/* ==========================================================================
   THE NEW CULTURE — Design System v3
   Ngôn ngữ thị giác: editorial media (theo chuẩn Complex)
   Kiến trúc: token → base → layout → components → utilities → responsive
   ========================================================================== */

/* ----- 1. DESIGN TOKENS ------------------------------------------------- */
:root{
  /* Màu nền & mực */
  --c-bg:            #FFFFFF;
  --c-bg-subtle:     #F5F5F3;
  --c-bg-invert:     #0B0B0B;
  --c-ink:           #0B0B0B;
  --c-ink-2:         #4A4A48;
  --c-ink-3:         #8A8A86;
  --c-line:          #E4E4E0;
  --c-line-strong:   #0B0B0B;

  /* Accent chuyên mục (dùng cho eyebrow/label) */
  --c-red:           #E11D0F;
  --c-blue:          #1D4ED8;
  --c-green:         #157F4B;
  --c-purple:        #6D28D9;
  --c-amber:         #B45309;

  /* Typography */
  --f-display: 'Archivo', -apple-system, BlinkMacSystemFont, sans-serif;
  --f-body:    'Archivo', -apple-system, BlinkMacSystemFont, sans-serif;
  --f-mono:    'IBM Plex Mono', ui-monospace, monospace;

  /* Type scale (fluid) */
  --t-xs:   0.75rem;
  --t-sm:   0.8125rem;
  --t-base: 0.9375rem;
  --t-md:   1.0625rem;
  --t-lg:   1.375rem;
  --t-xl:   clamp(1.5rem, 2.4vw, 2rem);
  --t-2xl:  clamp(2rem, 4vw, 3rem);
  --t-3xl:  clamp(2.5rem, 6vw, 4.25rem);

  /* Spacing scale */
  --s-1: 4px;  --s-2: 8px;  --s-3: 12px; --s-4: 16px;
  --s-5: 24px; --s-6: 32px; --s-7: 48px; --s-8: 64px; --s-9: 96px;

  /* Layout */
  --maxw: 1280px;
  --gutter: clamp(16px, 3vw, 40px);

  /* Motion */
  --ease: cubic-bezier(0.2, 0.6, 0.2, 1);
  --dur: 0.28s;
}

/* ----- 2. BASE / RESET -------------------------------------------------- */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0;}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth;}
body{
  background:var(--c-bg);
  color:var(--c-ink);
  font-family:var(--f-body);
  font-size:var(--t-base);
  line-height:1.55;
  font-weight:400;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
img{display:block;max-width:100%;height:auto;}
a{color:inherit;text-decoration:none;}
button{font:inherit;cursor:pointer;}
h1,h2,h3,h4{font-family:var(--f-display);line-height:1.08;font-weight:800;letter-spacing:-0.015em;}

::selection{background:var(--c-ink);color:var(--c-bg);}
:focus-visible{outline:2px solid var(--c-red);outline-offset:3px;}

/* ----- 3. LAYOUT PRIMITIVES -------------------------------------------- */
.container{max-width:var(--maxw);margin-inline:auto;padding-inline:var(--gutter);}
.stack > * + *{margin-top:var(--s-4);}
.divider{height:1px;background:var(--c-line);border:0;margin-block:var(--s-8);}
.divider--strong{height:2px;background:var(--c-line-strong);}

/* Grid helpers */
.grid{display:grid;gap:var(--s-6);}
.grid-3{grid-template-columns:repeat(3,1fr);}
.grid-4{grid-template-columns:repeat(4,1fr);}
.grid-2-1{grid-template-columns:2fr 1fr;}

/* ----- 4. COMPONENTS ---------------------------------------------------- */

/* 4.1 Eyebrow / category label -- mono, uppercase, có accent màu */
.eyebrow{
  font-family:var(--f-mono);
  font-size:var(--t-xs);
  font-weight:600;
  letter-spacing:0.08em;
  text-transform:uppercase;
  color:var(--c-red);
  display:inline-block;
}
.eyebrow--blue{color:var(--c-blue);}
.eyebrow--green{color:var(--c-green);}
.eyebrow--purple{color:var(--c-purple);}
.eyebrow--amber{color:var(--c-amber);}
.eyebrow--ink{color:var(--c-ink-3);}

/* 4.2 Byline */
.byline{font-family:var(--f-mono);font-size:var(--t-xs);color:var(--c-ink-3);letter-spacing:0.02em;}

/* 4.3 Media frame (thay ảnh thật bằng placeholder có kết cấu) */
.media{position:relative;overflow:hidden;background:#1a1a1a;display:block;}
.media::before{
  content:"";position:absolute;inset:0;z-index:0;
  background:
    radial-gradient(120% 80% at 20% 15%, rgba(225,29,15,0.22), transparent 55%),
    radial-gradient(100% 100% at 85% 90%, rgba(29,78,216,0.20), transparent 60%),
    linear-gradient(135deg, #232323, #0e0e0e);
}
.media::after{
  content:"";position:absolute;inset:0;z-index:1;
  background:
    repeating-linear-gradient(58deg, rgba(255,255,255,0.035) 0 1px, transparent 1px 9px),
    linear-gradient(0deg, rgba(0,0,0,0.32), transparent 60%);
  mix-blend-mode:screen;
}
.media img{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;z-index:2;}
.media--16-9{aspect-ratio:16/9;}
.media--4-3{aspect-ratio:4/3;}
.media--3-2{aspect-ratio:3/2;}
.media--1-1{aspect-ratio:1/1;}
.media__zoom{transition:transform var(--dur) var(--ease);}
a:hover .media__zoom{transform:scale(1.04);}

/* code hồ sơ lưu trữ dạng mono, đặt trên ảnh */
.archive-code{
  position:absolute;top:var(--s-3);left:var(--s-3);z-index:2;
  font-family:var(--f-mono);font-size:10px;font-weight:500;letter-spacing:0.1em;
  color:#fff;background:rgba(11,11,11,0.72);backdrop-filter:blur(4px);
  padding:4px 8px;border-radius:2px;
}

/* 4.4 Article card (đứng) */
.card{display:flex;flex-direction:column;}
.card .media{margin-bottom:var(--s-4);}
.card .eyebrow{margin-bottom:var(--s-2);}
.card h3{font-size:var(--t-md);line-height:1.22;margin-bottom:var(--s-2);transition:color var(--dur) var(--ease);}
.card:hover h3{color:var(--c-red);}
.card .byline{margin-top:auto;padding-top:var(--s-2);}

/* 4.5 Section heading */
.section{margin-top:var(--s-9);}
.section-head{
  display:flex;align-items:baseline;justify-content:space-between;
  gap:var(--s-4);padding-bottom:var(--s-3);
  border-bottom:2px solid var(--c-line-strong);margin-bottom:var(--s-6);
}
.section-head h2{font-size:var(--t-xl);}
.section-head .more{font-family:var(--f-mono);font-size:var(--t-xs);text-transform:uppercase;letter-spacing:0.06em;color:var(--c-ink-3);white-space:nowrap;transition:color var(--dur);}
.section-head .more:hover{color:var(--c-red);}

/* 4.6 Buttons */
.btn{
  display:inline-flex;align-items:center;gap:var(--s-2);
  font-family:var(--f-mono);font-size:var(--t-xs);font-weight:600;
  letter-spacing:0.06em;text-transform:uppercase;
  padding:11px 18px;border-radius:2px;border:1px solid transparent;
  transition:all var(--dur) var(--ease);
}
.btn--solid{background:var(--c-ink);color:var(--c-bg);}
.btn--solid:hover{background:var(--c-red);}
.btn--ghost{border-color:var(--c-line-strong);color:var(--c-ink);}
.btn--ghost:hover{background:var(--c-ink);color:var(--c-bg);}

/* ----- 5. HEADER -------------------------------------------------------- */
.masthead{position:sticky;top:0;z-index:50;background:var(--c-bg);border-bottom:1px solid var(--c-line);}
.masthead__util{border-bottom:1px solid var(--c-line);}
.masthead__util .container{display:flex;justify-content:space-between;align-items:center;height:34px;}
.masthead__util span,.masthead__util a{font-family:var(--f-mono);font-size:10px;letter-spacing:0.06em;text-transform:uppercase;color:var(--c-ink-3);}
.masthead__util a:hover{color:var(--c-red);}
.masthead__util .u-links{display:flex;gap:var(--s-5);}

.masthead__main .container{display:flex;align-items:center;justify-content:space-between;height:68px;}
.wordmark{font-family:var(--f-display);font-weight:900;font-size:1.5rem;letter-spacing:-0.03em;display:flex;align-items:center;gap:2px;}
.wordmark .tnc-badge{
  display:inline-grid;place-items:center;width:34px;height:34px;margin-right:8px;
  background:var(--c-red);color:#fff;font-size:1.05rem;font-weight:900;border-radius:3px;
}
.icon-btn{width:38px;height:38px;display:grid;place-items:center;border-radius:3px;color:var(--c-ink);transition:background var(--dur);}
.icon-btn:hover{background:var(--c-bg-subtle);}
.masthead__actions{display:flex;align-items:center;gap:var(--s-3);}

.masthead__nav{border-top:1px solid var(--c-line);}
.masthead__nav .container{display:flex;overflow-x:auto;scrollbar-width:none;}
.masthead__nav .container::-webkit-scrollbar{display:none;}
.masthead__nav a{
  font-family:var(--f-mono);font-size:var(--t-xs);font-weight:600;letter-spacing:0.05em;text-transform:uppercase;
  padding:13px 16px;white-space:nowrap;color:var(--c-ink-2);position:relative;transition:color var(--dur);
}
.masthead__nav a:first-child{padding-left:0;}
.masthead__nav a:hover{color:var(--c-ink);}
.masthead__nav a.is-active{color:var(--c-red);}
.masthead__nav a.is-active::after{content:"";position:absolute;left:16px;right:16px;bottom:-1px;height:2px;background:var(--c-red);}
.masthead__nav a:first-child.is-active::after{left:0;}

/* ----- 6. HERO ---------------------------------------------------------- */
.hero{padding-top:var(--s-7);}
.hero__grid{display:grid;grid-template-columns:1.6fr 1fr;gap:var(--s-6);}
.hero__lead{position:relative;}
.hero__lead .media{aspect-ratio:3/2;}
.hero__lead .hero__body{padding-top:var(--s-4);}
.hero__lead h1{font-size:var(--t-2xl);margin:var(--s-3) 0;max-width:16ch;}
.hero__lead p{font-size:var(--t-md);color:var(--c-ink-2);max-width:52ch;}
.hero__lead .byline{margin-top:var(--s-4);}

.hero__side{display:flex;flex-direction:column;gap:var(--s-5);}
.hero__side .side-item{display:grid;grid-template-columns:88px 1fr;gap:var(--s-4);align-items:start;padding-bottom:var(--s-5);border-bottom:1px solid var(--c-line);}
.hero__side .side-item:last-child{border-bottom:0;padding-bottom:0;}
.hero__side .side-item .media{aspect-ratio:1/1;}
.hero__side .side-item .eyebrow{margin-bottom:var(--s-1);font-size:10px;}
.hero__side .side-item h3{font-size:var(--t-base);line-height:1.24;transition:color var(--dur);}
.hero__side .side-item:hover h3{color:var(--c-red);}

/* ----- 7. TRENDING ------------------------------------------------------ */
.trending{margin-top:var(--s-8);}
.trending__grid{display:grid;grid-template-columns:repeat(2,1fr);gap:0 var(--s-8);}
.trending__item{display:grid;grid-template-columns:auto 1fr;gap:var(--s-4);padding:var(--s-4) 0;border-bottom:1px solid var(--c-line);align-items:baseline;}
.trending__num{font-family:var(--f-display);font-size:1.5rem;font-weight:800;color:var(--c-ink-3);min-width:1.6em;}
.trending__item .eyebrow{font-size:10px;display:block;margin-bottom:2px;}
.trending__item h4{font-size:var(--t-base);line-height:1.25;font-weight:700;font-family:var(--f-body);transition:color var(--dur);}
.trending__item:hover h4{color:var(--c-red);}

/* ----- 8. TOP STORY (feature ngang lớn) -------------------------------- */
.feature{display:grid;grid-template-columns:1.4fr 1fr;gap:var(--s-7);align-items:center;}
.feature .media{aspect-ratio:16/10;}
.feature h2{font-size:var(--t-2xl);margin:var(--s-3) 0;}
.feature p{font-size:var(--t-md);color:var(--c-ink-2);margin-bottom:var(--s-4);max-width:46ch;}

/* ----- 9. SERIES INDEX (khối bản đồ tri thức) -------------------------- */
.series-band{background:var(--c-bg-invert);color:#fff;margin-top:var(--s-9);padding-block:var(--s-8);}
.series-band .section-head{border-color:rgba(255,255,255,0.24);}
.series-band .section-head h2{color:#fff;}
.series-band .section-head .more{color:rgba(255,255,255,0.6);}
.series-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:1px;background:rgba(255,255,255,0.14);border:1px solid rgba(255,255,255,0.14);}
.series-cell{background:var(--c-bg-invert);padding:var(--s-5);display:flex;flex-direction:column;gap:var(--s-2);min-height:150px;transition:background var(--dur) var(--ease);}
.series-cell:hover{background:#161616;}
.series-cell__code{font-family:var(--f-mono);font-size:10px;letter-spacing:0.1em;color:rgba(255,255,255,0.4);}
.series-cell h3{font-size:var(--t-md);color:#fff;transition:color var(--dur);}
.series-cell:hover h3{color:var(--c-red);}
.series-cell p{font-size:var(--t-xs);color:rgba(255,255,255,0.55);line-height:1.5;margin-top:auto;}

/* ----- 10. VIDEO -------------------------------------------------------- */
.video-row{display:grid;grid-template-columns:repeat(3,1fr);gap:var(--s-6);}
.video-card .media{aspect-ratio:16/9;margin-bottom:var(--s-3);}
.video-card .play{position:absolute;inset:0;z-index:2;display:grid;place-items:center;}
.video-card .play span{width:52px;height:52px;border-radius:50%;background:rgba(255,255,255,0.92);display:grid;place-items:center;transition:transform var(--dur) var(--ease);}
.video-card:hover .play span{transform:scale(1.08);background:#fff;}
.video-card .play span::after{content:"";border-left:15px solid var(--c-ink);border-top:9px solid transparent;border-bottom:9px solid transparent;margin-left:4px;}
.video-card .dur{position:absolute;bottom:var(--s-3);right:var(--s-3);z-index:2;font-family:var(--f-mono);font-size:10px;color:#fff;background:rgba(11,11,11,0.8);padding:3px 7px;border-radius:2px;}
.video-card .eyebrow{margin-bottom:var(--s-1);}
.video-card h3{font-size:var(--t-base);line-height:1.24;transition:color var(--dur);}
.video-card:hover h3{color:var(--c-red);}

/* ----- 11. NEWSLETTER --------------------------------------------------- */
.newsletter{border-top:2px solid var(--c-line-strong);border-bottom:2px solid var(--c-line-strong);margin-top:var(--s-9);padding-block:var(--s-7);}
.newsletter .container{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:var(--s-5);}
.newsletter h2{font-size:var(--t-xl);}
.newsletter p{color:var(--c-ink-2);font-size:var(--t-sm);margin-top:var(--s-2);max-width:44ch;}
.newsletter form{display:flex;}
.newsletter input{border:1px solid var(--c-line-strong);border-right:0;padding:12px 14px;font-size:var(--t-sm);min-width:240px;font-family:var(--f-body);}
.newsletter input:focus{outline:none;}
.newsletter button{border:1px solid var(--c-ink);}

/* ----- 12. FOOTER ------------------------------------------------------- */
.footer{background:var(--c-bg-invert);color:rgba(255,255,255,0.7);margin-top:0;padding-block:var(--s-8) var(--s-6);}
.footer__grid{display:grid;grid-template-columns:1.6fr repeat(4,1fr);gap:var(--s-6);padding-bottom:var(--s-7);border-bottom:1px solid rgba(255,255,255,0.12);}
.footer .wordmark{color:#fff;margin-bottom:var(--s-4);}
.footer__brand p{font-size:var(--t-sm);max-width:34ch;margin-bottom:var(--s-4);}
.footer__social{display:flex;gap:var(--s-2);}
.footer__social a{width:34px;height:34px;border:1px solid rgba(255,255,255,0.2);border-radius:50%;display:grid;place-items:center;font-family:var(--f-mono);font-size:11px;color:rgba(255,255,255,0.7);transition:all var(--dur);}
.footer__social a:hover{border-color:var(--c-red);color:#fff;background:var(--c-red);}
.footer__col h4{font-family:var(--f-mono);font-size:10px;letter-spacing:0.1em;text-transform:uppercase;color:rgba(255,255,255,0.5);margin-bottom:var(--s-4);font-weight:600;}
.footer__col ul{list-style:none;}
.footer__col li{margin-bottom:var(--s-2);}
.footer__col a{font-size:var(--t-sm);color:rgba(255,255,255,0.75);}
.footer__col a:hover{color:var(--c-red);}
.footer__bottom{padding-top:var(--s-5);display:flex;justify-content:space-between;flex-wrap:wrap;gap:var(--s-3);}
.footer__bottom span{font-family:var(--f-mono);font-size:10px;letter-spacing:0.04em;color:rgba(255,255,255,0.45);text-transform:uppercase;}

/* ----- 13. RESPONSIVE --------------------------------------------------- */
@media (max-width:1024px){
  .hero__grid{grid-template-columns:1fr;}
  .hero__side{flex-direction:row;flex-wrap:wrap;}
  .hero__side .side-item{flex:1 1 260px;border-bottom:0;}
  .series-grid{grid-template-columns:repeat(3,1fr);}
  .footer__grid{grid-template-columns:1fr 1fr 1fr;}
  .footer__brand{grid-column:1 / -1;}
}
@media (max-width:768px){
  .grid-3,.grid-4,.video-row{grid-template-columns:1fr 1fr;}
  .trending__grid{grid-template-columns:1fr;}
  .feature{grid-template-columns:1fr;}
  .feature .media{order:-1;}
  .series-grid{grid-template-columns:repeat(2,1fr);}
  .hero__lead h1{font-size:var(--t-xl);}
  .wordmark{font-size:1.15rem;}
  .masthead__actions .btn{padding:9px 12px;}
}
@media (max-width:520px){
  .grid-3,.grid-4,.video-row{grid-template-columns:1fr;}
  .series-grid{grid-template-columns:1fr;}
  .hero__side{flex-direction:column;}
  .hero__side .side-item{grid-template-columns:72px 1fr;}
  .footer__grid{grid-template-columns:1fr 1fr;}
  .newsletter form{width:100%;}
  .newsletter input{flex:1;min-width:0;}
}
@media (prefers-reduced-motion:reduce){
  *{animation:none !important;transition:none !important;}
  html{scroll-behavior:auto;}
}

/* Đa dạng sắc thái ảnh placeholder theo vị trí */
.grid > *:nth-child(3n+1) .media::before{filter:hue-rotate(0deg);}
.grid > *:nth-child(3n+2) .media::before{filter:hue-rotate(140deg) saturate(0.8);}
.grid > *:nth-child(3n+3) .media::before{filter:hue-rotate(255deg) saturate(0.7);}
.video-row > *:nth-child(2) .media::before{filter:hue-rotate(120deg);}
.video-row > *:nth-child(3) .media::before{filter:hue-rotate(240deg);}
.hero__side .side-item:nth-child(2) .media::before{filter:hue-rotate(180deg);}

/* ==========================================================================
   MENU OVERLAY
   ========================================================================== */
.menu-overlay{position:fixed;inset:0;z-index:200;background:var(--c-bg);opacity:0;transition:opacity var(--dur) var(--ease);overflow-y:auto;}
.menu-overlay.is-open{opacity:1;}
.menu-overlay__bar{border-bottom:1px solid var(--c-line);position:sticky;top:0;background:var(--c-bg);}
.menu-overlay__bar .container{display:flex;align-items:center;justify-content:space-between;height:68px;}
.menu-overlay__body{display:grid;grid-template-columns:2fr 1fr 1fr;gap:var(--s-7);padding-block:var(--s-7) var(--s-9);}
.menu-col h4{font-family:var(--f-mono);font-size:10px;letter-spacing:0.12em;text-transform:uppercase;color:var(--c-ink-3);margin-bottom:var(--s-4);font-weight:600;}
.menu-col > a{display:block;font-family:var(--f-display);font-size:var(--t-lg);font-weight:700;letter-spacing:-0.01em;padding:var(--s-2) 0;transition:color var(--dur);}
.menu-col > a:hover{color:var(--c-red);}
.menu-series{display:grid;grid-template-columns:1fr 1fr;gap:0 var(--s-6);}
.menu-series a{display:flex;flex-direction:column;gap:2px;padding:var(--s-3) 0;border-bottom:1px solid var(--c-line);font-family:var(--f-display);font-weight:700;font-size:var(--t-md);transition:color var(--dur);}
.menu-series a:hover{color:var(--c-red);}
.menu-code{font-family:var(--f-mono);font-size:10px;font-weight:500;letter-spacing:0.08em;color:var(--c-ink-3);text-transform:none;}
@media (max-width:768px){
  .menu-overlay__body{grid-template-columns:1fr;gap:var(--s-6);}
  .menu-series{grid-template-columns:1fr;}
  .menu-col > a{font-size:var(--t-md);}
}

/* ==========================================================================
   TRANG PHỤ (info / landing đơn giản)
   ========================================================================== */
.page-hero{border-bottom:2px solid var(--c-line-strong);padding-block:var(--s-8) var(--s-6);margin-bottom:var(--s-7);}
.page-hero .eyebrow{font-size:var(--t-sm);margin-bottom:var(--s-3);}
.page-hero h1{font-size:var(--t-3xl);max-width:16ch;margin-bottom:var(--s-4);}
.page-hero p{font-size:var(--t-md);color:var(--c-ink-2);max-width:60ch;}
.prose{max-width:680px;font-size:var(--t-md);line-height:1.8;}
.prose p{margin-bottom:1.3em;}
.prose h2{font-size:var(--t-lg);margin:1.6em 0 0.5em;}
.info-cards{display:grid;grid-template-columns:repeat(3,1fr);gap:var(--s-5);margin-top:var(--s-6);}
.info-card{border:1px solid var(--c-line);padding:var(--s-5);border-radius:3px;}
.info-card .k{font-family:var(--f-mono);font-size:10px;text-transform:uppercase;letter-spacing:0.08em;color:var(--c-ink-3);margin-bottom:var(--s-2);}
.info-card h3{font-size:var(--t-md);margin-bottom:var(--s-2);}
.info-card p{font-size:var(--t-sm);color:var(--c-ink-2);}
.contact-grid{display:grid;grid-template-columns:1fr 1fr;gap:var(--s-4);max-width:560px;}
.contact-grid label{display:flex;flex-direction:column;gap:var(--s-2);font-family:var(--f-mono);font-size:var(--t-xs);text-transform:uppercase;letter-spacing:0.06em;color:var(--c-ink-2);}
.contact-grid label.full{grid-column:1/-1;}
.contact-grid input,.contact-grid textarea{border:1px solid var(--c-line-strong);padding:11px 13px;font-family:var(--f-body);font-size:var(--t-base);}
.contact-grid textarea{min-height:120px;resize:vertical;}
@media (max-width:768px){.info-cards{grid-template-columns:1fr;}.contact-grid{grid-template-columns:1fr;}}

/* ----- ARTICLE BODY ----- */
.article-body p{margin-bottom:1.4em;}
.article-body h2{font-size:var(--t-lg);margin:1.6em 0 0.6em;}
.article-body blockquote{border-left:3px solid var(--c-red);padding-left:var(--s-5);margin:1.6em 0;font-size:var(--t-lg);font-style:italic;color:var(--c-ink);line-height:1.4;}