* ====== TOÀN CỤC ====== */
* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: "Times New Roman", Times, serif;
    font-size: 12px;
    background: #0b3c8a;
    color: #fff;
    overflow: auto; /* ✅ cho phép cuộn */
}


/* ====== PHÁO HOA ====== */
canvas {
    position: fixed;
    top: 0;
    left: 0;
    z-index: 0;
}

/* ====== HEADER ====== */
header {
    position: relative;
    z-index: 2;
    height: 120px;
    display: flex;
    justify-content: center; /* căn giữa ngang */
    align-items: center; /* căn giữa dọc (nếu cần) */

    text-align: center;
    padding: 12px;
    background: rgba(0,0,0,0.3);
    border-bottom: 2px solid #1e88e5;
}

    header h2 {
        margin: 0;
        font-size: 36px;
        font-weight: bold;
        color: #ffeb3b;
    }

/* ====== BỐ CỤC ====== */
.container {
    display: flex;
    height: calc(100vh - 50px);
    position: relative;
    z-index: 2;
}

/* ====== MENU ====== */
.sidebar {
    width: 260px;
    background: rgba(13,71,161,0.9);
    padding: 15px;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

    .sidebar button {
        padding: 10px;
        font-family: "Times New Roman", Times, serif;
        font-size: 16px;
        background: #1565c0;
        color: #fff;
        border: none;
        border-radius: 5px;
        cursor: pointer;
        transition: 0.3s;
    }

        .sidebar button:hover {
            background: #0d47a1;
        }

/* ====== NỘI DUNG ====== */
.content {
    flex: 1;
    background: rgba(255,255,255,0.95);
    margin: 10px;
    border-radius: 8px;
    overflow: auto; /* ✅ QUAN TRỌNG */
    position: relative;
}


iframe {
    width: 100%;
    height: 100%;
    border: none;
    overflow: auto; /* ✅ */
}

/* ====== MÀN HÌNH CHÀO ====== */
#welcomeScreen {
    position: absolute;
    inset: 0;
    background-image: linear-gradient(rgba(255,255,255,0.8), rgba(255,255,255,0.8)), url("images.jpg");
    background-size: cover;
    background-position: center;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    z-index: 3; /* chỉ cao hơn iframe */
}


    #welcomeScreen img {
        width: 220px;
        margin-bottom: 20px;
    }

    #welcomeScreen h2 {
        font-size: 28px;
        color: #0d47a1;
        margin: 10px 0;
    }

    #welcomeScreen p {
        font-size: 16px;
        color: #333;
    }