:root {
  --bg: #f4f7fb;
  --surface: #ffffff;
  --surface-2: #f8fafc;
  --text: #1f2937;
  --muted: #64748b;
  --line: #dbe3ee;
  --primary: #2368d5;
  --primary-dark: #174ca8;
  --secondary: #0e8a78;
  --danger: #c83f4d;
  --warning: #9a6700;
  --success: #13795b;
  --shadow: 0 12px 35px rgba(28, 45, 70, .08);
  --radius: 18px;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--text);
  background: var(--bg);
}
* { box-sizing: border-box; }
html { min-height: 100%; }
body { margin: 0; min-height: 100vh; background: var(--bg); color: var(--text); }
button, input, textarea, select { font: inherit; }
button, select, input[type="file"] { cursor: pointer; }
a { color: inherit; }
img { max-width: 100%; }
[hidden] { display: none !important; }
.muted { color: var(--muted); }
.stack { display: grid; gap: 16px; }
.card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); }
.card.compact { padding: 16px; }
label { display: grid; gap: 7px; font-size: .9rem; font-weight: 700; color: #334155; }
input, textarea, select { width: 100%; border: 1px solid #cbd5e1; border-radius: 11px; padding: 11px 12px; background: #fff; color: var(--text); outline: none; }
input:focus, textarea:focus, select:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(35, 104, 213, .12); }
textarea { resize: vertical; min-height: 92px; }
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 7px; min-height: 42px; padding: 9px 14px; border: 1px solid transparent; border-radius: 11px; font-weight: 750; text-decoration: none; transition: transform .08s ease, background .15s ease, border-color .15s ease; }
.btn:hover { transform: translateY(-1px); }
.btn:disabled { opacity: .55; cursor: not-allowed; transform: none; }
.btn.primary { background: var(--primary); color: white; }
.btn.primary:hover { background: var(--primary-dark); }
.btn.secondary { background: var(--secondary); color: white; }
.btn.ghost { background: transparent; border-color: var(--line); color: #334155; }
.btn.danger { background: var(--danger); color: white; }
.btn.ghost.danger { color: var(--danger); background: #fff; }
.btn.small { min-height: 34px; padding: 6px 10px; font-size: .84rem; }
.btn.wide, .wide-select { width: 100%; }
.topbar { position: sticky; top: 0; z-index: 20; min-height: 68px; padding: 10px clamp(14px, 3vw, 34px); background: rgba(255,255,255,.94); backdrop-filter: blur(14px); border-bottom: 1px solid var(--line); display: flex; align-items: center; justify-content: space-between; gap: 16px; }
.brand { display: inline-flex; align-items: center; gap: 11px; text-decoration: none; min-width: 0; }
.brand-icon { font-size: 1.7rem; }
.brand strong, .brand small { display: block; }
.brand strong { font-size: 1.05rem; }
.brand small { color: var(--muted); font-size: .73rem; margin-top: 1px; }
.top-actions { display: flex; gap: 8px; align-items: center; }
.notice { max-width: 1200px; border: 1px solid #bfdbfe; background: #eff6ff; color: #1e3a8a; padding: 13px 16px; border-radius: 13px; display: flex; align-items: center; justify-content: space-between; gap: 16px; }
.notice.warning { border-color: #f3d59c; background: #fff8e8; color: #7c4b00; }
.notice.success { border-color: #9ed8c4; background: #effbf6; color: #0d664b; }
.notice.danger { border-color: #f0b1b8; background: #fff2f3; color: #8d2630; }
.error-text { color: #a82531; font-weight: 700; }
.login-page { display: grid; place-items: center; padding: 24px; background: radial-gradient(circle at 50% 0%, #e9f2ff 0, var(--bg) 42%); }
.login-shell { width: min(440px, 100%); }
.login-card { background: #fff; border: 1px solid var(--line); border-radius: 24px; padding: clamp(26px, 7vw, 42px); box-shadow: 0 25px 70px rgba(28, 45, 70, .14); text-align: center; }
.login-card form { text-align: left; margin-top: 26px; }
.login-card h1 { font-size: 2rem; margin: 8px 0 4px; }
.brand-mark { font-size: 3rem; }
.viewer-wrap, .admin-wrap { width: min(1280px, calc(100% - 28px)); margin: 22px auto 42px; }
.viewer-controls { display: grid; grid-template-columns: minmax(180px, 260px) minmax(180px, 260px) 1fr; gap: 14px; align-items: end; margin: 16px 0; }
.viewer-meta { display: grid; gap: 3px; text-align: right; align-self: center; }
.viewer-grid { display: grid; grid-template-columns: 260px minmax(0, 1fr); gap: 18px; align-items: start; }
.student-sidebar { padding: 10px; position: sticky; top: 90px; max-height: calc(100vh - 112px); overflow: auto; }
.student-list { display: grid; gap: 4px; margin-top: 5px; }
.student-row { width: 100%; border: 0; background: transparent; color: #334155; border-radius: 10px; padding: 10px 12px; text-align: left; font-weight: 650; }
.student-row:hover { background: #f1f5f9; }
.student-row.active { background: #eaf2ff; color: #1654b8; }
.book-card { min-height: 650px; padding: clamp(20px, 4vw, 42px); }
.cover-content { min-height: 540px; display: flex; flex-direction: column; align-items: center; justify-content: center; text-align: center; }
.cover-star { font-size: 3.4rem; }
.cover-content h1 { margin: 8px 0 0; font-size: clamp(2.2rem, 5vw, 4rem); letter-spacing: -.04em; }
.cover-content h2 { margin: 8px 0 0; color: #475569; font-size: clamp(1.2rem, 2.5vw, 1.8rem); }
.cover-school { margin: 8px 0 24px; color: var(--muted); font-size: 1.08rem; }
.cover-image { width: min(760px, 100%); max-height: 430px; object-fit: contain; border-radius: 16px; margin: 0 0 24px; }
.image-placeholder { width: min(620px, 100%); padding: 42px; border: 2px dashed #ccd6e3; border-radius: 16px; color: var(--muted); margin: 0 0 24px; }
.student-profile { max-width: 820px; margin: 0 auto; }
.profile-image, .profile-placeholder { width: 170px; height: 170px; border-radius: 50%; margin: 0 auto 18px; display: grid; place-items: center; object-fit: cover; border: 5px solid #e9f2ff; box-shadow: 0 10px 25px rgba(35,104,213,.12); }
.profile-placeholder { background: #f1f5f9; font-size: 4rem; }
.profile-name { text-align: center; margin: 0 0 28px; color: #1f5fbf; font-size: clamp(1.8rem, 4vw, 2.6rem); }
.memory-section { margin: 18px 0; padding: 20px; background: #fbfdff; border: 1px solid #e2e8f0; border-left: 5px solid #4f86db; border-radius: 13px; }
.memory-section h2 { margin: 0 0 13px; font-size: 1.12rem; }
.memory-row { display: grid; grid-template-columns: minmax(170px, .85fr) 1.7fr; gap: 14px; padding: 10px 0; border-top: 1px solid #edf1f5; }
.memory-row:first-of-type { border-top: 0; }
.memory-row p { margin: 0; white-space: pre-wrap; overflow-wrap: anywhere; }
.book-nav { display: grid; grid-template-columns: 1fr auto 1fr; gap: 10px; align-items: center; margin-top: 30px; border-top: 1px solid var(--line); padding-top: 18px; }
.book-nav > :last-child { justify-self: end; }
.nav-count { color: var(--muted); font-size: .84rem; font-weight: 700; }
.mobile-student-picker { display: none; }
.empty-state { text-align: center; color: var(--muted); padding: 30px; }
.admin-selector { display: grid; grid-template-columns: 1fr 1fr auto; gap: 14px; align-items: end; margin-bottom: 18px; }
.selector-actions { display: flex; gap: 8px; }
.admin-grid { display: grid; grid-template-columns: repeat(12, 1fr); gap: 18px; }
.admin-accordions { display: grid; gap: 12px; }
.admin-accordion { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); overflow: clip; }
.admin-accordion > summary { min-height: 62px; padding: 14px 18px; display: flex; align-items: center; justify-content: space-between; gap: 16px; cursor: pointer; font-weight: 800; list-style: none; }
.admin-accordion > summary::-webkit-details-marker { display: none; }
.admin-accordion > summary::after { content: '⌄'; color: var(--primary); font-size: 1.3rem; transition: transform .15s ease; }
.admin-accordion[open] > summary { border-bottom: 1px solid var(--line); }
.admin-accordion[open] > summary::after { transform: rotate(180deg); }
.admin-accordion > summary small { color: var(--muted); font-weight: 650; margin-left: auto; }
.admin-accordion > summary:focus-visible { outline: 3px solid rgba(35,104,213,.25); outline-offset: -3px; }
.accordion-content { padding: clamp(14px, 3vw, 20px); }
.subpanel { padding: 16px; background: var(--surface-2); border: 1px solid var(--line); border-radius: 13px; }
.copy-row { display: grid; grid-template-columns: minmax(0, 1fr) auto; align-items: end; gap: 10px; }
.panel { padding: 20px; min-width: 0; }
.credentials-panel { grid-column: span 6; }
.class-panel { grid-column: span 6; }
.students-panel { grid-column: span 4; }
.student-editor-panel { grid-column: span 8; }
.schema-panel { grid-column: span 8; }
.backup-panel { grid-column: span 4; }
.panel-heading { display: flex; justify-content: space-between; gap: 14px; align-items: flex-start; margin-bottom: 17px; }
.panel-heading h2 { margin: 2px 0 0; font-size: 1.25rem; }
.eyebrow { color: var(--muted); font-size: .72rem; font-weight: 800; text-transform: uppercase; letter-spacing: .08em; }
.badge { display: inline-flex; padding: 5px 9px; border-radius: 999px; font-size: .75rem; font-weight: 800; background: #eef2f7; color: #475569; }
.badge.success { background: #e6f7f0; color: #0c6a4d; }
.badge.danger { background: #fdecee; color: #a52f3a; }
.badge.neutral { background: #eef2f7; color: #475569; }
.form-grid.two { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.toggle-row { grid-template-columns: auto 1fr; align-items: center; justify-content: start; }
.toggle-row input { width: 20px; height: 20px; }
.image-editor { display: grid; gap: 10px; margin-top: 18px; }
.class-thumb { max-height: 240px; width: 100%; object-fit: contain; background: #f8fafc; border-radius: 13px; border: 1px solid var(--line); }
.file-button { position: relative; display: inline-flex; width: fit-content; align-items: center; justify-content: center; min-height: 42px; padding: 9px 14px; border: 1px solid var(--line); border-radius: 11px; font-weight: 750; background: #fff; color: #334155; cursor: pointer; }
.file-button input { position: absolute; inset: 0; opacity: 0; width: 100%; height: 100%; cursor: pointer; }
.danger-file { border-color: #f0b1b8; color: var(--danger); }
.inline-form { display: grid; grid-template-columns: 1fr auto; gap: 8px; align-items: end; }
.print-actions, .backup-actions { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 14px; }
.student-photo-row { display: flex; gap: 18px; align-items: center; }
.student-thumb { width: 120px; height: 120px; object-fit: cover; border-radius: 50%; border: 4px solid #e9f2ff; }
.dynamic-fields { display: grid; gap: 14px; }
.form-section { padding: 16px; border: 1px solid var(--line); border-radius: 13px; background: var(--surface-2); display: grid; gap: 12px; }
.form-section h3 { margin: 0 0 2px; font-size: 1rem; }
.schema-list { display: grid; gap: 13px; }
.schema-card { border: 1px solid var(--line); border-radius: 13px; padding: 12px; background: #fbfdff; }
.schema-heading { display: grid; grid-template-columns: 70px 1fr auto auto; gap: 8px; margin-bottom: 9px; }
.schema-field { display: grid; grid-template-columns: 1fr 130px auto auto; gap: 8px; padding: 8px 0; border-top: 1px solid #edf1f5; }
.schema-add-field { grid-template-columns: 1fr 130px auto; margin-top: 8px; }
.section-add { grid-template-columns: 75px 1fr auto; margin-top: 15px; }

@media (max-width: 900px) {
  .viewer-grid { grid-template-columns: 1fr; }
  .student-sidebar { display: none; }
  .mobile-student-picker { display: grid; }
  .viewer-controls { grid-template-columns: 1fr 1fr; }
  .viewer-meta { grid-column: 1 / -1; text-align: left; }
  .book-card { min-height: 0; }
  .credentials-panel, .class-panel, .students-panel, .student-editor-panel, .schema-panel, .backup-panel { grid-column: 1 / -1; }
  .admin-selector { grid-template-columns: 1fr 1fr; }
  .selector-actions { grid-column: 1 / -1; }
}

@media (max-width: 620px) {
  .topbar { align-items: flex-start; padding: 10px 12px; }
  .brand small { display: none; }
  .top-actions .btn { min-height: 38px; padding: 7px 9px; font-size: .8rem; }
  .viewer-wrap, .admin-wrap { width: min(100% - 18px, 1280px); margin-top: 12px; }
  .viewer-controls, .admin-selector { grid-template-columns: 1fr; }
  .selector-actions { grid-column: auto; display: grid; grid-template-columns: 1fr 1fr; }
  .book-card { padding: 18px 14px; border-radius: 14px; }
  .memory-row { grid-template-columns: 1fr; gap: 4px; }
  .memory-section { padding: 15px; }
  .book-nav { grid-template-columns: 1fr 1fr; }
  .nav-count { grid-column: 1 / -1; grid-row: 1; text-align: center; }
  .form-grid.two { grid-template-columns: 1fr; }
  .student-photo-row { align-items: flex-start; flex-direction: column; }
  .schema-heading { grid-template-columns: 64px 1fr; }
  .schema-heading .btn { width: 100%; }
  .schema-field, .schema-add-field { grid-template-columns: 1fr; }
  .section-add { grid-template-columns: 64px 1fr; }
  .section-add .btn { grid-column: 1 / -1; }
  .inline-form { grid-template-columns: 1fr; }
  .copy-row { grid-template-columns: 1fr; }
  .admin-accordion > summary { align-items: flex-start; min-height: 58px; padding: 13px 14px; }
  .admin-accordion > summary small { display: none; }
  .print-actions, .backup-actions { display: grid; }
}