:root {
    --primary: #5a4bda;
    --accent: #00c6ff;
    --bg-color: #f4f6f8;
    --card-bg: #ffffff;
    --text-main: #333333;
    --text-sub: #666666;
    --border: #e0e0e0;
    --green: #00b894;
    --shadow: 0 4px 12px rgba(0,0,0,0.05);
}

[data-theme="dark"] {
    --bg-color: #121212;
    --card-bg: #1e1e1e;
    --text-main: #ffffff;
    --text-sub: #b0b0b0;
    --border: #333333;
    --shadow: 0 4px 12px rgba(0,0,0,0.3);
}

* { margin: 0; padding: 0; box-sizing: border-box; font-family: 'Poppins', sans-serif; }

body {
    background-color: var(--bg-color);
    color: var(--text-main);
    transition: background-color 0.3s, color 0.3s;
    overflow-x: hidden;
}

#particles-js { position: fixed; width: 100%; height: 100%; top: 0; left: 0; z-index: -1; opacity: 0.5; }

/* Header */
header { background: var(--card-bg); padding: 15px 0 0 0; text-align: center; position: sticky; top: 0; z-index: 100; box-shadow: var(--shadow); }
.header-top { display: flex; justify-content: space-between; align-items: center; position: relative; padding: 0 20px; margin-bottom: 15px; }
.logo-container { display: flex; align-items: center; gap: 10px; }
#brand-title { font-size: 2.2rem; font-weight: 800; letter-spacing: 1px; background: linear-gradient(45deg, #ff0000, #ff7300, #fffb00, #48ff00, #00ffd5, #002bff, #7a00ff, #ff00c8, #ff0000); background-size: 400%; -webkit-background-clip: text; -webkit-text-fill-color: transparent; animation: rainbow 10s linear infinite; white-space: nowrap; }
@keyframes rainbow { 0%{background-position:0% 50%} 50%{background-position:100% 50%} 100%{background-position:0% 50%} }
.theme-btn { background: transparent; border: 1px solid var(--border); color: var(--text-main); padding: 8px 15px; border-radius: 20px; cursor: pointer; display: flex; align-items: center; gap: 5px; white-space: nowrap; }

/* Search */
.search-container { max-width: 600px; margin: 0 auto 20px auto; padding: 0 20px; }
.search-box { display: flex; align-items: center; background: var(--bg-color); border-radius: 12px; padding: 10px 15px; border: 1px solid var(--border); }
.search-box input { border: none; background: transparent; outline: none; width: 100%; margin-left: 10px; color: var(--text-main); font-size: 1rem; }
.header-border { height: 4px; background: linear-gradient(90deg, var(--primary), var(--accent)); width: 100%; }

/* Navigation */
#nav-controls { padding: 15px 20px; display: flex; align-items: center; gap: 15px; max-width: 1200px; margin: 0 auto; }
#back-btn { background: var(--card-bg); border: 1px solid var(--border); color: var(--text-main); padding: 8px 16px; border-radius: 8px; cursor: pointer; font-weight: 500; }
.hidden { display: none !important; }

/* Main Content */
#main-content { max-width: 1200px; margin: 20px auto; padding: 0 20px; min-height: 60vh; }
.grid-layout { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 20px; }

/* Cards */
.card { background: var(--card-bg); border: 1px solid var(--border); border-radius: 12px; overflow: hidden; transition: transform 0.2s, box-shadow 0.2s; cursor: pointer; }
.card:hover { transform: translateY(-5px); box-shadow: var(--shadow); }
.card-img { width: 100%; aspect-ratio: 16/9; object-fit: cover; background: #f4f6f8; border-bottom: 1px solid var(--border); }
.card-body { padding: 15px; }
.card-title { font-size: 1.1rem; font-weight: 600; margin-bottom: 5px; }
.card-meta { font-size: 0.85rem; color: var(--text-sub); display: flex; justify-content: space-between; align-items: center; }

/* List Items */
.subject-row { background: var(--card-bg); border: 1px solid var(--border); border-radius: 12px; padding: 20px; margin-bottom: 15px; display: flex; align-items: center; justify-content: space-between; cursor: pointer; transition: 0.2s; }
.subject-row:hover { border-color: var(--primary); }
.subject-left { display: flex; align-items: center; gap: 15px; }
.subject-icon { width: 50px; height: 50px; background: #eef2ff; color: var(--primary); border-radius: 10px; display: flex; align-items: center; justify-content: center; font-weight: bold; font-size: 1.2rem; }
.subject-info h3 { font-size: 1rem; margin-bottom: 4px; }
.subject-stats { font-size: 0.8rem; color: var(--text-sub); }

/* Progress Bar */
.progress-wrapper { width: 100px; text-align: right; }
.progress-text { font-size: 0.85rem; font-weight: bold; color: var(--green); display: block; margin-bottom: 5px;}
.progress-bar-bg { width: 100%; height: 4px; background: #eee; border-radius: 2px; }
.progress-fill { height: 100%; background: var(--green); border-radius: 2px; }

/* Tabs */
.tabs { display: flex; gap: 20px; margin-bottom: 20px; border-bottom: 1px solid var(--border); overflow-x: auto; white-space: nowrap; -ms-overflow-style: none; scrollbar-width: none; }
.tabs::-webkit-scrollbar { display: none; }
.tab { padding: 10px 5px; cursor: pointer; font-weight: 500; color: var(--text-sub); position: relative; }
.tab.active { color: var(--primary); }
.tab.active::after { content: ''; position: absolute; bottom: -1px; left: 0; width: 100%; height: 3px; background: var(--primary); }

.list-layout { display: flex; flex-direction: column; gap: 10px; }
.lecture-card, .resource-item { display: flex; justify-content: space-between; align-items: center; background: var(--card-bg); padding: 20px; border-radius: 12px; border: 1px solid var(--border); margin-bottom: 15px; }
.lecture-thumb { width: 120px; height: 70px; border-radius: 6px; object-fit: cover; background: #000; }
.lecture-info { flex: 1; }
.lecture-title { font-weight: 500; font-size: 0.95rem; margin-bottom: 5px; }
.lecture-meta { font-size: 0.8rem; color: var(--text-sub); }

.mark-complete-btn { width: 24px; height: 24px; border: 2px solid var(--border); border-radius: 50%; cursor: pointer; display: flex; align-items: center; justify-content: center; color: white; }
.mark-complete-btn.completed { background: var(--green); border-color: var(--green); }

.res-left { display: flex; align-items: center; gap: 15px; }
.res-icon { font-size: 1.5rem; color: var(--text-sub); }
.res-buttons { display: flex; gap: 10px; }
.btn-small { padding: 6px 12px; border-radius: 6px; font-size: 0.85rem; cursor: pointer; border: 1px solid var(--border); background: var(--bg-color); color: var(--text-main); text-decoration: none; display: inline-flex; align-items: center; gap: 5px; }

.empty-state { text-align: center; padding: 50px 0; color: var(--text-sub); }
.empty-icon { font-size: 4rem; margin-bottom: 10px; color: var(--border); }

/* Video Player */
#video-player-modal { position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: var(--bg-color); z-index: 200; overflow-y: auto; display: flex; flex-direction: column; }
.vp-header { padding: 15px 20px; border-bottom: 1px solid var(--border); display: flex; justify-content: space-between; align-items: center; background: var(--card-bg); }
.vp-body { flex: 1; display: flex; position: relative; height: calc(100% - 60px); }
.vp-video-container { flex: 1; padding: 20px; overflow-y: auto; display: flex; flex-direction: column; align-items: center; }
.video-wrapper { width: 100%; max-width: 1000px; aspect-ratio: 16/9; background: black; margin-bottom: 20px; border-radius: 12px; overflow: hidden; position: relative; }
.video-wrapper iframe { width: 100%; height: 100%; border: none; transform: none !important; }
.vp-info { max-width: 1000px; width: 100%; text-align: left; }
.vp-quote { margin-top: 10px; font-style: italic; color: var(--text-sub); font-size: 0.9rem; padding: 10px; background: rgba(0,0,0,0.03); border-radius: 8px; border-left: 3px solid var(--primary); }

.vp-sidebar { width: 300px; background: var(--card-bg); border-left: 1px solid var(--border); height: 100%; position: absolute; right: 0; top: 0; display: flex; flex-direction: column; box-shadow: -5px 0 15px rgba(0,0,0,0.1); }
.sidebar-header { padding: 15px; border-bottom: 1px solid var(--border); display: flex; justify-content: space-between; align-items: center; }
.sidebar-content { padding: 15px; overflow-y: auto; }
footer { text-align: center; padding: 20px; color: var(--text-sub); font-size: 0.8rem; border-top: 1px solid var(--border); margin-top: auto; }

/* Chapter Sidebar Layout (Desktop) */
.chapter-container { display: flex; gap: 20px; align-items: flex-start; height: calc(100vh - 120px); }
.chapter-sidebar { width: 300px; background: var(--card-bg); border: 1px solid var(--border); border-radius: 12px; display: flex; flex-direction: column; height: 100%; flex-shrink: 0; }
.sidebar-header { padding: 15px; font-weight: 700; color: var(--text-main); border-bottom: 1px solid var(--border); text-transform: uppercase; font-size: 0.9rem; letter-spacing: 0.5px; background: var(--bg-color); }
.sidebar-list { overflow-y: auto; flex: 1; padding: 10px; }
.chapter-list-item { padding: 12px 15px; margin-bottom: 5px; border-radius: 8px; cursor: pointer; font-size: 0.9rem; color: var(--text-sub); transition: all 0.2s; border-left: 4px solid transparent; }
.chapter-list-item:hover { background: var(--bg-color); color: var(--text-main); }
.chapter-list-item.active { background: #eef2ff; color: var(--primary); border-left-color: var(--primary); font-weight: 600; }
[data-theme="dark"] .chapter-list-item.active { background: rgba(90, 75, 218, 0.15); }
.chapter-content-area { flex: 1; background: var(--card-bg); border: 1px solid var(--border); border-radius: 12px; height: 100%; display: flex; flex-direction: column; overflow: hidden; }
.content-header { padding: 10px 20px; border-bottom: 1px solid var(--border); background: var(--bg-color); }
#content-list-container { padding: 20px; overflow-y: auto; flex: 1; }

/* Chapter Tag Style (New) */
.chapter-tag { font-size: 0.75rem; font-weight: 700; color: var(--primary); text-transform: uppercase; margin-bottom: 5px; letter-spacing: 0.5px; }
.lecture-status { font-size: 0.85rem; color: var(--text-sub); margin-top: 8px; font-weight: 500; }

/* ========================================= */
/* QUIZ & DASHBOARD STYLES (NEW)            */
/* ========================================= */

/* Quiz Result Dashboard */
.result-card {
    background: var(--card-bg);
    border-radius: 15px;
    padding: 30px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    margin-bottom: 20px;
    border: 1px solid var(--border);
}

.result-stats {
    display: flex;
    justify-content: space-around;
    margin: 20px 0;
    flex-wrap: wrap;
    gap: 10px;
}

.stat-box {
    text-align: center;
    padding: 15px;
    border-radius: 10px;
    background: var(--bg-color);
    min-width: 100px;
    border: 1px solid var(--border);
}

.stat-val { font-size: 1.5rem; font-weight: bold; display: block; }
.stat-label { font-size: 0.85rem; color: var(--text-sub); }

.review-btn {
    background: #6c5ce7;
    color: white;
    padding: 12px 25px;
    border: none;
    border-radius: 25px;
    font-size: 1rem;
    cursor: pointer;
    margin-top: 10px;
    transition: 0.2s;
}

.review-btn:hover { opacity: 0.9; transform: scale(1.05); }

/* Review Mode Colors */
.correct-ans { background-color: rgba(16, 185, 129, 0.1) !important; border-color: #10b981 !important; color: #065f46 !important; }
.wrong-ans { background-color: rgba(239, 68, 68, 0.1) !important; border-color: #ef4444 !important; color: #991b1b !important; }

/* Dark Mode Adjustments for Quiz */
[data-theme="dark"] .correct-ans { background-color: rgba(16, 185, 129, 0.2) !important; color: #a7f3d0 !important; }
[data-theme="dark"] .wrong-ans { background-color: rgba(239, 68, 68, 0.2) !important; color: #fca5a5 !important; }

/* --- QUIZ NAVIGATION STYLES (One-by-One) --- */
.quiz-nav-buttons {
    display: flex;
    justify-content: space-between;
    margin-top: 20px;
    padding-top: 15px;
    border-top: 1px solid var(--border);
}

.nav-btn {
    padding: 10px 20px;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    border: none;
    transition: 0.2s;
    font-size: 1rem;
    display: flex;
    align-items: center;
    gap: 8px;
}

.prev-btn {
    background: #e0e0e0;
    color: #333;
}
.prev-btn:hover { background: #d6d6d6; }
.prev-btn:disabled { opacity: 0.5; cursor: not-allowed; }

.next-btn {
    background: var(--primary);
    color: white;
}
.next-btn:hover { opacity: 0.9; }

.submit-btn-final {
    background: #2ecc71; /* Green */
    color: white;
}
.submit-btn-final:hover { background: #27ae60; }

.question-counter {
    text-align: center;
    margin-bottom: 15px;
    font-size: 0.9rem;
    color: var(--text-sub);
    font-weight: 600;
    background: var(--bg-color);
    padding: 5px;
    border-radius: 5px;
    display: inline-block;
}

/* Question Area Animation */
.question-block {
    animation: fadeIn 0.3s ease-in-out;
}
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(5px); }
    to { opacity: 1; transform: translateY(0); }
}


/* Mobile Responsive */
@media (max-width: 768px) {
    .header-top { padding: 0 15px; justify-content: space-between; }
    #brand-title { font-size: 1.5rem; }
    .theme-btn span { display: none; }
    .theme-btn { padding: 8px; border-radius: 50%; min-width: 35px; justify-content: center; }
    .vp-body { flex-direction: column; }
    .vp-sidebar { width: 100%; height: 50%; bottom: 0; top: auto; border-left: none; border-top: 1px solid var(--border); }
    .chapter-container { flex-direction: column; height: auto; }
    .chapter-sidebar { display: none; }
    .chapter-content-area { height: auto; border: none; background: transparent; }
    #content-list-container { padding: 0; }
}