:root{
  --bg:#0b0f12;
  --card:#071018;
  --muted:#88939a;
  --accent:#00d1b2;
  --accent-2:#7af0d9;
  --glass: rgba(255,255,255,0.03);
  --danger:#ff6b6b;
  --mono: ui-monospace, SFMono-Regular, Menlo, Monaco, "Roboto Mono", "Source Code Pro", monospace;
  --btn-hover-bg: rgba(0, 209, 178, 0.2);
  --btn-focus-outline: rgba(0, 209, 178, 0.5);
}

*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  font-family: Inter, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;
  background: linear-gradient(180deg, #020306 0%, #071219 100%);
  color: #e6eef0;
  -webkit-font-smoothing:antialiased;
  -moz-osx-font-smoothing:grayscale;
  padding:24px;
  display:flex;
  flex-direction:column;
  min-height: 100vh;
  align-items:center;
  justify-content:center;
}

/* page center */
.page {
  width:100%;
  max-width:980px;
  display:flex;
  align-items:center;
  justify-content:center;
  padding:12px;
  flex-grow:1;
}

/* boxed card */
.card{
  width:100%;
  background: linear-gradient(180deg, rgba(255,255,255,0.02), rgba(255,255,255,0.01));
  border: 1px solid rgba(255,255,255,0.04);
  border-radius: 14px;
  padding:22px;
  box-shadow: 0 8px 30px rgba(2,6,10,0.7);
  backdrop-filter: blur(6px);
  display:flex;
  flex-direction: column;
}

/* head */
.card-head { display:flex; flex-direction:column; gap:6px; margin-bottom:14px; }
.title { font-size:20px; margin:0; letter-spacing:0.4px; font-weight:700; }
.subtitle { margin:0; color:var(--muted); font-size:13px; }

/* form */
.form { display:flex; flex-direction:column; gap:10px; }
.label { color:var(--muted); font-size:13px; margin-bottom:6px; }
.input {
  background: var(--glass);
  border:1px solid rgba(255,255,255,0.03);
  color: #e6eef0;
  padding:12px 14px;
  border-radius:8px;
  outline:none;
  font-size:15px;
  width:100%;
  font-family: var(--mono);
}
.input::placeholder{
  color: rgba(230,238,240,0.35);
  font-family: var(--mono);
}

/* row of buttons */
.row { display:flex; gap:8px; width:100%; }
.btn {
  flex:1;
  padding:10px 12px;
  border-radius:10px;
  background:rgba(255,255,255,0.02);
  color: #d8eef0;
  border:1px solid rgba(255,255,255,0.03);
  font-weight:600;
  cursor:pointer;
  font-size:14px;
  transition: all .12s ease;
  user-select:none;
  -webkit-tap-highlight-color: transparent; /* remove default tap highlight */
}
.btn:hover,
.btn:focus-visible {
  background: var(--btn-hover-bg);
  outline: none;
  box-shadow: 0 0 6px var(--btn-focus-outline);
}
.primary {
  background: linear-gradient(90deg, rgba(0,209,178,0.12), rgba(122,240,217,0.06));
  border: 1px solid rgba(0,209,178,0.18);
  color: var(--accent-2);
  flex:1.35;
}

/* code panel */
.code-panel{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:10px;
  padding:14px;
  background: rgba(0,0,0,0.35);
  border-radius:10px;
  border:1px solid rgba(255,255,255,0.02);
  margin-top:6px;
}
.code-left { display:flex; flex-direction:column; gap:6px; }
.small { font-size:12px; color:var(--muted); }
.code {
  font-family: var(--mono);
  font-size:28px;
  letter-spacing:6px;
  color:#dffbf0;
  user-select: all;
}
.timer {
  font-weight:700;
  color:var(--accent-2);
  font-size:18px;
  font-family:var(--mono);
}

/* copy button & msg */
.copy-btn {
  margin-top: 10px;
  padding: 8px 12px;
  font-size: 13px;
  background: rgba(0,209,178,0.15);
  border: 1px solid rgba(0,209,178,0.3);
  color: var(--accent-2);
  border-radius: 8px;
  cursor: pointer;
  transition: background-color 0.15s ease;
  user-select:none;
}
.copy-btn:hover,
.copy-btn:focus-visible {
  background: var(--accent-2);
  color: var(--bg);
  outline: none;
}
.copy-msg {
  margin-top: 6px;
  font-size: 13px;
  color: var(--accent-2);
  min-height: 18px;
  font-weight: 600;
  user-select:none;
}

/* verify area */
.verify { margin-top:6px; display:flex; flex-direction:column; gap:8px; }
.verify-result {
  font-size:13px;
  min-height:18px;
  color:var(--muted);
}

/* error & note */
.error {
  color: var(--danger);
  font-size:13px;
  min-height:18px;
  margin-top:4px;
}
.note {
  margin-top:10px;
  font-size:12px;
  color:var(--muted);
}

/* responsive */
@media (max-width:720px){
  .card { padding:16px; border-radius:12px; }
  .code { font-size:24px; letter-spacing:5px; }
  .row { flex-direction:row; flex-wrap: wrap; }
  .btn { min-width: 70px; }
  .title { font-size:18px; }
}
@media (max-width:420px){
  .row { gap:6px; }
  .btn { padding:10px 8px; font-size:13px; }
  .code { font-size:22px; letter-spacing:4px; }
}