@import url("tokens/fonts.css");
@import url("tokens/colors.css");
@import url("tokens/typography.css");
@import url("tokens/spacing.css");
@import url("tokens/shape.css");
@import url("tokens/motion.css");
@import url("tokens/base.css");

html { scroll-behavior: smooth; }
body { background: var(--surface-page); color: var(--ink-800); font: var(--type-body); }
img, svg { display: block; }
.sr-only { position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap;border:0 }

/* ============ layout primitives ============ */
.wrap { max-width: var(--content-max); margin: 0 auto; }
.section { padding: 80px var(--gutter-screen); border-top: 1px solid var(--border-hairline); }
.section--sunken { background: var(--paper-25); }
.eyebrow { font: var(--fw-semibold) var(--text-micro)/1.2 var(--font-core); letter-spacing: var(--ls-caps); text-transform: uppercase; color: var(--brand); }
.section-head { max-width: 60ch; margin-bottom: 44px; }
.section-head h2 { margin: 14px 0 12px; font: var(--type-section); letter-spacing: var(--ls-title); color: var(--text-heading); }
.lede { font: var(--fw-regular) var(--text-body-lg)/var(--lh-relaxed) var(--font-core); color: var(--text-muted); text-wrap: pretty; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; }

/* ============ Icon (lucide) ============ */
.icon { display: inline-flex; align-items: center; justify-content: center; flex: 0 0 auto; color: currentColor; }

/* ============ Button ============ */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  gap: 7px; height: var(--control-h); padding: 0 14px;
  font: var(--fw-medium) var(--text-body-sm)/1 var(--font-core);
  border-radius: var(--radius-control); border: 1px solid transparent;
  cursor: pointer; text-decoration: none;
  transition: var(--transition-control), transform var(--dur-instant) var(--ease-standard);
}
.btn:hover { text-decoration: none; }
.btn:active { transform: scale(var(--press-scale)); box-shadow: none; }
.btn--sm { height: var(--control-h-sm); padding: 0 10px; gap: 6px; font-size: var(--text-label); }
.btn--sm .icon { width: 15px; height: 15px; }
.btn .icon { width: 16px; height: 16px; }
.btn--lg { height: var(--control-h-lg); padding: 0 20px; gap: 8px; font-size: var(--text-body); }
.btn--lg .icon { width: 18px; height: 18px; }
.btn--primary { background: var(--brand); color: var(--text-on-brand); box-shadow: var(--shadow-1); }
.btn--primary:hover { background: var(--brand-hover); color: var(--text-on-brand); }
.btn--primary:active { background: var(--brand-press); }
.btn--secondary { background: var(--surface-card); color: var(--ink-800); border-color: var(--border-hairline); box-shadow: var(--shadow-1); }
.btn--secondary:hover { background: var(--paper-50); border-color: var(--border-strong); color: var(--ink-800); }

/* ============ IconButton ============ */
.iconbtn {
  width: 34px; height: 34px; display: inline-flex; align-items: center; justify-content: center;
  border-radius: var(--radius-sm); border: 1px solid transparent; background: transparent;
  color: var(--text-muted); cursor: pointer; transition: var(--transition-control);
}
.iconbtn .icon { width: 17px; height: 17px; }
.iconbtn:hover { background: var(--surface-hover); }
.iconbtn--sm { width: 28px; height: 28px; }
.iconbtn--sm .icon { width: 15px; height: 15px; }
.iconbtn--outline { border-color: var(--border-hairline); }
.iconbtn:disabled { opacity: .4; cursor: not-allowed; }
.iconbtn:disabled:hover { background: transparent; }

/* ============ Card ============ */
.card {
  background: var(--surface-card); border: 1px solid var(--border-hairline);
  border-radius: var(--radius-card); padding: 20px; box-shadow: var(--shadow-1);
  transition: var(--transition-control), transform var(--dur-base) var(--ease-standard);
}
.card h3 { margin: 0 0 10px; font: var(--type-card-title); color: var(--text-heading); }
.card p { font: var(--type-body); color: var(--text-muted); text-wrap: pretty; }

/* ============ Tag ============ */
.tag {
  display: inline-flex; align-items: center; gap: 6px; height: 28px; padding: 0 10px;
  border-radius: var(--radius-pill); border: 1px solid var(--border-hairline);
  background: var(--surface-card); color: var(--ink-800);
  font: var(--fw-medium) var(--text-label)/1 var(--font-core);
}

/* ============ Badge ============ */
.badge {
  display: inline-flex; align-items: center; gap: 5px; height: 22px; padding: 0 8px;
  border-radius: var(--radius-sm); font: var(--fw-medium) var(--text-micro)/1 var(--font-core);
  letter-spacing: .01em; background: var(--surface-sunken); color: var(--ink-600);
}
.badge .icon { width: 12px; height: 12px; }
.badge--brand { background: var(--brand-subtle); color: var(--blue-700); }
.badge--success { background: var(--success-subtle); color: var(--leaf-700); }
.badge--warning { background: var(--warning-subtle); color: var(--amber-600); }

/* ============ Avatar ============ */
.avatar {
  flex: 0 0 auto; border-radius: var(--radius-pill); overflow: hidden;
  display: inline-flex; align-items: center; justify-content: center;
  width: 34px; height: 34px; font: var(--fw-semibold) 13px/1 var(--font-core);
  background: var(--blue-100); color: var(--blue-700);
}
.avatar--sm { width: 28px; height: 28px; font-size: 11px; }
.avatar--lg { width: 44px; height: 44px; font-size: 17px; }
.avatar--teacher { background: var(--amber-100); color: var(--amber-600); }
.avatar--ai { background: var(--brand); color: var(--text-on-brand); }

/* ============ SourceChip ============ */
.chip {
  display: inline-flex; align-items: center; gap: 6px; max-width: 280px; height: 26px;
  padding: 0 9px; background: var(--surface-sunken); border: 1px solid transparent;
  border-radius: var(--radius-sm); cursor: pointer; transition: var(--transition-control);
}
.chip:hover { background: var(--brand-subtle); border-color: var(--brand-border); }
.chip .icon { width: 12px; height: 12px; color: var(--brand); }
.chip__title { font: var(--fw-medium) var(--text-micro)/1 var(--font-core); color: var(--ink-800); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.chip__page { font: var(--fw-regular) var(--text-micro)/1 var(--font-core); color: var(--text-subtle); }
.chips { display: flex; flex-wrap: wrap; gap: 8px; }

/* ============ MessageBubble ============ */
.msg { display: flex; gap: 12px; justify-content: flex-start; }
.msg--user { justify-content: flex-end; }
.msg__col { display: flex; flex-direction: column; gap: 8px; max-width: 100%; }
.msg--user .msg__col { max-width: 78%; align-items: flex-end; }
.msg__name { font: var(--fw-medium) var(--text-label)/1 var(--font-core); color: var(--text-muted); }
.msg__body { position: relative; font: var(--fw-regular) var(--text-body)/var(--lh-relaxed) var(--font-core); color: var(--ink-800); display: flex; flex-direction: column; gap: 10px; }
.msg__content { display: flex; flex-direction: column; gap: 10px; }
/* Ba chấm nằm đè lên chỗ của câu trả lời nên khung không bị đẩy lên rồi hạ xuống. */
/* Đủ mạnh để thắng luật .spinner nằm bên dưới trong file này. */
.msg .msg__thinking { display: none; position: absolute; top: 6px; left: 0; }
.msg.is-thinking .msg__thinking { display: inline-flex; }
.msg.is-thinking .msg__content { visibility: hidden; }
.msg.is-thinking .msg__actions { visibility: hidden; }
.msg--user .msg__body { padding: 10px 14px; background: var(--brand-subtle); border: 1px solid var(--blue-100); border-radius: var(--radius-lg); }
.msg__steps { margin: 0; padding-left: 20px; display: flex; flex-direction: column; gap: 4px; }
.msg__steps li { padding-left: 2px; }
.msg__actions { display: flex; gap: 2px; opacity: 0; transition: opacity var(--dur-fast) var(--ease-standard); }
.msg:hover .msg__actions { opacity: 1; }

/* Spinner — three-dot thinking indicator */
.spinner { display: inline-flex; align-items: center; gap: 6px; }
.spinner span { width: 6px; height: 6px; border-radius: var(--radius-pill); background: var(--brand-border); animation: htt-pulse 900ms infinite; }
.spinner span:nth-child(2) { animation-delay: 300ms; }
.spinner span:nth-child(3) { animation-delay: 600ms; }
@keyframes htt-pulse { 0%, 100% { opacity: .35 } 33% { opacity: 1 } }

/* ============ Composer ============ */
.composer {
  display: flex; flex-direction: column; gap: 8px; padding: 10px;
  background: var(--surface-card); border: 1px solid var(--border-hairline);
  border-radius: var(--radius-xl); box-shadow: var(--shadow-1); transition: var(--transition-control);
}
.composer:focus-within { border-color: var(--border-focus); box-shadow: var(--shadow-2); }
.composer textarea {
  border: none; outline: none; resize: none; background: transparent; padding: 4px 6px;
  font: var(--fw-regular) var(--text-body)/var(--lh-normal) var(--font-core); color: var(--ink-800);
}
.composer__bar { display: flex; align-items: center; gap: 6px; }
.composer__ctx { display: inline-flex; align-items: center; gap: 5px; font: var(--fw-medium) var(--text-micro)/1 var(--font-core); color: var(--text-muted); }
.composer__ctx .icon { width: 12px; height: 12px; color: var(--text-subtle); }
.composer__spacer { flex: 1; }

/* ============ header ============ */
.site-header {
  position: sticky; top: 0; z-index: 40; height: 60px;
  background: rgba(250, 248, 244, .82); backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-hairline);
}
.site-header__inner { position: relative; max-width: var(--content-max); margin: 0 auto; padding: 0 var(--gutter-screen); height: 60px; display: flex; align-items: center; gap: 28px; }
.brand { display: flex; align-items: center; gap: 10px; color: var(--text-heading); }
.brand:hover { text-decoration: none; color: var(--text-heading); }
.brand img { border-radius: var(--radius-logo); }
.brand__name { font: var(--fw-semibold) 16px/1.2 var(--font-core); letter-spacing: var(--ls-title); }
.brand__name span { color: var(--text-muted); font-weight: var(--fw-regular); }
.site-nav { display: flex; align-items: center; gap: 22px; margin-left: auto; }
.site-nav a { font: var(--type-ui); color: var(--text-muted); }
.site-nav a:hover { color: var(--text-heading); text-decoration: none; }
.progress { position: absolute; left: 0; bottom: -1px; height: 2px; width: 0; background: var(--brand); border-radius: 0 999px 999px 0; }

/* ============ hero ============ */
.hero { position: relative; overflow-x: clip; padding: 88px var(--gutter-screen) 96px; }
.hero__blob { position: absolute; border-radius: 50%; pointer-events: none; }
.hero__blob--a { top: -160px; right: -140px; width: 520px; height: 520px; background: var(--blue-50); }
.hero__blob--b { top: 280px; left: -180px; width: 360px; height: 360px; background: var(--paper-100); }
.hero__grid { position: relative; max-width: var(--content-max); margin: 0 auto; display: grid; grid-template-columns: 1.02fr .98fr; gap: 56px; align-items: center; }
.hero h1 { margin: 0 0 20px; font: var(--fw-semibold) 54px/1.1 var(--font-display); letter-spacing: var(--ls-display); color: var(--text-heading); }
.hero h1 .line-mask { display: block; overflow: hidden; padding-bottom: 4px; }
.hero h1 .line { display: block; }
.hero__body { margin: 0 0 14px; max-width: 52ch; font: var(--fw-regular) var(--text-body-lg)/var(--lh-relaxed) var(--font-core); color: var(--ink-800); text-wrap: pretty; }
.hero__body--muted { color: var(--text-muted); margin-bottom: 30px; }
.hero__body strong { color: var(--ink-800); font-weight: var(--fw-semibold); }
.hero__cta { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.hero__tags { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 34px; }
.hero__tags--row2 { margin-top: 8px; }
.hero__panel { background: var(--surface-card); border: 1px solid var(--border-hairline); border-radius: 20px; box-shadow: 0 18px 40px -24px rgba(38,35,31,.28), 0 1px 2px rgba(38,35,31,.06); overflow: hidden; }
.panel__head { display: flex; align-items: center; gap: 10px; padding: 12px 16px; border-bottom: 1px solid var(--border-hairline); background: var(--paper-25); }
.panel__head img { border-radius: var(--radius-logo); }
.panel__head span { font: var(--type-ui); color: var(--text-heading); }
.panel__body { padding: 18px 16px; display: flex; flex-direction: column; gap: 14px; }
.panel__foot { padding: 0 16px 16px; }
.hero__disclaimer { margin: 12px 4px 0; font: var(--fw-regular) var(--text-body-sm)/var(--lh-normal) var(--font-core); color: var(--text-subtle); }

/* ============ feature icons ============ */
.feature-icon { width: 44px; height: 44px; border-radius: 14px; display: flex; align-items: center; justify-content: center; margin-bottom: 18px; background: var(--brand-subtle); color: var(--brand); }
.feature-icon .icon { width: 22px; height: 22px; }
.feature-icon--leaf { background: var(--leaf-50); color: var(--leaf-600); }
.feature-icon--amber { background: var(--amber-50); color: var(--amber-600); }

/* ============ teachers ============ */
.teacher-card { padding: 22px; height: 100%; }
.teacher-card h3 { font: var(--fw-semibold) var(--text-subtitle)/1.3 var(--font-core); margin-bottom: 3px; }
.teacher__subject { font: var(--fw-medium) var(--text-body-sm)/1.3 var(--font-core); color: var(--brand); }
.teacher-card .teacher__role { margin-bottom: 16px; }
.teacher-card .bullets li { font: var(--fw-regular) var(--text-body-sm)/var(--lh-relaxed) var(--font-core); }
.teacher__head { display: flex; align-items: center; gap: 12px; margin-bottom: 18px; }
.teacher__head h3 { margin: 0 0 4px; }
.teacher__role { font: var(--fw-medium) var(--text-body-sm)/1.3 var(--font-core); color: var(--text-muted); }
.bullets { margin: 0; padding: 0; list-style: none; display: flex; flex-direction: column; gap: 12px; }
.bullets li { display: flex; gap: 10px; font: var(--type-body); color: var(--ink-800); }
.bullets .icon { width: 16px; height: 16px; color: var(--brand); margin-top: 3px; }
.recruit { margin-top: 22px; display: flex; align-items: center; gap: 12px; padding: 16px 20px; border: 1px dashed var(--border-strong); border-radius: 14px; background: var(--paper-25); font: var(--type-body); color: var(--text-muted); }
.recruit .icon { width: 18px; height: 18px; color: var(--text-subtle); }

/* ============ roadmap ============ */
.roadmap { max-width: var(--content-max); margin: 0 auto; display: grid; grid-template-columns: .85fr 1.15fr; gap: 56px; align-items: start; }
.roadmap__aside { position: sticky; top: 110px; }
.roadmap__aside h2 { margin: 14px 0 14px; font: var(--type-section); letter-spacing: var(--ls-title); color: var(--text-heading); }
.roadmap__aside .lede { margin: 0 0 26px; }
.rail { position: relative; padding-left: 20px; }
.rail__track { position: absolute; left: 5px; top: 10px; bottom: 10px; width: 2px; background: var(--paper-200); border-radius: 999px; }
.rail__fill { position: absolute; left: 5px; top: 10px; width: 2px; height: 0; background: var(--brand); border-radius: 999px; transition: height 320ms cubic-bezier(.2,.8,.25,1); }
.rail ol { margin: 0; padding: 0; list-style: none; display: flex; flex-direction: column; gap: 2px; }
.rail li { display: flex; align-items: center; gap: 12px; padding: 10px 12px; border-radius: 10px; background: transparent; transition: background 200ms var(--ease-standard); }
.rail li .num { font: var(--fw-semibold) var(--text-micro)/1 var(--font-mono); color: var(--text-subtle); width: 18px; transition: color 200ms; }
.rail li .label { font: var(--type-ui); color: var(--text-muted); transition: color 200ms; }
.rail li.is-active { background: var(--surface-selected); }
.rail li.is-active .num { color: var(--brand); }
.rail li.is-active .label { color: var(--brand); font-weight: 600; }
.steps { display: flex; flex-direction: column; gap: 20px; }
.step__head { display: flex; align-items: center; gap: 12px; margin-bottom: 16px; }
.step__num { font: var(--fw-semibold) 13px/1 var(--font-mono); color: var(--brand); }

/* ============ ChatHTT band ============ */
.band { padding: 88px var(--gutter-screen); background: var(--brand); color: var(--text-on-brand); box-shadow: inset 0 1px 0 rgba(255,255,255,.14); }
.band__grid { max-width: var(--content-max); margin: 0 auto; display: grid; grid-template-columns: .92fr 1.08fr; gap: 56px; align-items: center; }
.band__eyebrow { display: flex; align-items: center; gap: 12px; margin-bottom: 22px; }
.band__eyebrow span { font: var(--fw-semibold) var(--text-micro)/1.2 var(--font-core); letter-spacing: var(--ls-caps); text-transform: uppercase; opacity: .8; }
.band h2 { margin: 0 0 18px; font: var(--fw-semibold) 40px/1.15 var(--font-display); letter-spacing: var(--ls-display); color: #fff; text-wrap: pretty; }
.band__lede { margin: 0 0 30px; max-width: 50ch; font: var(--fw-regular) var(--text-body-lg)/var(--lh-relaxed) var(--font-core); opacity: .9; text-wrap: pretty; }
.band__list { margin: 0 0 32px; padding: 0; list-style: none; display: flex; flex-direction: column; gap: 18px; }
.band__list li { display: flex; gap: 14px; }
.band__list .slot { flex: 0 0 auto; width: 34px; height: 34px; border-radius: 10px; background: rgba(255,255,255,.16); display: flex; align-items: center; justify-content: center; }
.band__list .slot .icon { width: 18px; height: 18px; }
.band__list strong { display: block; font: var(--fw-semibold) var(--text-body-lg)/1.4 var(--font-core); color: #fff; }
.band__list .desc { font: var(--type-body); opacity: .85; }
.chatbox { color: var(--ink-800); background: var(--surface-card); border-radius: 20px; box-shadow: 0 30px 60px -30px rgba(11,46,90,.55); overflow: hidden; }
.chatbox__head { display: flex; align-items: center; gap: 10px; padding: 14px 18px; border-bottom: 1px solid var(--border-hairline); background: var(--paper-25); }
.chatbox__head img { border-radius: var(--radius-logo); }
.chatbox__head .title { font: var(--type-ui); color: var(--text-heading); }
.chatbox__head .badge { margin-left: auto; }
.chatbox__body { padding: 20px 18px; display: flex; flex-direction: column; gap: 16px; min-height: 376px; }
.chatbox__foot { padding: 0 18px 18px; }

/* ============ nút nổi Thử ChatHTT ============ */
.float-cta {
  position: fixed; right: 32px; bottom: 44px; z-index: 60;
  display: inline-flex; align-items: center; gap: 9px;
  height: 52px; padding: 0 22px; border-radius: var(--radius-pill);
  background: var(--brand); color: var(--text-on-brand);
  font: var(--fw-semibold) var(--text-body)/1 var(--font-core);
  box-shadow: 0 14px 30px -10px rgba(5,118,241,.6), 0 2px 6px rgba(38,35,31,.14);
  transition: background var(--dur-fast) var(--ease-standard), transform var(--dur-base) var(--ease-standard), box-shadow var(--dur-base) var(--ease-standard);
}
.float-cta:hover { background: var(--brand-hover); color: var(--text-on-brand); text-decoration: none; transform: translateY(-2px); box-shadow: 0 18px 38px -10px rgba(5,118,241,.7), 0 3px 8px rgba(38,35,31,.16); }
.float-cta:active { transform: translateY(0) scale(var(--press-scale)); }
.float-cta .icon { width: 18px; height: 18px; position: relative; }
.float-cta span:last-child { position: relative; }
/* vòng sáng nhấp nháy nhẹ để nút bắt mắt hơn */
.float-cta__glow {
  position: absolute; inset: 0; border-radius: inherit;
  box-shadow: 0 0 0 0 rgba(5,118,241,.45);
  animation: htt-ring 2.6s var(--ease-out) infinite;
  pointer-events: none;
}
@keyframes htt-ring {
  0%   { box-shadow: 0 0 0 0 rgba(5,118,241,.45); }
  60%  { box-shadow: 0 0 0 16px rgba(5,118,241,0); }
  100% { box-shadow: 0 0 0 0 rgba(5,118,241,0); }
}

/* ============ contact ============ */
.contact-card h3 { margin: 0 0 8px; font: var(--fw-semibold) var(--text-subtitle)/1.3 var(--font-core); color: var(--text-heading); }
.contact-card p { margin: 0 0 14px; }
.contact-card .icon { width: 20px; height: 20px; color: var(--brand); margin-bottom: 14px; }
.contact-card .icon--zalo { width: 24px; height: 24px; border-radius: 6px; }
.muted-link { font: var(--type-ui); color: var(--text-subtle); }

/* ============ footer ============ */
.site-footer { padding: 36px var(--gutter-screen); border-top: 1px solid var(--border-hairline); background: var(--surface-page); }
.site-footer__inner { max-width: var(--content-max); margin: 0 auto; display: flex; align-items: center; gap: 20px; flex-wrap: wrap; }
.site-footer img { border-radius: var(--radius-logo); }
.site-footer .name { font: var(--fw-semibold) var(--text-body-sm)/1.3 var(--font-core); color: var(--text-heading); }
.site-footer .tagline { font: var(--fw-regular) var(--text-body-sm)/1.3 var(--font-core); color: var(--text-muted); }
.site-footer a { margin-left: auto; font: var(--type-ui); }

/* ============ responsive ============ */
@media (max-width: 960px) {
  .hero__grid, .roadmap, .band__grid { grid-template-columns: 1fr; gap: 40px; }
  .roadmap__aside { position: static; }
  .grid-3, .grid-2 { grid-template-columns: 1fr; }
  .hero h1 { font-size: 42px; }
  .band h2 { font-size: 32px; }
}
@media (max-width: 720px) {
  .site-nav { display: none; }
  .section, .hero, .band { padding-left: 18px; padding-right: 18px; }
  .hero { padding-top: 56px; padding-bottom: 64px; }
  .section, .band { padding-top: 56px; padding-bottom: 56px; }
  .hero h1 { font-size: 34px; }
  .hero__blob { display: none; }
  .float-cta { right: 16px; bottom: 28px; height: 46px; padding: 0 18px; font-size: var(--text-body-sm); }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { animation-duration: .01ms !important; transition-duration: .01ms !important; }
}