use a number display to avoid wrong input and support locales

htdocs/css/openwebrx.css

@@ -357,6 +357,13 @@ input[type=range]:disabled {
     flex: 1 0 auto;
     margin-right: 0;
     border-right: 1px solid #373737;
+    -moz-appearance: textfield;
+}
+
+.webrx-actual-freq .input-group input::-webkit-outer-spin-button,
+.webrx-actual-freq .input-group input::-webkit-inner-spin-button {
+    -webkit-appearance: none;
+    margin: 0;
 }
 
 .input-group > :not(:last-child) {

htdocs/lib/FrequencyDisplay.js

@@ -76,7 +76,7 @@ TuneableFrequencyDisplay.prototype = new FrequencyDisplay();
 
 TuneableFrequencyDisplay.prototype.setupElements = function() {
     FrequencyDisplay.prototype.setupElements.call(this);
-    this.input = $('<input>');
+    this.input = $('<input type="number" step="any">');
     this.suffixInput = $('<select tabindex="-1">');
     this.suffixInput.append($.map(this.suffixes, function(e, p) {
         return $('<option value="' + e + '">' + p + 'Hz</option>');