html {
  height: 100%;
  background-image: linear-gradient(120deg, #84fab0 0%, #8fd3f4 100%);
}

body {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  margin: 0;
  position: relative;
  overflow: hidden; /* 確保不出現拉霸 */
  background: transparent; /* 讓 html 的背景透出來 */
}

.login-box {
  background: rgba(0,0,0,.5);
  box-sizing: border-box;
  box-shadow: 0 15px 25px rgba(0,0,0,.6);
  border-radius: 10px;
  padding: 40px 50px;
  z-index: 9;
  width: 90%;       /* 手機自適應 */
  max-width: 400px; /* 桌機限制 */
  margin: 20px;     /* 手機邊界緩衝 */
}
.login-box h2 {
  margin: 0 0 30px;
  padding: 0;
  color: #fff;
  text-align: center;
}

.login-box .user-box {
  position: relative;
}

.login-box .user-box input {
  width: 100%;
  padding: 10px 0;
  font-size: 16px;
  color: #fff;
  margin-bottom: 30px;
  border: none;
  border-bottom: 1px solid #fff;
  outline: none;
  background: transparent;
  box-shadow: none;
}
.login-box .user-box label {
  position: absolute;
  top:0;
  left: 0;
  padding: 10px 0;
  font-size: 16px;
  color: #fff;
  pointer-events: none;
  transition: .5s;
}

.login-box .user-box input:focus ~ label,
.login-box .user-box input:valid ~ label {
  top: -20px;
  left: 0;
  color: #03e9f4;
  font-size: 12px;
}
.login-box .user-box input:-webkit-autofill {
  -webkit-box-shadow: 0 0 0px 1000px transparent inset !important;
  -webkit-text-fill-color: #fff !important;
  transition: background-color 5000s ease-in-out 0s;
}
.login-box form a {
  position: relative;
  display: inline-block;
  padding: 10px 20px;
  color: #03e9f4;
  font-size: 16px;
  text-decoration: none;
  text-transform: uppercase;
  overflow: hidden;
  transition: .5s;
  margin-top: 40px;
  letter-spacing: 4px
}
form button {
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
    outline: 0;
    background-color: white;
    border: 0;
    padding: 10px 15px;
    color: #53e3a6;
    border-radius: 3px;
    width: 100%;
    cursor: pointer;
    font-size: 18px;
    transition-duration: 0.25s;
}
form button:hover {
	background: #ffffffcc
}
.bg-bubbles {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 1;
	overflow: hidden;
}
.bg-bubbles li {
 
	
	
	list-style: none;
	position: absolute;
    bottom: auto;
    top: 100%; /* 從畫面下方開始 */
    width: 40px;
    height: 40px;
    background-color: rgba(255,255,255,0.15);
    animation: square 25s linear infinite;
	
	
}
.bg-bubbles li:nth-child(1) {
  animation-delay: -2s;
  left: 10%;
}
.bg-bubbles li:nth-child(2) {
  left: 20%;
  width: 80px;
  height: 80px;
  animation-delay: 2s;
  animation-duration: 17s;
}
.bg-bubbles li:nth-child(3) {
  left: 25%;
  animation-delay: -4s;
}
.bg-bubbles li:nth-child(4) {
  left: 40%;
  width: 60px;
  height: 60px;
  animation-duration: 22s;
  background-color: rgba(255, 255, 255, 0.25);
}
.bg-bubbles li:nth-child(5) {
  left: 70%;
}
.bg-bubbles li:nth-child(6) {
  left: 80%;
  width: 120px;
  height: 120px;
  animation-delay: 3s;
  background-color: rgba(255, 255, 255, 0.2);
}
.bg-bubbles li:nth-child(7) {
  left: 32%;
  width: 160px;
  height: 160px;
  animation-delay: -7s;
}
.bg-bubbles li:nth-child(8) {
  left: 55%;
  width: 20px;
  height: 20px;
  animation-delay: -15s;
  animation-duration: 40s;
}
.bg-bubbles li:nth-child(9) {
  left: 25%;
  width: 10px;
  height: 10px;
  animation-delay: 2s;
  animation-duration: 40s;
  background-color: rgba(255, 255, 255, 0.3);
}
.bg-bubbles li:nth-child(10) {
  left: 90%;
  width: 160px;
  height: 160px;
  animation-delay: 11s;
}
@keyframes square {
  0% { transform: translateY(0) rotate(0deg); }
  100% { transform: translateY(-120vh) rotate(600deg); }
}


/* 欄位驗證失敗時邊框紅色 */
input:invalid {
  border: 1px solid red;
}

/* 自訂提示訊息 */
input:invalid::placeholder {
  color: #db84a3;
  padding-left: 5vh; /* 右移10px */
}