:root {
    /* Primary Red Palette */
    --primary-color: #ff3b3b;
    --primary-hover: #e62e2e;
    --accent-glow: rgba(255, 59, 59, 0.2);
    
    /* Light Mode (Default) */
    --bg-main: #ffffff;
    --bg-alt: #f8f9fa;
    --card-bg: #ffffff;
    --text-main: #1a1a1a;
    --text-muted: #6c757d;
    --border-color: rgba(0, 0, 0, 0.08);
    --navbar-bg: rgba(255, 255, 255, 0.85);
    --footer-bg: #1a1a1a;
    
    --transition-smooth: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --accordion-icon-filter: invert(0);
}

[data-theme="dark"] {
    /* Dark Mode */
    --bg-main: #0a0a0a;
    --bg-alt: #121212;
    --card-bg: #161616;
    --text-main: #ffffff;
    --text-muted: #a1a1aa;
    --border-color: rgba(255, 255, 255, 0.08);
    --navbar-bg: rgba(10, 10, 10, 0.85);
    --footer-bg: #050505;
    --accordion-icon-filter: invert(1);
}

/* Primary Color Overrides */
.text-primary { color: var(--primary-color) !important; }
.bg-primary { background-color: var(--primary-color) !important; }
.btn-primary { 
    background-color: var(--primary-color) !important; 
    border-color: var(--primary-color) !important;
    color: #fff !important;
}
.btn-primary:hover {
    background-color: var(--primary-hover) !important;
    border-color: var(--primary-hover) !important;
}
.btn-outline-primary {
    color: var(--primary-color) !important;
    border-color: var(--primary-color) !important;
}
.btn-outline-primary:hover {
    background-color: var(--primary-color) !important;
    color: #fff !important;
}
.border-primary { border-color: var(--primary-color) !important; }
.badge.bg-primary-subtle {
    background-color: var(--accent-glow) !important;
    color: var(--primary-color) !important;
}

body {
    background-color: var(--bg-main);
    color: var(--text-main);
    font-family: 'Be Vietnam Pro', sans-serif;
    overflow-x: hidden;
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* Custom Scrollbar */
::-webkit-scrollbar {
    width: 8px;
}
::-webkit-scrollbar-track {
    background: var(--bg-main);
}
::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 10px;
}
::-webkit-scrollbar-thumb:hover {
    background: var(--primary-color);
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.animate-up {
    animation: fadeInUp 0.8s ease forwards;
}

/* Navbar */
.navbar {
    background: var(--navbar-bg);
    backdrop-filter: blur(15px);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 0;
    transition: var(--transition-smooth);
    z-index: 1030;
}

.navbar.shadow-sm {
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1) !important;
}

[data-theme="dark"] .navbar.shadow-sm {
    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.5) !important;
}

.navbar-brand {
    font-weight: 800;
    font-size: 1.5rem;
    color: var(--primary-color) !important;
    letter-spacing: -1px;
}

.nav-link {
    color: var(--text-muted) !important;
    font-weight: 500;
    transition: var(--transition-smooth);
}

.nav-link:hover, .nav-link.active {
    color: var(--primary-color) !important;
}

.course-title-link {
    color: var(--text-main);
    transition: var(--transition-smooth);
}

.course-title-link:hover {
    color: var(--primary-color);
}

/* Buttons */
.btn-primary {
    background-color: var(--primary-color);
    border: none;
    font-weight: 600;
    padding: 0.8rem 2rem;
    border-radius: 50px;
    transition: var(--transition-smooth);
    box-shadow: 0 4px 15px var(--accent-glow);
}

.btn-primary:hover {
    background-color: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: 0 8px 25px var(--accent-glow);
}

.btn-outline-primary {
    border-color: var(--primary-color);
    color: var(--primary-color);
    border-radius: 50px;
    padding: 0.8rem 2rem;
}

.btn-outline-primary:hover {
    background-color: var(--primary-color);
    border-color: var(--primary-color);
    color: #fff;
}

/* Hero Section */
.hero-section {
    padding: 180px 0 100px;
    position: relative;
}

.hero-glow {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, var(--accent-glow) 0%, transparent 70%);
    z-index: -1;
    filter: blur(80px);
}

.hero-title {
    font-size: 4rem;
    font-weight: 900;
    line-height: 1.1;
    margin-bottom: 1.5rem;
}

.hero-title span {
    color: var(--primary-color);
    text-shadow: 0 0 20px var(--accent-glow);
}

/* Section Common */
section {
    padding: 100px 0;
}

.section-bg-alt {
    background-color: var(--bg-alt);
}

.section-title {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 4rem;
    text-align: center;
    color: var(--text-main);
    letter-spacing: -1px;
}

.section-title span {
    color: var(--primary-color);
    text-shadow: 0 0 15px var(--accent-glow);
}

/* Cards */
.custom-card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 24px;
    padding: 3rem 2.5rem;
    height: 100%;
    transition: var(--transition-smooth);
    display: flex;
    flex-direction: column;
    box-shadow: 0 10px 30px -10px rgba(0, 0, 0, 0.1);
}

[data-theme="dark"] .custom-card {
    background: linear-gradient(145deg, #161616, #0d0d0d);
    box-shadow: 0 20px 40px -20px rgba(0, 0, 0, 0.5);
}

.custom-card.pricing-card.popular {
    border: 2px solid var(--primary-color);
}

.custom-card h4 {
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-main);
}

.text-muted {
    color: var(--text-muted) !important;
}

.custom-card:hover {
    transform: translateY(-12px);
    border-color: var(--primary-color);
    box-shadow: 0 20px 40px -10px var(--accent-glow);
}

.icon-box {
    width: 64px;
    height: 64px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-hover));
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 18px;
    font-size: 1.75rem;
    margin-bottom: 2rem;
    box-shadow: 0 8px 20px var(--accent-glow);
}

/* Speaker Section */
.speaker-img-container {
    position: relative;
    border-radius: 30px;
    overflow: hidden;
}

.speaker-img-container::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 50%;
    background: linear-gradient(to top, var(--bg-main), transparent);
}

/* Roadmap/Timeline */
.roadmap-item {
    position: relative;
    padding-left: 3rem;
    border-left: 2px solid var(--primary-color);
    padding-bottom: 3rem;
}

.roadmap-item::before {
    content: '';
    position: absolute;
    left: -11px;
    top: 0;
    width: 20px;
    height: 20px;
    background: var(--primary-color);
    border: 4px solid var(--bg-dark);
    border-radius: 50%;
}

/* Pricing */
.pricing-card {
    position: relative;
    overflow: hidden;
}

.pricing-card.popular {
    border: 2px solid var(--primary-color);
}

.popular-badge {
    position: absolute;
    top: 30px;
    right: -35px;
    background: var(--primary-color);
    color: #000;
    padding: 5px 40px;
    transform: rotate(45deg);
    font-size: 0.8rem;
    font-weight: 700;
}

/* Page Header Sections */
.detail-header, .pricing-header, .payment-header, .auth-section, .profile-section {
    padding: 140px 0 80px;
    position: relative;
}

.pricing-header {
    background: radial-gradient(circle at 50% 100%, var(--accent-glow), transparent 70%);
}

.payment-section {
    background-image: radial-gradient(circle at 50% 0%, var(--accent-glow), transparent 50%);
}

/* Badge Variants */
.popular-badge.ribbon {
    position: absolute;
    top: 20px;
    right: -35px;
    background: var(--primary-color);
    color: #000;
    padding: 5px 40px;
    transform: rotate(45deg);
    font-size: 0.8rem;
    font-weight: 700;
    z-index: 10;
}

.popular-badge.pill {
    position: absolute;
    top: 0;
    left: 50%;
    transform: translate(-50%, -50%);
    z-index: 10;
}

/* Footer */
footer {
    background: var(--bg-main);
    padding: 80px 0 30px;
    border-top: 1px solid var(--border-color);
    color: var(--text-main);
    transition: background-color 0.3s ease, color 0.3s ease;
}

.footer-link {
    color: var(--text-muted);
    text-decoration: none;
    transition: var(--transition-smooth);
}

.footer-link:hover {
    color: var(--primary-color);
}

.social-icons a {
    width: 40px;
    height: 40px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    background: var(--border-color);
    border-radius: 50%;
    color: var(--text-main);
    margin-right: 10px;
    transition: var(--transition-smooth);
}

.social-icons a:hover {
    background: var(--primary-color);
    color: #000;
    transform: translateY(-3px);
}

/* Countdown Timer */
.countdown-item {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 18px;
    padding: 1.25rem;
    min-width: 90px;
    text-align: center;
    backdrop-filter: blur(5px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.1);
}

[data-theme="dark"] .countdown-item {
    background: rgba(255, 255, 255, 0.05);
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.3);
}

.countdown-item span {
    display: block;
    font-size: 2rem;
    font-weight: 800;
    color: var(--primary-color);
    line-height: 1;
}

.countdown-item small {
    display: block;
    font-size: 0.75rem;
    color: var(--text-muted);
    text-transform: uppercase;
    margin-top: 5px;
    letter-spacing: 1px;
}

/* Modal Styling */
.modal-content {
    background-color: var(--card-bg);
    color: var(--text-main);
    border: 1px solid var(--border-color);
    backdrop-filter: blur(20px);
}

.form-control:focus {
    background-color: var(--bg-alt);
    border-color: var(--primary-color);
    color: var(--text-main);
    box-shadow: 0 0 0 0.25rem var(--accent-glow);
}

/* Accordion Adaptive */
.accordion-item {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
}

.accordion-button {
    background-color: var(--card-bg);
    color: var(--text-main);
}

.accordion-button:not(.collapsed) {
    background-color: var(--accent-glow);
    color: var(--primary-color);
}

.accordion-button::after {
    filter: var(--accordion-icon-filter);
}

/* Nav Tabs Adaptive */
.nav-tabs .nav-link {
    background-color: var(--bg-alt);
    color: var(--text-muted);
    border: none;
}

.nav-tabs .nav-link.active {
    background-color: var(--primary-color) !important;
    color: #fff !important;
}

/* Course Cards & Catalog */
.course-card {
    position: relative;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    overflow: hidden;
    transition: var(--transition-smooth);
    height: 100%;
}

.course-card:hover {
    transform: translateY(-10px);
    border-color: var(--primary-color);
}

.course-badge {
    position: absolute;
    top: 15px;
    right: 15px;
    padding: 5px 12px;
    border-radius: 50px;
    font-size: 0.75rem;
    font-weight: 700;
    z-index: 10;
}

.course-badge.free { background: #10b981; color: white; }
.course-badge.paid { background: var(--primary-color); color: black; }

.course-thumb {
    aspect-ratio: 16/9;
    overflow: hidden;
}

.course-thumb img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.5s ease;
}

.course-card:hover .course-thumb img {
    transform: scale(1.1);
}

/* Detailed Course Page */
.detail-header {
    padding: 120px 0 40px;
}

.tag-cloud {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.tag-item {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    color: var(--text-muted);
    padding: 6px 16px;
    border-radius: 50px;
    font-size: 0.85rem;
    text-decoration: none;
    transition: var(--transition-smooth);
}

.tag-item:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.pricing-sidebar {
    position: sticky;
    top: 100px;
    background: var(--card-bg);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 20px;
    padding: 30px;
}

/* LMS Player */
.lms-container {
    padding-top: 120px;
    padding-bottom: 60px;
}

.video-wrapper {
    position: relative;
    padding-bottom: 56.25%; /* 16:9 */
    height: 0;
    overflow: hidden;
    border-radius: 20px;
    background: #000;
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.video-wrapper iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

.playlist-sidebar {
    height: calc(100vh - 160px);
    overflow-y: auto;
    background: var(--card-bg);
    border-radius: 20px;
    border: 1px solid var(--border-color);
}

.playlist-item:hover, .playlist-item.active {
    background: var(--accent-glow);
    color: var(--primary-color);
}

/* Theme Toggle Button */
.theme-toggle {
    background: var(--bg-alt);
    border: 1px solid var(--border-color);
    color: var(--text-main);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition-smooth);
}

.theme-toggle:hover {
    background: var(--primary-color);
    color: #fff;
    transform: rotate(15deg);
}

[data-theme="dark"] .bi-sun-fill { display: block; }
[data-theme="dark"] .bi-moon-fill { display: none; }
.bi-sun-fill { display: none; }
.bi-moon-fill { display: block; }


.playlist-item i {
    margin-right: 15px;
    font-size: 1.2rem;
}