:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --bg: #f4f7fb;
  --card: #ffffff;
  --text: #172033;
  --muted: #64748b;
  --border: #e2e8f0;
  --success: #16a34a;
  --danger: #dc2626;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  background: var(--bg);
  color: var(--text);
}
.header {
  background: linear-gradient(135deg, var(--primary), #0f172a);
  color: #fff;
  padding: 18px 20px;
}
.nav-wrap {
  max-width: 1100px;
  margin: auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 15px;
}
.logo { font-size: 24px; font-weight: 800; }
.nav a {
  color: #fff;
  text-decoration: none;
  margin-left: 16px;
  font-weight: 600;
  font-size: 14px;
}
.hero {
  max-width: 1100px;
  margin: 35px auto 20px;
  padding: 0 20px;
  text-align: center;
}
.hero h1 {
  font-size: 42px;
  margin: 15px 0 10px;
}
.hero p {
  color: var(--muted);
  font-size: 18px;
}
.mail-card, .inbox-card, .content-card {
  max-width: 900px;
  margin: 22px auto;
  padding: 24px;
  background: var(--card);
  border-radius: 18px;
  box-shadow: 0 12px 35px rgba(15, 23, 42, .08);
  border: 1px solid var(--border);
}
.email-display {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  border: 2px dashed #bfdbfe;
  background: #eff6ff;
  border-radius: 14px;
  padding: 16px;
  margin-bottom: 18px;
}
.email-text {
  font-size: 24px;
  font-weight: 800;
  color: var(--primary-dark);
  word-break: break-all;
  text-align: left;
}
.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
}
button, .btn {
  border: 0;
  background: var(--primary);
  color: #fff;
  padding: 12px 18px;
  border-radius: 10px;
  font-weight: 700;
  cursor: pointer;
  text-decoration: none;
}
button:hover, .btn:hover { background: var(--primary-dark); }
button.secondary { background: #475569; }
button.danger { background: var(--danger); }
.status {
  margin-top: 12px;
  color: var(--muted);
  font-size: 14px;
}
.message {
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 16px;
  margin-top: 14px;
  background: #fff;
}
.message-top {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}
.message h3 { margin: 0 0 8px; }
.message small { color: var(--muted); }
.message-body {
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px solid var(--border);
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}
.empty {
  color: var(--muted);
  text-align: center;
  padding: 20px;
}
.grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin-top: 18px;
}
.feature {
  background: #f8fafc;
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 16px;
}
.feature h3 { margin-top: 0; }
.content-card { line-height: 1.7; }
.footer {
  background: #0f172a;
  color: #cbd5e1;
  text-align: center;
  padding: 25px 20px;
  margin-top: 40px;
}
@media (max-width: 700px) {
  .nav-wrap { flex-direction: column; }
  .nav a { margin: 5px 8px; display: inline-block; }
  .hero h1 { font-size: 30px; }
  .email-display { flex-direction: column; align-items: stretch; }
  .email-text { font-size: 19px; text-align: center; }
  .actions button { width: 100%; }
  .grid { grid-template-columns: 1fr; }
}