:root {
  color-scheme: light;
  --bg: #eef4fb;
  --panel: rgba(255, 255, 255, 0.92);
  --panel-strong: #ffffff;
  --panel-border: #d8e3f0;
  --text: #132238;
  --muted: #5e6d83;
  --accent: #1f6fff;
  --accent-soft: #e8f0ff;
  --sky-soft: #ebf6ff;
  --coral: #c83f2c;
  --coral-soft: #fdebe8;
  --success: #1d7d4d;
  --success-soft: #e4f6eb;
  --shadow: 0 18px 42px rgba(20, 42, 74, 0.09);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background:
    radial-gradient(circle at top left, rgba(31, 111, 255, 0.08), transparent 30%),
    linear-gradient(180deg, #f8fbff 0%, var(--bg) 100%);
  color: var(--text);
}

body.modal-open {
  overflow: hidden;
}

button,
input,
select {
  font: inherit;
}

h1,
h2,
h3,
p,
strong,
span {
  margin: 0;
  letter-spacing: 0;
}

.hidden {
  display: none !important;
}

.app-shell {
  max-width: 1080px;
  margin: 0 auto;
  padding: 20px 16px 32px;
  display: grid;
  gap: 16px;
}

.app-header,
.panel-head,
.summary-head,
.question-toolbar,
.auth-actions,
.metric-row,
.action-row,
.member-card,
.account-actions,
.image-modal-bar,
.header-side {
  display: flex;
  gap: 12px;
}

.app-header,
.panel-head,
.summary-head,
.member-card,
.image-modal-bar {
  align-items: center;
  justify-content: space-between;
}

.header-main {
  display: grid;
  gap: 4px;
  min-width: 0;
}

.header-title-row {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: nowrap;
  min-width: 0;
}

.header-side {
  align-items: flex-end;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.eyebrow {
  margin-bottom: 6px;
  color: var(--muted);
  font-size: 13px;
}

.app-header h1 {
  font-size: clamp(24px, 5.4vw, 36px);
}

.header-user {
  padding: 10px 14px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.72);
  border: 1px solid var(--panel-border);
  color: var(--muted);
  backdrop-filter: blur(8px);
}

.paper-switcher {
  display: block;
  min-width: 0;
  flex: 1 1 280px;
}

.paper-switcher select {
  width: 100%;
  min-height: 38px;
  border-radius: 12px;
  border: 1px solid var(--panel-border);
  background: rgba(255, 255, 255, 0.9);
  padding: 7px 12px;
}

.menu-bar {
  position: sticky;
  top: 12px;
  z-index: 20;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 6px;
  padding: 6px;
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.82);
  border: 1px solid rgba(216, 227, 240, 0.9);
  box-shadow: var(--shadow);
  backdrop-filter: blur(14px);
}

.menu-btn,
.primary-btn,
.ghost-btn,
.answer-option,
.topic-card,
.history-card,
.paper-card {
  border-radius: 14px;
}

.menu-btn,
.primary-btn,
.ghost-btn,
.topic-card,
.paper-card,
.nav-chip {
  min-height: 42px;
  border: 1px solid transparent;
  cursor: pointer;
}

.menu-btn {
  background: transparent;
  color: var(--muted);
  font-weight: 700;
  padding: 8px 6px;
  font-size: 15px;
}

.menu-btn.is-active {
  background: var(--panel-strong);
  color: var(--accent);
  border-color: #c9dbff;
  box-shadow: inset 0 0 0 1px rgba(31, 111, 255, 0.04);
}

.page-section,
.page-content,
.panel,
.summary-panel,
.question-panel,
.image-panel,
.navigator-panel,
.account-panel,
.mock-panel,
.landing-panel,
.paper-grid,
.topic-grid,
.history-list,
.question-card,
.answers,
.account-guest,
.account-member {
  display: grid;
  gap: 16px;
}

.panel {
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: 22px;
  box-shadow: var(--shadow);
  backdrop-filter: blur(10px);
  padding: 18px;
}

.paper-grid,
.topic-grid {
  grid-template-columns: repeat(1, minmax(0, 1fr));
}

.topic-card,
.paper-card {
  background: var(--panel-strong);
  border: 1px solid var(--panel-border);
  padding: 16px;
  text-align: left;
  display: grid;
  gap: 6px;
}

.topic-card strong,
.paper-card strong {
  font-size: 20px;
  line-height: 1.3;
}

.feature-kicker,
.summary-kicker,
.muted {
  color: var(--muted);
}

.topic-card:hover,
.paper-card:hover,
.topic-card.is-active,
.paper-card.is-active {
  border-color: #c9dbff;
  background: var(--accent-soft);
}

.notes-open-btn {
  white-space: nowrap;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0 14px;
}

.notes-chapter-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
}

.notes-chapter-card {
  padding: 12px 12px;
  gap: 4px;
}

.notes-chapter-card strong {
  font-size: 15px;
  line-height: 1.35;
}

.notes-frame-wrap {
  border: 1px solid var(--panel-border);
  border-radius: 18px;
  overflow: hidden;
  background: #f7fbff;
  min-height: 72vh;
}

.notes-frame {
  display: block;
  width: 100%;
  min-height: 72vh;
  border: 0;
  background: #f7fbff;
}

.empty-state {
  text-align: center;
  justify-items: center;
  gap: 12px;
}

.empty-state h2 {
  font-size: 24px;
}

.metric-row {
  flex-wrap: wrap;
}

.compact-metric-row {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 8px;
}

.metric-card {
  flex: 1 1 0;
  min-width: 92px;
  padding: 10px 12px;
  border-radius: 16px;
  display: grid;
  gap: 2px;
  border: 1px solid transparent;
}

.metric-card span {
  font-size: 12px;
  color: var(--muted);
}

.metric-card strong {
  font-size: 22px;
}

.blue-card {
  background: var(--accent-soft);
  border-color: #d4e1ff;
}

.sky-card {
  background: var(--sky-soft);
  border-color: #d2ebff;
}

.coral-card {
  background: var(--coral-soft);
  border-color: #f6d5cf;
}

.rate-card {
  background: #eef5ff;
  border-color: #d8e6ff;
}

.progress-bar {
  height: 10px;
  border-radius: 999px;
  background: #e5edf7;
  overflow: hidden;
}

.progress-bar > div {
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, #1f6fff, #5f97ff);
  transition: width 180ms ease;
}

.question-card h2,
.panel h2 {
  font-size: clamp(20px, 4.8vw, 30px);
  line-height: 1.32;
}

.answer-option {
  border: 1px solid var(--panel-border);
  background: var(--panel-strong);
  padding: 14px 16px;
  display: flex;
  gap: 12px;
  align-items: flex-start;
  transition: transform 140ms ease, border-color 140ms ease, background 140ms ease;
}

.answer-option:hover {
  transform: translateY(-1px);
  border-color: #bdd0e5;
}

.answer-option input {
  margin-top: 3px;
}

.answer-label {
  min-width: 24px;
  font-weight: 700;
}

.answer-option.correct {
  border-color: #9ad4b3;
  background: var(--success-soft);
}

.answer-option.incorrect {
  border-color: #f1b2a8;
  background: var(--coral-soft);
}

.split-row {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.practice-nav-wrap {
  display: grid;
  gap: 8px;
}

.practice-nav-row {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.center-row {
  grid-template-columns: minmax(0, 1fr);
  justify-items: center;
}

.skip-btn {
  min-width: 140px;
}

.feedback {
  border-radius: 16px;
  padding: 12px 14px;
  font-weight: 700;
  order: -1;
}

.feedback.correct {
  background: var(--success-soft);
  color: var(--success);
}

.feedback.incorrect {
  background: var(--coral-soft);
  color: var(--coral);
}

.image-placeholder,
.image-wrap {
  border-radius: 18px;
  border: 1px solid var(--panel-border);
  background: #f6f9fd;
}

.image-placeholder {
  min-height: 180px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 18px;
  color: var(--muted);
}

.image-wrap {
  padding: 12px;
  overflow: auto;
}

.image-wrap img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 12px;
  cursor: zoom-in;
}

.image-modal {
  position: fixed;
  inset: 0;
  z-index: 80;
  display: grid;
  place-items: center;
  padding: 18px;
}

.image-modal-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(9, 20, 38, 0.72);
  backdrop-filter: blur(6px);
}

.image-modal-dialog {
  position: relative;
  z-index: 1;
  width: min(100vw, 100%);
  height: calc(100vh - 20px);
  display: grid;
  grid-template-rows: auto minmax(0, 1fr);
  gap: 8px;
  padding: 12px;
  border-radius: 20px;
  background: rgba(10, 18, 32, 0.92);
  border: 1px solid rgba(255, 255, 255, 0.08);
  box-shadow: 0 24px 52px rgba(7, 18, 38, 0.28);
}

.image-modal-actions {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.image-modal-content {
  overflow: auto;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.02);
  display: flex;
  align-items: flex-start;
  justify-content: flex-start;
  touch-action: none;
  min-height: 0;
  overscroll-behavior: contain;
  -webkit-overflow-scrolling: touch;
  padding: 12px;
}

.image-modal-content.is-dragging {
  cursor: grabbing;
}

.image-modal-stage {
  display: flex;
  align-items: center;
  justify-content: center;
  flex: 0 0 auto;
}

.image-modal-content img {
  display: block;
  max-width: none;
  max-height: none;
  width: auto;
  height: auto;
  user-select: none;
  -webkit-user-drag: none;
  cursor: grab;
  touch-action: none;
}

.image-zoom-btn {
  min-width: 40px;
  min-height: 40px;
  padding: 0;
  font-size: 20px;
  font-weight: 700;
  line-height: 1;
}

.question-grid {
  display: grid;
  grid-template-columns: repeat(6, minmax(0, 1fr));
  gap: 6px;
}

.compact-question-grid {
  grid-template-columns: repeat(7, minmax(0, 1fr));
}

.nav-chip {
  min-height: 36px;
  border-radius: 10px;
  border: 1px solid var(--panel-border);
  background: var(--panel-strong);
  color: var(--text);
  font-weight: 700;
  font-size: 13px;
  padding: 6px 0;
}

.nav-chip.current {
  border-color: #c5d8ff;
  background: var(--accent-soft);
  color: var(--accent);
}

.nav-chip.correct {
  background: var(--sky-soft);
  border-color: #b9ddff;
  color: #1b5f9f;
}

.nav-chip.wrong {
  background: var(--coral-soft);
  border-color: #f1b2a8;
  color: var(--coral);
}

.history-list {
  gap: 10px;
}

.history-card {
  border: 1px solid var(--panel-border);
  background: var(--panel-strong);
  padding: 14px 16px;
  display: grid;
  gap: 4px;
}

.history-card strong {
  font-size: 24px;
}

.auth-form {
  display: grid;
  gap: 14px;
}

.auth-form label {
  display: grid;
  gap: 6px;
}

.auth-form input {
  min-height: 46px;
  border: 1px solid var(--panel-border);
  border-radius: 14px;
  background: var(--panel-strong);
  padding: 11px 14px;
}

.auth-actions,
.account-actions {
  flex-wrap: wrap;
}

.member-card {
  padding: 16px;
  border-radius: 18px;
  background: linear-gradient(135deg, rgba(31, 111, 255, 0.08), rgba(95, 151, 255, 0.04));
  border: 1px solid #d5e3ff;
}

.member-card h3 {
  font-size: 26px;
}

.inline-message {
  border-radius: 14px;
  padding: 13px 14px;
  font-weight: 700;
  background: var(--coral-soft);
  color: var(--coral);
}

.primary-btn {
  background: linear-gradient(135deg, #1f6fff, #3a84ff);
  color: #fff;
}

.ghost-btn {
  background: var(--panel-strong);
  color: var(--text);
  border-color: var(--panel-border);
}

.primary-btn,
.ghost-btn {
  padding: 11px 16px;
}

@media (min-width: 720px) {
  .menu-bar {
    grid-template-columns: repeat(6, minmax(0, 1fr));
  }

  .paper-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .topic-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .notes-chapter-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .question-grid {
    grid-template-columns: repeat(8, minmax(0, 1fr));
  }

  .compact-question-grid {
    grid-template-columns: repeat(10, minmax(0, 1fr));
  }
}

@media (max-width: 719px) {
  .app-shell {
    padding: 12px 10px 24px;
    gap: 12px;
  }

  .app-header,
  .panel-head,
  .summary-head,
  .member-card,
  .image-modal-bar {
    align-items: flex-start;
    flex-direction: column;
  }

  .header-side {
    width: 100%;
    align-items: stretch;
    gap: 8px;
  }

  .paper-switcher {
    width: auto;
    flex: 1 1 180px;
  }

  .paper-switcher select {
    width: 100%;
  }

  .eyebrow,
  .header-user {
    display: none !important;
  }

  .app-header h1 {
    font-size: 22px;
  }

  .header-title-row {
    align-items: center;
    gap: 8px;
  }

  .menu-bar {
    gap: 4px;
    padding: 4px;
  }

  .menu-btn {
    min-height: 38px;
    padding: 7px 4px;
    font-size: 14px;
  }

  .notes-chapter-grid {
    grid-template-columns: repeat(1, minmax(0, 1fr));
  }

  .notes-frame-wrap,
  .notes-frame {
    min-height: 66vh;
  }

  .metric-card {
    min-width: calc(50% - 6px);
    padding: 8px 10px;
    border-radius: 14px;
  }

  .metric-card span {
    font-size: 11px;
  }

  .metric-card strong {
    font-size: 18px;
  }

  .compact-metric-row {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 6px;
  }

  .split-row {
    grid-template-columns: 1fr;
  }

  .practice-nav-row {
    gap: 8px;
  }

  .skip-btn {
    width: 100%;
    min-width: 0;
  }

  .question-grid {
    grid-template-columns: repeat(5, minmax(0, 1fr));
  }

  .compact-question-grid {
    grid-template-columns: repeat(5, minmax(0, 1fr));
  }
}