/* —— reset & base —— */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { font-size: 16px; }
body {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, #00b4db, #0083b0);
  color: #333;
  min-height: 100vh;
  display: flex; justify-content: center; align-items: center;
  padding: env(safe-area-inset);
}

/* —— 通用容器 —— */
.container {
  background: rgba(255,255,255,0.95);
  border-radius: 12px; box-shadow: 0 10px 20px rgba(0,0,0,0.1);
  width: 90%; max-width: 900px; padding: 2.5rem; text-align: center;
}

/* —— 标题 & 文本 —— */
h1 { font-size: 2.5rem; color: #0083b0; margin-bottom: 1.5rem; }
h2 { font-size: 2rem; color: #0071a3; margin-bottom: 1rem; }
p { font-size: 1.125rem; color: #444; line-height: 1.6; margin-bottom: 1.5rem; }

/* —— 按钮 —— */
.btn {
  display: inline-block; padding: .75rem 1.5rem; border-radius: 30px;
  font-size: 1.125rem; font-weight: 500; text-decoration: none;
  box-shadow: 0 6px 12px rgba(0,0,0,0.1); transition: .3s;
}
.btn-primary { background: #0084ff; color: #fff; }
.btn-primary:hover { background: #006bb3; transform: translateY(-2px); }
.btn-secondary { background: #4caf50; color: #fff; }
.btn-danger { background: #f44336; color: #fff; }
.btn-warning { background: #ff9800; color: #fff; }

/* —— 表单元素 —— */
.form-group { margin-bottom: 1rem; text-align: left; }
label { display: block; margin-bottom: .5rem; font-weight: 500; }
input[type="text"], input[type="password"], input[type="email"] {
  width: 100%; padding: .75rem; border: 1px solid #ccc; border-radius: 6px;
  font-size: 1rem;
}

/* —— Footer —— */
footer {
  margin-top: 2rem; padding: 1rem; background: #333; color: #fff;
  border-radius: 0 0 12px 12px; font-size: .9rem;
}
footer a { color: #fff; text-decoration: none; }
footer a:hover { text-decoration: underline; }

/* —— 响应式 —— */
@media (max-width: 600px) {
  .container { border-radius: 0; padding: 1.5rem; box-shadow: none; }
  h1 { font-size: 1.8rem; }
  h2 { font-size: 1.4rem; }
  p, input[type="text"], input[type="password"], input[type="email"] {
    font-size: 1rem;
  }
  .btn { width: 100%; margin: .5rem 0; }
}