/* ========== RESET & BASE ========== */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --primary-light: #dbeafe;
    --accent: #818cf8;
    --teal: #06b6d4;
    --success: #16a34a;
    --success-light: #dcfce7;
    --danger: #dc2626;
    --danger-light: #fee2e2;
    --warning: #f59e0b;
    --background: #f8fafc;
    --surface: #ffffff;
    --text: #0f172a;
    --text-secondary: #475569;
    --text-muted: #94a3b8;
    --border: #e2e8f0;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow: 0 1px 3px rgba(0,0,0,0.1), 0 1px 2px rgba(0,0,0,0.06);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -1px rgba(0,0,0,0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -2px rgba(0,0,0,0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.1), 0 10px 10px -5px rgba(0,0,0,0.04);
    --radius: 12px;
    --radius-lg: 20px;
    --radius-xl: 28px;
    --transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
    --glow: 0 0 40px rgba(99,102,241,0.3);
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--background);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ========== LANDING PAGE ========== */
.landing-page {
    min-height: 100dvh;
    position: relative;
    overflow-x: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
    background: #030712;
}

/* Animated gradient background */
.landing-bg {
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse 80% 50% at 20% 40%, rgba(99,102,241,0.35) 0%, transparent 50%),
        radial-gradient(ellipse 60% 50% at 80% 20%, rgba(6,182,212,0.25) 0%, transparent 50%),
        radial-gradient(ellipse 60% 60% at 60% 80%, rgba(37,99,235,0.3) 0%, transparent 50%),
        radial-gradient(ellipse 40% 40% at 10% 90%, rgba(168,85,247,0.2) 0%, transparent 40%),
        linear-gradient(160deg, #030712 0%, #0a1628 40%, #0f2744 100%);
    z-index: 0;
}

/* Gradient orbs with glow */
.gradient-orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(60px);
    z-index: 0;
}

.orb-1 {
    width: clamp(280px, 40vw, 420px);
    height: clamp(280px, 40vw, 420px);
    background: radial-gradient(circle, rgba(99,102,241,0.5) 0%, rgba(99,102,241,0) 70%);
    top: -5%;
    right: 5%;
    animation: orbDrift1 12s ease-in-out infinite;
}

.orb-2 {
    width: clamp(200px, 30vw, 320px);
    height: clamp(200px, 30vw, 320px);
    background: radial-gradient(circle, rgba(6,182,212,0.45) 0%, rgba(6,182,212,0) 70%);
    bottom: 5%;
    left: 0;
    animation: orbDrift2 15s ease-in-out infinite;
}

.orb-3 {
    width: clamp(160px, 25vw, 260px);
    height: clamp(160px, 25vw, 260px);
    background: radial-gradient(circle, rgba(129,140,248,0.5) 0%, rgba(129,140,248,0) 70%);
    top: 40%;
    right: 30%;
    animation: orbDrift3 10s ease-in-out infinite;
}

.orb-4 {
    width: clamp(140px, 20vw, 220px);
    height: clamp(140px, 20vw, 220px);
    background: radial-gradient(circle, rgba(236,72,153,0.3) 0%, rgba(236,72,153,0) 70%);
    bottom: 20%;
    right: 10%;
    animation: orbDrift1 18s ease-in-out infinite reverse;
}

@keyframes orbDrift1 {
    0%, 100% { transform: translate(0, 0) scale(1); }
    33% { transform: translate(25px, -30px) scale(1.08); }
    66% { transform: translate(-15px, 20px) scale(0.95); }
}

@keyframes orbDrift2 {
    0%, 100% { transform: translate(0, 0) scale(1); }
    50% { transform: translate(30px, -25px) scale(1.1); }
}

@keyframes orbDrift3 {
    0%, 100% { transform: translate(0, 0); }
    50% { transform: translate(-20px, 25px); }
}

/* Particles */
.particles {
    position: absolute;
    inset: 0;
    z-index: 1;
    pointer-events: none;
    overflow: hidden;
}

.particle {
    position: absolute;
    width: var(--s);
    height: var(--s);
    background: rgba(255,255,255,0.15);
    border-radius: 50%;
    left: var(--x);
    bottom: -10px;
    animation: particleRise var(--dur) linear infinite;
    animation-delay: var(--d);
    box-shadow: 0 0 6px rgba(255,255,255,0.1);
}

@keyframes particleRise {
    0% { transform: translateY(0) scale(1); opacity: 0; }
    10% { opacity: 1; }
    90% { opacity: 1; }
    100% { transform: translateY(-110vh) scale(0.5); opacity: 0; }
}

/* Mesh grid overlay */
.mesh-overlay {
    position: absolute;
    inset: 0;
    z-index: 1;
    pointer-events: none;
    background-image:
        linear-gradient(rgba(255,255,255,0.015) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255,255,255,0.015) 1px, transparent 1px);
    background-size: 60px 60px;
}

/* Main container */
.landing-container {
    position: relative;
    z-index: 2;
    display: flex;
    align-items: center;
    gap: clamp(40px, 6vw, 80px);
    max-width: 1200px;
    width: 92%;
    padding: clamp(40px, 8vh, 80px) 0;
    min-height: 100dvh;
    justify-content: space-between;
}

/* Left content */
.landing-content {
    flex: 1;
    max-width: 600px;
    color: #fff;
}

/* Header: logo + badge */
.landing-header {
    display: flex;
    flex-direction: column;
    gap: 18px;
    margin-bottom: clamp(28px, 4vh, 48px);
    animation: fadeSlideUp 0.7s cubic-bezier(0.16, 1, 0.3, 1) both;
}

.landing-logo-wrap {
    position: relative;
    display: inline-flex;
    align-items: center;
    background: #ffffff;
    border: 1px solid rgba(255,255,255,0.3);
    border-radius: var(--radius-lg);
    padding: 10px 20px 10px 12px;
    box-shadow: 0 8px 32px rgba(0,0,0,0.3), 0 2px 8px rgba(0,0,0,0.2);
    width: fit-content;
}

.logo-glow {
    position: absolute;
    inset: -1px;
    border-radius: var(--radius-lg);
    background: rgba(255,255,255,0.9);
    z-index: -1;
}

.landing-logo-img {
    height: 36px;
    width: auto;
    display: block;
    position: relative;
    z-index: 1;
}

.landing-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: rgba(255,255,255,0.06);
    border: 1px solid rgba(255,255,255,0.1);
    border-radius: 50px;
    padding: 7px 18px;
    font-size: 13px;
    font-weight: 600;
    color: rgba(255,255,255,0.85);
    letter-spacing: 0.2px;
    backdrop-filter: blur(12px);
    width: fit-content;
    animation: fadeSlideUp 0.7s cubic-bezier(0.16, 1, 0.3, 1) 0.1s both;
}

.badge-dot {
    width: 7px;
    height: 7px;
    border-radius: 50%;
    background: #22c55e;
    box-shadow: 0 0 8px rgba(34,197,94,0.7);
    animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 1; transform: scale(1); }
    50% { opacity: 0.5; transform: scale(1.4); }
}

/* Hero title */
.landing-title {
    font-size: clamp(32px, 5.5vw, 60px);
    font-weight: 900;
    line-height: 1.05;
    margin-bottom: clamp(14px, 2vh, 22px);
    letter-spacing: -1.5px;
    animation: fadeSlideUp 0.7s cubic-bezier(0.16, 1, 0.3, 1) 0.2s both;
}

.title-gradient {
    background: linear-gradient(135deg, #818cf8 0%, #38bdf8 50%, #67e8f9 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Description */
.landing-desc {
    font-size: clamp(15px, 1.8vw, 18px);
    color: rgba(255,255,255,0.55);
    margin-bottom: clamp(24px, 4vh, 40px);
    line-height: 1.7;
    max-width: 520px;
    animation: fadeSlideUp 0.7s cubic-bezier(0.16, 1, 0.3, 1) 0.3s both;
}

/* Feature pills */
.landing-features {
    display: flex;
    gap: clamp(8px, 1.5vw, 12px);
    margin-bottom: clamp(28px, 4vh, 44px);
    flex-wrap: wrap;
    animation: fadeSlideUp 0.7s cubic-bezier(0.16, 1, 0.3, 1) 0.35s both;
}

.feature-pill {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: rgba(255,255,255,0.05);
    border: 1px solid rgba(255,255,255,0.1);
    padding: 10px 16px;
    border-radius: 50px;
    font-size: 13px;
    font-weight: 500;
    color: rgba(255,255,255,0.8);
    backdrop-filter: blur(8px);
    transition: var(--transition);
    white-space: nowrap;
}

.feature-pill:hover {
    background: rgba(255,255,255,0.1);
    border-color: rgba(255,255,255,0.2);
    transform: translateY(-2px);
    color: #fff;
}

.pill-icon {
    font-size: 16px;
}

/* CTA buttons */
.landing-cta {
    display: flex;
    gap: 14px;
    align-items: center;
    flex-wrap: wrap;
    animation: fadeSlideUp 0.7s cubic-bezier(0.16, 1, 0.3, 1) 0.45s both;
}

.btn-start {
    position: relative;
    display: inline-flex;
    align-items: center;
    background: linear-gradient(135deg, #6366f1 0%, #3b82f6 50%, #0ea5e9 100%);
    color: #fff;
    border: none;
    padding: 16px 36px;
    border-radius: var(--radius-xl);
    font-size: 16px;
    font-weight: 700;
    cursor: pointer;
    transition: var(--transition);
    font-family: inherit;
    box-shadow:
        0 0 0 1px rgba(255,255,255,0.1) inset,
        0 8px 32px rgba(99,102,241,0.45),
        0 2px 8px rgba(0,0,0,0.3);
    overflow: hidden;
    flex-shrink: 0;
}

.btn-shine {
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.25), transparent);
    transition: left 0.5s ease;
}

.btn-start:hover {
    transform: translateY(-3px);
    box-shadow:
        0 0 0 1px rgba(255,255,255,0.15) inset,
        0 16px 48px rgba(99,102,241,0.5),
        0 4px 12px rgba(0,0,0,0.3);
}

.btn-start:hover .btn-shine {
    left: 100%;
}

.btn-start:active {
    transform: translateY(-1px);
}

.btn-content {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    position: relative;
    z-index: 1;
}

.btn-icon {
    font-size: 20px;
}

.btn-explore {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: rgba(255,255,255,0.06);
    border: 1px solid rgba(255,255,255,0.15);
    color: rgba(255,255,255,0.85);
    padding: 16px 24px;
    border-radius: var(--radius-xl);
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    font-family: inherit;
    backdrop-filter: blur(10px);
    text-decoration: none;
    flex-shrink: 0;
}

.btn-explore:hover {
    background: rgba(255,255,255,0.12);
    border-color: rgba(255,255,255,0.25);
    transform: translateY(-2px);
    color: #fff;
}

.btn-explore-icon {
    font-size: 18px;
}

/* Resume section */
.landing-resume {
    margin-top: 24px;
    display: flex;
    gap: 12px;
    align-items: center;
    flex-wrap: wrap;
    animation: fadeSlideUp 0.7s cubic-bezier(0.16, 1, 0.3, 1) 0.5s both;
}

.resume-info {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 13px;
    color: rgba(255,255,255,0.4);
}

.resume-dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: #22c55e;
    box-shadow: 0 0 6px rgba(34,197,94,0.6);
}

.btn-resume {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: rgba(34,197,94,0.12);
    border: 1px solid rgba(34,197,94,0.25);
    color: #4ade80;
    padding: 10px 22px;
    border-radius: 50px;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    font-family: inherit;
}

.btn-resume:hover {
    background: rgba(34,197,94,0.2);
    border-color: rgba(34,197,94,0.4);
    transform: translateY(-1px);
}

.btn-reset-mini {
    background: none;
    border: none;
    color: rgba(255,255,255,0.3);
    font-size: 13px;
    cursor: pointer;
    padding: 8px 12px;
    transition: color 0.2s;
    font-family: inherit;
}

.btn-reset-mini:hover {
    color: rgba(255,255,255,0.6);
}

/* Right side: floating cards */
.landing-visual {
    flex: 0 0 auto;
    display: flex;
    flex-direction: column;
    gap: 18px;
    perspective: 1000px;
}

.float-card {
    animation: floatCard 0.8s cubic-bezier(0.16, 1, 0.3, 1) both;
}

.float-card:nth-child(1) { animation-delay: 0.3s; }
.float-card:nth-child(2) { animation-delay: 0.45s; }
.float-card:nth-child(3) { animation-delay: 0.6s; }

@keyframes floatCard {
    from { opacity: 0; transform: translateX(40px) rotateY(-8deg); }
    to { opacity: 1; transform: translateX(0) rotateY(0); }
}

.card-inner {
    background: rgba(255,255,255,0.05);
    border: 1px solid rgba(255,255,255,0.1);
    border-radius: var(--radius-lg);
    padding: 24px 28px;
    backdrop-filter: blur(20px);
    transition: all 0.35s cubic-bezier(0.16, 1, 0.3, 1);
    position: relative;
    overflow: hidden;
}

.card-inner::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, #6366f1, #38bdf8, #22d3ee);
    opacity: 0.7;
}

.card-inner::after {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(ellipse at top left, rgba(99,102,241,0.08), transparent 60%);
    pointer-events: none;
}

.float-card:hover .card-inner {
    background: rgba(255,255,255,0.09);
    border-color: rgba(255,255,255,0.18);
    transform: translateY(-4px) scale(1.02);
    box-shadow:
        0 20px 60px rgba(0,0,0,0.4),
        0 0 30px rgba(99,102,241,0.15);
}

.card-icon-wrap {
    width: 48px;
    height: 48px;
    border-radius: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    margin-bottom: 14px;
    background: rgba(255,255,255,0.08);
    border: 1px solid rgba(255,255,255,0.1);
}

.card-label {
    font-size: 16px;
    font-weight: 700;
    color: #fff;
    margin-bottom: 4px;
}

.card-sublabel {
    font-size: 13px;
    color: rgba(255,255,255,0.45);
}

/* Bottom wave decoration */
.landing-wave {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 1;
    opacity: 0.4;
    pointer-events: none;
}

.landing-wave svg {
    display: block;
    width: 100%;
    height: auto;
}

/* Keyframes */
@keyframes fadeSlideUp {
    from { opacity: 0; transform: translateY(24px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes floatGentle {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-8px); }
}

@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInRight {
    from { opacity: 0; transform: translateX(30px); }
    to { opacity: 1; transform: translateX(0); }
}

/* ========== BUTTONS ========== */
.btn-primary {
    background: linear-gradient(135deg, var(--primary), #3b82f6);
    color: #fff;
    border: none;
    padding: 14px 32px;
    border-radius: var(--radius);
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    font-family: inherit;
    box-shadow: 0 4px 16px rgba(37,99,235,0.3);
    position: relative;
    overflow: hidden;
}

.btn-primary::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, rgba(255,255,255,0.15), transparent);
    opacity: 0;
    transition: opacity 0.25s;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(37,99,235,0.4);
}

.btn-primary:hover::before {
    opacity: 1;
}

.btn-primary:disabled {
    background: var(--text-muted);
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.btn-large {
    padding: 18px 48px;
    font-size: 18px;
    border-radius: var(--radius-lg);
}

.btn-secondary {
    background: var(--surface);
    color: var(--text);
    border: 1px solid var(--border);
    padding: 10px 24px;
    border-radius: var(--radius);
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    font-family: inherit;
}

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

.btn-link {
    background: none;
    border: none;
    color: rgba(255,255,255,0.7);
    font-size: 14px;
    cursor: pointer;
    padding: 8px 16px;
    font-family: inherit;
    transition: var(--transition);
}

.btn-link:hover {
    color: #fff;
}

.btn-reset {
    background: none;
    border: 1px solid var(--border);
    color: var(--text-secondary);
    padding: 8px 16px;
    border-radius: var(--radius);
    font-size: 13px;
    cursor: pointer;
    transition: var(--transition);
    font-family: inherit;
    display: flex;
    align-items: center;
    gap: 6px;
}

.btn-reset:hover {
    border-color: var(--danger);
    color: var(--danger);
    background: var(--danger-light);
}

.btn-next {
    width: 100%;
    padding: 16px;
    font-size: 16px;
}

/* ========== APP LAYOUT ========== */
.app-container {
    min-height: 100vh;
}

/* ========== HEADER ========== */
.app-header {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    padding: 0 24px;
    height: 64px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-sm);
}

.header-left {
    display: flex;
    align-items: center;
    gap: 16px;
}

.header-divider {
    width: 1px;
    height: 24px;
    background: var(--border);
}

.header-logo-img {
    height: 32px;
    width: auto;
}

.course-title {
    font-size: 14px;
    font-weight: 600;
    color: var(--text-secondary);
}

.header-center {
    flex: 1;
    max-width: 400px;
    margin: 0 32px;
}

.progress-container {
    display: flex;
    align-items: center;
    gap: 12px;
}

.progress-label {
    font-size: 12px;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    white-space: nowrap;
}

.progress-bar {
    flex: 1;
    height: 8px;
    background: var(--background);
    border-radius: 999px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary), #3b82f6);
    border-radius: 999px;
    width: 0%;
    transition: width 0.5s ease;
}

.progress-percent {
    font-size: 12px;
    font-weight: 600;
    color: var(--primary);
    min-width: 32px;
    text-align: right;
}

.header-right {
    display: flex;
    align-items: center;
    gap: 12px;
}

/* ========== APP LAYOUT ========== */
.app-layout {
    display: flex;
    min-height: calc(100vh - 64px);
}

/* ========== SIDEBAR ========== */
.sidebar {
    width: 280px;
    background: var(--surface);
    border-right: 1px solid var(--border);
    padding: 24px 0;
    flex-shrink: 0;
    position: sticky;
    top: 64px;
    height: calc(100vh - 64px);
    overflow-y: auto;
}

.sidebar-header {
    padding: 0 20px;
    margin-bottom: 20px;
}

.sidebar-header h3 {
    font-size: 11px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-muted);
}

.step-nav {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.step-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 20px;
    cursor: pointer;
    transition: var(--transition);
    border-radius: 0;
    position: relative;
}

.step-item:not(.locked):hover {
    background: var(--primary-light);
}

.step-item.active {
    background: var(--primary-light);
    border-left: 3px solid var(--primary);
}

.step-item.completed .step-indicator .step-icon {
    background: var(--success);
    color: #fff;
}

.step-item.locked {
    cursor: not-allowed;
    opacity: 0.5;
}

.step-indicator {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: var(--background);
    border: 2px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    flex-shrink: 0;
    transition: var(--transition);
}

.step-info {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.step-name {
    font-size: 14px;
    font-weight: 500;
    color: var(--text);
}

.step-status {
    font-size: 12px;
    color: var(--text-muted);
}

.step-arrow {
    color: var(--text-muted);
    font-size: 18px;
    font-weight: 300;
}

/* ========== MAIN CONTENT ========== */
.main-content {
    flex: 1;
    padding: 32px;
    overflow-y: auto;
}

.content-area {
    max-width: 800px;
    margin: 0 auto;
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ========== CARDS ========== */
.card {
    background: var(--surface);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border);
    box-shadow: var(--shadow);
    overflow: hidden;
}

.card-header {
    padding: 24px 28px 0;
}

.card-header h2 {
    font-size: 22px;
    font-weight: 700;
    margin-bottom: 8px;
}

.card-header p {
    color: var(--text-secondary);
    font-size: 15px;
}

.card-body {
    padding: 24px 28px;
}

.card-footer {
    padding: 0 28px 24px;
    display: flex;
    gap: 12px;
    align-items: center;
}

/* ========== VIDEO SECTION ========== */
.video-wrapper {
    position: relative;
    width: 100%;
    border-radius: var(--radius-lg);
    overflow: hidden;
    background: #0f172a;
    aspect-ratio: 16/9;
    margin-bottom: 20px;
    box-shadow: 0 8px 24px rgba(0,0,0,0.15);
}

.video-wrapper iframe {
    width: 100%;
    height: 100%;
    border: none;
}

.video-wrapper video {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.video-placeholder {
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #1e293b, #334155);
    color: rgba(255,255,255,0.7);
    gap: 16px;
}

.video-placeholder-icon {
    font-size: 64px;
    opacity: 0.6;
}

.video-placeholder p {
    font-size: 14px;
}

.video-meta {
    margin-bottom: 20px;
}

.video-meta h3 {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 8px;
}

.video-meta p {
    color: var(--text-secondary);
    font-size: 15px;
    line-height: 1.7;
}

.video-status {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 12px 16px;
    background: var(--success-light);
    border-radius: var(--radius);
    color: var(--success);
    font-size: 14px;
    font-weight: 500;
    margin-bottom: 16px;
}

/* ========== PDF SECTION ========== */
.pdf-wrapper {
    width: 100%;
    border-radius: var(--radius);
    overflow: hidden;
    border: 1px solid var(--border);
    margin-bottom: 20px;
}

.pdf-wrapper iframe {
    width: 100%;
    height: 450px;
    border: none;
}

.pdf-placeholder {
    width: 100%;
    height: 300px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    background: var(--background);
    border: 2px dashed var(--border);
    border-radius: var(--radius);
    color: var(--text-secondary);
    gap: 12px;
}

.pdf-placeholder-icon {
    font-size: 48px;
}

.pdf-placeholder p {
    font-size: 15px;
    text-align: center;
}

.checkbox-wrapper {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 16px 20px;
    background: var(--background);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    margin-bottom: 16px;
}

.checkbox-wrapper input[type="checkbox"] {
    width: 20px;
    height: 20px;
    cursor: pointer;
    accent-color: var(--primary);
}

.checkbox-wrapper label {
    font-size: 15px;
    cursor: pointer;
    color: var(--text);
}

/* ========== FORM ========== */
.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    font-size: 14px;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 6px;
}

.form-group label .required {
    color: var(--danger);
}

.form-group input {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    font-size: 15px;
    font-family: inherit;
    transition: var(--transition);
    background: var(--surface);
    color: var(--text);
}

.form-group input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37,99,235,0.1);
}

.form-group input.error {
    border-color: var(--danger);
    box-shadow: 0 0 0 3px rgba(220,38,38,0.1);
}

.form-error {
    font-size: 13px;
    color: var(--danger);
    margin-top: 4px;
    display: none;
}

.form-group input.error + .form-error {
    display: block;
}

/* ========== QUIZ ========== */
.quiz-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border);
}

.quiz-progress-info {
    font-size: 14px;
    color: var(--text-secondary);
}

.quiz-progress-info strong {
    color: var(--primary);
}

.question-card {
    margin-bottom: 24px;
}

.question-text {
    font-size: 17px;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 20px;
    line-height: 1.6;
}

.options-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.option-item {
    display: flex;
    align-items: center;
    gap: 14px;
    padding: 14px 18px;
    border: 2px solid var(--border);
    border-radius: var(--radius);
    cursor: pointer;
    transition: var(--transition);
}

.option-item:hover {
    border-color: var(--primary);
    background: var(--primary-light);
}

.option-item.selected {
    border-color: var(--primary);
    background: var(--primary-light);
}

.option-item.correct {
    border-color: var(--success);
    background: var(--success-light);
}

.option-item.wrong {
    border-color: var(--danger);
    background: var(--danger-light);
}

.option-radio {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    border: 2px solid var(--border);
    flex-shrink: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.option-item.selected .option-radio,
.option-item.correct .option-radio,
.option-item.wrong .option-radio {
    border-color: currentColor;
}

.option-item.selected .option-radio {
    border-color: var(--primary);
    background: var(--primary);
    box-shadow: inset 0 0 0 2px #fff;
}

.option-item.correct .option-radio {
    border-color: var(--success);
    background: var(--success);
    box-shadow: inset 0 0 0 2px #fff;
}

.option-item.wrong .option-radio {
    border-color: var(--danger);
    background: var(--danger);
    box-shadow: inset 0 0 0 2px #fff;
}

.option-text {
    font-size: 15px;
    color: var(--text);
    flex: 1;
}

.quiz-feedback {
    padding: 14px 18px;
    border-radius: var(--radius);
    font-size: 14px;
    font-weight: 500;
    margin-top: 16px;
    display: none;
}

.quiz-feedback.show {
    display: flex;
    align-items: center;
    gap: 10px;
}

.quiz-feedback.correct {
    background: var(--success-light);
    color: var(--success);
    border: 1px solid var(--success);
}

.quiz-feedback.wrong {
    background: var(--danger-light);
    color: var(--danger);
    border: 1px solid var(--danger);
}

/* ========== CERTIFICATE ========== */
.certificate-lock {
    text-align: center;
    padding: 60px 20px;
}

.certificate-lock-icon {
    font-size: 64px;
    margin-bottom: 16px;
}

.certificate-lock h3 {
    font-size: 20px;
    margin-bottom: 8px;
}

.certificate-lock p {
    color: var(--text-secondary);
}

.certificate-container {
    display: none;
}

.certificate-container.show {
    display: block;
}

.certificate {
    background: #fff;
    border: 3px solid var(--primary);
    border-radius: var(--radius-lg);
    padding: 48px;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.certificate::before {
    content: '';
    position: absolute;
    inset: 8px;
    border: 1px solid var(--primary);
    border-radius: calc(var(--radius-lg) - 4px);
    pointer-events: none;
}

.certificate::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 6px;
    background: linear-gradient(90deg, var(--primary), #60a5fa, var(--primary));
}

.cert-logo {
    font-size: 24px;
    font-weight: 800;
    letter-spacing: 4px;
    color: var(--primary);
    margin-bottom: 8px;
}

.cert-logo-img {
    height: 50px;
    width: auto;
    margin-bottom: 12px;
}

.cert-title {
    font-size: 32px;
    font-weight: 700;
    color: var(--text);
    margin-bottom: 32px;
    text-transform: uppercase;
    letter-spacing: 6px;
}

.cert-subtitle {
    font-size: 16px;
    color: var(--text-secondary);
    margin-bottom: 8px;
}

.cert-name {
    font-size: 28px;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: 16px;
    border-bottom: 2px solid var(--primary);
    display: inline-block;
    padding-bottom: 4px;
}

.cert-course {
    font-size: 18px;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 32px;
}

.cert-details {
    display: flex;
    justify-content: space-between;
    align-items: flex-end;
    margin-top: 24px;
    padding-top: 24px;
    border-top: 1px solid var(--border);
}

.cert-date, .cert-number {
    font-size: 13px;
    color: var(--text-secondary);
}

.cert-date strong, .cert-number strong {
    display: block;
    font-size: 15px;
    color: var(--text);
    margin-top: 4px;
}

.cert-decoration {
    position: absolute;
    font-size: 120px;
    opacity: 0.04;
    color: var(--primary);
}

.cert-decoration.top-right {
    top: -20px;
    right: 20px;
}

.cert-decoration.bottom-left {
    bottom: -20px;
    left: 20px;
}

/* ========== NOTIFICATION ========== */
.notification {
    position: fixed;
    top: 80px;
    right: 24px;
    background: var(--surface);
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
    padding: 14px 20px;
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 14px;
    font-weight: 500;
    z-index: 1000;
    animation: slideIn 0.3s ease;
    max-width: 360px;
    border-left: 4px solid var(--primary);
}

.notification.success {
    border-left-color: var(--success);
}

.notification.error {
    border-left-color: var(--danger);
}

.notification.info {
    border-left-color: var(--primary);
}

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

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

/* ========== MODAL ========== */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
}

.modal-box {
    background: var(--surface);
    border-radius: var(--radius-lg);
    padding: 32px;
    max-width: 400px;
    width: 90%;
    box-shadow: var(--shadow-lg);
    text-align: center;
}

.modal-box p {
    font-size: 16px;
    margin-bottom: 24px;
    color: var(--text);
}

.modal-actions {
    display: flex;
    gap: 12px;
    justify-content: center;
}

.btn-danger {
    background: var(--danger);
    color: #fff;
    border: none;
    padding: 10px 24px;
    border-radius: var(--radius);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    font-family: inherit;
}

.btn-danger:hover {
    background: #b91c1c;
}


/* ========== RESPONSIVE ========== */
@media (max-width: 1024px) {
    .landing-container {
        gap: 40px;
    }
}

@media (max-width: 768px) {
    .landing-container {
        flex-direction: column;
        text-align: center;
        justify-content: center;
        gap: 32px;
        padding: clamp(32px, 6vh, 48px) 0;
    }

    .landing-content {
        max-width: 100%;
    }

    .landing-header {
        align-items: center;
    }

    .landing-desc {
        margin: 0 auto 28px;
    }

    .landing-features {
        justify-content: center;
    }

    .feature-pill {
        font-size: 12px;
        padding: 8px 14px;
    }

    .landing-cta {
        justify-content: center;
        flex-direction: column;
        width: 100%;
    }

    .btn-start, .btn-explore {
        width: 100%;
        justify-content: center;
        padding: 15px 28px;
    }

    .landing-visual {
        flex-direction: row;
        width: 100%;
        gap: 12px;
    }

    .float-card {
        flex: 1;
    }

    .card-inner {
        padding: 16px 18px;
    }

    .card-icon-wrap {
        width: 36px;
        height: 36px;
        font-size: 18px;
        margin-bottom: 10px;
    }

    .card-label {
        font-size: 13px;
    }

    .card-sublabel {
        display: none;
    }
}

@media (max-width: 480px) {
    .landing-container {
        padding: 24px 0;
    }

    .landing-title {
        font-size: 28px;
        letter-spacing: -0.5px;
    }

    .landing-badge {
        font-size: 11px;
        padding: 6px 14px;
    }

    .landing-features {
        gap: 6px;
    }

    .feature-pill {
        font-size: 11px;
        padding: 6px 12px;
        gap: 6px;
    }

    .landing-visual {
        gap: 8px;
    }

    .card-inner {
        padding: 12px 14px;
    }

    .card-icon-wrap {
        width: 30px;
        height: 30px;
        font-size: 15px;
        margin-bottom: 6px;
    }

    .card-label {
        font-size: 11px;
    }
}

@media (max-width: 768px) {
    .app-header {
        padding: 0 16px;
        gap: 8px;
    }

    .header-center {
        display: none;
    }

    .header-left .course-title {
        display: none;
    }

    .sidebar {
        position: fixed;
        bottom: 0;
        left: 0;
        right: 0;
        top: auto;
        height: auto;
        z-index: 100;
        border-right: none;
        border-top: 1px solid var(--border);
        padding: 0;
        background: var(--surface);
        box-shadow: 0 -4px 12px rgba(0,0,0,0.1);
        transform: translateY(100%);
        transition: transform 0.3s ease;
    }

    .sidebar.open {
        transform: translateY(0);
    }

    .sidebar-header {
        padding: 16px 20px 12px;
        display: none;
    }

    .step-nav {
        flex-direction: row;
        overflow-x: auto;
        padding: 0 8px 8px;
        gap: 2px;
    }

    .step-item {
        flex-direction: column;
        gap: 4px;
        padding: 10px 12px;
        border-radius: var(--radius);
        border-left: none;
        min-width: 72px;
        text-align: center;
    }

    .step-item.active {
        border-left: none;
        background: var(--primary-light);
    }

    .step-item.locked {
        opacity: 0.4;
    }

    .step-info {
        flex-direction: row;
        gap: 4px;
    }

    .step-status {
        display: none;
    }

    .step-arrow {
        display: none;
    }

    .step-icon {
        font-size: 18px;
    }

    .main-content {
        padding: 20px 16px;
        padding-bottom: 100px;
    }

    .content-area {
        max-width: 100%;
    }

    .card-header, .card-body, .card-footer {
        padding-left: 20px;
        padding-right: 20px;
    }

    .certificate {
        padding: 32px 20px;
    }

    .cert-title {
        font-size: 22px;
        letter-spacing: 3px;
    }

    .cert-name {
        font-size: 20px;
    }

    .cert-details {
        flex-direction: column;
        gap: 16px;
        align-items: flex-start;
    }
}

/* ========== PRINT ========== */
@media print {
    body * {
        visibility: hidden;
    }

    .certificate, .certificate * {
        visibility: visible;
    }

    .certificate {
        position: absolute;
        left: 0;
        top: 0;
        width: 100%;
        border: 3px solid #000;
        box-shadow: none;
    }

    .btn-print, .btn-download {
        display: none !important;
    }

    .cert-logo-img {
        display: block !important;
    }
    .cert-logo {
        display: none !important;
    }
}

/* ========== MOBILE SIDEBAR TOGGLE ========== */
.mobile-nav-toggle {
    display: none;
    position: fixed;
    bottom: 20px;
    right: 20px;
    width: 52px;
    height: 52px;
    background: var(--primary);
    color: #fff;
    border: none;
    border-radius: 50%;
    font-size: 22px;
    cursor: pointer;
    z-index: 99;
    box-shadow: var(--shadow-lg);
    transition: var(--transition);
}

.mobile-nav-toggle:hover {
    transform: scale(1.05);
}

.sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.5);
    z-index: 98;
}

@media (max-width: 768px) {
    .mobile-nav-toggle {
        display: flex;
        align-items: center;
        justify-content: center;
    }

    .sidebar.open + .mobile-nav-toggle {
        display: none;
    }

    .sidebar.open ~ .sidebar-overlay {
        display: block;
    }
}