:root {
  --sidebar-bg: #1e293b;
  --sidebar-fg: #cbd5e1;
  --sidebar-fg-active: #ffffff;
  --sidebar-active-bg: #2563eb;
  --content-bg: #f1f5f9;
  --card-bg: #ffffff;
  --border: #e2e8f0;
  --text: #1e293b;
  --text-muted: #64748b;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --success: #16a34a;
  --warning: #d97706;
  --danger: #dc2626;
  --radius: 10px;
  --shadow: 0 1px 3px rgba(15, 23, 42, 0.08), 0 1px 2px rgba(15, 23, 42, 0.04);
  --sidebar-w: 240px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--content-bg);
  color: var(--text);
  font-size: 14px;
  line-height: 1.5;
}

.hidden { display: none !important; }

/* ===== Layout: sidebar + main ===== */
.shell {
  display: grid;
  grid-template-columns: var(--sidebar-w) 1fr;
  grid-template-rows: 100vh;
  grid-template-areas: "sidebar main";
}

/* ===== Sidebar ===== */
.sidebar {
  grid-area: sidebar;
  background: var(--sidebar-bg);
  color: var(--sidebar-fg);
  display: flex;
  flex-direction: column;
  overflow-y: auto;
}
.sidebar .brand {
  padding: 20px 20px 16px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}
.sidebar .brand h1 {
  margin: 0;
  font-size: 17px;
  color: #fff;
  font-weight: 700;
}
.sidebar .brand p {
  margin: 4px 0 0;
  font-size: 12px;
  color: #94a3b8;
}
.sidebar .side-nav {
  display: flex;
  flex-direction: column;
  padding: 12px 12px;
  gap: 4px;
}
.sidebar .side-nav .tab {
  display: flex;
  align-items: center;
  gap: 10px;
  width: 100%;
  text-align: left;
  background: transparent;
  border: none;
  color: var(--sidebar-fg);
  padding: 11px 14px;
  border-radius: 8px;
  font-size: 14px;
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
}
.sidebar .side-nav .tab:hover { background: rgba(255, 255, 255, 0.06); color: #fff; }
.sidebar .side-nav .tab.active {
  background: var(--sidebar-active-bg);
  color: var(--sidebar-fg-active);
  font-weight: 600;
}
.sidebar .side-nav .tab .ic { font-size: 16px; width: 20px; text-align: center; }
.sidebar .side-foot {
  margin-top: auto;
  padding: 14px 20px;
  font-size: 11px;
  color: #64748b;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}

/* ===== Main column ===== */
.main {
  grid-area: main;
  display: flex;
  flex-direction: column;
  overflow-y: auto;
}
.topbar {
  position: sticky;
  top: 0;
  z-index: 5;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--card-bg);
  border-bottom: 1px solid var(--border);
  padding: 12px 24px;
}
.topbar .page-title { font-size: 16px; font-weight: 700; margin: 0; }
.topbar .page-sub { font-size: 12px; color: var(--text-muted); margin: 2px 0 0; }
.password-box {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}
.password-box span { font-size: 12px; color: var(--text-muted); }
.password-box input {
  padding: 7px 10px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 13px;
}
#adminUsernameBox { display: inline-flex; gap: 6px; align-items: center; }
.secondary-login-link { color: var(--primary); font-size: 12px; text-decoration: none; }
.secondary-login-link:hover { text-decoration: underline; }
.logout-btn {
  background: transparent;
  color: #ef4444;
  border: 1px solid #fecaca;
  border-radius: 8px;
  padding: 6px 12px;
  font-size: 12px;
}
.logout-btn:hover { background: #fef2f2; }

.content { padding: 24px; }

/* ===== Stat cards ===== */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 16px;
  margin-bottom: 20px;
}
.stat-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 18px;
  display: flex;
  flex-direction: column;
  gap: 6px;
  box-shadow: var(--shadow);
}
.stat-card span { font-size: 13px; color: var(--text-muted); }
.stat-card strong { font-size: 26px; font-weight: 700; }
.stat-card button {
  align-self: flex-start;
  background: #eff6ff;
  color: var(--primary);
  border: 1px solid #bfdbfe;
  border-radius: 8px;
  padding: 6px 12px;
  font-size: 13px;
  cursor: pointer;
}
.stat-card button:hover { background: #dbeafe; }

/* ===== Panels ===== */
.panel { display: none; }
.panel.active { display: block; }
.panel-head {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
  flex-wrap: wrap;
}
.panel-head h2 { font-size: 16px; margin: 0; }
.panel-head .actions { display: flex; align-items: center; gap: 10px; margin-left: auto; }
.panel-head select {
  padding: 7px 10px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: #fff;
  font-size: 13px;
}

/* ===== Buttons ===== */
button {
  font-family: inherit;
  border: none;
  border-radius: 8px;
  padding: 9px 16px;
  font-size: 13px;
  cursor: pointer;
  background: var(--primary);
  color: #fff;
  transition: background 0.15s;
}
button:hover { background: var(--primary-hover); }
button:disabled { background: #cbd5e1; cursor: not-allowed; }
button.secondary { background: #fff; color: var(--text); border: 1px solid var(--border); }
button.secondary:hover { background: #f8fafc; }
button.warn { background: #fff; color: var(--danger); border: 1px solid #fecaca; }
button.warn:hover { background: #fef2f2; }
button.danger-button { background: #fff; color: var(--danger); border: 1px solid #fecaca; }
button.danger-button:hover { background: #fef2f2; }
.secondary-button { background: #fff; color: var(--text); border: 1px solid var(--border); }
.secondary-button:hover { background: #f8fafc; }

/* ===== Lists / cards ===== */
.list { display: flex; flex-direction: column; gap: 12px; }
.item {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  display: flex;
  gap: 14px;
  align-items: flex-start;
  box-shadow: var(--shadow);
}
.item h3 { margin: 0 0 4px; font-size: 15px; }
.item p { margin: 2px 0; color: var(--text-muted); font-size: 13px; }
.item .actions { margin-left: auto; display: flex; gap: 8px; flex-wrap: wrap; }
.checkin-select { padding-top: 4px; }
.checkin-image { max-width: 160px; max-height: 160px; border-radius: 8px; margin-top: 8px; border: 1px solid var(--border); }
.checkin-image-link { display: inline-block; }

/* ===== Rankings ===== */
.rank-list { display: flex; flex-direction: column; gap: 8px; }
.rank-row {
  display: grid;
  grid-template-columns: 60px 1fr auto auto;
  align-items: center;
  gap: 12px;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 12px 16px;
  box-shadow: var(--shadow);
}
.rank-row strong { color: var(--primary); font-size: 15px; }
.rank-row span:last-child { color: var(--text-muted); font-size: 13px; }

/* ===== Forms ===== */
form label, .child-form label, .manual-hearts-form label {
  display: flex;
  flex-direction: column;
  gap: 5px;
  font-size: 13px;
  color: var(--text-muted);
  margin-bottom: 12px;
}
input, textarea, select {
  font-family: inherit;
  font-size: 14px;
  padding: 9px 11px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: #fff;
  color: var(--text);
  width: 100%;
}
textarea { resize: vertical; }
input:focus, textarea:focus, select:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.12); }
.checkbox-line { flex-direction: row; align-items: center; gap: 8px; color: var(--text); }
.checkbox-line input { width: auto; }

.child-form, .manual-hearts-form {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  display: flex;
  gap: 12px;
  align-items: flex-end;
  flex-wrap: wrap;
  margin-bottom: 16px;
  box-shadow: var(--shadow);
}
.child-form label, .manual-hearts-form label { margin-bottom: 0; flex: 1; min-width: 160px; }
.muted { color: var(--text-muted); font-size: 12px; }

/* ===== Gift / task cards ===== */
.gift-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 16px; }
.gift-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  box-shadow: var(--shadow);
}
.gift-card.draft-card { border: 2px dashed var(--primary); }
.gift-card label { font-size: 12px; color: var(--text-muted); display: flex; flex-direction: column; gap: 4px; }
.gift-card .image-upload-row { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.hidden-file-input { display: none; }
.upload-state { font-size: 12px; color: var(--text-muted); }
.gift-image-preview img { max-width: 100%; border-radius: 8px; border: 1px solid var(--border); }
.gift-card .actions, .subadmin-form .actions { display: flex; gap: 8px; margin-top: 4px; }

/* ===== Subadmin ===== */
.subadmin-layout { display: grid; grid-template-columns: 1fr; gap: 16px; }
.subadmin-form {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
}
.subadmin-form h3 { margin: 0 0 14px; font-size: 15px; }
.subadmin-form label { display: flex; flex-direction: column; gap: 5px; font-size: 13px; color: var(--text-muted); margin-bottom: 12px; }
.student-checks { display: grid; grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); gap: 6px; }
.subadmin-list { display: flex; flex-direction: column; gap: 12px; }

/* ===== Toast ===== */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: #0f172a;
  color: #fff;
  padding: 11px 20px;
  border-radius: 10px;
  font-size: 14px;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s, transform 0.2s;
  z-index: 100;
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* ===== Responsive: tablet ===== */
@media (max-width: 1024px) {
  :root { --sidebar-w: 200px; }
}

/* ===== Responsive: phone ===== */
@media (max-width: 768px) {
  .shell {
    grid-template-columns: 1fr;
    grid-template-rows: auto 1fr;
    grid-template-areas: "sidebar" "main";
    height: auto;
    min-height: 100vh;
  }

  /* 侧边栏变顶部深色条：品牌 + 横向滑动胶囊导航 */
  .sidebar {
    flex-direction: column;
    position: sticky;
    top: 0;
    z-index: 20;
  }
  .sidebar .brand {
    display: flex;
    align-items: baseline;
    gap: 8px;
    padding: 10px 14px;
    border-bottom: none;
  }
  .sidebar .brand h1 { font-size: 15px; }
  .sidebar .brand p { margin: 0; font-size: 11px; }
  .sidebar .side-nav {
    flex-direction: row;
    overflow-x: auto;
    padding: 8px 10px;
    gap: 6px;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
  }
  .sidebar .side-nav::-webkit-scrollbar { display: none; }
  .sidebar .side-nav .tab {
    flex: 0 0 auto;
    width: auto;
    padding: 7px 13px;
    border-radius: 999px;
    font-size: 13px;
    white-space: nowrap;
  }
  .sidebar .side-nav .tab .ic { width: auto; margin-right: 2px; }
  .sidebar .side-foot { display: none; }

  /* 主区 */
  .main { overflow: visible; }
  .topbar {
    flex-direction: column;
    align-items: stretch;
    gap: 10px;
    position: static;
    padding: 12px 14px;
  }
  .topbar .page-title { font-size: 15px; }
  .password-box {
    width: 100%;
    flex-wrap: wrap;
    gap: 8px;
  }
  .password-box span { width: 100%; }
  .password-box input { flex: 1 1 140px; min-width: 0; }
  .password-box button { flex: 0 0 auto; }
  #adminLoginModeLink { flex: 0 0 auto; }

  .content { padding: 14px; }

  .stats-grid { grid-template-columns: 1fr; gap: 12px; }
  .stat-card strong { font-size: 22px; }

  .panel-head { gap: 10px; }
  .panel-head h2 { font-size: 15px; width: 100%; }
  .panel-head select { flex: 1 1 auto; }
  .panel-head .actions { margin-left: 0; width: 100%; justify-content: space-between; }

  .list { gap: 10px; }
  .item { flex-direction: column; }
  .item .actions { margin-left: 0; width: 100%; }
  .item .actions button { flex: 1 1 auto; }

  .rank-row {
    grid-template-columns: 44px 1fr auto;
    grid-template-areas:
      "rank name hearts"
      "rank streak streak";
    row-gap: 2px;
    column-gap: 10px;
  }
  .rank-row strong { grid-area: rank; }
  .rank-row span:nth-child(2) { grid-area: name; }
  .rank-row span:nth-child(3) { grid-area: hearts; text-align: right; }
  .rank-row span:nth-child(4) { grid-area: streak; text-align: right; font-size: 12px; }

  .gift-grid { grid-template-columns: 1fr; }
  .child-form, .manual-hearts-form { flex-direction: column; align-items: stretch; }
  .child-form label, .manual-hearts-form label { min-width: 0; }
  .child-form button, .manual-hearts-form button { width: 100%; }

  .student-checks { grid-template-columns: 1fr 1fr; }
  .checkin-image { max-width: 100%; }
}