Add stylelint and fix a few errors

.stylelintrc

@@ -0,0 +1,5 @@
+extends: stylelint-config-standard
+
+rules:
+  color-hex-case: upper
+  selector-list-comma-newline-after: null

package.json

@@ -27,7 +27,10 @@
     "eslint-plugin-node": "5.0.0",
     "eslint-plugin-security": "1.3.0",
     "htmllint-cli": "0.0.6",
+    "npm-run-all": "4.0.2",
     "prettier": "1.4.4",
+    "stylelint": "7.11.0",
+    "stylelint-config-standard": "16.0.0",
     "watchify": "^3.9.0"
   },
   "engines": {
@@ -38,8 +41,10 @@
   "scripts": {
     "dev": "watchify frontend/src/main.js -o public/bundle.js -d | node server/portal_server.js",
     "format": "prettier 'frontend/src/*.js' 'server/*.js' 'public/*.css' --single-quote --write",
-    "lint": "eslint .",
+    "lint": "npm-run-all lint:*",
+    "lint:css": "stylelint 'public/*.css'",
     "lint:html": "htmllint 'views/*.handlebars'",
+    "lint:js": "eslint .",
     "start": "watchify frontend/src/main.js -o public/bundle.js -d | cross-env NODE_ENV=production node server/portal_server.js",
     "test": "echo \"Error: no test specified\" && exit 1"
   }

public/main.css

@@ -12,6 +12,7 @@ html {
   align-content: center;
   flex-direction: column;
 }
+
 input, select, textarea, button {
   font-family: inherit;
 }
@@ -34,7 +35,6 @@ input, select, textarea, button {
 
 .upload-window {
   border: 1px dashed;
-  width: 50%;
   margin: 0 auto;
   width: 470px;
   height: 250px;
@@ -120,7 +120,7 @@ td {
   visibility: hidden;
   width: 160px;
   background-color: #555;
-  color: #fff;
+  color: #FFF;
   text-align: center;
   border-radius: 6px;
   padding: 8px 0;
@@ -142,7 +142,7 @@ td {
   margin-left: -5px;
   border-width: 5px;
   border-style: solid;
-  border-color: #555 transparent transparent transparent;
+  border-color: #555 transparent transparent;
 }
 
 .popup .show {
@@ -154,7 +154,6 @@ td {
 
 /**   share-link    **/
 .share-window {
-  width: 50%;
   margin: 0 auto;
   width: 470px;
   height: 250px;