s var(--ease-out) forwards;
    opacity: 0;
    transform: translateY(6px);
}
.home-btns .btn:nth-child(1) { animation-delay: 0.05s; }
.home-btns .btn:nth-child(2) { animation-delay: 0.1s; }
.home-btns .btn:nth-child(3) { animation-delay: 0.15s; }

/* ===== 历史记录 ===== */
.history-item {
    background: var(--bg-elevated);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    padding: 14px 16px;
    margin-bottom: 10px;
    transition: all var(--speed-fast) var(--ease-smooth);
    animation: historyIn 0.3s var(--ease-out) forwards;
    opacity: 0;
    transform: translateY(4px);
}
@keyframes historyIn {
    to { opacity: 1; transform: translateY(0); }
}
.history-item:nth-child(1) { animation-delay: 0.03s; }
.history-item:nth-child(2) { animation-delay: 0.06s; }
.history-item:nth-child(3) { animation-delay: 0.09s; }
.history-item:nth-child(4) { animation-delay: 0.12s; }
.history-item:nth-child(5) { animation-delay: 0.15s; }
.history-item:hover {
    border-color: var(--border-active);
    background: var(--bg-card-hover);
    transform: translateX(2px);
}
.history-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 6px;
    border-bottom: 1px solid var(--border-subtle);
    padding-bottom: 6px;
    font-size: 12px;
}
.history-header span:first-child {
    font-weight: 600;
    color: var(--text-primary);
}
.history-header span:last-child {
    color: var(--text-muted);
}

/* ===== 设置 ===== */
.setting-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 14px 0;
    border-bottom: 1px solid var(--border-subtle);
    animation: settingIn 0.3s var(--ease-out) forwards;
    opacity: 0;
}
@keyframes settingIn {
    to { opacity: 1; }
}
.setting-item:nth-child(1) { animation-delay: 0.05s; }
.setting-item:nth-child(2) { animation-delay: 0.1s; }
.setting-item:last-of-type {
    border-bottom: none;
}
.setting-label {
    font-size: 14px;
    color: var(--text-primary);
    font-weight: 500;
}

/* ===== 证据文本只读框 ===== */
.evidence-readonly {
    background: var(--bg-elevated);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    padding: 12px 14px;
    font-size: 13px;
    color: var(--text-secondary);
    min-height: 60px;
    white-space: pre-line;
    line-height: 1.6;
    max-height: 200px;
    overflow-y: auto;
    margin: 8px 0;
    transition: border-color var(--speed-fast);
}
.evidence-readonly:hover {
    border-color: var(--border-mid);
}
.evidence-readonly:empty::after {
    content: '暂无关联证据文本，可先在"诈骗识别"页面上传图片进行OCR识别，或点击下方"从识别页导入"按钮。';
    color: var(--text-muted);
    font-style: italic;
}

/* ===== 全局底部 ===== */
.global-footer {
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    padding: 8px 20px;
    background: var(--bg-deep);
    border-top: 1px solid var(--border-subtle);
    font-size: 11px;
    text-align: center;
    z-index: 999;
    color: var(--text-muted);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
}

/* ===== 聊天卡片 ===== */
.chat-card {
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-subtle);
    margin-bottom: 28px;
    overflow: hidden;
    position: relative;
}
.chat-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--primary), var(--ai-gradient-end));
}
.chat-header {
    background: var(--bg-elevated);
    padding: 12px 18px;
    color: var(--text-primary);
    font-weight: 600;
    font-size: 14px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border-subtle);
}
.chat-clear-btn {
    background: transparent;
    border: 1px solid var(--border-mid);
    color: var(--text-muted);
    padding: 4px 14px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 12px;
    font-weight: 500;
    transition: all var(--speed-fast);
}
.chat-clear-btn:hover {
    border-color: var(--danger);
    color: var(--danger);
    background: var(--danger-bg);
}
.chat-messages {
    height: 340px;
    overflow-y: auto;
    padding: 16px;
    background: var(--bg-deepest);
    display: flex;
    flex-direction: column;
    gap: 12px;
}
.message {
    display: flex;
    align-items: flex-start;
    gap: 8px;
    max-width: 85%;
    animation: msgIn 0.25s var(--ease-out) forwards;
    opacity: 0;
    transform: translateY(6px);
}
@keyframes msgIn {
    to { opacity: 1; transform: translateY(0); }
}
.message.user {
    align-self: flex-end;
    flex-direction: row-reverse;
}
.message.bot {
    align-self: flex-start;
}
.message-bubble {
    background: var(--bg-elevated);
    padding: 10px 14px;
    border-radius: var(--radius-lg);
    border-bottom-left-radius: 4px;
    font-size: 14px;
    line-height: 1.6;
    word-break: break-word;
    border: 1px solid var(--border-subtle);
    color: var(--text-primary);
}
.message.user .message-bubble {
    background: var(--primary);
    color: var(--text-inverse);
    border: none;
    border-bottom-right-radius: 4px;
}
.message-bubble strong {
    font-weight: 700;
    color: var(--primary);
}
.message.user .message-bubble strong {
    color: var(--white);
}
.message-bubble em {
    font-style: italic;
}
.message-bubble code {
    background: rgba(0,0,0,0.2);
    padding: 1px 5px;
    border-radius: 3px;
    font-size: 13px;
    font-family: "SF Mono", "Fira Code", "Courier New", monospace;
}
.message.user .message-bubble code {
    background: rgba(255,255,255,0.2);
}
.message-bubble blockquote {
    border-left: 3px solid var(--border-mid);
    padding-left: 10px;
    color: var(--text-secondary);
    margin: 6px 0;
}
.message.user .message-bubble blockquote {
    color: rgba(255,255,255,0.9);
    border-left-color: rgba(255,255,255,0.3);
}
.message-avatar {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: var(--border-mid);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    font-size: 13px;
}
.message.user .message-avatar {
    background: rgba(255,255,255,0.2);
}
.chat-input-area {
    display: flex;
    padding: 12px 16px;
    background: var(--bg-card);
    border-top: 1px solid var(--border-subtle);
    gap: 10px;
    align-items: center;
}
.chat-input {
    flex: 1;
    border: 1px solid var(--border-mid);
    border-radius: 20px;
    padding: 8px 16px;
    font-size: 14px;
    outline: none;
    resize: none;
    min-height: 38px;
    transition: border-color var(--speed-fast), box-shadow var(--speed-fast), background var(--speed-fast);
    background: var(--bg-elevated);
    color: var(--text-primary);
}
.chat-input::placeholder {
    color: var(--text-muted);
}
.chat-input:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px var(--primary-glow);
    background: var(--bg-input-focus);
}
.chat-send-btn {
    background: var(--primary);
    border: none;
    color: var(--text-inverse);
    padding: 7px 18px;
    border-radius: 20px;
    font-weight: 600;
    font-size: 13px;
    cursor: pointer;
    min-width: 64px;
    transition: all var(--speed-fast);
}
.chat-send-btn:hover {
    background: var(--primary-dim);
    box-shadow: 0 2px 8px var(--primary-glow);
}
.chat-send-btn:active {
    transform: scale(0.97);
}
.chat-send-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* ===== 打字指示器 ===== */
.typing-indicator {
    display: flex;
    gap: 4px;
    padding: 8px 14px;
    background: var(--bg-elevated);
    border: 1px solid var(--border-subtle);
    border-radius: 18px;
    width: fit-content;
    animation: typingIn 0.2s var(--ease-out) forwards;
}
@keyframes typingIn {
    from { opacity: 0; transform: translateY(4px) scale(0.95); }
    to { opacity: 1; transform: translateY(0) scale(1); }
}
.typing-indicator span {
    width: 5px;
    height: 5px;
    background: var(--text-muted);
    border-radius: 50%;
    animation: typingBounce 1.4s infinite;
}
.typing-indicator span:nth-child(2) { animation-delay: 0.15s; }
.typing-indicator span:nth-child(3) { animation-delay: 0.3s; }
@keyframes typingBounce {
    0%, 80%, 100% { transform: scale(0.6); opacity: 0.4; }
    40% { transform: scale(1); opacity: 1; }
}

/* ===== OCR进度条 ===== */
.ocr-progress {
    margin: 14px 0;
    display: none;
}
.ocr-progress.active {
    display: block;
    animation: ocrIn 0.25s var(--ease-out) forwards;
}
@keyframes ocrIn {
    from { opacity: 0; transform: translateY(-4px); }
    to { opacity: 1; transform: translateY(0); }
}
.ocr-progress-bar-bg {
    width: 100%;
    height: 6px;
    background: var(--border-subtle);
    border-radius: 3px;
    overflow: hidden;
}
.ocr-progress-bar-fill {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, var(--primary), var(--ai-gradient-end));
    border-radius: 3px;
    transition: width 0.3s ease;
}
.ocr-progress-info {
    display: flex;
    justify-content: space-between;
    font-size: 12px;
    color: var(--text-muted);
    margin-bottom: 6px;
}

/* ===== 响应式 ===== */
@media (max-width: 768px) {
    body {
        background: var(--bg-deepest);
    }
    .container {
        padding: 14px;
    }
    .page-content {
        padding: 18px;
        border-radius: var(--radius-lg);
    }
    .btn-group {
        flex-direction: column;
    }
    .btn {
        width: 100% !important;
    }
    .chat-messages {
        height: 260px;
    }
    .message {
        max-width: 90%;
    }
    .header-top {
        flex-direction: column;
        align-items: flex-start;
    }
    .univ-brand {
        align-self: flex-end;
    }
    .home-btns .btn {
        min-width: unset;
        width: 100%;
    }
}