* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  padding: 40px 16px;
  background: linear-gradient(
    135deg,
    #e8f4fa 0%,
    #eaf7f2 55%,
    #f4f9fc 100%
  );
  color: #294c55;
  font-family: Arial, "Microsoft JhengHei", sans-serif;
  line-height: 1.7;
}

.container {
  width: 100%;
  max-width: 760px;
  margin: 0 auto;
  padding: 36px;
  background: rgba(255, 255, 255, 0.96);
  border: 1px solid #dcebea;
  border-radius: 20px;
  box-shadow: 0 12px 35px rgba(40, 90, 100, 0.08);
}

h1 {
  margin: 0;
  color: #245766;
  font-size: 30px;
  text-align: center;
  letter-spacing: 1px;
}

h1 + p {
  margin-top: 8px;
  margin-bottom: 30px;
  color: #78939a;
  font-size: 14px;
  text-align: center;
}

h2 {
  margin-top: 0;
  font-size: 19px;
  color: #287d78;
}

section {
  padding: 24px 0;
  border-top: 1px solid #e0eded;
}

#google-login {
  margin: 18px 0;
}

#login-status,
#message-status {
  color: #718e94;
  font-size: 14px;
}

textarea {
  width: 100%;
  min-height: 120px;
  padding: 14px;
  border: 1px solid #cbdedc;
  border-radius: 10px;
  background: #f8fcfb;
  color: #294c55;
  font: inherit;
  resize: vertical;
}

textarea:focus {
  outline: none;
  border-color: #54afa4;
  box-shadow: 0 0 0 3px rgba(84, 175, 164, 0.12);
}

button {
  margin-top: 12px;
  padding: 11px 22px;
  border: 0;
  border-radius: 9px;
  background: #329b91;
  color: #ffffff;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s;
}

button:hover {
  background: #267e76;
}

button:disabled {
  opacity: 0.55;
  cursor: not-allowed;
}

#message-list {
  margin-top: 16px;
}

.message-card {
  padding: 18px;
  margin-bottom: 14px;
  background: #f1f9f8;
  border: 1px solid #dcecea;
  border-radius: 12px;
}

.message-card strong {
  display: block;
  color: #287d78;
}

.message-card small {
  color: #829da0;
}

.message-card p {
  margin: 8px 0 0;
  color: #365b63;
  overflow-wrap: anywhere;
  white-space: pre-wrap;
}

[hidden] {
  display: none !important;
}

@media (max-width: 600px) {
  body {
    padding: 18px 10px;
  }

  .container {
    padding: 22px;
    border-radius: 14px;
  }

  h1 {
    font-size: 25px;
  }

  h1 + p {
    font-size: 12px;
  }
}