:root {
    --bg-gradient-1: #0f172a;
    --bg-gradient-2: #1d4ed8;
    --bg-gradient-3: #0f766e;
    --card-bg: rgba(15, 23, 42, 0.65);
    --card-border: rgba(148, 163, 184, 0.45);
    --text-main: #e5e7eb;
    --text-muted: #9ca3af;
    --accent: #3b82f6;
    --accent-strong: #2563eb;
}

/* Reset đơn giản */
* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

/* Nền full màn hình */
.login-page {
    position: relative;
    min-height: 100vh;
    width: 100%;
    background: radial-gradient(circle at top left, var(--bg-gradient-2), var(--bg-gradient-1)), radial-gradient(circle at bottom right, var(--bg-gradient-3), var(--bg-gradient-1));
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 16px;
    overflow: hidden;
}

/* Lớp mờ nhẹ phía sau */
.login-overlay {
    position: absolute;
    inset: 0;
    background: radial-gradient(circle at 10% 20%, rgba(59, 130, 246, 0.3), transparent 55%), radial-gradient(circle at 80% 80%, rgba(34, 197, 94, 0.25), transparent 55%);
    opacity: 0.9;
    pointer-events: none;
}

/* Panel trong suốt */
.login-panel {
    position: relative;
    z-index: 1;
    width: 100%;
    max-width: 380px;
    padding: 24px 22px 22px 22px;
    border-radius: 20px;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    backdrop-filter: blur(16px);
    box-shadow: 0 20px 40px rgba(15, 23, 42, 0.8), 0 0 0 1px rgba(15, 23, 42, 0.4);
    color: var(--text-main);
}

/* Logo */
.login-logo {
    width: 40px;
    height: 40px;
    border-radius: 999px;
    background: linear-gradient(135deg, #3b82f6, #22c55e);
    display: flex;
    align-items: center;
    justify-content: center;
    color: #f9fafb;
    font-weight: 700;
    font-size: 1.1rem;
    box-shadow: 0 0 0 1px rgba(248, 250, 252, 0.6), 0 10px 18px rgba(15, 23, 42, 0.7);
}

.login-brand {
    font-size: 0.95rem;
    font-weight: 600;
    color: #f9fafb;
}

.login-caption {
    font-size: 0.8rem;
    color: var(--text-muted);
}

/* Tiêu đề */
.login-title {
    font-size: 1.3rem;
    font-weight: 700;
    color: #f9fafb;
}

/* Label + input */
.form-label {
    font-size: 0.85rem;
    color: var(--text-main);
}

.form-control {
    border-radius: 12px;
    border: 1px solid rgba(148, 163, 184, 0.6);
    background-color: rgba(15, 23, 42, 0.7);
    color: var(--text-main);
    font-size: 0.95rem;
    padding: 9px 12px;
}

    .form-control:focus {
        border-color: var(--accent);
        box-shadow: 0 0 0 1px rgba(59, 130, 246, 0.7);
        background-color: rgba(15, 23, 42, 0.9);
        color: #f9fafb;
    }

/* Nút đăng nhập */
.btn-login {
    border-radius: 12px;
    border: none;
    background: linear-gradient(135deg, var(--accent), var(--accent-strong));
    color: #f9fafb;
    font-weight: 600;
    padding: 10px 16px;
    font-size: 0.95rem;
    box-shadow: 0 12px 24px rgba(37, 99, 235, 0.6), 0 0 0 1px rgba(15, 23, 42, 0.3);
    transition: all 0.15s ease-in-out;
    cursor: pointer;
}

    .btn-login:hover {
        filter: brightness(1.05);
        transform: translateY(-1px);
    }

/* Nút quay về trang chủ */
.btn-back {
    border-radius: 12px;
    border: 1px solid rgba(148, 163, 184, 0.8);
    background-color: rgba(15, 23, 42, 0.4);
    color: var(--text-main);
    font-weight: 500;
    padding: 9px 16px;
    font-size: 0.9rem;
    text-align: center;
    text-decoration: none;
    display: inline-block;
    transition: all 0.15s ease-in-out;
    cursor: pointer;
}

    .btn-back:hover {
        background-color: rgba(15, 23, 42, 0.8);
        color: #f9fafb;
    }

/* Thông báo lỗi */
.validation-summary {
    background-color: rgba(220, 38, 38, 0.08);
    border-radius: 12px;
    border: 1px solid rgba(248, 113, 113, 0.7);
    color: #fecaca;
    font-size: 0.85rem;
    padding: 6px 10px;
    margin-bottom: 0.75rem;
}

/* Text nhỏ lỗi (mặc định của asp-validation-for) */
.text-danger.small {
    font-size: 0.78rem;
}