/* ============================================================
   Custom CSS cho HTML build (phối hợp với water.css base).
   Áp dụng cho khối "Về tác giả" và một vài tinh chỉnh chung.
   ============================================================ */

/* --- Author card (Về tác giả) ---
   Structure (raw HTML in markdown to avoid pandoc <p> wrapping):
     .author-card
       > img.author-photo
       > .author-info
           > h3.author-name
           > p.author-role
           > p.author-bio
*/

.author-card {
  display: flex;
  align-items: center;
  gap: 2rem;
  margin: 2rem 0;
  padding: 1.5rem 1.75rem;
  background: rgba(58, 122, 254, 0.04);
  border-left: 4px solid #3a7afe;
  border-radius: 8px;
}

.author-card .author-photo {
  width: 220px;
  height: 220px;
  min-width: 220px;            /* prevent flex shrink */
  min-height: 220px;
  aspect-ratio: 1 / 1;
  object-fit: cover;
  border-radius: 50%;
  display: block;
  border: 4px solid #fff;
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.18);
}

.author-card .author-info {
  flex: 1 1 auto;
}

.author-card .author-name {
  font-size: 1.4rem;
  font-weight: 700;
  margin: 0 0 0.3rem 0;
}

.author-card .author-role {
  font-style: italic;
  color: #555;
  margin: 0 0 0.8rem 0;
}

.author-card .author-bio {
  margin: 0;
  line-height: 1.6;
  font-size: 1rem;
}

/* Social links — LinkedIn + Portfolio */
.author-card .author-social {
  margin: 0.6rem 0 0 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.linkedin-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.35rem 0.85rem;
  background: #0a66c2;
  color: #fff !important;
  border-radius: 6px;
  text-decoration: none !important;
  font-weight: 600;
  font-size: 0.9rem;
  transition: background 0.15s ease, transform 0.15s ease;
}

.linkedin-link:hover {
  background: #084d94;
  transform: translateY(-1px);
}

.linkedin-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.3rem;
  height: 1.3rem;
  background: #fff;
  color: #0a66c2;
  border-radius: 3px;
  font-weight: 800;
  font-size: 0.78rem;
  font-family: Arial, sans-serif;
  letter-spacing: -0.05em;
}

/* Portfolio link — gradient tím nhẹ, phân biệt với LinkedIn */
.portfolio-link {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.35rem 0.85rem;
  background: linear-gradient(135deg, #6366f1, #8b5cf6);
  color: #fff !important;
  border-radius: 6px;
  text-decoration: none !important;
  font-weight: 600;
  font-size: 0.9rem;
  transition: filter 0.15s ease, transform 0.15s ease;
}

.portfolio-link:hover {
  filter: brightness(0.9);
  transform: translateY(-1px);
}

/* --- Acknowledgments / Lời cảm ơn (dưới Về tác giả) --- */
.acknowledgments {
  margin-top: 2rem;
  padding: 1.5rem 1.75rem;
  background: linear-gradient(135deg, rgba(58, 122, 254, 0.04), rgba(31, 157, 85, 0.04));
  border: 1px solid rgba(58, 122, 254, 0.18);
  border-radius: 10px;
}

.acknowledgments h4 {
  margin: 0 0 0.8rem 0;
  font-size: 1.15rem;
  color: #2a5fb8;
}

.acknowledgments p {
  margin: 0 0 0.9rem 0;
  line-height: 1.65;
}

.mentors-list {
  list-style: none;
  padding: 0;
  margin: 0.8rem 0 1rem 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.4rem;
}

@media (min-width: 700px) {
  .mentors-list {
    grid-template-columns: 1fr 1fr;        /* 2 column trên màn rộng */
    gap: 0.5rem 1.5rem;
  }
  /* Item cuối ("… và nhiều anh/chị khác") trải hết width */
  .mentors-list li:last-child {
    grid-column: 1 / -1;
    margin-top: 0.5rem;
    padding-top: 0.6rem;
    border-top: 1px dashed rgba(0, 0, 0, 0.15);
    text-align: center;
    color: #555;
  }
}

.mentors-list li {
  padding: 0.35rem 0.6rem;
  background: #fff;
  border-left: 3px solid #3a7afe;
  border-radius: 4px;
  font-size: 0.96rem;
}

.acknowledgments-footer {
  margin-top: 1rem !important;
  padding: 0.8rem 1rem;
  background: rgba(255, 255, 255, 0.5);
  border-radius: 6px;
  font-size: 0.95rem;
  font-style: italic;
  color: #444;
  text-align: center;
}

/* Feedback callout — đóng góp ý kiến cho cuốn sách */
.feedback-callout {
  margin-top: 1.5rem;
  padding: 1.25rem 1.5rem;
  background: rgba(255, 165, 0, 0.06);
  border: 1px dashed rgba(255, 140, 0, 0.4);
  border-radius: 8px;
  text-align: center;
}

.feedback-callout h4 {
  margin: 0 0 0.7rem 0;
  font-size: 1.1rem;
  color: #b25f00;
}

.feedback-callout p {
  margin: 0 0 0.9rem 0;
  line-height: 1.65;
  text-align: left;
}

.feedback-btn {
  display: inline-block;
  padding: 0.55rem 1.3rem;
  background: #ff8c00;
  color: #fff !important;
  border-radius: 8px;
  text-decoration: none !important;
  font-weight: 600;
  font-size: 0.95rem;
  transition: background 0.15s ease, transform 0.15s ease;
}

.feedback-btn:hover {
  background: #e57c00;
  transform: translateY(-1px);
}

/* EngineerPro logo card */
.engineerpro-card {
  text-align: center;
  margin: 2rem 0;
}

.engineerpro-card .logo {
  width: 240px;
  max-width: 80%;
  height: auto;
  border-radius: 16px;
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.12);
}

/* --- Title block tweaks ---
   Thêm dòng "Project này được thực hiện bởi:" trước danh sách author.
   Pandoc render mỗi author dưới dạng <p class="author">; ta dùng pseudo-element
   để chèn text vào trước author đầu tiên mà không cần đụng metadata. */
/* Language-aware "Authors:" label injected before first <p class="author">.
   Pandoc sets <html lang="vi"> or <html lang="en"> from metadata.yaml `lang:` */
html[lang="vi"] .author:first-of-type::before {
  content: "Tác giả:";
  display: block;
  font-weight: 700;
  font-size: 1.05rem;
  margin: 1rem 0 0.3rem 0;
  color: #333;
}

html[lang="en"] .author:first-of-type::before {
  content: "Authors:";
  display: block;
  font-weight: 700;
  font-size: 1.05rem;
  margin: 1rem 0 0.3rem 0;
  color: #333;
}

/* --- Language switcher (inserted via --include-before-body) --- */
.lang-switcher {
  position: fixed;
  top: 1rem;
  right: 1rem;
  z-index: 100;
  display: flex;
  gap: 0.3rem;
  padding: 0.4rem;
  background: rgba(255, 255, 255, 0.96);
  border: 1px solid rgba(0, 0, 0, 0.1);
  border-radius: 999px;
  box-shadow: 0 4px 14px rgba(0, 0, 0, 0.12);
}

.lang-switcher a {
  display: inline-block;
  padding: 0.35rem 0.85rem;
  border-radius: 999px;
  text-decoration: none !important;
  font-weight: 600;
  font-size: 0.85rem;
  color: #555 !important;
  transition: background 0.15s ease, color 0.15s ease;
}

.lang-switcher a:hover {
  background: rgba(58, 122, 254, 0.1);
  color: #3a7afe !important;
}

.lang-switcher a.active {
  background: #3a7afe;
  color: #fff !important;
}

/* Push body content down so it doesn't hide behind floating switcher on mobile */
@media (max-width: 700px) {
  body {
    padding-top: 4rem;
  }
}

/* Khoảng cách giữa 2 author cho gần nhau hơn (như khối tác giả thật) */
.author + .author {
  margin-top: -0.4rem;
}

/* Abstract block (pandoc inserts ngay giữa title-block và TOC).
   Đây là chỗ chứa banner "Về EngineerPro" trên cùng. */
.abstract {
  margin: 2rem 0 3rem 0;
  padding: 1.5rem 2rem;
  background: linear-gradient(135deg, rgba(58, 122, 254, 0.06), rgba(58, 122, 254, 0.02));
  border: 1px solid rgba(58, 122, 254, 0.25);
  border-radius: 10px;
}

/* Ẩn "Abstract" heading mặc định của pandoc — đã set abstract-title=""
   trong metadata.yaml. Phòng hờ override CSS. */
.abstract .abstract-title {
  display: none;
}

.engineerpro-banner blockquote {
  border-left: 4px solid #3a7afe;
  background: rgba(58, 122, 254, 0.08);
  padding: 0.8rem 1.2rem;
  margin: 1rem 0;
  border-radius: 4px;
  font-size: 1.05rem;
}

.engineerpro-banner ul {
  list-style: none;
  padding-left: 0;
}

.engineerpro-banner ul li {
  padding: 0.25rem 0;
}

.engineerpro-banner ul li::before {
  content: "→ ";
  color: #3a7afe;
  font-weight: bold;
  margin-right: 0.3rem;
}

/* --- Donate box --- */
.donate-box {
  margin-top: 1.5rem;
  padding: 1.25rem 1.5rem;
  background: rgba(255, 78, 78, 0.04);
  border: 1px dashed rgba(255, 78, 78, 0.35);
  border-radius: 10px;
  text-align: center;
}

.donate-box > p {
  margin: 0 0 0.8rem 0;
  line-height: 1.6;
}

.donate-link {
  display: inline-block;
  margin: 0.2rem 0;
  padding: 0.6rem 1.4rem;
  background: #ff4e4e;
  color: #fff !important;
  border-radius: 999px;
  text-decoration: none !important;
  font-weight: 600;
  font-size: 1rem;
  transition: background 0.15s ease, transform 0.15s ease;
}

.donate-link:hover {
  background: #e63b3b;
  transform: translateY(-1px);
}

/* --- Gold sponsor tier --- */
.gold-sponsor {
  margin-top: 1.5rem;
  padding: 1.5rem 1.75rem;
  background: linear-gradient(135deg, #fff7d6 0%, #fde9a8 100%);
  border: 2px solid #d4a017;
  border-radius: 12px;
  text-align: left;
  box-shadow: 0 4px 18px rgba(212, 160, 23, 0.18);
}

.gold-sponsor h4 {
  margin: 0 0 0.8rem 0;
  font-size: 1.2rem;
  color: #7a5a00;
  text-align: center;
  letter-spacing: 0.2px;
}

.gold-sponsor p {
  margin: 0 0 0.8rem 0;
  line-height: 1.65;
  color: #3a2c00;
}

.gold-sponsor .gift-callout {
  margin: 1rem 0;
  padding: 1rem 1.25rem;
  background: #fffbeb;
  border-left: 4px solid #d4a017;
  border-radius: 6px;
  line-height: 1.7;
  color: #2a2200;
}

.fb-link {
  display: inline-block;
  margin-top: 0.4rem;
  padding: 0.6rem 1.4rem;
  background: #1877f2;
  color: #fff !important;
  border-radius: 8px;
  text-decoration: none !important;
  font-weight: 600;
  transition: background 0.15s ease, transform 0.15s ease;
}

.fb-link:hover {
  background: #145dbf;
  transform: translateY(-1px);
}

/* --- YouTube embed (responsive 16:9) ---
   Dùng iframe official embed code (có `?si=` token) — bypass embedding
   config error. Wrap trong .video-embed để force 16:9 aspect ratio. */
.video-embed {
  position: relative;
  width: 100%;
  max-width: 800px;
  margin: 1.5rem auto 0.75rem auto;
  padding-top: 56.25%;            /* 16:9 = 9/16 = 0.5625 */
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 6px 24px rgba(0, 0, 0, 0.18);
  background: #000;
}

.video-embed iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

/* --- Video card (legacy: thumbnail click-to-open YouTube) ---
   Giữ lại trong CSS phòng hờ cần fallback sau này nếu iframe lại die. */
.video-card {
  position: relative;
  display: block;
  width: 100%;
  max-width: 800px;
  margin: 1.5rem auto 0.75rem auto;
  border-radius: 12px;
  overflow: hidden;
  text-decoration: none !important;
  box-shadow: 0 6px 24px rgba(0, 0, 0, 0.18);
  transition: transform 0.18s ease, box-shadow 0.18s ease;
}

.video-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 32px rgba(0, 0, 0, 0.25);
}

.video-card img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 12px;
}

.video-card .play-button {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 80px;
  height: 80px;
  border-radius: 50%;
  background: rgba(255, 0, 0, 0.92);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.2rem;
  padding-left: 0.4rem;             /* nudge ▶ visually center */
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
  transition: background 0.15s ease, transform 0.15s ease;
}

.video-card:hover .play-button {
  background: rgba(220, 0, 0, 1);
  transform: translate(-50%, -50%) scale(1.08);
}

.video-card .video-card-overlay {
  position: absolute;
  bottom: 1rem;
  left: 1.25rem;
  padding: 0.4rem 0.9rem;
  background: rgba(0, 0, 0, 0.75);
  color: #fff;
  border-radius: 6px;
  font-size: 0.95rem;
  font-weight: 600;
}

.video-caption {
  text-align: center;
  font-size: 0.95rem;
  color: #555;
  margin-bottom: 1.5rem;
}

.video-caption a {
  color: #c00;
  font-weight: 500;
}

/* Project goal block — đặt ở đầu abstract, trước EngineerPro card. */
.project-goal {
  margin-bottom: 1.8rem;
  padding: 1.25rem 1.5rem;
  border-left: 4px solid #1f9d55;
  background: rgba(31, 157, 85, 0.05);
  border-radius: 6px;
}

.project-goal > p {
  margin: 0 0 0.7rem 0;
  line-height: 1.65;
}

/* Course callout — cuốn sách + khoá học EngineerPro */
.course-callout {
  margin-top: 1.2rem;
  padding: 1.1rem 1.25rem;
  background: #fff;
  border: 1px solid rgba(31, 157, 85, 0.25);
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
}

.course-callout p {
  margin: 0 0 1rem 0;
  line-height: 1.65;
  font-size: 0.98rem;
}

.course-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  justify-content: flex-start;
}

.course-btn {
  display: inline-block;
  padding: 0.55rem 1.2rem;
  border-radius: 8px;
  text-decoration: none !important;
  font-weight: 600;
  font-size: 0.95rem;
  transition: background 0.15s ease, transform 0.15s ease;
  background: #1f9d55;
  color: #fff !important;
}

.course-btn:hover {
  background: #178246;
  transform: translateY(-1px);
}

.course-btn-secondary {
  background: #1877f2;
}

.course-btn-secondary:hover {
  background: #145dbf;
}

/* On narrow screens, stack photo above text */
@media (max-width: 700px) {
  .author-card {
    flex-direction: column;
    align-items: center;
    text-align: center;
    gap: 1.2rem;
    padding: 1.5rem 1rem;
  }
  .author-card .author-photo {
    width: 180px;
    height: 180px;
    min-width: 180px;
    min-height: 180px;
  }
}

/* --- Tinh chỉnh nhỏ cho TOC + nav --- */
nav#TOC ul {
  list-style: none;
  padding-left: 1rem;
}
nav#TOC ul ul {
  padding-left: 1.5rem;
  margin-top: 0.2rem;
  margin-bottom: 0.4rem;
}
nav#TOC a {
  text-decoration: none;
}
nav#TOC a:hover {
  text-decoration: underline;
}

/* Code blocks readable */
pre {
  font-size: 0.92rem;
  line-height: 1.45;
}

/* Inline code */
code {
  font-size: 0.92em;
}