/* ==========================================================
   WEBHOI — Design System v2.0
   Đào Hội Hoàng Thiện | daohoihoangthien.com
   ========================================================== */

@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:ital,wght@0,300;0,400;0,500;0,600;0,700;0,800;1,400&family=JetBrains+Mono:wght@400;500&display=swap');

/* === DESIGN TOKENS === */
:root {
    --bg-primary:    #05050a;
    --bg-secondary:  #0b0b14;
    --bg-card:       rgba(255, 255, 255, 0.04);
    --bg-card-hover: rgba(255, 255, 255, 0.07);

    --primary:       #7c6ff1;
    --primary-light: #a89ef8;
    --primary-dark:  #5b50d6;
    --secondary:     #06b6d4;
    --accent:        #f472b6;

    --text-primary:  #f0f4ff;
    --text-secondary: #c4cde0;
    --text-muted:    #6b7a9a;

    --border:        rgba(255, 255, 255, 0.07);
    --border-hover:  rgba(124, 111, 241, 0.4);
    --glow:          rgba(124, 111, 241, 0.25);
    --glow-cyan:     rgba(6, 182, 212, 0.2);

    --radius-sm:  8px;
    --radius-md:  14px;
    --radius-lg:  20px;
    --radius-xl:  28px;

    --shadow-card: 0 4px 30px rgba(0,0,0,0.5);
    --shadow-glow: 0 0 40px var(--glow);

    --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
    --font: 'Plus Jakarta Sans', system-ui, sans-serif;
    --font-mono: 'JetBrains Mono', monospace;
}

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

html { scroll-behavior: smooth; }

body {
    font-family: var(--font);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.7;
    min-height: 100vh;
    overflow-x: hidden;
}

/* === BACKGROUND GLOW EFFECTS === */
.bg-glow {
    position: fixed;
    pointer-events: none;
    z-index: 0;
    border-radius: 50%;
    filter: blur(120px);
    opacity: 0.4;
}
.bg-glow-1 {
    width: 600px; height: 600px;
    background: radial-gradient(circle, rgba(124,111,241,0.3), transparent 70%);
    top: -200px; left: -150px;
    animation: drift1 18s ease-in-out infinite alternate;
}
.bg-glow-2 {
    width: 500px; height: 500px;
    background: radial-gradient(circle, rgba(6,182,212,0.2), transparent 70%);
    bottom: 0; right: -100px;
    animation: drift2 22s ease-in-out infinite alternate;
}

@keyframes drift1 { to { transform: translate(80px, 60px); } }
@keyframes drift2 { to { transform: translate(-60px, -80px); } }

/* === LAYOUT === */
.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
    position: relative;
    z-index: 1;
}

/* === NAVBAR === */
.navbar {
    position: sticky;
    top: 0;
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 18px 32px;
    background: rgba(5, 5, 10, 0.75);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 12px;
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 700;
    font-size: 0.95rem;
    letter-spacing: 0.5px;
    transition: var(--transition);
}
.nav-brand:hover { opacity: 0.8; }

.brand-logo {
    width: 36px; height: 36px;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    border-radius: 10px;
    display: flex; align-items: center; justify-content: center;
    font-weight: 800;
    font-size: 1rem;
    color: white;
    box-shadow: 0 0 20px var(--glow);
    flex-shrink: 0;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 4px;
}
.nav-links a {
    text-decoration: none;
    color: var(--text-muted);
    font-size: 0.9rem;
    font-weight: 500;
    padding: 8px 16px;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}
.nav-links a:hover,
.nav-links a.active {
    color: var(--text-primary);
    background: var(--bg-card);
}

/* === HERO SECTION === */
.hero {
    padding: 100px 0 80px;
    position: relative;
    z-index: 1;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: rgba(124, 111, 241, 0.12);
    border: 1px solid rgba(124, 111, 241, 0.3);
    border-radius: 999px;
    padding: 6px 16px;
    font-size: 0.8rem;
    color: var(--primary-light);
    font-weight: 500;
    margin-bottom: 28px;
    letter-spacing: 0.3px;
}
.hero-badge-dot-wrapper {
    position: relative;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 10px;
    height: 10px;
    margin-right: 4px;
}
.hero-badge-dot {
    width: 7px; height: 7px;
    border-radius: 50%;
    background: #10b981;
    box-shadow: 0 0 10px #10b981;
    position: relative;
    z-index: 1;
}
.hero-badge-ping {
    position: absolute;
    width: 100%; height: 100%;
    border-radius: 50%;
    background: #10b981;
    opacity: 0.75;
    animation: radar-ping 2s cubic-bezier(0, 0, 0.2, 1) infinite;
}
@keyframes radar-ping {
    0% { transform: scale(1); opacity: 0.8; }
    70%, 100% { transform: scale(3.2); opacity: 0; }
}

.hero-title {
    font-size: clamp(2.8rem, 6vw, 5rem);
    font-weight: 800;
    line-height: 1.1;
    letter-spacing: -2px;
    margin-bottom: 24px;
}
.hero-title .gradient-text {
    background: linear-gradient(135deg, var(--primary-light) 0%, var(--secondary) 50%, var(--accent) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-desc {
    font-size: 1.15rem;
    color: var(--text-secondary);
    max-width: 620px;
    line-height: 1.8;
    margin-bottom: 40px;
}

.hero-actions {
    display: flex;
    gap: 14px;
    flex-wrap: wrap;
}

.btn-primary {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
    text-decoration: none;
    padding: 14px 28px;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 0.95rem;
    border: none;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: 0 0 30px var(--glow);
    position: relative;
    overflow: hidden;
}
.btn-primary::after {
    content: '';
    position: absolute;
    top: -50%;
    left: -80%;
    width: 50%;
    height: 200%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.35), transparent);
    transform: rotate(25deg);
    transition: transform 0.65s cubic-bezier(0.4, 0, 0.2, 1);
    pointer-events: none;
}
.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 40px var(--glow);
    filter: brightness(1.1);
}
.btn-primary:hover::after {
    transform: translateX(450%) rotate(25deg);
}
.btn-primary:active,
.btn-secondary:active {
    transform: translateY(1px) scale(0.98);
}

.btn-secondary {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: var(--bg-card);
    color: var(--text-secondary);
    text-decoration: none;
    padding: 14px 28px;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 0.95rem;
    border: 1px solid var(--border);
    cursor: pointer;
    transition: var(--transition);
}
.btn-secondary:hover {
    border-color: var(--border-hover);
    color: var(--text-primary);
    background: var(--bg-card-hover);
    transform: translateY(-2px);
}

/* === SECTION STYLES === */
.section {
    padding: 80px 0;
    position: relative;
    z-index: 1;
}

.section-header {
    margin-bottom: 48px;
}
.section-label {
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 2px;
    color: var(--primary-light);
    margin-bottom: 10px;
}
.section-title {
    font-size: clamp(1.8rem, 3vw, 2.4rem);
    font-weight: 800;
    letter-spacing: -1px;
    color: var(--text-primary);
    margin-bottom: 12px;
}
.section-subtitle {
    color: var(--text-muted);
    font-size: 1rem;
    max-width: 500px;
}

/* === CARDS === */
.card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 28px;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}
.card::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, rgba(124,111,241,0.06), transparent);
    opacity: 0;
    transition: var(--transition);
    border-radius: inherit;
}
.card:hover {
    border-color: var(--border-hover);
    transform: translateY(-4px);
    box-shadow: var(--shadow-card), 0 0 30px rgba(124,111,241,0.1);
}
.card:hover::before { opacity: 1; }

/* === BLOG CARDS === */
.posts-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 24px;
}

.post-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: var(--transition);
    text-decoration: none;
    color: inherit;
    display: flex;
    flex-direction: column;
    position: relative;
}
.post-card::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--primary), var(--secondary), var(--accent));
    transform: scaleX(0);
    transform-origin: left;
    transition: var(--transition);
}
.post-card:hover {
    border-color: var(--border-hover);
    transform: translateY(-6px);
    box-shadow: var(--shadow-card), 0 0 40px rgba(124,111,241,0.12);
}
.post-card:hover::before { transform: scaleX(1); }

.post-card-body {
    padding: 28px;
    flex: 1;
    display: flex;
    flex-direction: column;
}

.post-tags {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    margin-bottom: 14px;
}
.post-tag {
    font-size: 0.72rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    padding: 4px 10px;
    border-radius: 999px;
    background: rgba(124, 111, 241, 0.15);
    color: var(--primary-light);
    border: 1px solid rgba(124, 111, 241, 0.25);
}

.post-title {
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--text-primary);
    line-height: 1.4;
    margin-bottom: 12px;
    letter-spacing: -0.3px;
}

.post-excerpt {
    font-size: 0.9rem;
    color: var(--text-muted);
    line-height: 1.7;
    flex: 1;
    margin-bottom: 20px;
}

.post-meta {
    display: flex;
    align-items: center;
    gap: 16px;
    font-size: 0.8rem;
    color: var(--text-muted);
    padding-top: 16px;
    border-top: 1px solid var(--border);
}
.post-meta-item {
    display: flex;
    align-items: center;
    gap: 5px;
}

/* === SINGLE POST === */
.post-hero {
    padding: 60px 0 40px;
}

.post-content {
    max-width: 740px;
    margin: 0 auto;
    padding: 40px 0 80px;
}

.post-content h1, .post-content h2, .post-content h3,
.post-content h4, .post-content h5, .post-content h6 {
    font-weight: 700;
    letter-spacing: -0.5px;
    color: var(--text-primary);
    margin: 40px 0 16px;
    line-height: 1.3;
}
.post-content h1 { font-size: 2rem; }
.post-content h2 { font-size: 1.55rem; border-bottom: 1px solid var(--border); padding-bottom: 10px; }
.post-content h3 { font-size: 1.25rem; }

.post-content p {
    color: var(--text-secondary);
    margin-bottom: 20px;
    line-height: 1.85;
    font-size: 1.05rem;
}

.post-content a {
    color: var(--primary-light);
    text-decoration: none;
    border-bottom: 1px solid rgba(124,111,241,0.3);
    transition: var(--transition);
}
.post-content a:hover { border-color: var(--primary-light); }

.post-content ul, .post-content ol {
    color: var(--text-secondary);
    padding-left: 24px;
    margin-bottom: 20px;
}
.post-content li { margin-bottom: 8px; line-height: 1.7; }

.post-content pre {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: 20px 24px;
    overflow-x: auto;
    margin: 24px 0;
    font-family: var(--font-mono);
    font-size: 0.88rem;
    line-height: 1.7;
}

.post-content code:not(pre code) {
    font-family: var(--font-mono);
    background: rgba(124,111,241,0.15);
    color: var(--primary-light);
    padding: 2px 8px;
    border-radius: 5px;
    font-size: 0.88em;
}

.post-content blockquote {
    border-left: 3px solid var(--primary);
    padding: 14px 20px;
    background: rgba(124,111,241,0.07);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    margin: 24px 0;
    color: var(--text-secondary);
    font-style: italic;
}

.post-content img {
    max-width: 100%;
    border-radius: var(--radius-md);
    border: 1px solid var(--border);
}

/* === TECH STACK GRID === */
.tech-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(130px, 1fr));
    gap: 14px;
}
.tech-item {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: 16px;
    text-align: center;
    transition: var(--transition);
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-secondary);
}
.tech-item:hover {
    border-color: var(--border-hover);
    color: var(--text-primary);
    transform: translateY(-3px);
}
.tech-item .tech-icon { font-size: 1.5rem; margin-bottom: 6px; display: block; }

/* === DIVIDER === */
.divider {
    width: 100%;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--border), transparent);
    border: none;
    margin: 0;
}

/* === FOOTER === */
footer {
    position: relative;
    z-index: 1;
    border-top: 1px solid var(--border);
    padding: 40px 32px;
    text-align: center;
    color: var(--text-muted);
    font-size: 0.85rem;
}
footer a { color: var(--primary-light); text-decoration: none; }
footer a:hover { text-decoration: underline; }

/* === SKELETON LOADING === */
.skeleton {
    background: linear-gradient(90deg, var(--bg-card) 25%, rgba(255,255,255,0.06) 50%, var(--bg-card) 75%);
    background-size: 200% 100%;
    animation: shimmer 1.5s infinite;
    border-radius: var(--radius-sm);
}
@keyframes shimmer { to { background-position: -200% 0; } }

/* === EMPTY STATE === */
.empty-state {
    text-align: center;
    padding: 80px 20px;
    color: var(--text-muted);
}
.empty-state .empty-icon { font-size: 3rem; margin-bottom: 16px; opacity: 0.5; }

/* === TAG FILTER === */
.filter-bar {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
    margin-bottom: 36px;
}
.filter-tag {
    padding: 7px 16px;
    border-radius: 999px;
    border: 1px solid var(--border);
    background: var(--bg-card);
    color: var(--text-muted);
    font-size: 0.82rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}
.filter-tag:hover,
.filter-tag.active {
    border-color: var(--border-hover);
    color: var(--primary-light);
    background: rgba(124,111,241,0.12);
}

/* === BACK LINK === */
.back-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    margin-bottom: 32px;
    transition: var(--transition);
}
.back-link:hover { color: var(--primary-light); }

/* === CARD SPOTLIGHT (từ kho hiệu ứng wiweb) === */
.card-spotlight {
    position: absolute;
    inset: 0;
    pointer-events: none;
    background: radial-gradient(
        350px circle at var(--spot-x, 50%) var(--spot-y, 50%),
        rgba(124, 111, 241, 0.15),
        transparent 70%
    );
    opacity: 0;
    transition: opacity 0.3s ease;
    border-radius: inherit;
    z-index: 1;
}
.card:hover .card-spotlight,
.post-card:hover .card-spotlight,
.tech-item:hover .card-spotlight {
    opacity: 1;
}

/* === SCROLL REVEAL ANIMATION === */
.reveal {
    opacity: 0;
    transform: translateY(28px);
    transition: opacity 0.75s cubic-bezier(0.16, 1, 0.3, 1), transform 0.75s cubic-bezier(0.16, 1, 0.3, 1);
    will-change: opacity, transform;
}
.reveal.revealed {
    opacity: 1;
    transform: translateY(0);
}

/* === READING PROGRESS BAR (cho bài viết) === */
.reading-progress-bar {
    position: fixed;
    top: 0;
    left: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--primary), var(--secondary), var(--accent));
    width: 0%;
    z-index: 1000;
    transition: width 0.1s ease-out;
    box-shadow: 0 0 12px var(--primary-light);
}

/* === MOBILE NAVIGATION === */
.nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 40px;
    height: 40px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    cursor: pointer;
    padding: 9px;
    z-index: 102;
    transition: var(--transition);
}
.nav-toggle:hover {
    border-color: var(--border-hover);
}
.nav-toggle span {
    display: block;
    width: 100%;
    height: 2px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: transform 0.3s, opacity 0.3s;
}
.nav-toggle.active span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}
.nav-toggle.active span:nth-child(2) {
    opacity: 0;
}
.nav-toggle.active span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

.mobile-nav-drawer {
    display: none;
    position: fixed;
    top: 65px;
    left: 0;
    right: 0;
    background: rgba(5, 5, 10, 0.95);
    backdrop-filter: blur(25px);
    -webkit-backdrop-filter: blur(25px);
    border-bottom: 1px solid var(--border);
    padding: 24px;
    flex-direction: column;
    gap: 12px;
    z-index: 99;
    box-shadow: 0 16px 40px rgba(0,0,0,0.6);
}
.mobile-nav-drawer.open {
    display: flex;
    animation: drawerSlide 0.25s ease-out;
}
@keyframes drawerSlide {
    from { opacity: 0; transform: translateY(-10px); }
    to { opacity: 1; transform: translateY(0); }
}
.mobile-nav-drawer a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 1.05rem;
    font-weight: 600;
    padding: 12px 16px;
    border-radius: var(--radius-sm);
    background: var(--bg-card);
    border: 1px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: space-between;
    transition: var(--transition);
}
.mobile-nav-drawer a.active,
.mobile-nav-drawer a:hover {
    color: var(--text-primary);
    border-color: var(--border-hover);
    background: rgba(124, 111, 241, 0.12);
}

/* === RESPONSIVE === */
@media (max-width: 768px) {
    .navbar { padding: 14px 20px; }
    .nav-links { display: none; }
    .nav-cta { display: none; }
    .nav-toggle { display: flex; }
    .hero { padding: 70px 0 60px; }
    .hero-title { letter-spacing: -1px; }
    .posts-grid { grid-template-columns: 1fr; }
    .tech-grid { grid-template-columns: repeat(2, 1fr); }
    .hero-actions { flex-direction: column; align-items: stretch; }
    .hero-actions a { justify-content: center; }
}