/* assets/css/base.css
   Nen tang giao dien dung chung: reset, layout, hero, panel, nut, toolbar, tab, sidebar, bang, footer.
   Nen load truoc cac file lesson.css, visual.css va them-geometry.css.
*/

*{box-sizing:border-box}

html{scroll-behavior:smooth}

body{
  margin:0;
  font-family:var(--font);
  background:var(--page-bg);
  color:var(--ink);
}

button,input,select{font:inherit}

a{color:inherit}

.shell{
  max-width:1220px;
  margin:0 auto;
  padding:24px;
}

.hero{
  display:grid;
  grid-template-columns:1.15fr .85fr;
  gap:22px;
  align-items:stretch;
  margin-bottom:22px;
}

.hero-card,
.panel{
  background:rgba(255,255,255,.92);
  border:1px solid var(--border);
  border-radius:var(--radius);
  box-shadow:var(--shadow);
}

.hero-card{
  padding:28px;
  position:relative;
  overflow:hidden;
  min-height:330px;
}

.hero-card:before{
  content:"";
  position:absolute;
  inset:-120px -160px auto auto;
  width:360px;
  height:360px;
  border-radius:50%;
  background:radial-gradient(circle,var(--hero-glow),transparent 68%);
}

.eyebrow{
  display:inline-flex;
  gap:8px;
  align-items:center;
  background:var(--soft);
  color:var(--eyebrow-ink);
  border-radius:999px;
  padding:8px 12px;
  font-weight:700;
  font-size:.88rem;
}

h1{
  font-size:clamp(2.1rem,5vw,4.3rem);
  line-height:1.04;
  margin:18px 0 14px;
  letter-spacing:-.06em;
}

.lead{
  font-size:1.1rem;
  color:var(--muted);
  max-width:68ch;
  line-height:1.65;
}

.hero-actions{
  display:flex;
  gap:12px;
  flex-wrap:wrap;
  margin-top:22px;
}

.btn{
  border:0;
  border-radius:14px;
  background:var(--brand);
  color:#fff;
  padding:12px 16px;
  font-weight:800;
  cursor:pointer;
  box-shadow:0 10px 22px var(--brand-shadow);
  transition:.2s transform,.2s box-shadow,.2s background;
}

.btn:hover{
  transform:translateY(-1px);
  box-shadow:0 14px 28px var(--brand-shadow-strong);
}

.btn.secondary{
  background:#fff;
  color:var(--ink);
  border:1px solid var(--border);
  box-shadow:none;
}

.btn.green{
  background:var(--brand2);
  box-shadow:0 10px 22px var(--brand2-shadow);
}

.btn.small{
  padding:8px 11px;
  border-radius:12px;
  font-size:.9rem;
}

.stats{
  display:grid;
  gap:14px;
  padding:18px;
}

.stat{
  background:linear-gradient(135deg,#fff,#f5f8ff);
  border:1px solid var(--border);
  border-radius:18px;
  padding:16px;
}

.stat strong{
  font-size:2rem;
  display:block;
  color:var(--brand);
}

.stat span{color:var(--muted)}

.toolbar{
  position:sticky;
  top:0;
  z-index:10;
  backdrop-filter:blur(14px);
  background:rgba(246,248,255,.82);
  border:1px solid rgba(223,229,242,.85);
  border-radius:20px;
  padding:12px;
  margin-bottom:22px;
  display:grid;
  grid-template-columns:1fr auto auto;
  gap:10px;
  align-items:center;
}

.search{
  display:flex;
  gap:8px;
  align-items:center;
  background:#fff;
  border:1px solid var(--border);
  border-radius:15px;
  padding:10px 12px;
}

.search input{
  border:0;
  outline:0;
  width:100%;
  background:transparent;
  color:var(--ink);
}

.tabs{
  display:flex;
  gap:8px;
  overflow:auto;
  padding:4px 0;
  margin-bottom:22px;
}

.tab{
  white-space:nowrap;
  border:1px solid var(--border);
  background:#fff;
  color:var(--muted);
  padding:10px 13px;
  border-radius:999px;
  cursor:pointer;
  font-weight:800;
}

.tab.active{
  background:var(--ink);
  color:#fff;
  border-color:var(--ink);
}

.grid{
  display:grid;
  grid-template-columns:360px 1fr;
  gap:22px;
  align-items:start;
}

.sidebar{
  position:sticky;
  top:92px;
  display:grid;
  gap:12px;
}

.toc-item{
  border:1px solid var(--border);
  border-radius:16px;
  background:#fff;
  padding:13px;
  cursor:pointer;
  transition:.2s;
  display:flex;
  gap:10px;
  align-items:center;
}

.toc-item:hover,
.toc-item.active{
  border-color:var(--toc-hover-border);
  box-shadow:var(--toc-hover-shadow);
  transform:translateY(-1px);
}

.toc-icon{
  width:38px;
  height:38px;
  display:grid;
  place-items:center;
  border-radius:12px;
  background:var(--soft);
  font-weight:900;
  color:var(--brand);
}

.toc-title{font-weight:900}

.toc-sub{
  font-size:.88rem;
  color:var(--muted);
  margin-top:3px;
}

.content{
  display:grid;
  gap:18px;
}

.topic{display:none}

.topic.active{display:block}

.panel{
  padding:20px;
  overflow:hidden;
}

.topic-head{
  display:flex;
  gap:14px;
  justify-content:space-between;
  align-items:flex-start;
  margin-bottom:16px;
}

.topic h2{
  margin:0;
  font-size:1.8rem;
  letter-spacing:-.03em;
}

.topic p{line-height:1.65}

.pill{
  display:inline-flex;
  align-items:center;
  gap:6px;
  background:var(--soft2);
  color:#057665;
  padding:7px 10px;
  border-radius:999px;
  font-weight:800;
  font-size:.88rem;
}

.split{
  display:grid;
  grid-template-columns:1fr 1.1fr;
  gap:16px;
  align-items:stretch;
}

.note{
  background:#fff7df;
  border:1px solid #ffe0a6;
  border-radius:14px;
  padding:12px;
  color:#5e4300;
}

.summary-grid{
  display:grid;
  grid-template-columns:repeat(2,minmax(0,1fr));
  gap:14px;
}

.mini-card{
  background:#fff;
  border:1px solid var(--border);
  border-radius:16px;
  padding:15px;
}

.mini-card h3{
  margin:0 0 8px;
  font-size:1.05rem;
}

.mini-card ul{
  margin:8px 0 0;
  padding-left:20px;
  line-height:1.65;
  color:var(--muted);
}

.table-wrap{
  overflow:auto;
  border-radius:16px;
  border:1px solid var(--border);
}

table{
  border-collapse:collapse;
  width:100%;
  background:#fff;
}

th,td{
  padding:12px;
  border-bottom:1px solid var(--border);
  text-align:left;
  vertical-align:top;
}

th{
  background:#f4f7ff;
  color:#293757;
}

tr:last-child td{border-bottom:0}

.kbd{
  font-family:ui-monospace,Consolas,monospace;
  background:#eef2ff;
  border-radius:6px;
  padding:2px 6px;
  font-weight:800;
  color:#304bb8;
}

.footer{
  margin-top:28px;
  text-align:center;
  color:var(--muted);
  padding:20px;
}

.hidden{display:none!important}

.toast{
  position:fixed;
  right:20px;
  bottom:20px;
  background:#111827;
  color:#fff;
  border-radius:16px;
  padding:12px 16px;
  box-shadow:var(--shadow);
  opacity:0;
  transform:translateY(10px);
  transition:.25s;
  z-index:99;
}

.toast.show{
  opacity:1;
  transform:translateY(0);
}

@media(max-width:980px){
  .hero,
  .grid,
  .split{
    grid-template-columns:1fr;
  }

  .sidebar{position:static}

  .toolbar{grid-template-columns:1fr}

  .summary-grid,
  .cards,
  .shape-props{
    grid-template-columns:1fr;
  }

  .hero-card{min-height:auto}
}

@media print{
  .toolbar,
  .tabs,
  .sidebar,
  .hero-actions,
  .controls,
  .btn,
  .quiz,
  .footer{
    display:none!important;
  }

  body{background:#fff}

  .shell{max-width:none}

  .topic{
    display:block!important;
    break-inside:avoid;
  }

  .panel{
    box-shadow:none;
    margin-bottom:14px;
  }

  .grid,
  .split{
    display:block;
  }

  .proof{display:block!important}
}