/* Đặt font và nền chung */
body {
    margin: 0;
    padding: 0;
    font-family: Arial, sans-serif;
    background: #000000;           /* nền đen */
    color: #ffffff;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}

/* Container cho form */
form {
    background: #111111;
    border: 1px solid #1e3a8a;     /* viền xanh dương đậm */
    border-radius: 8px;
    padding: 30px 40px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.8);
    min-width: 320px;
}

/* Tiêu đề lỗi */
p[style*="color:red"] {
    color: #f87171 !important;     /* đỏ nhạt hơn, dễ nhìn hơn */
    text-align: center;
    margin-bottom: 15px;
}

/* Label và input */
label {
    display: block;
    margin-bottom: 15px;
    font-size: 14px;
    color: #e5e7eb;
}

input[type="text"],
input[type="password"] {
    width: 100%;
    padding: 10px 12px;
    margin-top: 5px;
    border-radius: 4px;
    border: 1px solid #1f2937;
    background-color: #020617;     /* gần đen */
    color: #e5e7eb;
    outline: none;
    transition: all 0.2s ease;
}

/* Hiệu ứng focus: viền gradient xanh–đỏ */
input[type="text"]:focus,
input[type="password"]:focus {
    border: 2px solid transparent;
    background:
        linear-gradient(#020617, #020617) padding-box,
        linear-gradient(45deg, #3b82f6, #ef4444) border-box; /* xanh + đỏ */
}

/* Nút login màu gradient xanh–đỏ */
button[type="submit"] {
    width: 100%;
    padding: 10px 0;
    margin-top: 10px;
    border: none;
    border-radius: 4px;
    background: linear-gradient(45deg, #3b82f6, #ef4444);   /* xanh + đỏ */
    color: #ffffff;
    font-size: 15px;
    font-weight: bold;
    cursor: pointer;
    text-transform: uppercase;
    letter-spacing: 1px;
    transition: transform 0.1s ease, box-shadow 0.1s ease, background 0.2s ease;
}

/* Hover/active */
button[type="submit"]:hover {
    background: linear-gradient(65deg, #3b82f6, #ef4444);
    box-shadow: 0 0 10px rgba(59, 130, 246, 0.6);
}

button[type="submit"]:active {
    transform: scale(0.97);
    box-shadow: none;
}