body {
    background-color: black;
    color: white;
    font-family: Arial, sans-serif;
    margin: 0;
}

body::before {
    content: "";
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: url("../Images/bg.png");
    background-size: cover;
    filter: blur(4px);
    z-index: -1;
}

body.white::before {
    filter: blur(4px) invert(1);
}

.welcome-section {
    text-align: center;
    margin-top: 50px;
    font-size: 25px;
}

.welcome-section h1 {
    font-size: 50px;
    color: #d5d5d5;
    font-family: "Concert One", sans-serif;
}

.welcome-section p {
    font-family: "Slabo 27px", serif;
    margin-top: 20px;
}

.subject-buttons {
    text-align: center;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 30px;
}

.subject-button {
    width: calc(33.33% - 20px);
    max-width: 300px;
    height: 200px;
    margin: 10px;
    text-align: center;
    border: none;
    display: flex;
    flex-direction: column;
    align-items: center;
    background-color: transparent;
    transition: transform 0.2s, background-color 0.3s;
    text-decoration: none;
    cursor: pointer;
}

.subject-button:hover {
    transform: scale(1.05);
    background-color: #3c3b3b;
    border-radius: 10px;
}

.subject-button:hover .subject-title {
    color: #ffffff !important;
}

.subject-button .subject-name {
    text-align: center;
}

.subject-icon img {
    width: 100px;
    height: 100px;
    margin-top: 20px;
}

.subject-name {
    font-family: "Merriweather", serif;
    font-size: 35px;
    margin-top: 10px;
}

.subject-title {
    color: white;
    transition: color 0.3s;
}

.popup-container {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 5;
    align-items: center;
    justify-content: center;
}

.popup-content {
    background-color: #282828;
    padding: 0 20px 20px 20px;
    border-radius: 5px;
    position: relative;
    width: 95%;
    height: 95%;
    overflow: auto;
}

.popup-header {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 7%;
}

.centered-heading {
    display: block;
    text-align: center;
    color: #fff;
    word-wrap: break-word;
}

.popup-buttons {
    position: absolute;
    right: 5px;
    display: flex;
    gap: 10px;
    flex-direction: row;
}

.close-button, .download-button {
    width: 35px;
    height: 35px;
    background-color: #444;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 35px;
    border: none;
    cursor: pointer;
    transition: background-color 0.3s, color 0.3s;
}

.close-button:hover, .download-button:hover {
    background-color: #5a5a5a;
}

iframe {
    width: 100%;
    height: 92%;
    border: none;
    margin: 0;
}

@media screen and (max-width: 768px) {
    .subject-buttons {
        flex-direction: column;
        align-items: center;
        gap: 20px;
    }

    .subject-button {
        width: calc(100% - 20px);
    }
}

@media screen and (max-width: 1024px) {
    .subject-button {
        width: 100%
    }
}