/* ==========================================================================
   STLab Classroom — hệ thống thiết kế
   Ý tưởng: "phòng lab điện tử" — nền gần trắng ngả xanh nhạt như sợi thủy
   tinh của board mạch (fiberglass PCB), mực gần đen ngả than-xanh, điểm nhấn
   là màu hổ phách như đèn LED đang sáng, và xanh mạch (circuit) cho trạng
   thái phụ/thành công. Mỗi lộ trình học có 1 màu thiết bị riêng, tất cả cùng
   độ đậm vừa phải — như nhãn dán trên thiết bị lab, không phải màu kẹo.
   ========================================================================== */
:root {
  /* Nền & chữ */
  --ink: #171c22;
  --ink-soft: #4b5560;
  --paper: #f3f6f3;
  --card: #ffffff;
  --line: #dee4dd;
  --line-soft: #eaefe9;
  --radius: 14px;
  --radius-sm: 9px;
  --shadow: 0 1px 2px rgba(23, 28, 34, 0.05), 0 10px 26px rgba(23, 28, 34, 0.07);
  --shadow-sm: 0 1px 2px rgba(23, 28, 34, 0.06);

  /* Điểm nhấn chính — hổ phách, như đèn LED báo nguồn đang sáng */
  --accent: #e2932a;
  --accent-deep: #b9701c;
  --accent-ink: #8a560f;
  --accent-soft: #fdeed4;

  /* Điểm nhấn phụ — xanh mạch (circuit trace), dùng cho trạng thái/thành công */
  --circuit: #2f7a5d;
  --circuit-soft: #e1f0e7;

  /* Liên kết chéo giữa 2 khóa khác nhau (vd. Cơ khí <-> In 3D) — không gắn với 1 track cụ thể nào */
  --dev-link: #2b7a9e;
  --dev-link-soft: #e3eff3;

  /* Màu thiết bị theo từng lộ trình — cùng tông đậm vừa, khác hue */
  --dev-ai: #a6467b;       --dev-ai-soft: #f7e9f1;      /* Cấp độ 2 · AI */
  --dev-py: var(--circuit); --dev-py-soft: var(--circuit-soft); /* Cấp độ 3 · Python */
  --dev-esp: #3c6e9c;      --dev-esp-soft: #e4eef5;     /* Robotics · nền tảng + ESP32 */
  --dev-ard: #1c8c82;      --dev-ard-soft: #dff3f0;     /* Robotics · Arduino */
  --dev-rpi: #b4443a;      --dev-rpi-soft: #f8e6e1;     /* Robotics · Raspberry Pi */
  --dev-cb: #8a5a34;       --dev-cb-soft: #f1e6d8;      /* Robotics · CyberBrick */
  --dev-mech: #8a7a4a;     --dev-mech-soft: #f2eddc;    /* Cơ khí Robot · Nhập môn */
  --dev-mech2: #5c6b7a;    --dev-mech2-soft: #e5e9ec;   /* Cơ khí Robot · Làm khớp robot */
  --dev-mech3: #3f4a5c;    --dev-mech3-soft: #e1e4e9;   /* Cơ khí Robot · Cánh tay hoàn chỉnh */
  --dev-print: #52606b;    --dev-print-soft: #e7ebee;   /* In 3D */
  --dev-print2: #c98a1f;   --dev-print2-soft: #f7ecd9;  /* In 3D nhập môn · Tinkercad */
  --dev-print3: #d1638a;   --dev-print3-soft: #fbe7ee;  /* In 3D · Hoạt động bé 5-9 tuổi */
  --dev-audio: #c0526b;    --dev-audio-soft: #f8e5e9;   /* Âm thanh · Loa giấy nhập môn */
  --dev-audio2: #8a3f52;   --dev-audio2-soft: #f0e0e4;  /* Âm thanh · Lắp loa thật */
  --dev-audio3: #5c2f3d;   --dev-audio3-soft: #e8dcdf;  /* Âm thanh · Thiết kế vỏ loa 3D */
  --dev-web: #4a5fa8;      --dev-web-soft: #e7e9f5;     /* Web & App */
  --dev-game: #b8571f;     --dev-game-soft: #f5e4d6;    /* Pygame */
  --dev-ai2: #6d3fc0;      --dev-ai2-soft: #ede7fb;     /* AI cho trẻ em */
  --dev-comp: #c2652a;     --dev-comp-soft: #f6e8dc;    /* Thi đấu Robot · Nhập môn */
  --dev-comp2: #8f4a1f;    --dev-comp2-soft: #ecdfd4;   /* Thi đấu Robot · Trung cấp */
  --dev-comp3: #5c3016;    --dev-comp3-soft: #e3d6cc;   /* Thi đấu Robot · Cao cấp */
  --dev-idea: #2e9e6b;     --dev-idea-soft: #e2f3ec;    /* Sáng tạo & Đổi mới */
  --dev-drone: #1f7a99;    --dev-drone-soft: #e2eef2;   /* Drone · Nhập môn */
  --dev-drone2: #145a72;   --dev-drone2-soft: #dde8ea;  /* Drone · Lập trình nâng cao */

  --font-display: "Archivo", "Public Sans", system-ui, sans-serif;
  --font-body: "Public Sans", "Segoe UI", system-ui, sans-serif;
  --font-mono: "IBM Plex Mono", Consolas, "Courier New", monospace;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: var(--font-body);
  background: var(--paper);
  color: var(--ink);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

h1, h2, h3 { font-family: var(--font-display); font-weight: 800; letter-spacing: -0.01em; text-wrap: balance; }

a { color: var(--accent-ink); }

/* ---------- Top bar ---------- */
.topbar {
  background: var(--card);
  color: var(--ink);
  padding: 0.8rem 1.4rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.7rem;
  position: sticky;
  top: 0;
  z-index: 50;
  border-bottom: 1.5px solid var(--line);
}
.brand {
  color: var(--ink);
  text-decoration: none;
  display: flex;
  align-items: baseline;
  gap: 0.4rem;
}
.brand-mark {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.25rem;
  letter-spacing: -0.01em;
}
.brand-mark em { font-style: normal; color: var(--accent-ink); }
.brand-sub {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.09em;
  color: var(--ink-soft);
}
.topbar nav { display: flex; align-items: center; gap: 0.15rem; flex-wrap: wrap; }
.topbar nav a {
  color: var(--ink-soft);
  text-decoration: none;
  padding: 0.5rem 0.7rem;
  border-radius: 999px;
  font-size: 0.88rem;
  font-weight: 600;
  transition: background 0.12s, color 0.12s;
}
.topbar nav a:hover { background: var(--line-soft); color: var(--ink); }

/* ---------- Droplist "Khóa học" ở navbar ---------- */
.nav-dropdown { position: relative; }
.nav-dropdown-trigger {
  font-family: inherit; color: var(--ink-soft); background: none; border: none; cursor: pointer;
  padding: 0.5rem 0.7rem; border-radius: 999px; font-size: 0.88rem; font-weight: 600;
  display: inline-flex; align-items: center; gap: 0.25rem; transition: background 0.12s, color 0.12s;
}
.nav-dropdown-trigger:hover, .nav-dropdown-trigger.is-active { background: var(--line-soft); color: var(--ink); }
.nav-caret { font-size: 0.7em; transition: transform 0.15s; }
.nav-dropdown-trigger.is-active .nav-caret { transform: rotate(180deg); }
.nav-dropdown-panel {
  position: absolute; top: calc(100% + 8px); left: 0; z-index: 60;
  width: min(720px, calc(100vw - 2.4rem));
  background: var(--card); border: 1.5px solid var(--line); border-radius: var(--radius);
  box-shadow: var(--shadow); padding: 1.1rem 1.3rem;
}
.nav-dropdown-head {
  display: flex; align-items: baseline; justify-content: space-between; flex-wrap: wrap; gap: 0.5rem;
  padding-bottom: 0.8rem; margin-bottom: 0.9rem; border-bottom: 1px dashed var(--line);
}
.nav-dropdown-head strong { font-size: 0.95rem; }
.nav-dropdown-head a { font-size: 0.82rem; color: var(--accent-ink); font-weight: 600; text-decoration: none; }
.nav-dropdown-head a:hover { text-decoration: underline; }
.nav-dropdown-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.1rem 1.4rem;
  max-height: 70vh; overflow-y: auto;
}
.nav-dropdown-group h4 {
  font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.04em;
  margin-bottom: 0.45rem; font-weight: 800;
}
.nav-dropdown-group { display: flex; flex-direction: column; }
.nav-dropdown-group a {
  color: var(--ink); text-decoration: none; font-size: 0.85rem; padding: 0.22rem 0;
  line-height: 1.35;
}
.nav-dropdown-group a:hover { color: var(--accent-ink); text-decoration: underline; }
@media (max-width: 720px) {
  .nav-dropdown-panel { position: fixed; left: 1.2rem; right: 1.2rem; top: 64px; width: auto; }
  .nav-dropdown-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 440px) {
  .nav-dropdown-grid { grid-template-columns: 1fr; }
}
.topbar nav a.nav-user {
  color: var(--accent-ink);
  background: var(--accent-soft);
  margin-left: 0.3rem;
}
.topbar nav a.nav-user:hover { background: var(--accent-soft); filter: brightness(0.97); }

/* ---------- Tài khoản (đăng nhập/đăng xuất) ---------- */
.nav-account { display: flex; align-items: center; gap: 0.5rem; font-size: 0.85rem; }
.nav-account a { color: var(--ink-soft); text-decoration: none; font-weight: 600; }
.nav-account a:hover { text-decoration: underline; }
.nav-account-name { color: var(--ink); font-weight: 700; }

/* ---------- Flash messages ---------- */
.flash-messages { margin-bottom: 1.2rem; display: flex; flex-direction: column; gap: 0.5rem; }
.flash { padding: 0.7rem 1rem; border-radius: 10px; font-size: 0.9rem; border: 1.5px solid transparent; }
.flash-success { background: #e6f6ec; color: #1a7a3f; border-color: #b6e6c7; }
.flash-danger { background: #fce8e8; color: #a3271f; border-color: #f3bcb8; }
.flash-warning { background: #fff6e0; color: #8a6100; border-color: #f2dd9e; }
.flash-info { background: #e8f1fb; color: #1c5f9c; border-color: #bcdaf3; }

/* ---------- Đăng nhập học sinh ---------- */
.login-section { display: flex; justify-content: center; padding: 2.4rem 0; }
.login-card {
  width: min(360px, 100%); background: var(--card); border: 1.5px solid var(--line);
  border-radius: var(--radius); box-shadow: var(--shadow); padding: 1.8rem;
}
.login-form { display: flex; flex-direction: column; gap: 0.5rem; margin-top: 1rem; }
.login-form label { font-size: 0.82rem; font-weight: 700; color: var(--ink-soft); }
.login-form input {
  padding: 0.6rem 0.8rem; border-radius: 8px; border: 1.5px solid var(--line);
  font-size: 1rem; margin-bottom: 0.6rem;
}
.login-form select {
  padding: 0.6rem 0.8rem; border-radius: 8px; border: 1.5px solid var(--line);
  font-size: 1rem; margin-bottom: 0.6rem; background: var(--card);
}
.login-form button { margin-top: 0.3rem; }
.login-hint { font-size: 0.8rem; color: var(--ink-soft); margin-top: 1rem; }

/* ---------- Quản trị: gán khóa học ---------- */
.admin-section { padding: 1rem 0 2rem; }
.admin-table { width: 100%; border-collapse: collapse; margin-top: 1rem; }
.admin-table th, .admin-table td { text-align: left; padding: 0.6rem 0.8rem; border-bottom: 1px solid var(--line); }
.admin-pin-form { display: flex; align-items: end; gap: 0.6rem; margin: 1rem 0; }
.admin-pin-form label { font-size: 0.82rem; font-weight: 700; color: var(--ink-soft); }
.admin-pin-form input { padding: 0.5rem 0.7rem; border-radius: 8px; border: 1.5px solid var(--line); }
.admin-track-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 0.5rem 1rem; margin: 1rem 0; }
.admin-track-item { display: flex; align-items: center; gap: 0.5rem; font-size: 0.9rem; }


/* ---------- Layout ---------- */
.container { width: min(1100px, 94vw); margin: 0 auto; padding: 1.6rem 0 3rem; flex: 1; }
.footer { text-align: center; padding: 1.2rem; color: var(--ink-soft); font-size: 0.85rem; }
.footer a { color: var(--accent-ink); }

/* ---------- Hero ---------- */
.hero {
  padding: 2.6rem 0 1.8rem;
  position: relative;
  border-bottom: 1.5px solid var(--line);
  margin-bottom: 1.8rem;
}
.hero h1 {
  font-size: clamp(1.9rem, 3vw, 2.5rem);
  line-height: 1.15;
  max-width: 20ch;
}
.hero .hl { color: var(--accent-ink); }
.hero p { max-width: 60ch; margin: 0.9rem 0 1.3rem; color: var(--ink-soft); font-size: 1.05rem; }
.hero-actions { display: flex; gap: 0.7rem; flex-wrap: wrap; }
.eyebrow {
  color: var(--accent-ink); font-family: var(--font-mono); font-size: 0.74rem;
  font-weight: 700; letter-spacing: 0.06em; text-transform: uppercase;
}
.hero .eyebrow { margin: 0 0 0.55rem; }

/* Dải số liệu — sinh từ dữ liệu thật (số buổi/lộ trình), đặt cạnh hero */
.stats-strip {
  display: flex;
  flex-wrap: wrap;
  gap: 0;
  margin-top: 1.8rem;
  border-top: 1.5px solid var(--line);
}
.stat-item {
  flex: 1 1 140px;
  padding: 0.9rem 1.2rem 0.2rem 0;
  border-right: 1.5px dashed var(--line);
}
.stat-item:last-child { border-right: none; }
.stat-num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-weight: 600;
  font-size: 1.5rem;
  color: var(--ink);
}
.stat-label { font-size: 0.8rem; color: var(--ink-soft); margin-top: 0.15rem; }

/* ---------- Guided exploration ---------- */
.start-section, .learning-principles { margin-top: 3.2rem; }
.section-heading { max-width: 62ch; margin-bottom: 1.15rem; }
.section-heading .eyebrow { margin-bottom: 0.4rem; }
.section-heading h2, .catalogue-heading h2 { font-size: 1.45rem; line-height: 1.2; }
.section-heading p:last-child { color: var(--ink-soft); margin-top: 0.4rem; }
.starter-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 0.9rem; }
.starter-card {
  background: var(--card); border: 1.5px solid var(--line); border-left: 4px solid var(--accent);
  border-radius: var(--radius-sm); color: var(--ink); display: flex; flex-direction: column;
  gap: 0.42rem; min-height: 230px; padding: 1.1rem; text-decoration: none;
  transition: transform 0.15s, box-shadow 0.15s;
}
.starter-card:hover { box-shadow: var(--shadow); transform: translateY(-3px); }
.starter-emoji { font-size: 1.7rem; line-height: 1; }
.starter-kicker { color: var(--ink-soft); font-family: var(--font-mono); font-size: 0.75rem; font-weight: 600; }
.starter-card strong { font-family: var(--font-display); font-size: 1.05rem; line-height: 1.3; }
.starter-card > span:not(.starter-emoji):not(.starter-kicker):not(.starter-action) { color: var(--ink-soft); font-size: 0.87rem; }
.starter-action { color: var(--accent-ink); font-size: 0.84rem; font-weight: 700; margin-top: auto; }
.learning-principles {
  background: var(--ink); color: #fff; border-radius: var(--radius);
  padding: 2.8rem;
}
.learning-principles .eyebrow { color: #f4bd6a; }
.learning-principles h2 { color: #fff; }
.principles-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.4rem; }
.principles-grid article { border-top: 1px solid rgba(255,255,255,.3); padding-top: 0.8rem; }
.principles-grid span { color: #f4bd6a; font-family: var(--font-mono); font-size: 0.82rem; }
.principles-grid h3 { font-size: 1rem; margin: 0.55rem 0 0.35rem; }
.principles-grid p { color: #dce5df; font-size: 0.9rem; }
.catalogue-heading { align-items: end; display: flex; gap: 1rem; justify-content: space-between; margin-top: 3.2rem; }
.catalogue-heading .eyebrow { margin-bottom: 0.4rem; }
@media (max-width: 720px) {
  .starter-grid, .principles-grid { grid-template-columns: 1fr; }
  .starter-card { min-height: auto; }
  .learning-principles { padding-top: 2rem; padding-bottom: 2rem; }
  .catalogue-heading { align-items: start; flex-direction: column; }
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-block;
  background: var(--card);
  border: 1.5px solid var(--line);
  color: var(--ink);
  padding: 0.6rem 1.15rem;
  border-radius: 999px;
  text-decoration: none;
  font-size: 0.92rem;
  font-weight: 700;
  cursor: pointer;
  transition: transform 0.12s, box-shadow 0.12s, border-color 0.12s;
}
.btn:hover { transform: translateY(-1px); box-shadow: var(--shadow-sm); border-color: var(--ink-soft); }
.btn-primary { background: var(--accent); border-color: var(--accent); color: #241505; }
.btn-primary:hover { background: var(--accent-deep); border-color: var(--accent-deep); color: #fff; }
.btn-wide { display: block; width: 100%; text-align: center; margin-bottom: 0.5rem; }
.btn-small { padding: 0.32rem 0.8rem; font-size: 0.82rem; }

/* ---------- Level sections / cards ---------- */
.level { margin-top: 2.4rem; scroll-margin-top: 84px; }
.level h2 {
  font-size: 1.25rem; margin-bottom: 0.9rem; display: flex; align-items: center;
  gap: 0.6rem; flex-wrap: wrap; font-weight: 800;
}
.badge {
  font-family: var(--font-mono); font-size: 0.72rem; font-weight: 600; letter-spacing: 0.01em;
  color: var(--accent-ink); background: var(--accent-soft); padding: 0.25rem 0.7rem; border-radius: 999px;
}
.badge-py { color: var(--dev-py); background: var(--dev-py-soft); }
.badge-ai { color: var(--dev-ai); background: var(--dev-ai-soft); }
.badge-robot { color: var(--dev-esp); background: var(--dev-esp-soft); }
.badge-robot2 { color: var(--dev-ard); background: var(--dev-ard-soft); }
.badge-robot3 { color: var(--dev-rpi); background: var(--dev-rpi-soft); }
.badge-robot4 { color: var(--dev-cb); background: var(--dev-cb-soft); }
.badge-mech { color: var(--dev-mech); background: var(--dev-mech-soft); }
.badge-mech2 { color: var(--dev-mech2); background: var(--dev-mech2-soft); }
.badge-mech3 { color: var(--dev-mech3); background: var(--dev-mech3-soft); }
.badge-audio { color: var(--dev-audio); background: var(--dev-audio-soft); }
.badge-audio2 { color: var(--dev-audio2); background: var(--dev-audio2-soft); }
.badge-audio3 { color: var(--dev-audio3); background: var(--dev-audio3-soft); }
.badge-print { color: var(--dev-print); background: var(--dev-print-soft); }
.badge-print2 { color: var(--dev-print2); background: var(--dev-print2-soft); }
.badge-print3 { color: var(--dev-print3); background: var(--dev-print3-soft); }
.badge-web { color: var(--dev-web); background: var(--dev-web-soft); }
.badge-pygame { color: var(--dev-game); background: var(--dev-game-soft); }
.badge-ai2 { color: var(--dev-ai2); background: var(--dev-ai2-soft); }
.badge-comp { color: var(--dev-comp); background: var(--dev-comp-soft); }
.badge-comp2 { color: var(--dev-comp2); background: var(--dev-comp2-soft); }
.badge-comp3 { color: var(--dev-comp3); background: var(--dev-comp3-soft); }
.badge-idea { color: var(--dev-idea); background: var(--dev-idea-soft); }
.badge-drone { color: var(--dev-drone); background: var(--dev-drone-soft); }
.badge-drone2 { color: var(--dev-drone2); background: var(--dev-drone2-soft); }
.badge-scratch { color: var(--accent-ink); background: var(--accent-soft); }

.level-scratchjr {
  background: var(--card); border: 1.5px solid var(--line); border-radius: var(--radius);
  padding: 1.3rem 1.5rem; border-left: 4px solid var(--accent);
}
.level-desc { color: var(--ink-soft); font-size: 0.93rem; margin: 0.3rem 0 1rem; max-width: 65ch; }
.chapter-chips { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-bottom: 1.1rem; }
.chapter-chip {
  background: var(--accent-soft); color: var(--accent-ink); text-decoration: none;
  font-size: 0.83rem; font-weight: 700; padding: 0.4rem 0.85rem; border-radius: 999px;
  transition: filter 0.12s;
}
.chapter-chip:hover { filter: brightness(0.96); }

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(210px, 1fr));
  gap: 0.9rem;
}
.card {
  position: relative;
  background: var(--card);
  border: 1.5px solid var(--line);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius-sm);
  padding: 1rem 1.1rem;
  text-decoration: none;
  color: var(--ink);
  display: flex;
  gap: 0.75rem;
  align-items: flex-start;
  transition: transform 0.12s, box-shadow 0.12s, border-color 0.12s;
}
.card:hover { transform: translateY(-2px); box-shadow: var(--shadow); }
.card-done { position: absolute; top: 8px; right: 10px; font-size: 0.95rem; }
.card-continue { border-left-width: 5px; box-shadow: 0 0 0 2px var(--accent-deep) inset; }
.card-continue-badge {
  position: absolute; top: -9px; left: 10px;
  background: var(--accent-deep); color: #fff; font-size: 0.66rem; font-weight: 800;
  padding: 0.15rem 0.55rem; border-radius: 999px; letter-spacing: 0.02em; white-space: nowrap;
}
.card-icons { display: inline-flex; gap: 0.3rem; margin-left: 0.4rem; }
.card-tool, .card-extra { font-size: 0.78rem; }
.level-progress { font-size: 0.78rem; font-weight: 600; color: var(--ink-soft); margin-left: 0.3rem; }
.card-game { border-left-color: var(--accent-deep); }
.card-py { border-left-color: var(--dev-py); }
.card-l3 { border-left-color: var(--dev-ai); }
.card-robot { border-left-color: var(--dev-esp); }
.card-robot2 { border-left-color: var(--dev-ard); }
.card-robot3 { border-left-color: var(--dev-rpi); }
.card-robot4 { border-left-color: var(--dev-cb); }
.card-mech { border-left-color: var(--dev-mech); }
.card-mech2 { border-left-color: var(--dev-mech2); }
.card-mech3 { border-left-color: var(--dev-mech3); }
.card-audio { border-left-color: var(--dev-audio); }
.card-audio2 { border-left-color: var(--dev-audio2); }
.card-audio3 { border-left-color: var(--dev-audio3); }
.card-print { border-left-color: var(--dev-print); }
.card-print2 { border-left-color: var(--dev-print2); }
.card-print3 { border-left-color: var(--dev-print3); }
.card-web { border-left-color: var(--dev-web); }
.card-pygame { border-left-color: var(--dev-game); }
.card-ai2 { border-left-color: var(--dev-ai2); }
.card-comp { border-left-color: var(--dev-comp); }
.card-comp2 { border-left-color: var(--dev-comp2); }
.card-comp3 { border-left-color: var(--dev-comp3); }
.card-idea { border-left-color: var(--dev-idea); }
.card-drone { border-left-color: var(--dev-drone); }
.card-drone2 { border-left-color: var(--dev-drone2); }
.card-emoji { font-size: 1.5rem; line-height: 1.2; }
.card-num {
  font-family: var(--font-mono); font-size: 0.74rem; font-weight: 600;
  color: var(--ink-soft); text-transform: uppercase; letter-spacing: 0.02em;
}
.card-title { font-weight: 700; margin: 0.15rem 0; }
.card-product { font-size: 0.85rem; color: var(--ink-soft); }
.linked { font-size: 0.8rem; }

/* ---------- Teacher tips ---------- */
.teacher-tips { margin-top: 2.6rem; }
.teacher-tips h2 { font-size: 1.25rem; margin-bottom: 0.9rem; }
.tips-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 0.9rem; }
.tip {
  background: var(--card); border: 1.5px solid var(--line);
  border-radius: var(--radius-sm); padding: 0.95rem 1.05rem; font-size: 0.92rem;
}
.tip strong { color: var(--accent-ink); }

/* ---------- Lesson page ---------- */
.crumb { font-size: 0.86rem; color: var(--ink-soft); margin-bottom: 1.1rem; }
.crumb a { color: var(--accent-ink); text-decoration: none; }

.lesson-head { display: flex; gap: 1rem; align-items: center; margin-bottom: 1.5rem; }
.lesson-emoji { font-size: 2.6rem; }
.lesson-head h1 { font-size: 1.6rem; }
.lesson-product { color: var(--ink-soft); margin-top: 0.2rem; }

.lesson-prior {
  margin-top: 0.8rem; padding-top: 0.7rem; border-top: 1px dashed var(--line);
  font-size: 0.88rem; color: var(--ink-soft);
}
.lesson-prior strong { color: var(--ink); }

.lesson-grid { display: grid; grid-template-columns: 1fr 320px; gap: 1.2rem; align-items: start; }
@media (max-width: 860px) { .lesson-grid { grid-template-columns: 1fr; } }

.panel {
  background: var(--card);
  border: 1.5px solid var(--line);
  border-radius: var(--radius);
  padding: 1.15rem 1.3rem;
  margin-bottom: 1rem;
}
.panel h2 { font-size: 1rem; margin-bottom: 0.6rem; font-weight: 700; }
.panel-note { border-left: 4px solid var(--accent); background: var(--accent-soft); }
.panel-note h2, .panel-note p { color: var(--accent-ink); }
.panel-rules { border-left: 4px solid var(--circuit); background: var(--circuit-soft); }
.panel-rules h2 { color: var(--circuit); }
.panel-mblock { border: 2px solid var(--ink); }
.panel-vocab { border-left: 4px solid var(--circuit); background: var(--circuit-soft); }
.panel-vocab h2 { color: var(--circuit); }
.vocab-list { display: grid; gap: 0.7rem; }
.vocab-item dt { display: flex; align-items: baseline; gap: 0.5rem; flex-wrap: wrap; }
.vocab-term { font-family: var(--font-mono); font-weight: 600; font-size: 0.95rem; color: var(--ink); }
.vocab-phien-am { font-size: 0.82rem; color: var(--ink-soft); font-style: italic; }
.vocab-item dd { margin: 0.15rem 0 0; font-size: 0.9rem; color: var(--ink-soft); }
.panel-vocab .side-hint { margin-top: 0.9rem; padding-top: 0.7rem; border-top: 1px dashed var(--line); }
.panel-vocab .side-hint a { color: var(--circuit); font-weight: 600; text-decoration: none; }
.panel-vocab .side-hint a:hover { text-decoration: underline; }
.glossary-grid { grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); }

.panel-catalog { border-left: 4px solid var(--dev-print); background: var(--dev-print-soft); }
.panel-catalog h2 { color: var(--dev-print); }

.panel-related { border-left: 4px solid var(--dev-link); background: var(--dev-link-soft); }
.panel-related h2 { color: var(--dev-link); }
.related-list { list-style: none; display: grid; gap: 0.5rem; }
.related-list li { font-size: 0.92rem; }
.related-list a { color: var(--dev-link); font-weight: 700; text-decoration: none; }
.related-list a:hover { text-decoration: underline; }
.related-why { color: var(--ink-soft); }
.catalog-group-title { margin: 1.1rem 0 0.6rem; font-size: 0.98rem; }
.catalog-group-title:first-of-type { margin-top: 0.8rem; }
.catalog-list { display: grid; gap: 0.7rem; }
.catalog-item {
  background: var(--card); border: 1.5px solid var(--line); border-radius: 10px;
  padding: 0.7rem 0.9rem;
}
.catalog-item-head { display: flex; align-items: baseline; gap: 0.5rem; flex-wrap: wrap; margin-bottom: 0.3rem; }
.catalog-name { font-family: var(--font-mono); font-weight: 700; font-size: 0.92rem; color: var(--ink); }
.catalog-vi { font-size: 0.82rem; color: var(--ink-soft); font-style: italic; }
.catalog-item p { margin: 0.25rem 0; font-size: 0.88rem; }
.catalog-recommend { color: var(--dev-print); font-weight: 600; }
.glossary-grid .vocab-item {
  background: var(--card); border: 1.5px solid var(--line); border-radius: var(--radius-sm);
  padding: 0.8rem 1rem;
}

.block-list li, .step-list li { margin: 0.35rem 0 0.35rem 1.2rem; }
.block-list li::marker { content: "▸ "; color: var(--accent-ink); }

.code {
  background: var(--ink);
  color: #e7ece7;
  border-radius: 10px;
  padding: 1rem 1.2rem;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  line-height: 1.6;
}

/* Khối "Dành cho giáo viên" — gộp chuẩn bị + kịch bản dạy + lưu ý vào 1 nơi, ẩn mặc định
   để trang bài học ưu tiên hiển thị gọn cho học sinh, giáo viên bấm mở khi cần. */
.panel-teacher { border-style: dashed; background: var(--line-soft); }
.panel-teacher summary {
  font-size: 1rem; font-weight: 700; cursor: pointer;
  list-style: none; display: flex; align-items: center; justify-content: space-between; gap: 0.6rem;
}
.panel-teacher summary::-webkit-details-marker { display: none; }
.panel-teacher summary::after { content: "▾"; color: var(--ink-soft); font-weight: 400; flex: none; transition: transform 0.15s; }
.panel-teacher[open] summary::after { transform: rotate(180deg); }
.panel-teacher summary:hover { color: var(--accent-ink); }
.panel-teacher summary:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; border-radius: 4px; }
.panel-teacher .teacher-body { margin-top: 1rem; padding-top: 1rem; border-top: 1px dashed var(--line); }
.panel-teacher h3 {
  font-family: var(--font-mono); font-size: 0.72rem; font-weight: 600; text-transform: uppercase; letter-spacing: 0.05em;
  color: var(--ink-soft); margin: 1.1rem 0 0.5rem;
}
.panel-teacher h3:first-child { margin-top: 0; }

/* Timeline */
.timeline { display: flex; flex-direction: column; gap: 0.6rem; }
.phase { display: flex; gap: 0.9rem; }
.phase-time {
  flex: 0 0 76px; text-align: center; font-family: var(--font-mono); font-weight: 600; font-size: 0.78rem;
  color: var(--accent-ink); background: var(--accent-soft); border-radius: 8px;
  padding: 0.3rem 0.2rem; height: fit-content;
}
.phase-body p { font-size: 0.94rem; color: var(--ink); }

/* Sidebar */
.lesson-side { position: sticky; top: 76px; }
.side-note { font-size: 0.87rem; color: var(--ink-soft); margin-bottom: 0.5rem; }
.side-hint { font-size: 0.78rem; color: var(--ink-soft); margin-top: 0.4rem; }
.panel hr { border: none; border-top: 1px solid var(--line); margin: 0.8rem 0; }

/* Sơ đồ khối (scratchblocks) */
.sb-hint { font-size: 0.8rem; color: var(--ink-soft); margin-bottom: 0.6rem; }
pre.blocks {
  background: var(--paper);
  border: 1.5px dashed var(--line);
  border-radius: 10px;
  padding: 0.8rem 1rem;
  margin: 0.6rem 0;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.86rem;
  line-height: 1.6;
}
pre.blocks svg { max-width: 100%; }

/* Kho tài nguyên */
.res-list { display: flex; flex-direction: column; gap: 0.9rem; }
.res-item {
  background: var(--card); border: 1.5px solid var(--line);
  border-radius: var(--radius); padding: 1.05rem 1.2rem;
}
.res-head { display: flex; align-items: center; gap: 0.6rem; flex-wrap: wrap; }
.res-name { font-weight: 700; color: var(--accent-ink); text-decoration: none; font-size: 1.02rem; }
.res-name:hover { text-decoration: underline; }
.res-badge { font-family: var(--font-mono); font-size: 0.78rem; color: var(--ink-soft); margin: 0.15rem 0 0.4rem; }
.res-item p { font-size: 0.93rem; margin: 0.3rem 0; }
.res-use { background: var(--paper); border-radius: 8px; padding: 0.5rem 0.8rem; }

/* Danh mục khóa học */
.catalogue-list { display: flex; flex-direction: column; gap: 0.8rem; margin-bottom: 1.5rem; }
.catalogue-item {
  background: var(--card); border: 1.5px solid var(--line);
  border-radius: var(--radius); padding: 1rem 1.2rem;
}
.catalogue-item-head { display: flex; align-items: center; gap: 0.7rem; flex-wrap: wrap; justify-content: space-between; }
.catalogue-title { font-weight: 700; font-size: 1.02rem; }
.catalogue-desc { font-size: 0.93rem; color: var(--ink-soft); margin-top: 0.4rem; }

/* Pager */
.pager { display: flex; justify-content: space-between; gap: 0.8rem; margin-top: 1.6rem; flex-wrap: wrap; }

/* Diễn đàn Ý tưởng + Sổ tâm sự */
.forum-tabs {
  display: flex; gap: 0.4rem; flex-wrap: wrap; margin-bottom: 1.3rem;
  border-bottom: 1.5px solid var(--line); padding-bottom: 0;
}
.forum-tab {
  font-weight: 700; font-size: 0.92rem; color: var(--ink-soft); text-decoration: none;
  padding: 0.55rem 0.9rem; border-bottom: 2.5px solid transparent; margin-bottom: -1.5px;
  transition: color 0.12s, border-color 0.12s;
}
.forum-tab:hover { color: var(--ink); }
.forum-tab.is-active { color: var(--dev-idea); border-bottom-color: var(--dev-idea); }
.forum-tabs-admin { display: flex; gap: 0.4rem; margin-left: auto; }
.forum-tab-admin { color: var(--accent-ink); }
.forum-tab-admin.is-active { color: var(--accent-deep); border-bottom-color: var(--accent-deep); }
.forum-list { display: flex; flex-direction: column; gap: 0.8rem; margin-bottom: 1.5rem; }
.forum-item {
  display: block; background: var(--card); border: 1.5px solid var(--line);
  border-left: 3px solid var(--dev-idea); border-radius: var(--radius);
  padding: 1rem 1.2rem; text-decoration: none; color: inherit; transition: transform 0.12s, box-shadow 0.12s;
}
a.forum-item:hover { transform: translateY(-2px); box-shadow: var(--shadow); }
.forum-item-pending { border-left-color: var(--accent); }
.forum-item-title { font-weight: 700; font-size: 1.02rem; color: var(--ink); }
.forum-item-excerpt { font-size: 0.93rem; color: var(--ink-soft); margin-top: 0.35rem; }
.forum-item-meta { font-size: 0.8rem; color: var(--ink-soft); margin-top: 0.5rem; }
.forum-item-actions { display: flex; gap: 0.6rem; margin-top: 0.7rem; }
.forum-content { font-size: 0.97rem; line-height: 1.65; white-space: pre-wrap; }
.forum-form { display: flex; flex-direction: column; gap: 0.6rem; }
.forum-form input[type="text"], .forum-form textarea {
  width: 100%; padding: 0.6rem 0.8rem; border: 1.5px solid var(--line); border-radius: var(--radius-sm);
  font-family: inherit; font-size: 0.95rem; resize: vertical;
}
.forum-form input[type="text"]:focus, .forum-form textarea:focus { outline: 2px solid var(--accent); border-color: var(--accent); }
.forum-inline-form { display: inline-block; margin-top: 0.6rem; }
.forum-comment {
  border-top: 1px dashed var(--line); padding-top: 0.7rem; margin-top: 0.7rem;
}
.forum-comment-meta { display: flex; align-items: center; gap: 0.5rem; font-size: 0.82rem; color: var(--ink-soft); font-weight: 600; }
.forum-comment-del {
  border: none; background: none; color: var(--ink-soft); cursor: pointer; font-size: 0.9rem; line-height: 1;
  padding: 0.1rem 0.3rem; border-radius: 4px;
}
.forum-comment-del:hover { background: var(--accent-soft); color: var(--accent-ink); }
.mood-picker { display: flex; gap: 0.5rem; }
.mood-option { cursor: pointer; }
.mood-option input { position: absolute; opacity: 0; width: 0; height: 0; }
.mood-option span {
  display: flex; align-items: center; justify-content: center; width: 2.4rem; height: 2.4rem;
  font-size: 1.3rem; border: 1.5px solid var(--line); border-radius: 50%; transition: border-color 0.12s, background 0.12s;
}
.mood-option input:checked + span { border-color: var(--dev-idea); background: var(--dev-idea-soft); }
.mood-option input:focus-visible + span { outline: 2px solid var(--accent); outline-offset: 2px; }

/* Quản trị hệ thống (/quan-tri) — dùng lại tông forum-tabs/panel, không phải màu riêng */
.admin-tabs {
  display: flex; gap: 0.4rem; flex-wrap: wrap; margin-bottom: 1.3rem;
  border-bottom: 1.5px solid var(--line); padding-bottom: 0;
}
.admin-tab {
  font-weight: 700; font-size: 0.92rem; color: var(--ink-soft); text-decoration: none;
  padding: 0.55rem 0.9rem; border-bottom: 2.5px solid transparent; margin-bottom: -1.5px;
  transition: color 0.12s, border-color 0.12s;
}
.admin-tab:hover { color: var(--ink); }
.admin-tab.is-active { color: var(--accent-deep); border-bottom-color: var(--accent-deep); }

.admin-cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(230px, 1fr)); gap: 1rem; margin-bottom: 1.5rem; }
.admin-card {
  display: block; background: var(--card); border: 1.5px solid var(--line);
  border-radius: var(--radius); padding: 1.1rem 1.2rem; text-decoration: none; color: inherit;
  transition: transform 0.12s, box-shadow 0.12s;
}
.admin-card:hover { transform: translateY(-2px); box-shadow: var(--shadow); }
.admin-card-ic { font-size: 1.5rem; }
.admin-card-title { font-weight: 700; font-size: 1rem; color: var(--ink); margin-top: 0.4rem; }
.admin-card-desc { font-size: 0.85rem; color: var(--ink-soft); margin-top: 0.3rem; }

.admin-error {
  background: var(--accent-soft); color: var(--accent-ink); border-radius: var(--radius-sm);
  padding: 0.65rem 0.9rem; font-size: 0.9rem; font-weight: 600; margin-bottom: 1rem;
}

.admin-create-form { display: flex; gap: 0.6rem; flex-wrap: wrap; align-items: center; }
.admin-create-form input[type="text"], .admin-create-form input[type="password"] {
  padding: 0.5rem 0.75rem; border: 1.5px solid var(--line); border-radius: var(--radius-sm);
  font-family: inherit; font-size: 0.92rem;
}
.admin-create-form select {
  padding: 0.5rem 0.6rem; border: 1.5px solid var(--line); border-radius: var(--radius-sm);
  font-family: inherit; font-size: 0.92rem; background: var(--card);
}

.admin-table-wrap { overflow-x: auto; margin-bottom: 1.6rem; }
.admin-table {
  width: 100%; border-collapse: collapse; background: var(--card);
  border: 1.5px solid var(--line); border-radius: var(--radius); overflow: hidden;
}
.admin-table th, .admin-table td { padding: 0.7rem 0.9rem; text-align: left; font-size: 0.9rem; }
.admin-table th {
  font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.03em; color: var(--ink-soft);
  border-bottom: 1.5px solid var(--line); font-weight: 700;
}
.admin-table tbody tr:not(:last-child) td { border-bottom: 1px solid var(--line-soft); }
.admin-you { font-size: 0.78rem; color: var(--ink-soft); font-weight: 400; }

.role-badge {
  font-family: var(--font-mono); font-size: 0.72rem; font-weight: 600; letter-spacing: 0.01em;
  padding: 0.25rem 0.65rem; border-radius: 999px; white-space: nowrap;
}
.role-admin { color: var(--accent-ink); background: var(--accent-soft); }
.role-student { color: var(--circuit); background: var(--circuit-soft); }

.admin-actions { display: flex; gap: 0.5rem; flex-wrap: wrap; align-items: center; }
.admin-actions select {
  padding: 0.35rem 0.5rem; border: 1.5px solid var(--line); border-radius: var(--radius-sm);
  font-family: inherit; font-size: 0.85rem; background: var(--card);
}
.admin-pass-form { display: flex; gap: 0.35rem; }
.admin-pass-form input {
  width: 9.5rem; padding: 0.35rem 0.6rem; border: 1.5px solid var(--line); border-radius: var(--radius-sm);
  font-family: inherit; font-size: 0.85rem;
}
.admin-danger { border-color: var(--dev-rpi); color: var(--dev-rpi); }
.admin-danger:hover { background: var(--dev-rpi-soft); border-color: var(--dev-rpi); }

@media (max-width: 640px) {
  .stat-item { flex: 1 1 45%; border-right: none; border-bottom: 1.5px dashed var(--line); padding-bottom: 0.7rem; }
  .admin-pass-form input { width: 7rem; }
}