Clarify Steam API key domain field is not validated

Adds a visible callout in the settings dialog and a "Don't have a
domain?" note + common-failure list in the README, so users (and the
friends they share the app with) don't bounce off the registration
page thinking they need to own a real domain.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

README.md

@@ -53,9 +53,17 @@ pacman -S python-steam
 
 You need a free Steam Web API key to fetch your library.
 
-1. Go to [steamcommunity.com/dev/apikey](https://steamcommunity.com/dev/apikey) and log in.
-2. Enter any domain name (e.g. `localhost`) and click **Register**.
-3. Copy the 32-character key shown on the page.
+1. Go to [steamcommunity.com/dev/apikey](https://steamcommunity.com/dev/apikey) and log in with your Steam account.
+2. In the **Domain Name** field, type any string and click **Register**.
+3. Copy the 32-character key shown on the next page — paste it into Steam Dice's settings dialog.
+
+> **Don't have a domain?** You don't need one. Steam's "Domain Name" field is **not validated** — `localhost`, your name, `personal`, or any other text works. It's just a label Steam stores alongside your key; it doesn't have to be a real domain you own.
+
+If the page refuses to issue a key, the usual causes are:
+
+- Your Steam account has spent **less than $5** lifetime on Steam (Valve's anti-spam threshold for API access).
+- Your account is **limited** (new account with no purchases) or has an unverified email.
+- You're signed into the wrong Steam account in your browser.
 
 ### 2. Steam ID (64-bit)
 

steam_dice.py

@@ -965,12 +965,20 @@ class SettingsDialog(QDialog):
 
         key_help = QLabel(
             'Get your free key at '
-            '<a href="https://steamcommunity.com/dev/apikey">steamcommunity.com/dev/apikey</a>.'
-            '<br>Log in with Steam, enter any domain name (e.g. <i>localhost</i>), and copy the key shown.'
+            '<a href="https://steamcommunity.com/dev/apikey">steamcommunity.com/dev/apikey</a>. '
+            'Log in with Steam, then copy the 32-character key shown after registering.'
+            '<br><br>'
+            '<b>Don\'t have a domain?</b> You don\'t need one. The <i>Domain Name</i> field '
+            'on Steam\'s page is <b>not validated</b> — type literally anything '
+            '(<i>localhost</i>, your name, <i>personal</i>) and click <b>Register</b>.'
         )
         key_help.setOpenExternalLinks(True)
         key_help.setWordWrap(True)
-        key_help.setStyleSheet("color: #8f98a0; font-size: 9pt; padding-bottom: 10px;")
+        key_help.setStyleSheet(
+            "color: #c7d5e0; font-size: 9pt; "
+            "background-color: #1f2a36; border: 1px solid #2a475e; border-radius: 4px; "
+            "padding: 8px 10px; margin-bottom: 10px;"
+        )
         layout.addWidget(key_help)
 
         # --- Steam ID ---