diff --git a/js/package-lock.json b/js/package-lock.json
index 214a7c0..4a51a48 100644
--- a/js/package-lock.json
+++ b/js/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "jupyter-splitpanes",
-  "version": "0.1.0",
+  "version": "0.2.0",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
@@ -521,17 +521,6 @@
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           }
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-          "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.2.4.tgz",
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-          "dev": true,
-          "requires": {
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-            "nanoid": "^3.1.20",
-            "source-map": "^0.6.1"
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@@ -2527,6 +2516,23 @@
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           "dev": true
+        },
+        "postcss": {
+          "version": "7.0.36",
+          "resolved": "https://registry.npmjs.org/postcss/-/postcss-7.0.36.tgz",
+          "integrity": "sha512-BebJSIUMwJHRH0HAQoxN4u1CN86glsrwsW0q7T+/m44eXOUAxSNdHRkNZPYz5vVUbg17hFgOQDE7fZk7li3pZw==",
+          "dev": true,
+          "requires": {
+            "chalk": "^2.4.2",
+            "source-map": "^0.6.1",
+            "supports-color": "^6.1.0"
+          }
+        },
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+          "version": "0.6.1",
+          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
+          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
+          "dev": true
         }
       }
     },
@@ -4184,6 +4190,25 @@
       "dev": true,
       "requires": {
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+      },
+      "dependencies": {
+        "postcss": {
+          "version": "7.0.36",
+          "resolved": "https://registry.npmjs.org/postcss/-/postcss-7.0.36.tgz",
+          "integrity": "sha512-BebJSIUMwJHRH0HAQoxN4u1CN86glsrwsW0q7T+/m44eXOUAxSNdHRkNZPYz5vVUbg17hFgOQDE7fZk7li3pZw==",
+          "dev": true,
+          "requires": {
+            "chalk": "^2.4.2",
+            "source-map": "^0.6.1",
+            "supports-color": "^6.1.0"
+          }
+        },
+        "source-map": {
+          "version": "0.6.1",
+          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
+          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
+          "dev": true
+        }
       }
     },
     "ieee754": {
@@ -5166,12 +5191,6 @@
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       "optional": true
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-    "nanoid": {
-      "version": "3.1.20",
-      "resolved": "https://registry.npmjs.org/nanoid/-/nanoid-3.1.20.tgz",
-      "integrity": "sha512-a1cQNyczgKbLX9jwbS/+d7W8fX/RfgYR7lVWwWOGIPNgK2m0MWvrGF6/m4kk6U3QcFMnZf3RIhL0v2Jgh/0Uxw==",
-      "dev": true
-    },
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       "resolved": "https://registry.npmjs.org/nanomatch/-/nanomatch-1.2.13.tgz",
@@ -5658,36 +5677,27 @@
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-      "version": "7.0.26",
-      "resolved": "https://registry.npmjs.org/postcss/-/postcss-7.0.26.tgz",
-      "integrity": "sha512-IY4oRjpXWYshuTDFxMVkJDtWIk2LhsTlu8bZnbEJA4+bYT16Lvpo8Qv6EvDumhYRgzjZl489pmsY3qVgJQ08nA==",
+      "version": "8.3.4",
+      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.3.4.tgz",
+      "integrity": "sha512-/tZY0PXExXXnNhKv3TOvZAOUYRyuqcCbBm2c17YMDK0PlVII3K7/LKdt3ScHL+hhouddjUWi+1sKDf9xXW+8YA==",
       "dev": true,
       "requires": {
-        "chalk": "^2.4.2",
-        "source-map": "^0.6.1",
-        "supports-color": "^6.1.0"
+        "colorette": "^1.2.2",
+        "nanoid": "^3.1.23",
+        "source-map-js": "^0.6.2"
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       "dependencies": {
-        "has-flag": {
-          "version": "3.0.0",
-          "resolved": "https://registry.npmjs.org/has-flag/-/has-flag-3.0.0.tgz",
-          "integrity": "sha1-tdRU3CGZriJWmfNGfloH87lVuv0=",
+        "colorette": {
+          "version": "1.2.2",
+          "resolved": "https://registry.npmjs.org/colorette/-/colorette-1.2.2.tgz",
+          "integrity": "sha512-MKGMzyfeuutC/ZJ1cba9NqcNpfeqMUcYmyF1ZFY6/Cn7CNSAKx6a+s48sqLqyAiZuaP2TcqMhoo+dlwFnVxT9w==",
           "dev": true
         },
-        "source-map": {
-          "version": "0.6.1",
-          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
-          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
+        "nanoid": {
+          "version": "3.1.23",
+          "resolved": "https://registry.npmjs.org/nanoid/-/nanoid-3.1.23.tgz",
+          "integrity": "sha512-FiB0kzdP0FFVGDKlRLEQ1BgDzU87dy5NnzjeW9YZNt+/c3+q82EQDUwniSAUxp/F0gFNI1ZhKU1FqYsMuqZVnw==",
           "dev": true
-        },
-        "supports-color": {
-          "version": "6.1.0",
-          "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-6.1.0.tgz",
-          "integrity": "sha512-qe1jfm1Mg7Nq/NSh6XE24gPXROEVsWHxC1LIx//XNlD9iw7YZQGjZNjYN7xGaEG6iKdA8EtNFW6R0gjnVXp+wQ==",
-          "dev": true,
-          "requires": {
-            "has-flag": "^3.0.0"
-          }
         }
       }
     },
@@ -5698,6 +5708,25 @@
       "dev": true,
       "requires": {
         "postcss": "^7.0.5"
+      },
+      "dependencies": {
+        "postcss": {
+          "version": "7.0.36",
+          "resolved": "https://registry.npmjs.org/postcss/-/postcss-7.0.36.tgz",
+          "integrity": "sha512-BebJSIUMwJHRH0HAQoxN4u1CN86glsrwsW0q7T+/m44eXOUAxSNdHRkNZPYz5vVUbg17hFgOQDE7fZk7li3pZw==",
+          "dev": true,
+          "requires": {
+            "chalk": "^2.4.2",
+            "source-map": "^0.6.1",
+            "supports-color": "^6.1.0"
+          }
+        },
+        "source-map": {
+          "version": "0.6.1",
+          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
+          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
+          "dev": true
+        }
       }
     },
     "postcss-modules-local-by-default": {
@@ -5710,6 +5739,25 @@
         "postcss": "^7.0.16",
         "postcss-selector-parser": "^6.0.2",
         "postcss-value-parser": "^4.0.0"
+      },
+      "dependencies": {
+        "postcss": {
+          "version": "7.0.36",
+          "resolved": "https://registry.npmjs.org/postcss/-/postcss-7.0.36.tgz",
+          "integrity": "sha512-BebJSIUMwJHRH0HAQoxN4u1CN86glsrwsW0q7T+/m44eXOUAxSNdHRkNZPYz5vVUbg17hFgOQDE7fZk7li3pZw==",
+          "dev": true,
+          "requires": {
+            "chalk": "^2.4.2",
+            "source-map": "^0.6.1",
+            "supports-color": "^6.1.0"
+          }
+        },
+        "source-map": {
+          "version": "0.6.1",
+          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
+          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
+          "dev": true
+        }
       }
     },
     "postcss-modules-scope": {
@@ -5720,6 +5768,25 @@
       "requires": {
         "postcss": "^7.0.6",
         "postcss-selector-parser": "^6.0.0"
+      },
+      "dependencies": {
+        "postcss": {
+          "version": "7.0.36",
+          "resolved": "https://registry.npmjs.org/postcss/-/postcss-7.0.36.tgz",
+          "integrity": "sha512-BebJSIUMwJHRH0HAQoxN4u1CN86glsrwsW0q7T+/m44eXOUAxSNdHRkNZPYz5vVUbg17hFgOQDE7fZk7li3pZw==",
+          "dev": true,
+          "requires": {
+            "chalk": "^2.4.2",
+            "source-map": "^0.6.1",
+            "supports-color": "^6.1.0"
+          }
+        },
+        "source-map": {
+          "version": "0.6.1",
+          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
+          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
+          "dev": true
+        }
       }
     },
     "postcss-modules-values": {
@@ -5730,6 +5797,25 @@
       "requires": {
         "icss-utils": "^4.0.0",
         "postcss": "^7.0.6"
+      },
+      "dependencies": {
+        "postcss": {
+          "version": "7.0.36",
+          "resolved": "https://registry.npmjs.org/postcss/-/postcss-7.0.36.tgz",
+          "integrity": "sha512-BebJSIUMwJHRH0HAQoxN4u1CN86glsrwsW0q7T+/m44eXOUAxSNdHRkNZPYz5vVUbg17hFgOQDE7fZk7li3pZw==",
+          "dev": true,
+          "requires": {
+            "chalk": "^2.4.2",
+            "source-map": "^0.6.1",
+            "supports-color": "^6.1.0"
+          }
+        },
+        "source-map": {
+          "version": "0.6.1",
+          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
+          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
+          "dev": true
+        }
       }
     },
     "postcss-selector-parser": {
@@ -6439,6 +6525,12 @@
       "integrity": "sha1-igOdLRAh0i0eoUyA2OpGi6LvP8w=",
       "dev": true
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+    "source-map-js": {
+      "version": "0.6.2",
+      "resolved": "https://registry.npmjs.org/source-map-js/-/source-map-js-0.6.2.tgz",
+      "integrity": "sha512-/3GptzWzu0+0MBQFrDKzw/DvvMTUORvgY6k6jd/VS6iCR4RDTKWH6v6WPwQoUO8667uQEf9Oe38DxAYWY5F/Ug==",
+      "dev": true
+    },
     "source-map-resolve": {
       "version": "0.5.3",
       "resolved": "https://registry.npmjs.org/source-map-resolve/-/source-map-resolve-0.5.3.tgz",