/* --- Global Styles --- */
body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    color: #333;
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto; /* Centers the content */
}

/* --- Header & Navigation --- */
header {
    background: #fff;
    border-bottom: 1px solid #eee;
    padding: 15px 0;
    /* ADD THESE TWO LINES TO FIX THE DROPDOWN */
    position: relative;
    z-index: 100;
}

header .container {
    display: flex;
    justify-content: space-between; /* Puts logo on left, nav on right */
    align-items: center;
}

.logo-link {
    display: flex;
    align-items: center;
    text-decoration: none;
    color: #000;
    font-weight: bold;
    font-size: 14px;
}

.logo {
    height: 40px;
    margin-right: 10px;
}

nav ul {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
}

nav ul li {
    margin-left: 25px;
    position: relative; /* Needed for the dropdown */
}

nav ul li a {
    text-decoration: none;
    color: #555;
    font-weight: bold;
    font-size: 16px;
    padding: 10px 15px;
    border-radius: 5px;
    transition: background-color 0.3s;
}

/* The active "Home" button */
nav ul li a.active {
    background-color: #333;
    color: #fff;
}

nav ul li a:hover {
    background-color: #f0f0f0;
}

/* --- Dropdown Menu Styling --- */
.sub-menu {
    display: none; /* Hidden by default */
    position: absolute; /* Takes it out of the normal flow */
    top: 100%; /* Positions it right below the parent */
    left: 0;
    background: #fff;
    border: 1px solid #eee;
    border-radius: 5px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.05);
    min-width: 200px;
    padding: 10px 0;
}

/* This class will be added by JavaScript */
.sub-menu.active {
    display: block;
}

.sub-menu li {
    margin: 0;
    width: 100%;
}

.sub-menu li a {
    display: block;
    width: auto;
    padding: 10px 20px;
    color: #333;
    background: #fff; /* Override nav link styles */
}

/* Level 3 sub-menu (for Semesters) */
.sub-menu .sub-menu {
    top: 0;
    left: 100%; /* Position to the right of the parent */
}


/* --- Hero Section --- */
.hero {
    padding: 60px 0;
}

.hero-content {
    display: flex;
    align-items: center;
    gap: 40px; /* Space between text and image */
}

/* Left column (text) */
.hero-text {
    flex: 1; /* Takes up 1 part of the space */
}

/* Right column (image) */
.hero-image {
    flex: 1; /* Takes up 1 part of the space */
}

.hero-image img {
    width: 100%;
    height: auto;
}

.hero-subheading {
    font-size: 18px;
    color: #666;
    margin: 0;
}

.hero-text h1 {
    font-size: 52px;
    margin: 10px 0 20px 0;
}

.hero-text p {
    font-size: 18px;
    color: #555;
    margin-bottom: 30px;
}

/* --- Button Styling --- */
.btn {
    display: block;
    width: 70%;
    max-width: 300px;
    padding: 15px 25px;
    margin-bottom: 20px;
    text-align: left;
    text-decoration: none;
    color: #fff;
    font-size: 18px;
    font-weight: bold;
    border-radius: 50px; /* Makes it pill-shaped */
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    transition: transform 0.2s, box-shadow 0.2s;
}

.btn span {
    float: right; /* Puts the arrow on the right */
    font-size: 24px;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0,0,0,0.15);
}

/* "Join Now" button gradient */
.btn-primary {
    background-image: linear-gradient(to right, #62cff8, #4a8dff);
}

/* "Courses" button gradient */
.btn-secondary {
    background-image: linear-gradient(to right, #83f7f0, #61d7f8);
}
/* --- Hamburger Menu (Hidden on Desktop) --- */
.hamburger {
    display: none; /* Hide by default */
    background: none;
    border: none;
    cursor: pointer;
    padding: 10px;
}

.hamburger span {
    display: block;
    width: 25px;
    height: 3px;
    background-color: #333;
    margin: 5px 0;
    transition: all 0.3s;
}

/* --- MOBILE STYLES (RESPONSIVENESS) --- */

/* This line means "apply these rules ONLY if the screen is 800px wide or less" */
@media (max-width: 800px) {

    /* --- Mobile Header --- */
    .hamburger {
        display: block; /* Show the hamburger button */
        z-index: 1001; /* Keep it on top */
    }

    nav {
        position: fixed; /* Make menu full-screen overlay */
        top: 0;
        left: -100%; /* Hide it off-screen to the left */
        width: 100%;
        height: 100vh;
        background-color: white;
        padding-top: 80px;
        transition: left 0.3s ease-in-out;
        z-index: 1000;
    }
    
    /* This class will be added by JavaScript to show the menu */
    nav.active {
        left: 0; /* Slide the menu in */
    }

    nav ul {
        flex-direction: column; /* Stack menu items vertically */
        align-items: center;
    }

    nav ul li {
        margin: 15px 0;
    }

    /* Make dropdowns work in the new vertical layout */
    .sub-menu {
        position: static; /* Remove absolute positioning */
        display: none; /* Still hidden by default */
        box-shadow: none;
        border: none;
        background: #f9f9f9; /* Add a slight background to see them */
        padding-left: 20px;
    }

    .sub-menu.active {
        display: block;
    }

    /* --- Mobile Hero Section --- */
    .hero-content {
        flex-direction: column; /* Stack text on top of image */
        text-align: center;
    }

    .hero-text {
        order: 2; /* Put text below image (optional, or 1 for on top) */
    }

    .hero-image {
        order: 1; /* Put image on top */
    }

    .hero-text h1 {
        font-size: 36px; /* Make heading smaller */
    }

    .btn {
        width: 90%; /* Make buttons wider */
        max-width: none;
        margin: 15px auto; /* Center the buttons */
        text-align: left;
    }
}
/* ======================================= */
/* --- Semester 3 Page Specific Styles --- */
/* ======================================= */

/* Style the banner text (Same as before) */
.semester-page .hero-text h1 {
    font-size: 52px;
    margin-bottom: 0;
}

.semester-page .hero-text .sub-title {
    font-size: 24px;
    font-weight: bold;
    color: #333;
    margin-top: 5px;
    margin-bottom: 20px;
}

.semester-page .hero-text .quote {
    font-size: 16px;
    font-style: italic;
    color: #555;
    margin-bottom: 25px;
}

.semester-page .scroll-down {
    font-size: 14px;
    color: #777;
    text-decoration: none;
    letter-spacing: 1px;
}
.semester-page .scroll-down:hover {
    text-decoration: underline;
}

/* Style the new Subject Buttons section (Same as before) */
.subject-links {
    padding: 40px 0;
    background-color: #f9f9f9; 
}


/* --- NEW Two-Layer Button Styles --- */

/* This is the OUTER button (the green border) */
.subject-btn-outer {
    display: block;
    width: 80%;
    max-width: 800px;
    margin: 15px auto;
    text-decoration: none;
    border-radius: 50px;
    padding: 4px; /* This padding creates the border thickness */
    
    /* The GREEN gradient for the border */
    background-image: linear-gradient(to right, #50e3c2, #47c6a9); 
    
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    transition: all 0.2s ease-in-out;
}

.subject-btn-outer:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(0,0,0,0.15);
}

/* This is the INNER button (the purple fill) */
.subject-btn-outer span {
    display: block;
    padding: 15px 30px;
    border-radius: 46px; /* Slightly smaller than the outer radius */
    
    /* The PURPLE gradient for the fill */
    background-image: linear-gradient(to right, #b27cf7, #8646f0);
    
    color: white;
    font-size: 18px;
    font-weight: bold;
    text-align: center;
}


/* --- Make Semester Page Responsive (Same as before) --- */
@media (max-width: 800px) {
    .subject-btn-outer {
        width: 95%; /* Make buttons wider on mobile */
    }

    .semester-page .hero-text {
        text-align: center;
    }
}
/* --- Style for the 'back' link on subject pages --- */
.back-link {
    text-decoration: none;
    color: #007bff; /* A nice blue color */
    font-weight: bold;
    font-size: 16px;
}
.back-link:hover {
    text-decoration: underline;
}
/* === PDF MODAL STYLES === */

:root {
    --primary-text: #1e293b; 
}

.pdf-modal-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background-color: rgba(0, 0, 0, 0.7);
    z-index: 40;
}

.pdf-modal-content {
    display: none;
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 90%;
    height: 90%;
    max-width: 1200px;
    background-color: #fff;
    border-radius: 0.75rem;
    z-index: 50;
    box-shadow: 0 10px 30px rgba(0,0,0,0.3);
    /* Flexbox setup to make iframe fill space */
    display: flex;
    flex-direction: column;
}

.pdf-modal-header {
    padding: 1rem;
    border-bottom: 1px solid #e2e8f0;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-shrink: 0; /* Prevents header from shrinking */
}

.pdf-modal-title {
    font-weight: 600;
    color: var(--primary-text);
    font-size: 1.125rem;
    /* Truncate long text */
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    padding-right: 1rem;
}

.pdf-modal-close-btn {
    font-size: 1.75rem;
    font-weight: 700;
    color: #94a3b8;
    cursor: pointer;
    background: none;
    border: none;
    line-height: 1;
}
.pdf-modal-close-btn:hover {
    color: var(--primary-text);
}

.pdf-modal-iframe {
    width: 100%;
    height: 100%; /* Iframe will fill remaining space */
    border: none;
    border-bottom-left-radius: 0.75rem;
    border-bottom-right-radius: 0.75rem;
    flex-grow: 1; /* Makes iframe take all available vertical space */
}