/* 登录界面 - 简洁深灰色 */
.login-screen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100vh;
    background: #504d4d; /* 深灰色背景 */
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.login-container {
    background: rgba(255, 255, 255, 0.95);
    padding: 40px 30px;
    border-radius: 8px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
    width: 100%;
    max-width: 380px;
    animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(-20px); }
    to { opacity: 1; transform: translateY(0); }
}

.login-title {
    text-align: center;
    color: #333;
    margin-bottom: 30px;
    font-size: 22px;
    font-weight: 600;
    letter-spacing: 1px;
}

.login-form {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.form-group label {
    font-size: 13px;
    color: #393535;
    font-weight: 500;
    letter-spacing: 0.5px;
}

.form-group input {
    padding: 12px 15px;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 15px;
    background: #fff;
    transition: all 0.3s;
    color: #4a4545;
}

.form-group input:focus {
    outline: none;
    border-color: #4a6fd8;
    box-shadow: 0 0 0 2px rgba(74, 111, 216, 0.1);
}

.error-message {
    color: #f5222d;
    font-size: 13px;
    min-height: 20px;
    text-align: center;
    font-weight: 500;
}

.login-btn {
    background: #4a6fd8;
    color: white;
    border: none;
    padding: 13px;
    border-radius: 4px;
    font-size: 15px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s;
    margin-top: 5px;
    letter-spacing: 1px;
}

.login-btn:hover {
    background: #3a5ec8;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(74, 111, 216, 0.3);
}

.login-btn:active {
    transform: translateY(0);
}