body {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    overflow-x: hidden;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    font-size: 15px;
}

html, body {
    height: 100%;
}

.cosmic-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #0a0e27 0%, #1a1042 25%, #2d1b69 50%, #1a1042 75%, #0a0e27 100%);
    z-index: -2;
}

.stars {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
}

.star {
    position: absolute;
    background: white;
    border-radius: 50%;
    animation: twinkle 3s infinite;
}

@keyframes twinkle {
    0%, 100% { opacity: 0.3; }
    50% { opacity: 1; }
}

@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-20px); }
}

@keyframes rotate {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

@keyframes pulse {
    0%, 100% { transform: scale(1); opacity: 0.8; }
    50% { transform: scale(1.05); opacity: 1; }
}

@keyframes slideInLeft {
    from { transform: translateX(-100px); opacity: 0; }
    to { transform: translateX(0); opacity: 1; }
}

@keyframes slideInRight {
    from { transform: translateX(100px); opacity: 0; }
    to { transform: translateX(0); opacity: 1; }
}

@keyframes fadeInUp {
    from { transform: translateY(50px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

.floating {
    animation: float 6s ease-in-out infinite;
}

.rotating {
    animation: rotate 20s linear infinite;
}

.pulsing {
    animation: pulse 3s ease-in-out infinite;
}

.content-section {
    opacity: 0;
    transform: translateY(50px);
    transition: all 0.8s ease-out;
}

.content-section.visible {
    opacity: 1;
    transform: translateY(0);
}

.glass-effect {
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.gradient-text {
    background: linear-gradient(135deg, #ffd700 0%, #ffed4e 50%, #ffd700 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.feature-card {
    transition: all 0.3s ease;
    cursor: pointer;
}

.feature-card:hover {
    transform: translateY(-10px) scale(1.02);
}

.nav-link {
    position: relative;
    transition: all 0.3s ease;
    font-size: 12px;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: linear-gradient(90deg, #ffd700, #ffed4e);
    transition: width 0.3s ease;
}

.nav-link:hover::after {
    width: 100%;
}

.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    z-index: 1000;
    justify-content: center;
    align-items: center;
}

.modal.active {
    display: flex;
}

.scroll-indicator {
    position: fixed;
    top: 0;
    left: 0;
    height: 4px;
    background: linear-gradient(90deg, #ffd700, #ffed4e, #ffd700);
    z-index: 100;
    transition: width 0.1s ease;
}

.page-section {
    min-height: 100%;
    padding-top: 80px;
}

.page-section.active {
    display: block;
}

.reading-controls {
    position: fixed;
    bottom: 20px;
    right: 20px;
    z-index: 50;
}

.speed-indicator {
    position: fixed;
    top: 50%;
    left: 20px;
    transform: translateY(-50%);
    z-index: 50;
}

.longform-content {
    max-width: 800px;
    margin: 0 auto;
    line-height: 1.8;
    color: #ffffff;
}

.longform-content p {
    margin-bottom: 1.5rem;
    font-size: 1.1rem;
    transition: all 0.3s ease;
    color: #ffffff;
}

.longform-content.fast-reading p {
    margin-bottom: 0.8rem;
    font-size: 1rem;
    line-height: 1.5;
    color: #ffffff;
}

.longform-content h2 {
    font-size: 2rem;
    margin: 2rem 0 1rem 0;
    color: #ffd700;
}

.longform-content h3 {
    font-size: 1.5rem;
    margin: 1.5rem 0 1rem 0;
    color: #ffed4e;
}

.article-image {
    width: 100%;
    max-width: 600px;
    margin: 2rem auto;
    border-radius: 15px;
    overflow: hidden;
    box-shadow: 0 20px 40px rgba(255, 215, 0, 0.2);
}

.infographic {
    background: rgba(255, 255, 255, 0.05);
    border-radius: 20px;
    padding: 2rem;
    margin: 2rem 0;
    border: 1px solid rgba(255, 215, 0, 0.3);
}

input, textarea {
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    color: #ffffff !important;
    padding: 12px;
    border-radius: 8px;
    width: 100%;
    transition: all 0.3s ease;
}
input {
    height: 38px;
    padding-left: 12px!important;
}

input:focus, textarea:focus {
    outline: none;
    border-color: #ffd700;
    background: rgba(255, 255, 255, 0.15);
    color: #ffffff !important;
}

input::placeholder, textarea::placeholder {
    color: rgba(255, 255, 255, 0.5);
}

.loading-spinner {
    display: none;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-top-color: #ffd700;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

.success-message {
    display: none;
    background: rgba(34, 197, 94, 0.2);
    border: 1px solid rgba(34, 197, 94, 0.5);
    color: #4ade80;
    padding: 12px;
    border-radius: 8px;
    margin-top: 16px;
}

.error-message {
    display: none;
    background: rgba(239, 68, 68, 0.2);
    border: 1px solid rgba(239, 68, 68, 0.5);
    color: #f87171;
    padding: 12px;
    border-radius: 8px;
    margin-top: 16px;
}

.video-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.video-card {
    background: rgba(255, 255, 255, 0.05);
    border-radius: 15px;
    overflow: hidden;
    transition: all 0.3s ease;
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.video-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 20px 40px rgba(255, 215, 0, 0.2);
}

.video-thumbnail {
    aspect-ratio: 16/9;
    background: linear-gradient(135deg, #1a1042, #2d1b69);
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
}

.play-button {
    width: 60px;
    height: 60px;
    background: rgba(255, 215, 0, 0.9);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
}

.play-button:hover {
    background: #ffd700;
    transform: scale(1.1);
}

.audio-player {
    background: rgba(255, 255, 255, 0.05);
    border-radius: 15px;
    padding: 1.5rem;
    margin: 1rem 0;
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.progress-bar {
    width: 100%;
    height: 6px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 3px;
    margin: 1rem 0;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, #ffd700, #ffed4e);
    border-radius: 3px;
    transition: width 0.3s ease;
}

.slide-container {
    max-width: 900px;
    margin: 0 auto;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 20px;
    overflow: hidden;
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.slide {
    display: none;
    padding: 3rem;
    text-align: center;
    min-height: 500px;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.slide.active {
    display: flex;
}

.slide h2 {
    font-size: 2.5rem;
    margin-bottom: 2rem;
    color: #ffd700;
}

.slide-controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    background: rgba(0, 0, 0, 0.3);
}

.slide-nav {
    background: rgba(255, 215, 0, 0.2);
    border: 1px solid #ffd700;
    color: #ffd700;
    padding: 0.5rem 1rem;
    border-radius: 25px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.slide-nav:hover {
    background: #ffd700;
    color: #1a1042;
}

.slide-nav:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.mobile-menu {
    display: none;
}

@media (max-width: 768px) {
    .desktop-menu {
        display: none;
    }

    .mobile-menu {
        display: block;
    }

    .longform-content {
        padding: 0 1rem;
    }

    .slide {
        padding: 2rem 1rem;
    }

    .slide h2 {
        font-size: 1.8rem;
    }
}

@view-transition { navigation: auto; }

.player-controls {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-top: 10px;
}

.progress-bar {
    flex: 1;
    height: 5px;
    cursor: pointer;
    accent-color: #4a90d9; /* màu thanh kéo trên Chrome/Edge/Firefox mới */
}

.time-current, .time-duration {
    font-size: 13px;
    color: #555;
    min-width: 40px;
    text-align: center;
}

/*
.btn-play-pause {
    width: 45px;
    height: 45px;
    border-radius: 50%;
    border: none;
    background: #4a90d9;
    color: #fff;
    font-size: 18px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
}
.btn-play-pause.playing {
    background: #d94a4a;
}*/