/* ============================================================
   ViFast — giao diện kem ấm, điểm nhấn đỏ
   Chỉ dùng font hệ thống; không font ngoài, không CDN.
   ============================================================ */

:root {
  --bg: #FFF8EC; --card: #FFFCF7; --text: #3B2A22; --muted: #7A6558;
  --accent: #C0392B; --accent-2: #E5352B; --accent-strong: #A93226; --border: #EADBCC;
  --radius: 16px; --max: 1080px;
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

*, *::before, *::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

@media (prefers-reduced-motion: no-preference) {
  html { scroll-behavior: smooth; }
}

body {
  margin: 0; min-height: 100vh; background: var(--bg); color: var(--text);
  font-family: var(--font); font-size: 16px; line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); text-decoration: none; }

:focus-visible {
  outline: 2px solid var(--accent-2); outline-offset: 3px; border-radius: 4px;
}

::selection { background: #F3D9D4; color: var(--text); }

/* Tiện ích chung ------------------------------------------------ */
.container {
  width: 100%; max-width: var(--max); margin-inline: auto; padding-inline: 24px;
}

.sr-only {
  position: absolute; width: 1px; height: 1px; margin: -1px; padding: 0;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}

.skip-link {
  position: absolute; left: 16px; top: -48px; z-index: 50; padding: 8px 14px;
  border-radius: 8px; background: var(--accent); color: #fff;
  font-size: 14px; font-weight: 600; transition: top .15s ease;
}
.skip-link:focus { top: 12px; }

[hidden] { display: none !important; }

/* Đầu trang ----------------------------------------------------- */
.site-header {
  position: sticky; top: 0; z-index: 20;
  background: rgba(255, 248, 236, .94);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(6px);
}

.site-header__inner {
  display: flex; align-items: center; justify-content: space-between;
  gap: 24px; min-height: 64px;
}

.brand {
  display: inline-flex; align-items: center; gap: 10px;
  color: var(--text); font-size: 18px; font-weight: 700;
  letter-spacing: -.01em;
}

.brand__mark {
  display: grid; place-items: center; width: 30px; height: 30px;
  border-radius: 8px; background: var(--accent); color: #fff;
  font-size: 15px; font-weight: 800; transition: background-color .18s ease;
}
.brand:hover { color: var(--accent); }
.brand:hover .brand__mark { background: var(--accent-strong); }

.site-nav__list {
  display: flex; align-items: center; gap: 28px;
  margin: 0; padding: 0; list-style: none;
}
.site-nav a {
  color: var(--muted); font-size: 15px; font-weight: 500;
  transition: color .18s ease;
}
.site-nav a:hover { color: var(--accent); }

.nav-toggle {
  display: none; align-items: center; justify-content: center;
  width: 42px; height: 42px; padding: 0;
  border: 1px solid var(--border); border-radius: 10px;
  background: var(--card); color: var(--text); cursor: pointer;
}

.nav-toggle__bars,
.nav-toggle__bars::before,
.nav-toggle__bars::after {
  display: block; width: 18px; height: 2px; border-radius: 2px;
  background: currentColor; transition: transform .18s ease, background-color .18s ease;
}
.nav-toggle__bars { position: relative; }
.nav-toggle__bars::before,
.nav-toggle__bars::after { position: absolute; left: 0; content: ""; }
.nav-toggle__bars::before { top: -6px; }
.nav-toggle__bars::after { top: 6px; }

.site-header.is-open .nav-toggle__bars { background: transparent; }
.site-header.is-open .nav-toggle__bars::before { transform: translateY(6px) rotate(45deg); }
.site-header.is-open .nav-toggle__bars::after { transform: translateY(-6px) rotate(-45deg); }

/* Hero ---------------------------------------------------------- */
.hero { padding: 88px 0 64px; }

.eyebrow {
  margin: 0 0 14px; color: var(--accent); font-size: 13px;
  font-weight: 600; letter-spacing: .08em; text-transform: uppercase;
}

.hero h1 {
  max-width: 900px; margin: 0 0 20px;
  font-size: clamp(2rem, 5.2vw, 3.25rem);
  font-weight: 800; line-height: 1.12; letter-spacing: -.02em;
}

.hero__lead {
  max-width: 680px; margin: 0 0 28px;
  color: var(--muted); font-size: 1.0625rem;
}

.hero__actions {
  display: flex; flex-wrap: wrap; align-items: center; gap: 14px 22px;
}

/* Nút và liên kết ----------------------------------------------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  padding: 12px 20px; border: 1px solid transparent; border-radius: 10px;
  background: var(--accent); color: #fff; font-size: 15px; font-weight: 600;
  line-height: 1.2; transition: background-color .18s ease;
}
.btn:hover { background: var(--accent-strong); }

.link-arrow { color: var(--accent); font-size: 15px; font-weight: 600; }
.link-arrow:hover {
  color: var(--accent-strong); text-decoration: underline; text-underline-offset: 3px;
}

/* Khu vực nội dung ---------------------------------------------- */
.section { padding: 72px 0; border-top: 1px solid var(--border); }
.section__head { margin-bottom: 32px; }
.section__head h2 {
  margin: 0; font-size: clamp(1.5rem, 3vw, 1.875rem);
  line-height: 1.2; letter-spacing: -.01em;
}
.section__en { margin: 6px 0 0; color: var(--muted); font-size: 14px; }
section[id] { scroll-margin-top: 80px; }

/* Thẻ dự án ----------------------------------------------------- */
.cards {
  display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 24px;
}

.card {
  display: flex; flex-direction: column; gap: 16px; height: 100%;
  padding: 28px 24px 24px; border: 1px solid var(--border);
  border-radius: var(--radius); background: var(--card);
  box-shadow: 0 1px 3px rgba(0, 0, 0, .06);
}

.card__head {
  display: flex; flex-wrap: wrap; align-items: center;
  justify-content: space-between; gap: 8px 10px;
}
.card__name { margin: 0; font-size: 1.25rem; letter-spacing: -.01em; }
.card__desc { flex: 1 1 auto; margin: 0; color: var(--muted); font-size: 15px; }
.card code {
  padding: 1px 4px; border: 1px solid var(--border); border-radius: 5px;
  background: var(--bg); font-family: var(--mono); font-size: .86em;
}

.chips {
  display: flex; flex-wrap: wrap; gap: 6px; margin: 0; padding: 0;
  list-style: none;
}
.chip, .release {
  padding: 3px 9px; border: 1px solid var(--border); border-radius: 999px;
  background: var(--bg); color: var(--muted); font-family: var(--mono);
  font-size: 11.5px; line-height: 1.5; white-space: nowrap;
}
.release {
  border-color: #F0C6BE; background: #FBEAE7;
  color: var(--accent); font-weight: 700;
}

.wip {
  align-self: flex-start; margin: -6px 0 0; padding: 3px 10px;
  border: 1px solid #F0C6BE; border-radius: 999px;
  background: #FBEAE7; color: var(--accent); font-size: 12px; font-weight: 600;
}

.btn--card { width: 100%; margin-top: 4px; padding: 11px 16px; font-size: 14px; }

/* Vì sao ViFast ------------------------------------------------- */
.why {
  display: grid; grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 28px; margin: 0; padding: 0; list-style: none;
}
.why__item { padding-left: 18px; border-left: 2px solid var(--accent); }
.why__title { margin: 0 0 6px; font-size: 1.0625rem; line-height: 1.4; }
.why__item p { margin: 0; color: var(--muted); font-size: 15px; }
.nowrap { white-space: nowrap; }

/* Cân chiều cao tiêu đề để các đoạn văn thẳng hàng trên desktop */
@media (min-width: 961px) {
  .why__title { min-height: 2.8em; }
}

/* Mã nguồn ------------------------------------------------------ */
.repos {
  margin: 0; padding: 0; list-style: none;
  border-top: 1px solid var(--border);
}
.repo {
  display: flex; flex-wrap: wrap; align-items: baseline;
  justify-content: space-between; gap: 4px 24px;
  padding: 18px 4px; border-bottom: 1px solid var(--border);
  color: var(--text); transition: color .18s ease;
}
.repo:hover { color: var(--accent); }
.repo__name { font-weight: 600; }
.repo__path { color: var(--muted); font-family: var(--mono); font-size: 13px; }
.repo:hover .repo__path { color: var(--accent); }

/* Chân trang ---------------------------------------------------- */
.site-footer { padding: 28px 0; border-top: 1px solid var(--border); }
.site-footer__inner {
  display: flex; flex-wrap: wrap; align-items: center;
  justify-content: space-between; gap: 12px 24px;
}
.site-footer__copy { margin: 0; color: var(--muted); font-size: 14px; }
.site-footer__links {
  display: flex; flex-wrap: wrap; gap: 18px; margin: 0; padding: 0;
  list-style: none;
}
.site-footer__links a {
  color: var(--muted); font-family: var(--mono); font-size: 13px;
}
.site-footer__links a:hover {
  color: var(--accent); text-decoration: underline; text-underline-offset: 3px;
}

/* Màn hình nhỏ -------------------------------------------------- */
@media (max-width: 960px) {
  .container { padding-inline: 20px; }
  .nav-toggle { display: inline-flex; }

  .site-nav {
    display: none; position: absolute; top: 100%; left: 0; right: 0;
    background: var(--card); border-bottom: 1px solid var(--border);
  }
  .site-nav.is-open { display: block; }
  .site-nav__list {
    flex-direction: column; align-items: stretch; gap: 0;
    padding: 8px 20px 16px;
  }
  .site-nav__list li + li { border-top: 1px solid var(--border); }
  .site-nav a { display: block; padding: 12px 4px; font-size: 16px; }

  .hero { padding: 56px 0 48px; }
  .section { padding: 40px 0; }
  .cards, .why { grid-template-columns: 1fr; }
  .cards { gap: 16px; }
  .why { gap: 20px; }
}

@media (max-width: 480px) {
  .container { padding-inline: 16px; }
  .hero__actions .btn { width: 100%; }
}

/* Tôn trọng lựa chọn giảm chuyển động --------------------------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: .01ms !important; animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
  }
}