CSS3实现的账号密码输入框提示效果

news2025/6/4 0:25:31

以下是通过CSS3实现输入框提示效果的常用方法，包含浮动标签和动态提示两种经典实现方案：

一、浮动标签效果

<div class="input-group">
  <input type="text" required>
  <label>用户名</label>
</div>

<style>
.input-group {
  position: relative;
  margin: 20px;
}

input {
  width: 100%;
  padding: 10px;
  border: 2px solid #ccc;
  border-radius: 4px;
  transition: border-color 0.3s;
}

input:focus {
  outline: none;
  border-color: #2196F3;
}

label {
  position: absolute;
  left: 10px;
  top: 50%;
  transform: translateY(-50%);
  color: #999;
  pointer-events: none;
  transition: 0.3s;
}

input:focus + label,
input:valid + label {
  top: -10px;
  left: 5px;
  font-size: 12px;
  color: #2196F3;
  background: white;
  padding: 0 5px;
}
</style>

二、动态提示效果

<input type="password" placeholder=" "> <!-- 留空占位符 -->
<div class="hint">请输入6-20位字符</div>

<style>
input {
  width: 100%;
  padding: 12px;
  border: 1px solid #ddd;
  transition: 0.3s;
}

input:focus {
  border-color: #4CAF50;
  box-shadow: 0 0 8px rgba(76,175,80,0.3);
}

/* 自定义占位符效果 */
input::placeholder {
  color: transparent;
}

.hint {
  position: absolute;
  opacity: 0;
  transform: translateY(10px);
  transition: 0.3s;
  color: #666;
  font-size: 12px;
}

input:focus ~ .hint {
  opacity: 1;
  transform: translateY(5px);
}
</style>

三、验证状态反馈

/* 有效状态 */
input:valid {
  border-color: #4CAF50;
}

/* 无效状态 */
input:invalid {
  border-color: #f44336;
  animation: shake 0.3s;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(5px); }
  75% { transform: translateX(-5px); }
}