:root {
  color-scheme: light;
  --bg: #f7f8f5;
  --surface: #ffffff;
  --surface-soft: #eef4ef;
  --ink: #1f2d35;
  --muted: #64727d;
  --line: #d9e1df;
  --green: #167a5b;
  --green-soft: #dff1ea;
  --blue: #245e9c;
  --blue-soft: #e4eef9;
  --amber: #a86110;
  --amber-soft: #fff0cf;
  --coral: #b5483d;
  --coral-soft: #fae4df;
  --shadow: 0 14px 38px rgba(29, 47, 58, 0.09);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    linear-gradient(180deg, rgba(36, 94, 156, 0.08), transparent 340px),
    var(--bg);
  color: var(--ink);
  font-family: "Segoe UI", system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
  font-size: 15px;
  line-height: 1.5;
}

button,
input,
select,
textarea {
  font: inherit;
}

button {
  border: 0;
}

.app-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 14px clamp(16px, 4vw, 44px);
  border-bottom: 1px solid rgba(31, 45, 53, 0.1);
  background: rgba(247, 248, 245, 0.92);
  backdrop-filter: blur(16px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  min-width: 0;
  color: inherit;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  width: 42px;
  height: 42px;
  place-items: center;
  border-radius: 8px;
  background: var(--ink);
  color: white;
  font-weight: 800;
}

.brand strong,
.brand small {
  display: block;
}

.brand strong {
  line-height: 1.1;
}

.brand small {
  color: var(--muted);
}

.top-nav {
  display: inline-flex;
  gap: 8px;
  padding: 4px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
}

.nav-button,
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 38px;
  padding: 8px 13px;
  border-radius: 7px;
  background: transparent;
  color: var(--ink);
  cursor: pointer;
  transition: 0.15s ease;
}

.nav-button:hover,
.button:hover {
  background: rgba(22, 122, 91, 0.08);
}

.nav-button.active,
.button.primary {
  background: var(--green);
  color: white;
}

.button.secondary {
  border: 1px solid var(--line);
  background: var(--surface);
}

.button.danger {
  background: var(--coral-soft);
  color: var(--coral);
}

.button:disabled {
  cursor: wait;
  opacity: 0.72;
}

.button.small {
  min-height: 32px;
  padding: 6px 10px;
  font-size: 13px;
}

.app-main {
  width: min(1180px, calc(100% - 28px));
  margin: 0 auto;
  padding: 24px 0 46px;
}

.loading-screen,
.empty-state {
  display: grid;
  min-height: 360px;
  place-items: center;
  text-align: center;
  color: var(--muted);
}

.loader {
  width: 34px;
  height: 34px;
  border: 3px solid var(--line);
  border-top-color: var(--green);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

.hero-band {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(280px, 0.65fr);
  gap: 20px;
  align-items: stretch;
  margin-bottom: 20px;
}

.intro-panel,
.summary-panel,
.config-panel,
.history-panel,
.bank-panel,
.auth-panel,
.exam-header,
.question-card {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.intro-panel {
  padding: 24px;
  overflow: hidden;
}

.eyebrow {
  margin: 0 0 7px;
  color: var(--green);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  margin: 0;
  line-height: 1.18;
}

h1 {
  max-width: 720px;
  font-size: 34px;
}

h2 {
  font-size: 22px;
}

h3 {
  font-size: 17px;
}

.lead {
  max-width: 760px;
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 16px;
}

.study-strip {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 8px;
  margin-top: 22px;
}

.study-strip span {
  min-height: 46px;
  padding: 10px;
  border-radius: 8px;
  background: var(--blue-soft);
  color: var(--blue);
  font-weight: 700;
}

.study-strip span:nth-child(2n) {
  background: var(--green-soft);
  color: var(--green);
}

.study-strip span:nth-child(3n) {
  background: var(--amber-soft);
  color: var(--amber);
}

.summary-panel {
  display: grid;
  gap: 10px;
  padding: 16px;
}

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

.stat {
  min-height: 82px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fbfcfa;
}

.stat strong {
  display: block;
  font-size: 24px;
}

.stat span {
  color: var(--muted);
  font-size: 13px;
}

.workspace {
  display: grid;
  grid-template-columns: minmax(320px, 0.9fr) minmax(0, 1.1fr);
  gap: 20px;
}

.config-panel,
.history-panel,
.bank-panel {
  padding: 18px;
}

.auth-panel {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  align-items: center;
  margin-bottom: 16px;
  padding: 16px;
  background: #fbfdff;
}

.auth-panel p {
  margin: 6px 0 0;
  color: var(--muted);
}

.auth-hint {
  font-size: 13px;
}

.auth-warning {
  color: #9a3412;
  font-weight: 700;
}

.auth-actions,
.auth-key-row {
  display: flex;
  gap: 8px;
  align-items: center;
  flex-wrap: wrap;
}

.auth-key-row {
  justify-content: flex-end;
  min-width: min(100%, 520px);
}

.left-stack,
.right-stack {
  display: grid;
  align-content: start;
  gap: 20px;
}

.panel-heading {
  display: flex;
  align-items: start;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 16px;
}

.panel-heading p {
  margin: 5px 0 0;
  color: var(--muted);
}

.field-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.field {
  display: grid;
  gap: 6px;
}

.field.full {
  grid-column: 1 / -1;
}

.field label,
.fieldset-label {
  color: var(--ink);
  font-size: 13px;
  font-weight: 700;
}

.input,
.select,
.textarea {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #fff;
  color: var(--ink);
  outline: none;
}

.input,
.select {
  min-height: 40px;
  padding: 8px 10px;
}

.textarea {
  min-height: 132px;
  resize: vertical;
  padding: 11px 12px;
}

.input:focus,
.select:focus,
.textarea:focus {
  border-color: var(--green);
  box-shadow: 0 0 0 3px rgba(22, 122, 91, 0.12);
}

.category-list {
  display: grid;
  gap: 8px;
  margin-top: 8px;
}

.check-row {
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: 10px;
  align-items: center;
  padding: 10px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fbfcfa;
}

.check-row input {
  width: 18px;
  height: 18px;
  accent-color: var(--green);
}

.count-pill,
.status-pill {
  display: inline-flex;
  align-items: center;
  min-height: 24px;
  padding: 2px 8px;
  border-radius: 999px;
  background: var(--blue-soft);
  color: var(--blue);
  font-size: 12px;
  font-weight: 700;
}

.status-pill.draft {
  background: var(--amber-soft);
  color: var(--amber);
}

.status-pill.submitted {
  background: var(--blue-soft);
  color: var(--blue);
}

.status-pill.grading {
  background: var(--amber-soft);
  color: var(--amber);
}

.status-pill.graded {
  background: var(--green-soft);
  color: var(--green);
}

.form-actions,
.history-actions,
.exam-actions,
.grade-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.form-actions {
  margin-top: 16px;
}

.history-list,
.question-list,
.bank-list {
  display: grid;
  gap: 12px;
}

.history-item,
.bank-item {
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fbfcfa;
}

.history-top,
.question-top {
  display: flex;
  align-items: start;
  justify-content: space-between;
  gap: 12px;
}

.meta-line {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 8px;
  color: var(--muted);
  font-size: 13px;
}

.bank-tools {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-bottom: 12px;
}

.bank-page {
  display: grid;
  gap: 20px;
}

.bank-panel-wide {
  box-shadow: none;
}

.bank-item h3 {
  margin-bottom: 6px;
}

.bank-item p {
  margin: 0;
  color: var(--muted);
}

.bank-answer-block {
  margin-top: 12px;
}

.exam-view {
  display: grid;
  gap: 16px;
}

.exam-header {
  position: sticky;
  top: 82px;
  z-index: 10;
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 16px;
  align-items: center;
  padding: 16px;
}

.progress-wrap {
  display: grid;
  gap: 8px;
  margin-top: 12px;
}

.progress {
  height: 9px;
  overflow: hidden;
  border-radius: 999px;
  background: #e8eeec;
}

.progress span {
  display: block;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--green), var(--blue));
}

.question-card {
  padding: 18px;
}

.question-number {
  color: var(--green);
  font-weight: 800;
}

.question-title {
  margin-top: 7px;
  font-size: 18px;
}

.answer-block {
  margin-top: 14px;
  padding: 13px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fbfcfa;
}

.answer-block h4 {
  margin: 0 0 8px;
  font-size: 14px;
}

.source-answer {
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px solid var(--line);
}

.source-answer summary {
  width: fit-content;
  cursor: pointer;
  color: var(--blue);
  font-weight: 800;
}

.source-answer .muted {
  margin: 8px 0;
}

.answer-toggle {
  margin-top: 12px;
}

.answer-toggle > summary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 36px;
  padding: 7px 12px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: var(--surface);
  color: var(--blue);
  cursor: pointer;
  font-weight: 800;
  list-style: none;
}

.answer-toggle > summary::-webkit-details-marker {
  display: none;
}

.feedback-block,
.grading-note,
.grading-error {
  margin-top: 12px;
  padding: 12px;
  border-radius: 8px;
}

.feedback-block {
  border: 1px solid var(--blue-soft);
  background: #f5f9fe;
}

.feedback-block h4,
.feedback-block p {
  margin: 0;
}

.feedback-block h4 {
  margin-bottom: 6px;
  font-size: 14px;
}

.grading-note {
  background: var(--green-soft);
  color: var(--green);
}

.grading-error {
  background: var(--coral-soft);
  color: var(--coral);
}

.markdown-answer {
  color: #2d3a40;
}

.markdown-answer p {
  margin: 0 0 8px;
}

.markdown-answer ul {
  margin: 6px 0 10px;
  padding-left: 20px;
}

.markdown-answer table {
  width: 100%;
  border-collapse: collapse;
  margin: 10px 0;
  font-size: 14px;
}

.markdown-answer th,
.markdown-answer td {
  padding: 8px;
  border: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

.markdown-answer th {
  background: var(--surface-soft);
}

.markdown-answer code {
  padding: 1px 5px;
  border-radius: 5px;
  background: #eef2f3;
}

.grade-actions {
  margin-top: 12px;
}

.grade-button {
  border: 1px solid var(--line);
  background: #fff;
}

.grade-button.active[data-grade="wrong"] {
  background: var(--coral);
  color: white;
}

.grade-button.active[data-grade="partial"] {
  background: var(--amber);
  color: white;
}

.grade-button.active[data-grade="correct"] {
  background: var(--green);
  color: white;
}

.toast {
  position: fixed;
  right: 18px;
  bottom: 18px;
  z-index: 40;
  max-width: min(360px, calc(100vw - 36px));
  padding: 12px 14px;
  border-radius: 8px;
  background: var(--ink);
  color: white;
  box-shadow: var(--shadow);
  opacity: 0;
  pointer-events: none;
  transform: translateY(10px);
  transition: 0.18s ease;
}

.toast.show {
  opacity: 1;
  transform: translateY(0);
}

.muted {
  color: var(--muted);
}

.hidden {
  display: none !important;
}

@media (max-width: 900px) {
  .app-header,
  .hero-band,
  .workspace,
  .exam-header,
  .auth-panel {
    grid-template-columns: 1fr;
  }

  .auth-panel {
    display: grid;
    align-items: stretch;
  }

  .auth-actions,
  .auth-key-row,
  .auth-key-row .input {
    width: 100%;
  }

  .app-header {
    align-items: stretch;
  }

  .top-nav,
  .nav-button {
    width: 100%;
  }

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

  .bank-tools,
  .field-grid,
  .stat-grid {
    grid-template-columns: 1fr;
  }

  h1 {
    font-size: 27px;
  }
}