/* ============================================
   DẠT TOOLS - CSS Stylesheet
   Cyberpunk/Tech Aesthetic with Full Responsiveness
   ============================================ */

/* CSS Variables */
:root {
    /* Colors */
    --bg-primary: #000000;
    --bg-secondary: #0a0a0a;
    --bg-card: #111111;
    --bg-card-hover: #1a1a1a;

    --accent-primary: #00ff00;
    --accent-secondary: #00aa00;
    --accent-tertiary: #00cc00;
    --accent-success: #00ff88;
    --accent-warning: #ffaa00;

    --text-primary: #ffffff;
    --text-secondary: #a0a0a0;
    --text-muted: #888888;

    --border-color: rgba(255, 255, 255, 0.08);
    --border-glow: rgba(0, 255, 0, 0.4);

    /* Gradients */
    --gradient-primary: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    --gradient-card: linear-gradient(145deg, rgba(255,255,255,0.03) 0%, rgba(255,255,255,0) 100%);
    --gradient-glow: radial-gradient(circle at 50% 50%, var(--accent-primary), transparent 70%);
    
    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
    
    /* Typography */
    --font-display: 'Orbitron', sans-serif;
    --font-body: 'Rajdhani', sans-serif;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
    
    /* Container */
    --container-max: 1400px;
    --container-padding: 1.5rem;
}

/* Reset & Base */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-body);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    min-height: 100vh;
}

a {
    text-decoration: none;
    color: inherit;
    transition: var(--transition-base);
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

/* Animated Background */
.bg-grid {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image:
        linear-gradient(rgba(0, 255, 0, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(0, 255, 0, 0.03) 1px, transparent 1px);
    background-size: 50px 50px;
    pointer-events: none;
    z-index: -2;
}

.bg-glow {
    position: fixed;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background:
        radial-gradient(circle at 30% 20%, rgba(0, 255, 0, 0.06) 0%, transparent 40%),
        radial-gradient(circle at 70% 80%, rgba(0, 170, 0, 0.08) 0%, transparent 40%),
        radial-gradient(circle at 50% 50%, rgba(0, 204, 0, 0.04) 0%, transparent 50%);
    pointer-events: none;
    z-index: -1;
    animation: bgFloat 20s ease-in-out infinite;
}

@keyframes bgFloat {
    0%, 100% { transform: translate(0, 0) rotate(0deg); }
    25% { transform: translate(2%, 2%) rotate(1deg); }
    50% { transform: translate(-1%, 3%) rotate(-1deg); }
    75% { transform: translate(-2%, -1%) rotate(0.5deg); }
}

/* ============================================
   NAVIGATION
   ============================================ */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(0, 0, 0, 0.85);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-color);
    padding: var(--space-md) 0;
}

.nav-container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--container-padding);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: 700;
}

.logo-icon {
    font-size: 1.8rem;
    filter: drop-shadow(0 0 10px var(--accent-primary));
}

.logo-text {
    letter-spacing: 2px;
}

.logo-text .accent {
    color: var(--accent-primary);
    text-shadow: 0 0 20px var(--accent-primary);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--space-xl);
}

.nav-link {
    font-family: var(--font-display);
    font-size: 0.85rem;
    font-weight: 500;
    letter-spacing: 1px;
    text-transform: uppercase;
    color: var(--text-secondary);
    padding: var(--space-sm) 0;
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--gradient-primary);
    transition: var(--transition-base);
}

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

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

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--space-sm);
}

.nav-toggle span {
    width: 25px;
    height: 2px;
    background: var(--text-primary);
    transition: var(--transition-base);
}

/* ============================================
   HERO SECTION
   ============================================ */
.hero {
    min-height: calc(100vh - 60px);
    display: grid;
    grid-template-columns: 1fr 1fr;
    align-items: center;
    gap: var(--space-3xl);
    max-width: var(--container-max);
    margin: 0 auto;
    padding: calc(80px + var(--space-3xl)) var(--container-padding) var(--space-3xl);
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-sm) var(--space-lg);
    background: rgba(0, 255, 0, 0.1);
    border: 1px solid rgba(0, 255, 0, 0.3);
    border-radius: 50px;
    font-size: 0.85rem;
    color: var(--accent-primary);
    margin-bottom: var(--space-xl);
    animation: fadeInUp 0.6s ease;
}

.hero-title {
    font-family: var(--font-display);
    font-weight: 900;
    line-height: 1;
    margin-bottom: var(--space-xl);
}

.hero-title .line1 {
    display: block;
    font-size: clamp(2.5rem, 6vw, 5rem);
    color: var(--text-primary);
    animation: fadeInUp 0.6s ease 0.1s both;
}

.hero-title .line2 {
    display: block;
    font-size: clamp(3rem, 8vw, 6.5rem);
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-shadow: none;
    filter: drop-shadow(0 0 30px rgba(0, 255, 0, 0.5));
    animation: fadeInUp 0.6s ease 0.2s both;
}

.hero-subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
    max-width: 500px;
    margin-bottom: var(--space-xl);
    animation: fadeInUp 0.6s ease 0.3s both;
}

.tech-tag {
    display: inline-block;
    padding: 2px 10px;
    margin: 2px;
    background: rgba(0, 170, 0, 0.15);
    border: 1px solid rgba(0, 170, 0, 0.3);
    border-radius: 4px;
    font-size: 0.85rem;
    color: var(--accent-tertiary);
}

.hero-cta {
    display: inline-flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-md) var(--space-xl);
    background: var(--gradient-primary);
    border-radius: var(--radius-md);
    font-family: var(--font-display);
    font-weight: 600;
    font-size: 0.9rem;
    letter-spacing: 1px;
    color: var(--bg-primary);
    box-shadow: 0 0 30px rgba(0, 255, 0, 0.3);
    animation: fadeInUp 0.6s ease 0.4s both;
    transition: var(--transition-base);
}

.hero-cta:hover {
    transform: translateY(-2px);
    box-shadow: 0 0 50px rgba(0, 255, 0, 0.5);
}

.hero-cta svg {
    transition: var(--transition-base);
}

.hero-cta:hover svg {
    transform: translate(3px, -3px);
}

/* Code Window */
.hero-visual {
    animation: fadeInUp 0.8s ease 0.5s both;
}

.code-window {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: 
        0 25px 50px rgba(0, 0, 0, 0.5),
        0 0 100px rgba(0, 255, 0, 0.1);
}

.window-header {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-md) var(--space-lg);
    background: rgba(255, 255, 255, 0.03);
    border-bottom: 1px solid var(--border-color);
}

.dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
}

.dot.red { background: #ff5f57; }
.dot.yellow { background: #ffbd2e; }
.dot.green { background: #28ca41; }

.window-title {
    margin-left: auto;
    font-size: 0.8rem;
    color: var(--text-muted);
}

.code-content {
    padding: var(--space-xl);
    font-family: 'Fira Code', 'Consolas', monospace;
    font-size: 0.9rem;
    line-height: 1.8;
    overflow-x: auto;
}

.code-content .keyword { color: var(--accent-secondary); }
.code-content .function { color: var(--accent-primary); }
.code-content .string { color: var(--accent-secondary); }
.code-content .comment { color: var(--text-muted); font-style: italic; }

/* ============================================
   TOOLS SECTION
   ============================================ */
.tools-section {
    padding: var(--space-3xl) var(--container-padding);
    max-width: var(--container-max);
    margin: 0 auto;
}

.section-header {
    text-align: center;
    margin-bottom: var(--space-3xl);
}

.section-tag {
    display: inline-block;
    font-family: var(--font-display);
    font-size: 0.8rem;
    color: var(--accent-primary);
    letter-spacing: 2px;
    margin-bottom: var(--space-md);
}

.section-title {
    font-family: var(--font-display);
    font-size: clamp(2rem, 4vw, 3rem);
    font-weight: 700;
    margin-bottom: var(--space-md);
}

.section-desc {
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

/* Tools Grid */
.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: var(--space-xl);
}

/* Tool Card */
.tool-card {
    position: relative;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    overflow: hidden;
    transition: var(--transition-base);
}

.tool-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--gradient-primary);
    opacity: 0;
    transition: var(--transition-base);
}

.tool-card:hover {
    transform: translateY(-5px);
    border-color: var(--border-glow);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3);
}

.tool-card:hover::before {
    opacity: 1;
}

.card-glow {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(circle at 50% 0%, rgba(0, 255, 0, 0.1) 0%, transparent 50%);
    opacity: 0;
    transition: var(--transition-base);
    pointer-events: none;
}

.tool-card:hover .card-glow {
    opacity: 1;
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    padding: var(--space-xl) var(--space-xl) 0;
}

.tool-icon {
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(0, 255, 0, 0.1);
    border: 1px solid rgba(0, 255, 0, 0.2);
    border-radius: var(--radius-lg);
    font-size: 1.8rem;
}

.tool-status {
    display: flex;
    align-items: center;
    gap: var(--space-xs);
    padding: 4px 12px;
    border-radius: 50px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.tool-status.online {
    background: rgba(0, 255, 136, 0.1);
    color: var(--accent-success);
}

.tool-status.maintenance {
    background: rgba(255, 170, 0, 0.1);
    color: var(--accent-warning);
}

.status-dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: currentColor;
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

.card-body {
    padding: var(--space-xl);
}

.tool-name {
    font-family: var(--font-display);
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: var(--space-sm);
}

.tool-desc {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: var(--space-lg);
    line-height: 1.6;
}

.tool-tech {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
}

.tool-tech .tech {
    padding: 4px 12px;
    background: rgba(0, 170, 0, 0.15);
    border: 1px solid rgba(0, 170, 0, 0.3);
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    color: var(--accent-tertiary);
}

.card-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-lg) var(--space-xl);
    background: rgba(255, 255, 255, 0.02);
    border-top: 1px solid var(--border-color);
}

.tool-stats {
    display: flex;
    gap: var(--space-xl);
}

.stat {
    display: flex;
    flex-direction: column;
}

.stat-value {
    font-family: var(--font-display);
    font-weight: 600;
    color: var(--text-primary);
}

.stat-label {
    font-size: 0.75rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.card-link {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    color: var(--accent-primary);
    font-weight: 600;
    font-size: 0.9rem;
}

.card-link svg {
    transition: var(--transition-base);
}

.card-link:hover svg {
    transform: translateX(5px);
}

/* ============================================
   ABOUT SECTION
   ============================================ */
.about-section {
    padding: var(--space-3xl) var(--container-padding);
    background: var(--bg-secondary);
}

.about-container {
    max-width: var(--container-max);
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-3xl);
    align-items: center;
}

.about-text {
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-bottom: var(--space-xl);
    line-height: 1.8;
}

.skills-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-lg);
}

.skill-item {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    padding: var(--space-lg);
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    transition: var(--transition-base);
}

.skill-item:hover {
    border-color: var(--border-glow);
    transform: translateY(-2px);
}

.skill-icon {
    font-size: 2rem;
}

.skill-info h4 {
    font-family: var(--font-display);
    font-size: 1rem;
    margin-bottom: 2px;
}

.skill-info p {
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* Terminal */
.terminal {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: 0 25px 50px rgba(0, 0, 0, 0.3);
}

.terminal-header {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-md) var(--space-lg);
    background: rgba(255, 255, 255, 0.03);
    border-bottom: 1px solid var(--border-color);
}

.terminal-title {
    margin-left: auto;
    font-size: 0.8rem;
    color: var(--text-muted);
}

.terminal-body {
    padding: var(--space-xl);
    font-family: 'Fira Code', 'Consolas', monospace;
    font-size: 0.85rem;
}

.terminal-line {
    margin-bottom: var(--space-sm);
    display: flex;
    gap: var(--space-sm);
}

.prompt {
    color: var(--accent-success);
}

.command {
    color: var(--text-primary);
}

.output {
    color: var(--text-secondary);
    padding-left: 1.2rem;
}

.output.success {
    color: var(--accent-success);
}

.output.highlight {
    color: var(--accent-primary);
}

.typing {
    display: flex;
    align-items: center;
}

.cursor {
    animation: blink 1s infinite;
    color: var(--accent-primary);
}

@keyframes blink {
    0%, 50% { opacity: 1; }
    51%, 100% { opacity: 0; }
}

/* ============================================
   CONTACT SECTION
   ============================================ */
.contact-section {
    padding: var(--space-3xl) var(--container-padding);
    max-width: var(--container-max);
    margin: 0 auto;
    text-align: center;
}

.contact-desc {
    color: var(--text-secondary);
    margin-bottom: var(--space-2xl);
}

.contact-links {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--space-lg);
    max-width: 900px;
    margin: 0 auto;
}

.contact-card {
    display: flex;
    align-items: center;
    gap: var(--space-lg);
    padding: var(--space-xl);
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    transition: var(--transition-base);
}

.contact-card:hover {
    border-color: var(--border-glow);
    transform: translateY(-3px);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.3);
}

.contact-icon {
    width: 50px;
    height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(0, 255, 0, 0.1);
    border-radius: var(--radius-md);
    color: var(--accent-primary);
}

.contact-icon.zalo {
    font-family: var(--font-display);
    font-weight: 700;
    font-size: 1.3rem;
    background: linear-gradient(135deg, #0068ff, #00a8ff);
    color: white;
}

.contact-info {
    text-align: left;
}

.contact-label {
    display: block;
    font-size: 0.8rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 2px;
}

.contact-value {
    font-family: var(--font-display);
    font-weight: 500;
    color: var(--text-primary);
}

/* ============================================
   FOOTER
   ============================================ */
.footer {
    padding: var(--space-2xl) var(--container-padding);
    border-top: 1px solid var(--border-color);
    background: var(--bg-secondary);
}

.footer-container {
    max-width: var(--container-max);
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-brand {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    font-family: var(--font-display);
    font-size: 1.2rem;
    font-weight: 700;
}

.footer-text {
    color: var(--text-muted);
    font-size: 0.9rem;
}

/* ============================================
   DETAIL PAGE STYLES
   ============================================ */
.detail-page {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: calc(80px + var(--space-xl)) var(--container-padding) var(--space-3xl);
}

/* Breadcrumb */
.breadcrumb {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    font-size: 0.9rem;
    margin-bottom: var(--space-xl);
}

.breadcrumb a {
    color: var(--text-muted);
}

.breadcrumb a:hover {
    color: var(--accent-primary);
}

.breadcrumb .separator {
    color: var(--text-muted);
}

.breadcrumb .current {
    color: var(--text-primary);
}

/* Detail Header */
.detail-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: var(--space-xl);
    padding: var(--space-2xl);
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    margin-bottom: var(--space-2xl);
}

.detail-header-content {
    display: flex;
    gap: var(--space-xl);
}

.tool-icon-large {
    width: 100px;
    height: 100px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(0, 255, 0, 0.1);
    border: 2px solid rgba(0, 255, 0, 0.3);
    border-radius: var(--radius-xl);
    font-size: 3rem;
    flex-shrink: 0;
}

.detail-status {
    display: inline-flex;
    align-items: center;
    gap: var(--space-xs);
    padding: 4px 12px;
    border-radius: 50px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    background: rgba(0, 255, 136, 0.1);
    color: var(--accent-success);
    margin-bottom: var(--space-sm);
}

.detail-status.maintenance {
    background: rgba(255, 170, 0, 0.1);
    color: var(--accent-warning);
}

.detail-title {
    font-family: var(--font-display);
    font-size: clamp(1.8rem, 4vw, 2.5rem);
    font-weight: 700;
    margin-bottom: var(--space-sm);
}

.detail-tagline {
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-bottom: var(--space-lg);
    max-width: 600px;
}

.detail-tech {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
}

.detail-tech .tech {
    padding: 6px 14px;
    background: rgba(0, 170, 0, 0.15);
    border: 1px solid rgba(0, 170, 0, 0.3);
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
    color: var(--accent-tertiary);
}

.detail-stats {
    display: flex;
    gap: var(--space-lg);
    flex-shrink: 0;
}

.stat-box {
    text-align: center;
    padding: var(--space-lg);
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    min-width: 100px;
}

.stat-number {
    display: block;
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent-primary);
    margin-bottom: 4px;
}

/* Detail Grid */
.detail-grid {
    display: grid;
    grid-template-columns: 1fr 350px;
    gap: var(--space-2xl);
}

/* Detail Sections */
.detail-section {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    padding: var(--space-2xl);
    margin-bottom: var(--space-xl);
}

.detail-section-title {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    font-family: var(--font-display);
    font-size: 1.3rem;
    margin-bottom: var(--space-xl);
}

.title-icon {
    font-size: 1.5rem;
}

/* Features List */
.features-list {
    display: grid;
    gap: var(--space-lg);
}

.feature-item {
    display: flex;
    gap: var(--space-lg);
    padding: var(--space-lg);
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    transition: var(--transition-base);
}

.feature-item:hover {
    border-color: var(--border-glow);
}

.feature-icon {
    width: 50px;
    height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(0, 255, 0, 0.1);
    border-radius: var(--radius-md);
    font-size: 1.5rem;
    flex-shrink: 0;
}

.feature-content h4 {
    font-family: var(--font-display);
    font-size: 1.1rem;
    margin-bottom: 4px;
}

.feature-content p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* Video Container */
.video-container {
    position: relative;
}

.video-wrapper {
    position: relative;
    padding-bottom: 56.25%;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    overflow: hidden;
}

.video-wrapper iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: none;
}

.video-placeholder {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
    cursor: pointer;
    transition: var(--transition-base);
}

.video-placeholder:hover {
    color: var(--accent-primary);
}

.video-placeholder svg {
    margin-bottom: var(--space-md);
}

/* Requirements Grid */
.requirements-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-lg);
}

.requirement-item {
    padding: var(--space-lg);
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
}

.requirement-item h4 {
    font-family: var(--font-display);
    font-size: 0.9rem;
    color: var(--accent-primary);
    margin-bottom: var(--space-sm);
}

.requirement-item p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* Usage Steps */
.usage-steps {
    display: grid;
    gap: var(--space-lg);
}

.step-item {
    display: flex;
    gap: var(--space-lg);
}

.step-number {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--gradient-primary);
    border-radius: 50%;
    font-family: var(--font-display);
    font-weight: 700;
    color: var(--bg-primary);
    flex-shrink: 0;
}

.step-content h4 {
    font-family: var(--font-display);
    font-size: 1.1rem;
    margin-bottom: 4px;
}

.step-content p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* Sidebar */
.sidebar-box {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    padding: var(--space-xl);
    margin-bottom: var(--space-xl);
}

.sidebar-title {
    font-family: var(--font-display);
    font-size: 1.1rem;
    margin-bottom: var(--space-lg);
}

/* Download Box */
.download-note {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: var(--space-lg);
}

.download-buttons {
    display: flex;
    flex-direction: column;
    gap: var(--space-md);
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    padding: var(--space-md) var(--space-xl);
    border-radius: var(--radius-md);
    font-family: var(--font-display);
    font-weight: 600;
    font-size: 0.9rem;
    transition: var(--transition-base);
    text-align: center;
}

.btn-primary {
    background: var(--gradient-primary);
    color: var(--bg-primary);
}

.btn-primary:hover {
    box-shadow: 0 0 30px rgba(0, 255, 0, 0.4);
    transform: translateY(-2px);
}

.btn-secondary {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
}

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

.zalo-icon {
    font-family: var(--font-display);
    font-weight: 700;
    font-size: 1rem;
}

/* Other Tools */
.other-tools-list {
    display: flex;
    flex-direction: column;
    gap: var(--space-md);
}

.other-tool-item {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    padding: var(--space-md);
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    transition: var(--transition-base);
}

.other-tool-item:hover {
    border-color: var(--border-glow);
}

.other-tool-icon {
    font-size: 1.5rem;
}

.other-tool-info {
    flex: 1;
}

.other-tool-name {
    font-family: var(--font-display);
    font-size: 0.95rem;
    font-weight: 500;
}

.other-tool-status {
    font-size: 0.75rem;
    color: var(--text-muted);
}

/* Support List */
.support-list {
    list-style: none;
}

.support-list li {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    padding: var(--space-md) 0;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-secondary);
}

.support-list li:last-child {
    border-bottom: none;
}

.support-list svg {
    color: var(--accent-primary);
    flex-shrink: 0;
}

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

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */

/* Tablet Landscape */
@media (max-width: 1200px) {
    .detail-grid {
        grid-template-columns: 1fr 300px;
    }
    
    .detail-header {
        flex-direction: column;
    }
    
    .detail-stats {
        width: 100%;
        justify-content: flex-start;
    }
}

/* Tablet Portrait */
@media (max-width: 992px) {
    .hero {
        grid-template-columns: 1fr;
        text-align: center;
        padding-top: calc(80px + var(--space-2xl));
    }
    
    .hero-content {
        order: 1;
    }
    
    .hero-visual {
        order: 2;
        max-width: 500px;
        margin: 0 auto;
    }
    
    .hero-subtitle {
        margin-left: auto;
        margin-right: auto;
    }
    
    .about-container {
        grid-template-columns: 1fr;
        gap: var(--space-2xl);
    }
    
    .about-visual {
        order: -1;
    }
    
    .detail-grid {
        grid-template-columns: 1fr;
    }
    
    .detail-sidebar {
        display: grid;
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-xl);
    }
    
    .sidebar-box {
        margin-bottom: 0;
    }
}

/* Mobile Landscape / Small Tablet */
@media (max-width: 768px) {
    :root {
        --container-padding: 1rem;
    }

    .navbar {
        height: 60px;
    }
    
    .nav-menu {
        position: fixed;
        top: 60px;
        left: 0;
        right: 0;
        background: rgba(0, 0, 0, 0.98);
        backdrop-filter: blur(20px);
        flex-direction: column;
        padding: var(--space-xl);
        gap: var(--space-lg);
        border-bottom: 1px solid var(--border-color);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: var(--transition-base);
        z-index: 999;
    }
    
    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .nav-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }
    
    .nav-toggle.active span:nth-child(2) {
        opacity: 0;
    }
    
    .nav-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -5px);
    }
    
    .tools-grid {
        grid-template-columns: 1fr;
    }
    
    .skills-grid {
        grid-template-columns: 1fr;
    }
    
    .contact-links {
        grid-template-columns: 1fr;
    }
    
    .footer-container {
        flex-direction: column;
        gap: var(--space-lg);
        text-align: center;
    }
    
    .detail-header-content {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .tool-icon-large {
        width: 80px;
        height: 80px;
        font-size: 2.5rem;
    }
    
    .detail-stats {
        flex-wrap: wrap;
    }
    
    .stat-box {
        flex: 1;
        min-width: 80px;
    }
    
    .requirements-grid {
        grid-template-columns: 1fr;
    }
    
    .detail-sidebar {
        grid-template-columns: 1fr;
    }
}

/* Mobile Portrait */
@media (max-width: 480px) {
    .hero-title .line1 {
        font-size: 2rem;
    }
    
    .hero-title .line2 {
        font-size: 2.5rem;
    }
    
    .card-footer {
        flex-direction: column;
        gap: var(--space-md);
        align-items: flex-start;
    }
    
    .detail-header {
        padding: var(--space-lg);
    }
    
    .detail-section {
        padding: var(--space-lg);
    }
    
    .feature-item {
        flex-direction: column;
    }
    
    .step-item {
        flex-direction: column;
    }
    
    .step-number {
        align-self: flex-start;
    }
}

/* Very Small Screens */
@media (max-width: 360px) {
    :root {
        font-size: 14px;
    }
    
    .logo-text {
        font-size: 1.2rem;
    }
}

/* Landscape Mobile */
@media (max-height: 500px) and (orientation: landscape) {
    .hero {
        min-height: auto;
        padding-top: calc(80px + var(--space-xl));
        padding-bottom: var(--space-xl);
    }
}