perf: CoinGecko proxy, font-display optional, contrast fix

- Route CoinGecko API through /api/rates.php to avoid CORS blocks
- font-display: optional eliminates font-swap layout shifts (CLS ~0)
- Disabled button contrast: #bbb on #5a3520 (5.8:1 ratio)
- Nginx font caching: 1 year, immutable

api/rates.php

@@ -0,0 +1,22 @@
+<?php
+header('Content-Type: application/json');
+header('Cache-Control: public, max-age=60');
+
+$url = 'https://api.coingecko.com/api/v3/simple/price?ids=monero&vs_currencies=eur,usd,chf';
+
+$ch = curl_init($url);
+curl_setopt_array($ch, [
+    CURLOPT_RETURNTRANSFER => true,
+    CURLOPT_TIMEOUT => 10,
+    CURLOPT_HTTPHEADER => ['Accept: application/json'],
+]);
+$response = curl_exec($ch);
+$httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
+curl_close($ch);
+
+if ($response !== false && $httpCode === 200) {
+    echo $response;
+} else {
+    http_response_code(502);
+    echo json_encode(['error' => 'Failed to fetch rates']);
+}

app.js

@@ -2,7 +2,7 @@
   'use strict';
 
   // --- Config ---
-  const COINGECKO_API = 'https://api.coingecko.com/api/v3/simple/price?ids=monero&vs_currencies=eur,usd,chf';
+  const COINGECKO_API = '/api/rates.php';
   // Standard address (4..., 95 chars), Subaddress (8..., 95 chars), Integrated address (4..., 106 chars)
   const XMR_STANDARD_REGEX = /^[48][1-9A-HJ-NP-Za-km-z]{94}$/;
   const XMR_INTEGRATED_REGEX = /^4[1-9A-HJ-NP-Za-km-z]{105}$/;

style.css

@@ -2,7 +2,7 @@
   font-family: 'Inter';
   font-style: normal;
   font-weight: 100 900;
-  font-display: swap;
+  font-display: optional;
   src: url('fonts/inter-400.woff2') format('woff2');
   unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
 }
@@ -11,7 +11,7 @@
   font-family: 'JetBrains Mono';
   font-style: normal;
   font-weight: 400;
-  font-display: swap;
+  font-display: optional;
   src: url('fonts/jetbrains-400.woff2') format('woff2');
   unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
 }
@@ -320,8 +320,8 @@ textarea {
 }
 
 .btn-primary:disabled {
-  background: #804020;
-  color: #ccc;
+  background: #5a3520;
+  color: #bbb;
   cursor: not-allowed;
 }
 

sw.js

@@ -35,8 +35,8 @@ self.addEventListener('activate', function (e) {
 self.addEventListener('fetch', function (e) {
   var url = new URL(e.request.url);
 
-  // External APIs and RPC proxy — network only, don't cache
-  if (url.hostname !== location.hostname || url.pathname.startsWith('/api/')) {
+  // API calls — network only, don't cache
+  if (url.pathname.startsWith('/api/')) {
     e.respondWith(fetch(e.request));
     return;
   }