/* ==========================================================================
   HKAEE REDESIGN CORE STYLESHEET (Green Building Engineering Theme)
   ========================================================================== */

:root {
    --primary-green: #2e7d32;   /* Eco-Green Accent */
    --primary-dark: #1e293b;    /* Deep Slate/Charcoal Professional Core */
    --accent-blue: #1565c0;     /* Engineering Blue */
    --bg-light: #f8fafc;        /* Soft White Gray Background */
    --text-dark: #334155;       /* Primary Reading Text */
    --white: #ffffff;
    --transition: all 0.3s ease;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-light);
    color: var(--text-dark);
    line-height: 1.6;
}

a {
    text-decoration: none;
    color: inherit;
    transition: var(--transition);
}

/* --- Header & Navigation Components --- */
header {
    background-color: var(--white);
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.top-bar {
    background-color: var(--primary-dark);
    color: var(--white);
    padding: 8px 5%;
    display: flex;
    justify-content: space-between;
    font-size: 0.85rem;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 5%;
    max-width: 1400px;
    margin: 0 auto;
    position: relative; /* Setup relative bounding for mobile menu icon placement */
}

.logo-area h1 {
    color: var(--primary-green);
    font-size: 1.5rem;
    font-weight: 700;
}
.logo-area p {
    font-size: 0.75rem;
    color: var(--text-dark);
    text-transform: uppercase;
    letter-spacing: 1px;
}

/* Hidden by default on desktop viewports */
#menu-toggle, .menu-icon {
    display: none;
}

.nav-links {
    display: flex;
    list-style: none;
}

.nav-links > li {
    position: relative;
    padding: 10px 15px;
}

.nav-links a {
    font-weight: 600;
    color: var(--primary-dark);
}

.nav-links a:hover, .nav-links li.active > a {
    color: var(--primary-green);
}

/* Dropdown Menu Style */
.dropdown {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    background-color: var(--white);
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
    list-style: none;
    min-width: 220px;
    border-top: 3px solid var(--primary-green);
}

.dropdown li {
    border-bottom: 1px solid #f1f5f9;
}

.dropdown a {
    display: block;
    padding: 10px 15px;
    font-size: 0.9rem;
    font-weight: 500;
}

.dropdown a:hover {
    background-color: var(--bg-light);
    padding-left: 20px;
}

/* --- Desktop Only Navigation Interaction --- */
@media (min-width: 769px) {
    /* Kept exactly the same; strictly activates only on desktop screens */
    .nav-links li:hover .dropdown {
        display: block;
    }
}

/* --- Layout Layout Containers --- */
.hero-banner {
    background: linear-gradient(rgba(30, 41, 59, 0.50), rgba(30, 41, 59, 0.50)), url('images/main_banner.jpg') no-repeat center center/cover;
    color: var(--white);
    padding: 100px 5%;
    text-align: center;
}

.hero-banner h2 {
    font-size: 2.5rem;
    margin-bottom: 15px;
}

.main-wrapper {
    max-width: 1200px;
    margin: 40px auto;
    padding: 0 20px;
    display: grid;
    grid-template-columns: 3fr 1fr;
    gap: 30px;
}

.full-width-wrapper {
    max-width: 1200px;
    margin: 40px auto;
    padding: 0 20px;
}

.content-block {
    background: var(--white);
    padding: 40px;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.02);
    border-left: 4px solid var(--primary-green);
}

.content-block h3 {
    color: var(--primary-green);
    margin-bottom: 20px;
    font-size: 1.75rem;
    border-bottom: 2px solid #f1f5f9;
    padding-bottom: 10px;
}

/* --- Side Panels --- */
aside {
    background: var(--white);
    padding: 25px;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.02);
    height: fit-content;
}

aside h4 {
    color: var(--primary-dark);
    margin-bottom: 15px;
    border-bottom: 2px solid var(--primary-green);
    padding-bottom: 5px;
}

.sidebar-menu {
    list-style: none;
}

.sidebar-menu li {
    margin-bottom: 10px;
}

.sidebar-menu a {
    display: block;
    padding: 8px 12px;
    background: var(--bg-light);
    border-radius: 4px;
    font-weight: 500;
}

.sidebar-menu a:hover {
    background: var(--primary-green);
    color: var(--white);
}

/* --- Data Presentation / Form Modularity --- */
.data-table {
    width: 100%;
    border-collapse: collapse;
    margin: 20px 0;
}

.data-table th, .data-table td {
    padding: 12px 15px;
    text-align: left;
    border-bottom: 1px solid #e2e8f0;
}

.data-table th {
    background-color: var(--primary-dark);
    color: var(--white);
}

.data-table tr:nth-child(even) {
    background-color: var(--bg-light);
}

.btn {
    display: inline-block;
    background-color: var(--primary-green);
    color: var(--white);
    padding: 12px 25px;
    border-radius: 4px;
    font-weight: 600;
    border: none;
    cursor: pointer;
    margin-top: 15px;
}

.btn:hover {
    background-color: var(--primary-dark);
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 6px;
    font-weight: 600;
}

.form-group input, .form-group select, .form-group textarea {
    width: 100%;
    padding: 10px;
    border: 1px solid #cbd5e1;
    border-radius: 4px;
}

/* --- Footer Area --- */
footer {
    background-color: var(--primary-dark);
    color: #94a3b8;
    padding: 40px 5% 20px;
    margin-top: 60px;
}

.footer-container {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 40px;
    padding-bottom: 20px;
    border-bottom: 1px solid #334155;
}

.footer-info h4 {
    color: var(--white);
    margin-bottom: 15px;
}

.copyright {
    text-align: center;
    padding-top: 20px;
    font-size: 0.85rem;
}

/* --- Responsive Adjustments --- */
@media (max-width: 768px) {
    .main-wrapper {
        grid-template-columns: 1fr;
    }
    
    .nav-container {
        flex-direction: column;
        align-items: flex-start;
    }
    
    /* 1. Hamburger Menu Minimization Control */
    .menu-icon {
        display: block;
        position: absolute;
        top: 25px;
        right: 5%;
        cursor: pointer;
        font-size: 1.8rem;
        color: var(--primary-green);
        user-select: none;
    }

    /* Standard hamburger 3-line symbol (☰) */
    .menu-icon::before {
        content: "\2630";
    }

    /* Changes symbol to an '✕' close button when expanded */
    #menu-toggle:checked ~ .menu-icon::before {
        content: "\2715";
    }

    /* Keeps entire navigation links container hidden when not explicitly toggled */
    .nav-links {
        display: none;
        margin-top: 20px;
        width: 100%;
        flex-direction: column;
    }
    
    /* Reveal menu items vertically when clicked */
    #menu-toggle:checked ~ .nav-links {
        display: flex;
    }

    .nav-links > li {
        width: 100%;
        padding: 0;
        border-bottom: 1px solid #e2e8f0;
    }

    .nav-links a {
        display: block;
        padding: 12px 15px;
        width: 100%;
    }

    /* 2. Mobile Click-Only Submenu Logic */
    .dropdown {
        display: none; 
        position: relative; /* Switches off absolute overlay so it flows stackably */
        top: 0;
        width: 100%;
        box-shadow: none;
        border-top: none;
        background-color: var(--bg-light);
    }

    .dropdown a {
        padding-left: 30px; /* Indent child sub-links */
    }

    /* REVEAL ON CLICK/TAP FIXED:
       Using :focus-within on the list item works wonderfully on mobile, 
       provided the parent menu structure allows focus states to persist.
    */
    .nav-links li:focus-within .dropdown {
        display: block;
    }

    /* Optional engineering tweak: visually shows the user which parent menu is expanded */
    .nav-links li:focus-within > a {
        color: var(--primary-green);
        background-color: #f1f5f9;
    }

    .footer-container {
        grid-template-columns: 1fr;
    }
}