body {
    background: url("../../img/4.jpg") no-repeat center fixed;
    background-size: cover;
    background-color: rgba(100, 146, 235, 0.7);
    min-height: 100vh; 
    margin: 0;
    overflow-y: auto;
    padding-top: 95px;
    padding-bottom: 80px;
}

/* ===== 登录框 ===== */
.login_box {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 380px;
    padding: 40px 35px;
    background: rgba(255, 255, 255, 0.70);  / 改成半透明白色 */
    backdrop-filter: blur(12px); 
    border-radius: 16px;
    box-shadow: 0 8px 40px rgba(0, 0, 0, 0.25);
    z-index: 20;
    text-align: center;
}

.login_box h2 {
    font-size: 35px;
    font-weight: 700;
    color: #333;
    margin-bottom: 30px;
    letter-spacing: 2px;
}

.login_box .input_group {
    margin-bottom: 22px;
    text-align: left;
}

.login_box .input_group label {
    display: block;
    font-size: 18px;
    font-weight: 600;
    color: #555;
    margin-bottom: 6px;
}

.login_box .input_group input {
    width: 100%;
    padding: 12px 16px;
    font-size: 15px;
    border: 2px solid #e0e0e0;
    border-radius: 10px;
    box-sizing: border-box;
    outline: none;
    transition: border-color 0.3s;
    background: #f9f9f9;
}

.login_box .input_group input:focus {
    border-color: #4A90D9;
    background: #ffffff;
}

.login_box .login_btn {
    width: 100%;
    padding: 13px;
    font-size: 18px;
    font-weight: 700;
    color: #fff;
    background: #4A90D9;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    transition: background 0.3s;
    margin-top: 6px;
    letter-spacing: 4px;
}

.login_box .login_btn:hover {
    background: #2C6FB0;
}

.login_box .register_link {
    margin-top: 18px;
    font-size: 14px;
    color: #888;
}

.login_box .register_link a {
    color: #4A90D9;
    text-decoration: none;
    font-weight: 600;
}

.login_box .register_link a:hover {
    text-decoration: underline;
}
/* ===== 切换标签 ===== */
.tab_wrap {
    display: flex;
    border-radius: 12px;
    background: #f0f2f5;
    padding: 4px;
    margin-bottom: 28px;
}

.tab_item {
    flex: 1;
    text-align: center;
    padding: 10px 0;
    font-size: 17px;
    font-weight: 700;
    color: #888;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.3s;
    user-select: none;
}

.tab_item.active {
    background: #4A90D9;
    color: #fff;
    box-shadow: 0 4px 14px rgba(74, 144, 217, 0.35);
}

.tab_item:hover:not(.active) {
    color: #4A90D9;
}

/* ===== 注册表单（隐藏） ===== */
#registerForm {
    display: none;
}

/* ===== 提示消息 ===== */
.toast {
    position: fixed;
    top: 120px;
    left: 50%;
    transform: translateX(-50%) translateY(-20px);
    padding: 12px 30px;
    border-radius: 10px;
    font-size: 15px;
    font-weight: 600;
    color: #fff;
    background: rgba(0, 0, 0, 0.75);
    backdrop-filter: blur(6px);
    z-index: 999;
    opacity: 0;
    transition: all 0.4s ease;
    pointer-events: none;
}

.toast.show {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

.toast.success {
    background: rgba(46, 180, 80, 0.92);
}

.toast.error {
    background: rgba(220, 60, 60, 0.92);
}