:root {
  --bg: #f3f6fb;
  --card: #ffffff;
  --text: #1e293b;
  --primary: #2563eb;
  --error: #dc2626;
  --ok: #16a34a;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: "Microsoft YaHei", "PingFang SC", "Segoe UI", sans-serif;
  font-size: 15px;
  line-height: 1.45;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  color: var(--text);
  background: linear-gradient(180deg, #eef3ff 0%, var(--bg) 100%);
}

.container {
  max-width: 720px;
  margin: 22px auto;
  padding: 0 16px;
}

.container.wide { max-width: 860px; }

.card {
  background: var(--card);
  border-radius: 12px;
  padding: 12px;
  box-shadow: 0 6px 16px rgba(30, 41, 59, 0.08);
  margin: 8px 0;
}

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

input, button {
  width: 100%;
  padding: 9px 11px;
  border: 1px solid #cbd5e1;
  border-radius: 8px;
  margin-bottom: 8px;
}

button {
  background: var(--primary);
  color: white;
  border: none;
  font-weight: 600;
  cursor: pointer;
}

button:hover { opacity: 0.95; }

h1 { margin: 0 0 6px; line-height: 1.2; }
h2, h3 { margin: 8px 0; line-height: 1.25; }
.hint { color: #334155; }
.error { color: var(--error); }
.success { color: var(--ok); }
.hidden { display: none; }
.footer-link a { color: var(--primary); }
ul { margin: 8px 0 0; padding-left: 18px; }
li { margin: 6px 0; }

.mail-item {
  border: 1px solid #dbe3ef;
  border-radius: 8px;
  padding: 8px 10px;
  margin: 8px 0;
  background: #f8fbff;
}

.mail-item summary {
  cursor: pointer;
  list-style: none;
}

.mail-item summary::-webkit-details-marker { display: none; }

.mail-body pre {
  white-space: pre-line;
  word-break: break-word;
  background: #ffffff;
  border: 1px solid #e2e8f0;
  border-radius: 6px;
  padding: 10px;
  margin-top: 8px;
  max-height: 300px;
  overflow: auto;
  font-family: "Microsoft YaHei", "PingFang SC", sans-serif;
  font-size: 15px;
  line-height: 1.45;
  letter-spacing: 0;
  color: #0f172a;
}

@media (max-width: 640px) {
  body {
    font-size: 14px;
    line-height: 1.4;
  }

  .container {
    margin: 10px auto;
    padding: 0 10px;
  }

  .card {
    border-radius: 10px;
    padding: 10px;
    margin: 6px 0;
  }

  h1 {
    font-size: 32px;
    margin-bottom: 4px;
  }

  h2 {
    font-size: 24px;
  }

  .hint {
    font-size: 18px;
  }

  label {
    font-size: 22px;
    margin-bottom: 4px;
  }

  input,
  button {
    font-size: 20px;
    padding: 10px;
    margin-bottom: 6px;
  }

  .mail-item {
    padding: 8px;
    margin: 6px 0;
  }

  .mail-item summary div {
    line-height: 1.35;
  }

  .mail-body pre {
    max-height: 220px;
    font-size: 16px;
    line-height: 1.4;
    padding: 8px;
  }
}