/* ========== 全局变量与重置 ========== */
:root {
    --bg-primary: #0f0f1a;
    --bg-secondary: #1a1a2e;
    --bg-tertiary: #252540;
    --bg-card: #1e1e36;
    --bg-hover: #2a2a48;
    --border: #2d2d4a;
    --text-primary: #e8e8f0;
    --text-secondary: #9898b0;
    --text-muted: #6b6b85;
    --accent: #6366f1;
    --accent-hover: #818cf8;
    --accent-glow: rgba(99, 102, 241, 0.3);
    --success: #10b981;
    --danger: #ef4444;
    --warning: #f59e0b;
    --mistake: #ef4444;
    --note: #3b82f6;
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --shadow-sm: 0 2px 8px rgba(0,0,0,0.2);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.3);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.4);
    --transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    overflow-x: hidden;
}

/* 背景装饰 */
body::before {
    content: '';
    position: fixed;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background:
        radial-gradient(circle at 20% 20%, rgba(99, 102, 241, 0.08) 0%, transparent 40%),
        radial-gradient(circle at 80% 80%, rgba(139, 92, 246, 0.06) 0%, transparent 40%),
        radial-gradient(circle at 50% 50%, rgba(59, 130, 246, 0.04) 0%, transparent 60%);
    pointer-events: none;
    z-index: 0;
}

/* ========== 布局 ========== */
.app {
    display: flex;
    min-height: 100vh;
    position: relative;
    z-index: 1;
}

/* ========== 侧边栏 ========== */
.sidebar {
    width: 280px;
    background: var(--bg-secondary);
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    padding: 24px 20px;
    position: fixed;
    height: 100vh;
    left: 0;
    top: 0;
    z-index: 100;
    transition: transform 0.3s ease;
}

.sidebar-header {
    margin-bottom: 28px;
}

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

.logo-icon {
    font-size: 28px;
    filter: drop-shadow(0 0 8px var(--accent-glow));
}

.logo-text {
    font-size: 20px;
    font-weight: 700;
    background: linear-gradient(135deg, var(--accent), #a78bfa);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* 统计卡片 */
.sidebar-stats {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
    margin-bottom: 28px;
}

.stat-card {
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
    padding: 14px 12px;
    text-align: center;
    border: 1px solid var(--border);
    transition: var(--transition);
}

.stat-card:hover {
    border-color: var(--accent);
    transform: translateY(-2px);
}

.stat-num {
    font-size: 24px;
    font-weight: 700;
    color: var(--accent-hover);
    line-height: 1.2;
}

.stat-label {
    font-size: 12px;
    color: var(--text-muted);
    margin-top: 4px;
}

/* 导航区 */
.nav-section {
    flex: 1;
    overflow-y: auto;
}

.nav-title {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 12px;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 12px;
    padding: 0 8px;
}

.nav-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.nav-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 12px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: var(--transition);
    color: var(--text-secondary);
    font-size: 14px;
    position: relative;
}

.nav-item:hover {
    background: var(--bg-hover);
    color: var(--text-primary);
}

.nav-item.active {
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.2), rgba(139, 92, 246, 0.15));
    color: var(--text-primary);
    border: 1px solid rgba(99, 102, 241, 0.3);
}

.nav-item .cat-icon {
    font-size: 16px;
    width: 20px;
    text-align: center;
}

.nav-item .cat-name {
    flex: 1;
}

.nav-item .cat-count {
    font-size: 12px;
    color: var(--text-muted);
    background: var(--bg-tertiary);
    padding: 2px 8px;
    border-radius: 10px;
}

.nav-item.active .cat-count {
    background: rgba(99, 102, 241, 0.3);
    color: var(--accent-hover);
}

.cat-delete {
    opacity: 0;
    font-size: 12px;
    padding: 2px 6px;
    border-radius: 4px;
    transition: var(--transition);
}

.nav-item:hover .cat-delete {
    opacity: 1;
}

.cat-delete:hover {
    background: var(--danger);
    color: white;
}

/* 侧边栏底部 */
.sidebar-footer {
    margin-top: 20px;
    padding-top: 20px;
    border-top: 1px solid var(--border);
}

/* ========== 按钮 ========== */
.btn-primary {
    background: linear-gradient(135deg, var(--accent), #8b5cf6);
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: var(--radius-md);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    box-shadow: 0 4px 16px var(--accent-glow);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 24px var(--accent-glow);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-secondary {
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--border);
    padding: 12px 24px;
    border-radius: var(--radius-md);
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
}

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

.btn-block {
    width: 100%;
}

.btn-icon {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    width: 32px;
    height: 32px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 16px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

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

.btn-icon-inner {
    font-size: 16px;
}

/* ========== 主内容区 ========== */
.main-content {
    flex: 1;
    margin-left: 280px;
    padding: 24px 32px;
    min-height: 100vh;
}

/* 顶栏 */
.topbar {
    display: flex;
    align-items: center;
    gap: 20px;
    margin-bottom: 28px;
}

.search-box {
    flex: 1;
    max-width: 480px;
    position: relative;
}

.search-icon {
    position: absolute;
    left: 16px;
    top: 50%;
    transform: translateY(-50%);
    font-size: 16px;
    opacity: 0.5;
}

.search-box input {
    width: 100%;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    color: var(--text-primary);
    padding: 12px 16px 12px 44px;
    border-radius: var(--radius-md);
    font-size: 14px;
    transition: var(--transition);
    outline: none;
}

.search-box input:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

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

.filter-group {
    display: flex;
    gap: 4px;
    background: var(--bg-secondary);
    padding: 4px;
    border-radius: var(--radius-md);
    border: 1px solid var(--border);
}

.filter-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    padding: 8px 16px;
    border-radius: var(--radius-sm);
    font-size: 13px;
    cursor: pointer;
    transition: var(--transition);
}

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

.filter-btn.active {
    background: var(--accent);
    color: white;
}

.menu-toggle {
    display: none;
}

/* 内容头部 */
.content-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
}

.page-title {
    font-size: 28px;
    font-weight: 700;
    letter-spacing: -0.5px;
}

.view-toggle {
    display: flex;
    gap: 4px;
    background: var(--bg-secondary);
    padding: 4px;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border);
}

.view-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    width: 36px;
    height: 32px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 14px;
    transition: var(--transition);
}

.view-btn.active {
    background: var(--bg-tertiary);
    color: var(--text-primary);
}

/* ========== 笔记卡片 ========== */
.notes-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 20px;
}

.notes-container.list-view {
    grid-template-columns: 1fr;
}

.note-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 20px;
    cursor: pointer;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
    animation: cardIn 0.4s ease backwards;
}

@keyframes cardIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.note-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--note);
    opacity: 0;
    transition: var(--transition);
}

.note-card.mistake::before {
    background: var(--mistake);
}

.note-card:hover {
    transform: translateY(-4px);
    border-color: var(--accent);
    box-shadow: var(--shadow-lg);
}

.note-card:hover::before {
    opacity: 1;
}

.card-delete-btn {
    position: absolute;
    top: 12px;
    right: 12px;
    width: 28px;
    height: 28px;
    background: rgba(0,0,0,0.5);
    color: white;
    border: none;
    border-radius: 50%;
    font-size: 12px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: var(--transition);
    z-index: 2;
}

.note-card:hover .card-delete-btn {
    opacity: 1;
}

.card-delete-btn:hover {
    background: var(--danger);
    transform: scale(1.1);
}

.note-card-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 12px;
}

.note-type-badge {
    font-size: 11px;
    font-weight: 600;
    padding: 4px 10px;
    border-radius: 20px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.note-type-badge.note {
    background: rgba(59, 130, 246, 0.15);
    color: #60a5fa;
}

.note-type-badge.mistake {
    background: rgba(239, 68, 68, 0.15);
    color: #f87171;
}

.note-category-tag {
    font-size: 12px;
    padding: 4px 10px;
    border-radius: 20px;
    display: flex;
    align-items: center;
    gap: 4px;
}

.note-card-title {
    font-size: 17px;
    font-weight: 600;
    margin-bottom: 10px;
    line-height: 1.4;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.note-card-content {
    font-size: 13px;
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 14px;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.note-card-images {
    display: flex;
    gap: 6px;
    margin-bottom: 14px;
    overflow: hidden;
}

.note-card-images img {
    width: 60px;
    height: 60px;
    object-fit: cover;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border);
}

.note-card-images .more-images {
    width: 60px;
    height: 60px;
    background: var(--bg-tertiary);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    color: var(--text-muted);
    border: 1px solid var(--border);
}

.note-card-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 12px;
    border-top: 1px solid var(--border);
}

.note-card-date {
    font-size: 12px;
    color: var(--text-muted);
}

.note-card-tags {
    display: flex;
    gap: 4px;
    flex-wrap: wrap;
}

.note-tag {
    font-size: 11px;
    padding: 2px 8px;
    background: var(--bg-tertiary);
    color: var(--text-muted);
    border-radius: 10px;
}

/* 列表视图 */
.list-view .note-card {
    display: flex;
    gap: 20px;
    align-items: center;
}

.list-view .note-card-main {
    flex: 1;
}

.list-view .note-card-thumb {
    width: 80px;
    height: 80px;
    border-radius: var(--radius-md);
    object-fit: cover;
    flex-shrink: 0;
}

/* 空状态 */
.empty-state {
    text-align: center;
    padding: 80px 20px;
}

.empty-icon {
    font-size: 64px;
    margin-bottom: 20px;
    opacity: 0.5;
}

.empty-state h3 {
    font-size: 20px;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.empty-state p {
    color: var(--text-muted);
    margin-bottom: 24px;
    font-size: 14px;
}

/* ========== 模态框 ========== */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.6);
    backdrop-filter: blur(8px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    padding: 20px;
}

.modal-overlay.active {
    opacity: 1;
    visibility: visible;
}

.modal {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius-xl);
    width: 100%;
    max-width: 600px;
    max-height: 90vh;
    display: flex;
    flex-direction: column;
    transform: scale(0.95) translateY(20px);
    transition: var(--transition);
    box-shadow: var(--shadow-lg);
}

.modal-overlay.active .modal {
    transform: scale(1) translateY(0);
}

.note-modal {
    max-width: 640px;
}

.detail-modal {
    max-width: 720px;
}

.category-modal {
    max-width: 440px;
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 24px 28px;
    border-bottom: 1px solid var(--border);
}

.modal-header h2 {
    font-size: 20px;
    font-weight: 600;
}

.detail-header-info {
    display: flex;
    align-items: center;
    gap: 12px;
    flex: 1;
}

.detail-actions {
    display: flex;
    gap: 4px;
}

.modal-body {
    padding: 24px 28px;
    overflow-y: auto;
    flex: 1;
}

.modal-footer {
    display: flex;
    justify-content: flex-end;
    gap: 12px;
    padding: 20px 28px;
    border-top: 1px solid var(--border);
}

/* 表单 */
.form-group {
    margin-bottom: 20px;
}

.form-group:last-child {
    margin-bottom: 0;
}

.form-group label {
    display: block;
    font-size: 13px;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 8px;
}

.form-input,
.form-textarea,
select.form-input {
    width: 100%;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    color: var(--text-primary);
    padding: 12px 16px;
    border-radius: var(--radius-md);
    font-size: 14px;
    transition: var(--transition);
    outline: none;
    font-family: inherit;
}

.form-input:focus,
.form-textarea:focus,
select.form-input:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

.form-textarea {
    min-height: 140px;
    resize: vertical;
    line-height: 1.6;
}

select.form-input {
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%239898b0' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 16px center;
    padding-right: 40px;
}

/* 类型选择器 */
.type-selector {
    display: flex;
    gap: 12px;
}

.type-option {
    flex: 1;
    cursor: pointer;
}

.type-option input {
    display: none;
}

.type-label {
    display: block;
    text-align: center;
    padding: 12px;
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    font-size: 14px;
    font-weight: 500;
    transition: var(--transition);
    background: var(--bg-tertiary);
}

.type-option input:checked + .type-label.note-type {
    border-color: var(--note);
    background: rgba(59, 130, 246, 0.1);
    color: #60a5fa;
}

.type-option input:checked + .type-label.mistake-type {
    border-color: var(--mistake);
    background: rgba(239, 68, 68, 0.1);
    color: #f87171;
}

/* 上传区域 */
.upload-area {
    border: 2px dashed var(--border);
    border-radius: var(--radius-md);
    padding: 24px;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    background: var(--bg-tertiary);
}

.upload-area:hover,
.upload-area.dragover {
    border-color: var(--accent);
    background: rgba(99, 102, 241, 0.05);
}

.upload-icon {
    font-size: 32px;
    display: block;
    margin-bottom: 8px;
}

.upload-placeholder p {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 4px;
}

.upload-hint {
    font-size: 12px;
    color: var(--text-muted);
}

.upload-preview {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 16px;
    justify-content: center;
}

.preview-item {
    position: relative;
    width: 80px;
    height: 80px;
    border-radius: var(--radius-sm);
    overflow: hidden;
    border: 1px solid var(--border);
}

.preview-item img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.preview-remove {
    position: absolute;
    top: 4px;
    right: 4px;
    width: 20px;
    height: 20px;
    background: rgba(0,0,0,0.7);
    color: white;
    border: none;
    border-radius: 50%;
    font-size: 12px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
}

/* 图标/颜色选择器 */
.icon-picker,
.color-picker {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.icon-option {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    border: 2px solid transparent;
    transition: var(--transition);
    background: var(--bg-tertiary);
}

.icon-option:hover {
    background: var(--bg-hover);
}

.icon-option.active {
    border-color: var(--accent);
    background: rgba(99, 102, 241, 0.15);
}

.color-option {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    cursor: pointer;
    border: 3px solid transparent;
    transition: var(--transition);
}

.color-option.active {
    border-color: white;
    box-shadow: 0 0 0 2px var(--accent);
}

/* ========== 详情页 ========== */
.detail-type-badge {
    font-size: 12px;
    font-weight: 600;
    padding: 4px 12px;
    border-radius: 20px;
}

.detail-type-badge.note {
    background: rgba(59, 130, 246, 0.15);
    color: #60a5fa;
}

.detail-type-badge.mistake {
    background: rgba(239, 68, 68, 0.15);
    color: #f87171;
}

.detail-meta {
    display: flex;
    gap: 16px;
    margin-bottom: 20px;
    font-size: 13px;
    color: var(--text-muted);
}

.detail-category {
    display: flex;
    align-items: center;
    gap: 4px;
}

.detail-tags {
    display: flex;
    gap: 6px;
    flex-wrap: wrap;
    margin-bottom: 20px;
}

.detail-content {
    font-size: 15px;
    line-height: 1.8;
    color: var(--text-secondary);
    white-space: pre-wrap;
    margin-bottom: 24px;
}

.detail-images {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 12px;
}

.detail-images img {
    width: 100%;
    border-radius: var(--radius-md);
    border: 1px solid var(--border);
    cursor: pointer;
    transition: var(--transition);
}

.detail-images img:hover {
    transform: scale(1.02);
}

/* ========== Toast ========== */
.toast-container {
    position: fixed;
    top: 24px;
    right: 24px;
    z-index: 2000;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.toast {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-left: 4px solid var(--accent);
    padding: 14px 20px;
    border-radius: var(--radius-md);
    font-size: 14px;
    box-shadow: var(--shadow-lg);
    animation: toastIn 0.3s ease;
    min-width: 240px;
}

.toast.success { border-left-color: var(--success); }
.toast.error { border-left-color: var(--danger); }

@keyframes toastIn {
    from { opacity: 0; transform: translateX(100%); }
    to { opacity: 1; transform: translateX(0); }
}

.toast.out {
    animation: toastOut 0.3s ease forwards;
}

@keyframes toastOut {
    to { opacity: 0; transform: translateX(100%); }
}

/* ========== 响应式 ========== */
@media (max-width: 900px) {
    .sidebar {
        transform: translateX(-100%);
    }
    .sidebar.open {
        transform: translateX(0);
    }
    .main-content {
        margin-left: 0;
        padding: 16px;
    }
    .menu-toggle {
        display: inline-flex;
    }
    .topbar {
        flex-wrap: wrap;
    }
    .search-box {
        max-width: 100%;
        order: 3;
        flex-basis: 100%;
    }
    .notes-container {
        grid-template-columns: 1fr;
    }
    .page-title {
        font-size: 22px;
    }
}

@media (max-width: 480px) {
    .filter-group {
        display: none;
    }
    .modal-header,
    .modal-body,
    .modal-footer {
        padding: 16px;
    }
}

/* 滚动条 */
::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}

::-webkit-scrollbar-track {
    background: transparent;
}

::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--text-muted);
}