* {
    box-sizing: border-box;
}

html,
body {
    margin: 0;
    width: 100%;
    min-height: 100%;
}

body {
    min-height: 100vh;

    font-family: Arial, sans-serif;

    background-image:
        linear-gradient(
            rgba(10, 15, 30, 0.35),
            rgba(10, 15, 30, 0.65)
        ),
        url("images/background.jpg");

    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    background-attachment: fixed;
}


/* KHUNG CĂN GIỮA */

.login-container {
    min-height: 100vh;

    display: flex;
    justify-content: center;
    align-items: center;

    padding: 20px;
}


/* HỘP LOGIN */

.login-box {
    width: 100%;
    max-width: 380px;

    padding: 32px 30px;

    background: rgba(20, 25, 40, 0.88);

    border: 1px solid rgba(255, 255, 255, 0.12);

    border-radius: 18px;

    box-shadow:
        0 15px 45px rgba(0, 0, 0, 0.55);

    text-align: center;
}


/* TIÊU ĐỀ */

.login-box h1 {
    margin: 0 0 10px;

    color: white;

    font-size: 30px;

    letter-spacing: 6px;
}


/* DÒNG MÔ TẢ */

.subtitle {
    margin: 0 0 25px;

    color: #b5b8c5;

    font-size: 14px;
}


/* FORM */

form {
    display: flex;
    flex-direction: column;
}


/* Ô NHẬP MẬT KHẨU */

.login-box input {
    width: 100%;

    padding: 13px 15px;

    border: 1px solid #555d70;

    border-radius: 10px;

    background: #303746;

    color: white;

    font-size: 15px;

    outline: none;

    margin-bottom: 12px;
}

.login-box input::placeholder {
    color: #9ca3af;
}

.login-box input:focus {
    border-color: #7568ff;

    box-shadow:
        0 0 0 3px rgba(117, 104, 255, 0.15);
}


/* NÚT ĐĂNG NHẬP */

.login-box button {
    width: 100%;

    padding: 13px;

    border: none;

    border-radius: 10px;

    background: linear-gradient(
        135deg,
        #7568ff,
        #5b52d9
    );

    color: white;

    font-size: 15px;

    font-weight: bold;

    cursor: pointer;

    transition: 0.2s;
}

.login-box button:hover {
    transform: translateY(-2px);

    box-shadow:
        0 6px 20px rgba(100, 90, 255, 0.40);
}


/* THÔNG BÁO LỖI */

.error {
    margin-bottom: 15px;

    padding: 10px;

    background: rgba(255, 70, 70, 0.15);

    border: 1px solid rgba(255, 70, 70, 0.3);

    border-radius: 8px;

    color: #ff8a8a;

    font-size: 13px;
}


/* MOBILE */

@media (max-width: 500px) {

    .login-box {
        max-width: 100%;

        padding: 28px 22px;
    }

    .login-box h1 {
        font-size: 26px;

        letter-spacing: 4px;
    }

}

.developer-credit {
    position: fixed;
    right: 25px;
    bottom: 18px;

    color: rgba(255, 255, 255, 0.6);
    font-size: 13px;
    font-weight: 400;

    letter-spacing: 0.3px;
    z-index: 10;
}

.developer-credit:hover {
    color: rgba(255, 255, 255, 0.9);
}