:root {
    --bg-main: #f8f9fa;
    --bg-canvas: #ffffff;
    --text-primary: #1a1d23;
    --text-secondary: #64748b;
    --accent: #3b82f6;
    --accent-hover: #2563eb;
    --border-color: #e2e8f0;
    --node-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
    --header-height: 64px;
    --panel-bg: rgba(255, 255, 255, 0.8);
}

* {
    box-sizing: border-box;
    outline: none;
}

body, html {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-main);
    color: var(--text-primary);
    overflow: hidden;
}

body.hand-drawn {
    font-family: 'Architects Daughter', cursive;
}

/* Drop Zone */
#drop-zone {
    position: fixed;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    background: var(--bg-main);
    padding: 20px;
}

.drop-card {
    background: white;
    padding: 48px;
    border-radius: 24px;
    box-shadow: 0 20px 40px rgba(0,0,0,0.05);
    text-align: center;
    max-width: 400px;
    width: 100%;
    border: 2px dashed var(--border-color);
    transition: all 0.3s ease;
}

#drop-zone.drag-over .drop-card {
    border-color: var(--accent);
    background: #f0f7ff;
    transform: scale(1.02);
}

.drop-icon {
    margin-bottom: 24px;
    color: var(--accent);
}

/* App Header */
.app-header {
    height: var(--header-height);
    background: var(--panel-bg);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 24px;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
}

.logo {
    font-weight: 700;
    font-size: 20px;
    letter-spacing: -0.5px;
    color: var(--accent);
}

.filename {
    margin-left: 16px;
    padding-left: 16px;
    border-left: 1px solid var(--border-color);
    color: var(--text-secondary);
    font-size: 14px;
}

.mode-selector {
    background: #f1f5f9;
    padding: 4px;
    border-radius: 12px;
    display: flex;
}

.mode-btn {
    padding: 8px 16px;
    border: none;
    border-radius: 8px;
    background: transparent;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
}

.mode-btn.active {
    background: white;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
    color: var(--accent);
}

/* Canvas Area */
#canvas-container {
    width: 100vw;
    height: 100vh;
    background-color: var(--bg-canvas);
    background-image: 
        radial-gradient(#e2e8f0 1px, transparent 0);
    background-size: 24px 24px;
}

#canvas-viewport {
    width: 100%;
    height: 100%;
    cursor: grab;
    overflow: hidden;
}

#canvas-viewport.edit-mode {
    cursor: crosshair;
}

#canvas-content {
    position: absolute;
    transform-origin: 0 0;
    will-change: transform;
}

#edges-layer {
    position: absolute;
    pointer-events: none;
    overflow: visible;
}

/* Nodes */
.node {
    position: absolute;
    background: white;
    border-radius: 12px;
    box-shadow: var(--node-shadow);
    border: 1px solid var(--border-color);
    overflow: hidden;
    display: flex;
    flex-direction: column;
    transition: box-shadow 0.2s;
    cursor: default;
}

.node:hover {
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.08);
}

.edit-mode .node {
    cursor: move;
}

.node-content {
    padding: 16px;
    font-size: 14px;
    line-height: 1.6;
    color: #334155;
    flex: 1;
    overflow-y: auto;
    overflow-x: hidden;
}

/* View mode scrollbar styling - 只在 view mode 下显示滚动条 */
#canvas-viewport:not(.edit-mode) .node-content::-webkit-scrollbar {
    width: 6px;
}

#canvas-viewport:not(.edit-mode) .node-content::-webkit-scrollbar-track {
    background: transparent;
}

#canvas-viewport:not(.edit-mode) .node-content::-webkit-scrollbar-thumb {
    background: #cbd5e1;
    border-radius: 3px;
}

#canvas-viewport:not(.edit-mode) .node-content::-webkit-scrollbar-thumb:hover {
    background: #94a3b8;
}

/* Edit mode 下隐藏滚动条 */
#canvas-viewport.edit-mode .node-content {
    overflow-y: hidden;
}

.node-group {
    background: rgba(241, 245, 249, 0.5);
    border: 2px dashed var(--border-color);
    box-shadow: none;
    z-index: 0 !important;
}

.node-group-label {
    position: absolute;
    top: -28px;
    left: 4px;
    font-weight: 600;
    font-size: 13px;
    color: var(--text-secondary);
}

/* Buttons */
.primary-btn {
    background: var(--accent);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 10px;
    font-weight: 500;
    cursor: pointer;
    transition: background 0.2s;
}

.primary-btn:hover { background: var(--accent-hover); }

.ghost-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    padding: 8px 16px;
    border-radius: 10px;
    cursor: pointer;
    font-size: 14px;
}

/* Floating Controls */
.floating-controls {
    position: fixed;
    bottom: 24px;
    right: 24px;
    background: var(--panel-bg);
    backdrop-filter: blur(12px);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 8px 16px;
    display: flex;
    align-items: center;
    gap: 16px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.05);
    z-index: 100;
}

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

.control-group button {
    width: 32px;
    height: 32px;
    border: 1px solid var(--border-color);
    background: white;
    border-radius: 8px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
}

#zoom-level {
    font-size: 13px;
    font-weight: 600;
    min-width: 40px;
    text-align: center;
}

.divider {
    width: 1px;
    height: 24px;
    background: var(--border-color);
}

/* Edit Toolbar */
.edit-toolbar {
    position: fixed;
    top: 50%;
    left: 24px;
    transform: translateY(-50%);
    background: var(--panel-bg);
    backdrop-filter: blur(12px);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 8px;
    display: flex;
    flex-direction: column;
    gap: 8px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.05);
    z-index: 100;
}

.edit-toolbar button {
    width: 44px;
    height: 44px;
    border: none;
    background: transparent;
    border-radius: 12px;
    cursor: pointer;
    color: var(--text-secondary);
    transition: all 0.2s;
}

.edit-toolbar button:hover {
    background: #f1f5f9;
    color: var(--accent);
}

/* Context Menu */
.context-menu {
    position: fixed;
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    z-index: 1000;
    min-width: 160px;
    padding: 6px;
}

.context-menu ul {
    list-style: none;
    margin: 0;
    padding: 0;
}

.context-menu li {
    padding: 8px 12px;
    font-size: 13px;
    cursor: pointer;
    border-radius: 6px;
    transition: background 0.2s;
}

.context-menu li:hover {
    background: #f1f5f9;
}

.context-menu li.danger {
    color: #ef4444;
}

.context-menu li.danger:hover {
    background: #fef2f2;
}

.separator {
    height: 1px;
    background: var(--border-color);
    margin: 4px 0;
}

/* Modal */
.modal {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.4);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
}

.modal-content {
    background: white;
    padding: 32px;
    border-radius: 24px;
    width: 100%;
    max-width: 500px;
    box-shadow: 0 20px 50px rgba(0,0,0,0.2);
}

.form-group label {
    display: block;
    font-size: 13px;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-secondary);
}

textarea {
    width: 100%;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 12px;
    font-family: inherit;
    resize: vertical;
}

.modal-actions {
    margin-top: 24px;
    display: flex;
    justify-content: flex-end;
    gap: 12px;
}

/* Toggle Switch */
.switch {
    position: relative;
    display: inline-block;
    width: 32px;
    height: 18px;
}

.switch input { opacity: 0; width: 0; height: 0; }

.slider {
    position: absolute;
    cursor: pointer;
    inset: 0;
    background-color: #cbd5e1;
    transition: .4s;
    border-radius: 18px;
}

.slider:before {
    position: absolute;
    content: "";
    height: 14px;
    width: 14px;
    left: 2px;
    bottom: 2px;
    background-color: white;
    transition: .4s;
    border-radius: 50%;
}

input:checked + .slider { background-color: var(--accent); }
input:checked + .slider:before { transform: translateX(14px); }

.hidden { display: none !important; }