Add better instruction on how to customize the theme

BTCPayServer/BTCPayServer.csproj

@@ -2,7 +2,7 @@
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <TargetFramework>netcoreapp2.1</TargetFramework>
-		<Version>1.0.3.15</Version>
+		<Version>1.0.3.16</Version>
     <NoWarn>NU1701,CA1816,CA1308,CA1810,CA2208</NoWarn>
   </PropertyGroup>
   <PropertyGroup>

BTCPayServer/Models/AppViewModels/UpdatePointOfSaleViewModel.cs

@@ -26,12 +26,15 @@ namespace BTCPayServer.Models.AppViewModels
 
         [Required]
         [MaxLength(30)]
+        [Display(Name = "Text to display on each buttons for items with a specific price")]
         public string ButtonText { get; set; }
         [Required]
         [MaxLength(30)]
+        [Display(Name = "Text to display on buttons next to the input allowing the user to enter a custom amount")]
         public string CustomButtonText { get; set; }
 
         [MaxLength(500)]
+        [Display(Name = "Custom bootstrap CSS file")]
         public string CustomCSSLink { get; set; }
     }
 }

BTCPayServer/Services/ThemesSettings.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
 using System.Linq;
 using System.Threading.Tasks;
 using Newtonsoft.Json;
@@ -9,6 +10,8 @@ namespace BTCPayServer.Services
     public class ThemeSettings
     {
         [JsonProperty(DefaultValueHandling = DefaultValueHandling.Populate)]
+        [MaxLength(500)]
+        [Display(Name = "Custom bootstrap CSS file")]
         public string BootstrapCssUri { get; set; }
 
         [JsonProperty(DefaultValueHandling = DefaultValueHandling.Populate)]

BTCPayServer/Views/Apps/UpdatePointOfSale.cshtml

@@ -43,16 +43,17 @@
                         <input asp-for="CustomButtonText" class="form-control" />
                         <span asp-validation-for="CustomButtonText" class="text-danger"></span>
                     </div>
+                    <div class="form-group">
+                        <label asp-for="CustomCSSLink" class="control-label"></label>
+                        <a href="https://docs.btcpayserver.org/development/theme#bootstrap-themes" target="_blank"><span class="fa fa-question-circle-o" title="More information..."></span></a>
+                        <input asp-for="CustomCSSLink" class="form-control" />
+                        <span asp-validation-for="CustomCSSLink" class="text-danger"></span>
+                    </div>
                     <div class="form-group">
                         <label asp-for="Template" class="control-label"></label>*
                         <textarea asp-for="Template" rows="20" cols="40" class="form-control"></textarea>
                         <span asp-validation-for="Template" class="text-danger"></span>
                     </div>
-                    <div class="form-group">
-                        <label asp-for="CustomCSSLink" class="control-label"></label>
-                        <input asp-for="CustomCSSLink" class="form-control" />
-                        <span asp-validation-for="CustomCSSLink" class="text-danger"></span>
-                    </div>
                     <div class="form-group">
                         <h5>Host button externally</h5>
                         <p>You can host point of sale buttons in an external website with the following code.</p>

BTCPayServer/Views/Server/Theme.cshtml

@@ -16,6 +16,7 @@
         <form method="post">
             <div class="form-group">
                 <label asp-for="BootstrapCssUri"></label>
+                <a href="https://docs.btcpayserver.org/development/theme#bootstrap-themes" target="_blank"><span class="fa fa-question-circle-o" title="More information..."></span></a>
                 <input asp-for="BootstrapCssUri" class="form-control" />
                 <span asp-validation-for="BootstrapCssUri" class="text-danger"></span>
                 <p class="form-text text-muted">