* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 16px;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  background: linear-gradient(135deg, #1e3a8a, #2563eb);
}

.card {
  width: 100%;
  max-width: 420px;
  background: #fff;
  border-radius: 14px;
  padding: 32px 28px;
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.25);
}

h1 { margin: 0 0 6px; font-size: 26px; color: #111827; }
.sub { margin: 0 0 24px; color: #6b7280; }

label { display: block; margin-bottom: 6px; font-weight: 600; color: #374151; }

.phone-wrap {
  display: flex;
  border: 2px solid #d1d5db;
  border-radius: 8px;
  overflow: hidden;
}
.phone-wrap:focus-within { border-color: #2563eb; }

.prefix {
  padding: 12px 14px;
  background: #f3f4f6;
  color: #374151;
  font-weight: 600;
}

input {
  flex: 1;
  border: 0;
  padding: 12px;
  font-size: 16px;
  outline: none;
  min-width: 0;
}

.hint { display: block; margin-top: 6px; color: #9ca3af; }

button {
  width: 100%;
  margin-top: 20px;
  padding: 13px;
  font-size: 16px;
  font-weight: 600;
  color: #fff;
  background: #2563eb;
  border: 0;
  border-radius: 8px;
  cursor: pointer;
}
button:hover { background: #1d4ed8; }
button:disabled { background: #93c5fd; cursor: not-allowed; }

#message { margin-top: 16px; padding: 0; border-radius: 8px; font-size: 14px; }
#message.success { padding: 12px; background: #dcfce7; color: #166534; }
#message.error { padding: 12px; background: #fee2e2; color: #991b1b; }