:root {
  --bg: #f4f5f7; --card: #fff; --text: #16181d; --muted: #6b7280; --line: #e5e7eb;
  --primary: #2563eb; --primary-text: #fff; --danger: #dc2626; --ok: #059669; --mark: #fef3c7;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #0f1115; --card: #171a21; --text: #e7e9ee; --muted: #9aa3b2; --line: #262b36;
          --primary: #3b82f6; --danger: #ef4444; --ok: #10b981; --mark: #3b2f0b; }
}
* { box-sizing: border-box; }
/* The hidden attribute only carries UA-stylesheet weight; any display rule
   below would override it and show empty code rows on JS-rendered letters. */
[hidden] { display: none !important; }
body { margin: 0; background: var(--bg); color: var(--text); font: 16px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif; }
a { color: var(--primary); }
.top { display: flex; justify-content: space-between; align-items: center; padding: 14px 20px; }
.brand { color: var(--text); text-decoration: none; font-weight: 700; }
.langs a { margin-left: 10px; text-decoration: none; color: var(--muted); font-size: 13px; }
.langs a.on { color: var(--text); font-weight: 700; }
.wrap { max-width: 760px; margin: 0 auto; padding: 0 16px 40px; }
.card { background: var(--card); border: 1px solid var(--line); border-radius: 14px; padding: 22px; margin-bottom: 16px; }
.center { text-align: center; }
h1 { font-size: 26px; margin: 0 0 8px; }
h2 { font-size: 20px; margin: 16px 0 6px; }
.muted { color: var(--muted); }
.small { font-size: 13px; }
.label { font-size: 12px; text-transform: uppercase; letter-spacing: .04em; color: var(--muted); }
.note, .err, .ok { padding: 10px 12px; border-radius: 10px; margin: 12px 0; font-size: 14px; }
.note { background: var(--line); }
.err { color: var(--danger); background: rgba(220,38,38,.08); }
.ok { color: var(--ok); background: rgba(5,150,105,.08); }
.code-form { display: flex; flex-direction: column; gap: 10px; align-items: center; margin-top: 18px; }
.code-form input { font: inherit; font-size: 22px; letter-spacing: .12em; text-align: center; text-transform: uppercase;
  padding: 12px 14px; border: 1px solid var(--line); border-radius: 10px; background: var(--bg); color: var(--text); width: 260px; }
.btn { display: inline-block; font: inherit; font-size: 14px; padding: 8px 14px; border-radius: 10px; border: 1px solid var(--line);
  background: var(--card); color: var(--text); cursor: pointer; text-decoration: none; }
.btn:hover { border-color: var(--primary); }
.btn.primary { background: var(--primary); border-color: var(--primary); color: var(--primary-text); }
.btn.danger { color: var(--danger); border-color: var(--danger); }
.btn.big { font-size: 17px; padding: 12px 22px; }
.btn.small { font-size: 13px; padding: 6px 10px; }
.address-row { display: flex; justify-content: space-between; gap: 16px; align-items: flex-start; flex-wrap: wrap; }
hr.sep { border: 0; border-top: 1px solid var(--line); margin: 14px 0; }
.address { font-size: 22px; font-weight: 700; word-break: break-all; margin: 2px 0; }
.actions { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; }
.actions form { margin: 0; }
.empty { text-align: center; padding: 30px 10px; }
.spinner { width: 28px; height: 28px; border: 3px solid var(--line); border-top-color: var(--primary); border-radius: 50%;
  margin: 0 auto 12px; animation: spin 1s linear infinite; }
@keyframes spin { to { transform: rotate(360deg); } }
.messages { list-style: none; margin: 0; padding: 0; }
.msg { border-top: 1px solid var(--line); padding: 14px 0; }
.msg:first-child { border-top: 0; }
.msg-head { display: flex; align-items: center; gap: 8px; font-size: 13px; color: var(--muted); }
.msg-head .time { margin-left: auto; }
.msg .kind { font-weight: 600; }
/* Which half of an issued pair the letter landed in. */
.msg .box { border: 1px solid var(--line); border-radius: 999px; padding: 1px 8px; font-size: 12px; }
.msg .box-contact { border-color: var(--primary); color: var(--primary); }
.kind-verification_code .kind { color: var(--ok); }
.kind-restriction .kind { color: var(--danger); }
.msg-from { font-size: 14px; margin-top: 4px; }
.msg-subject { font-weight: 600; margin: 4px 0 8px; }
.code-row { display: flex; align-items: center; gap: 10px; margin: 8px 0; flex-wrap: wrap; }
mark.code { background: var(--mark); color: var(--text); font-size: 24px; font-weight: 700; letter-spacing: .1em; padding: 4px 10px; border-radius: 8px; }
.msg-actions { display: flex; gap: 8px; flex-wrap: wrap; }
.frame-holder iframe { width: 100%; height: 520px; border: 1px solid var(--line); border-radius: 10px; margin-top: 10px; background: #fff; }
.flash { position: fixed; bottom: 20px; left: 50%; transform: translateX(-50%); background: var(--text); color: var(--bg); padding: 8px 14px; border-radius: 10px; font-size: 14px; opacity: 0; transition: opacity .2s; pointer-events: none; }
.flash.show { opacity: 1; }
@media (max-width: 520px) { .address { font-size: 18px; } .frame-holder iframe { height: 420px; } }