/* ====================================
   Variables & Basic Resets
   ==================================== */
:root {
    --header-height: 60px;
    --sidebar-width-medium: 250px;
    --sidebar-width-large: 300px;
    --transition-duration: 0.3s;
    --primary-bg: #282c34;
    --secondary-bg: #3c4048;
    --text-color: #f0f0f0;
    --accent-color: #61dafb;
    --translucent-bg: rgba(40, 44, 52, 0.75);
    --transition-curve: cubic-bezier(0.4, 0, 0.2, 1);
}

body {
    margin: 0;
    font-family: Arial, sans-serif;
    color: var(--text-color);
    background-color: var(--primary-bg);
    overflow-x: hidden;
}

a { color: #B2E0E7; text-decoration: none; }
a:hover { text-decoration: underline; }

#backgroundI {
    position: fixed;
    top: 0; left: 0; width: 100vw; height: 100vh;
    z-index: -1;
    background-size: cover;
    background-position: center;
    filter: brightness(0.4);
}

/* ====================================
   Header & Navigation
   ==================================== */
#mainHeader {
    background-color: var(--secondary-bg);
    height: var(--header-height);
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 20px;
    position: fixed; /* Sticky top */
    top: 0;
    width: 100%;
    box-sizing: border-box;
    z-index: 1001;
    box-shadow: 0 2px 10px rgba(0,0,0,0.3);
}

#siteTitle { font-size: 1.4em; font-weight: bold; }

#sidebarToggleBtn {
    background: none; border: none; color: var(--text-color);
    cursor: pointer; display: flex; align-items: center;
}

#sidebarToggleBtn .close-icon { display: none; }
body.sidebar-open #sidebarToggleBtn .menu-icon { display: none; }
body.sidebar-open #sidebarToggleBtn .close-icon { display: block; }

/* ====================================
   Content & Container Layout
   ==================================== */
#container {
    display: flex;
    margin-top: var(--header-height); /* Offset for fixed header */
    min-height: calc(100vh - var(--header-height));
}

#content {
    flex-grow: 1;
    padding: 20px;
    transition: margin var(--transition-duration) var(--transition-curve);
    max-width: 100%;
    box-sizing: border-box;
}

/* Block Styling */
#block1, #block2, #block3, .block {
    margin-bottom: 25px;
    background-color: var(--translucent-bg);
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.2);
    overflow: hidden; /* For expansion logic */
}

#block1, #block3, .block { 
   padding: 20px; 
}

#block1a, .blockTitle { 
   font-size: 1.5em; 
   font-weight: bold; 
   margin-bottom: 10px; 
   color: var(--accent-color); 
}

.blockTitleSpan {
   float: right;
   font-size: 0.8em;
}

/* ====================================
   Modern Minimalist Expansion (Block 2)
   ==================================== */
.intro-section { 
    padding: 20px 20px 0 20px; 
    font-weight: bold; 
}

.expand-wrapper {
    display: grid;
    grid-template-rows: 0fr; /* Secret to animating auto-height */
    transition: grid-template-rows var(--transition-duration) var(--transition-curve);
}

.is-open-wrapper { grid-template-rows: 1fr; }

.content-inner { overflow: hidden; }
.expanded-body { padding: 0 20px 20px 20px; }

.preview-hint {
    height: 45px;
    overflow: hidden;
    padding: 0 20px;
    position: relative;
    transition: opacity 0.2s;
}

.is-open-card .preview-hint { height: 0; opacity: 0; padding: 0; }

.overlay {
    position: absolute;
    bottom: 0; left: 0; width: 100%; height: 100%;
    background: linear-gradient(to bottom, transparent, var(--translucent-bg));
    pointer-events: none;
}

.video-container {
    position: relative; padding-bottom: 56.25%; height: 0;
    margin-top: 15px; border-radius: 8px; overflow: hidden; background: #000;
}
.video-container iframe { position: absolute; top: 0; left: 0; width: 100%; height: 100%; }

#buttonWrapper { padding: 10px 20px 20px; text-align: right; }
.toggle-btn {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--accent-color);
    color: var(--accent-color);
    padding: 6px 14px; border-radius: 6px; cursor: pointer;
    display: inline-flex; align-items: center; gap: 8px; font-weight: bold;
}
.toggle-btn:hover { background: rgba(97, 218, 251, 0.1); }

/* ====================================
   Desktop Sidebar (Fixed & Positioned)
   ==================================== */
#desktopSidebar {
    position: fixed;
    top: var(--header-height);
    height: calc(100vh - var(--header-height));
    background-color: var(--secondary-bg);
    overflow-y: auto;
    z-index: 1000;
    display: none; /* Mobile hidden */
    box-shadow: 2px 0 10px rgba(0,0,0,0.3);
}

#sideBarList { list-style: none; padding: 0; margin: 0; }
#sideBarListTitle { padding: 20px; font-weight: bold; border-bottom: 2px solid var(--accent-color); }
.sideBarListItem { padding: 12px 20px; border-bottom: 1px solid rgba(255,255,255,0.05); }

/* ====================================
   Mobile Overlay Menu
   ==================================== */
#mobileSidebarOverlay {
    position: fixed;
    top: var(--header-height);
    left: 0; width: 100%; height: calc(100vh - var(--header-height));
    background-color: rgba(0,0,0,0.85);
    z-index: 1005;
    display: none; /* Triggered by JS */
    opacity: 0;
    transition: opacity 0.3s;
}

body.sidebar-open #mobileSidebarOverlay { display: block; opacity: 1; }

#dropdownContent {
    background-color: var(--secondary-bg);
    width: 280px; height: 100%; padding: 20px; box-sizing: border-box;
    transform: translateX(-100%);
    transition: transform 0.3s var(--transition-curve);
}

body.sidebar-open #dropdownContent { transform: translateX(0); }

#dropdownList { list-style: none; padding: 0; }
.dropdownItem { padding: 15px 0; border-bottom: 1px solid rgba(255,255,255,0.1); opacity: 0; }
.dropdownHeader { font-weight: bold; color: var(--accent-color); border-bottom: 2px solid var(--accent-color); }

@keyframes fadeInSlideIn {
    from { opacity: 0; transform: translateX(-20px); }
    to { opacity: 1; transform: translateX(0); }
}

/* ====================================
   Responsive Breakpoints
   ==================================== */

/* Medium (Tablets/iPad Portrait - 600px to 768px) */
@media (min-width: 600px) {
    #desktopSidebar { 
        display: block; 
        right: 0; /* Sidebar on RIGHT for tablet */
        width: var(--sidebar-width-medium); 
    }
    #content { margin-right: var(--sidebar-width-medium); margin-left: 0; }
    #sidebarToggleBtn { display: flex; } /* Toggle for Mobile Overlay remains */
}

/* Large (Desktop/iPad Landscape - 769px+) */
@media (min-width: 769px) {
    #sidebarToggleBtn { display: none; } /* Hide hamburger */
    #desktopSidebar { 
        right: auto; 
        left: 0; /* Sidebar on LEFT for desktop */
        width: var(--sidebar-width-large); 
    }
    #content { margin-left: var(--sidebar-width-large); margin-right: 0; }
    body.sidebar-open { overflow: auto; } /* Ensure scroll is back */
}