:root {
  --ink: #172026;
  --muted: #65717a;
  --line: #d7dee5;
  --panel: #ffffff;
  --paper: #f4f7f6;
  --accent: #0d7c73;
  --accent-dark: #095f58;
  --sun: #f3b43f;
  --rose: #cc5a71;
  --shadow: 0 18px 50px rgba(34, 48, 60, 0.14);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  font-family:
    "Yu Gothic", "Hiragino Kaku Gothic ProN", Meiryo, system-ui, sans-serif;
  background:
    linear-gradient(120deg, rgba(13, 124, 115, 0.08), transparent 32%),
    linear-gradient(260deg, rgba(243, 180, 63, 0.12), transparent 26%),
    var(--paper);
}

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

.app-shell {
  width: min(1420px, 100%);
  margin: 0 auto;
  padding: 28px;
}

.workspace {
  display: grid;
  grid-template-columns: minmax(320px, 430px) minmax(0, 1fr);
  gap: 20px;
  min-height: calc(100vh - 56px);
}

.panel,
.output-area {
  background: rgba(255, 255, 255, 0.92);
  border: 1px solid rgba(215, 222, 229, 0.9);
  box-shadow: var(--shadow);
}

.builder-panel {
  border-radius: 8px;
  padding: 24px;
  align-self: start;
  position: sticky;
  top: 28px;
}

.brand-block {
  display: flex;
  gap: 14px;
  align-items: center;
  margin-bottom: 24px;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  border-radius: 8px;
  background: var(--ink);
  color: white;
  font-weight: 800;
  font-size: 24px;
}

h1,
h2,
h3,
p {
  margin: 0;
}

h1 {
  font-size: 24px;
  line-height: 1.15;
}

.brand-block p,
.eyebrow {
  color: var(--muted);
  font-size: 13px;
}

.lesson-form {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

label,
fieldset {
  display: grid;
  gap: 7px;
  color: #34434d;
  font-size: 13px;
  font-weight: 700;
}

.wide {
  grid-column: 1 / -1;
}

input,
select,
textarea {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--ink);
  background: #fbfcfd;
  padding: 11px 12px;
  outline: none;
}

textarea {
  resize: vertical;
  line-height: 1.65;
}

input:focus,
select:focus,
textarea:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(13, 124, 115, 0.12);
}

fieldset {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 13px;
  grid-template-columns: 1fr 1fr;
}

legend {
  padding: 0 6px;
}

.check {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
}

.check input {
  width: 16px;
  height: 16px;
  accent-color: var(--accent);
}

.file-field input {
  padding: 9px 10px;
}

.field-note {
  color: var(--muted);
  font-size: 12px;
  font-weight: 600;
  line-height: 1.5;
}

.field-note.error {
  color: #b2374f;
}

.primary-button {
  grid-column: 1 / -1;
  border: 0;
  border-radius: 8px;
  background: var(--accent);
  color: white;
  padding: 13px 16px;
  font-weight: 800;
  cursor: pointer;
}

.primary-button:hover {
  background: var(--accent-dark);
}

.output-area {
  border-radius: 8px;
  overflow: hidden;
  min-width: 0;
}

.output-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  padding: 22px 24px;
  border-bottom: 1px solid var(--line);
}

.output-header > div:first-child {
  min-width: 0;
}

.output-header h2 {
  margin-top: 4px;
  font-size: 28px;
  overflow-wrap: anywhere;
}

.actions {
  display: flex;
  flex: 0 0 auto;
  flex-wrap: wrap;
  gap: 8px;
  justify-content: flex-end;
  max-width: 360px;
}

.actions button {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  color: var(--ink);
  min-width: auto;
  min-height: 38px;
  padding: 7px 10px;
  font-size: 13px;
  line-height: 1.2;
  white-space: nowrap;
  font-weight: 800;
  cursor: pointer;
}

.tab {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  color: var(--ink);
  min-width: 46px;
  padding: 9px 12px;
  font-weight: 800;
  cursor: pointer;
}

.actions button:hover,
.tab:hover {
  border-color: var(--accent);
}

.tabs {
  display: flex;
  gap: 8px;
  padding: 14px 24px 0;
}

.tab.active {
  background: var(--ink);
  border-color: var(--ink);
  color: white;
}

.result-panel {
  padding: 24px;
  display: grid;
  gap: 16px;
}

.hidden {
  display: none;
}

.material-card {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  padding: 18px;
}

.material-card h3 {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 12px;
  font-size: 18px;
}

.tag {
  width: 10px;
  height: 22px;
  border-radius: 5px;
  background: var(--accent);
}

.material-card:nth-child(2n) .tag {
  background: var(--sun);
}

.material-card:nth-child(3n) .tag {
  background: var(--rose);
}

.material-card ul,
.material-card ol {
  margin: 0;
  padding-left: 22px;
  line-height: 1.8;
}

.material-card li + li {
  margin-top: 4px;
}

.prompt-box {
  white-space: pre-wrap;
  line-height: 1.75;
  background: #11191f;
  color: #e8f2f1;
  border-radius: 8px;
  padding: 20px;
  overflow: auto;
}

.markdown-output {
  line-height: 1.8;
  font-size: 15px;
}

.markdown-output h2,
.markdown-output h3,
.markdown-output h4 {
  line-height: 1.35;
  margin: 20px 0 8px;
}

.markdown-output h2 {
  font-size: 22px;
  padding-bottom: 7px;
  border-bottom: 1px solid var(--line);
}

.markdown-output h3 {
  font-size: 18px;
}

.markdown-output h4 {
  font-size: 15px;
  color: var(--accent-dark);
}

.markdown-output h5,
.markdown-output h6 {
  margin: 12px 0 6px;
  font-size: 14px;
  color: var(--muted);
}

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

.markdown-output ul,
.markdown-output ol {
  margin: 8px 0 12px;
}

.markdown-output strong {
  color: var(--accent-dark);
}

.markdown-output em {
  color: #34434d;
}

.markdown-output code {
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #f4f7f6;
  padding: 1px 5px;
  font-family: Consolas, "Courier New", monospace;
  font-size: 0.92em;
}

.markdown-output blockquote {
  margin: 10px 0;
  border-left: 4px solid var(--accent);
  padding: 8px 12px;
  background: #f8fbfa;
  color: #34434d;
}

.markdown-output hr {
  border: 0;
  border-top: 1px solid var(--line);
  margin: 18px 0;
}

.markdown-output table {
  width: 100%;
  border-collapse: collapse;
  margin: 12px 0;
  font-size: 14px;
}

.markdown-output th,
.markdown-output td {
  border: 1px solid var(--line);
  padding: 8px 10px;
  text-align: left;
  vertical-align: top;
}

.markdown-output th {
  background: #f4f7f6;
  font-weight: 800;
}

.markdown-editor {
  width: 100%;
  min-height: 58vh;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--ink);
  background: #fbfcfd;
  padding: 14px;
  line-height: 1.75;
  resize: vertical;
}

.actions button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

.ai-edit-panel {
  margin: 0 24px 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  padding: 14px;
}

.ai-edit-panel label {
  font-size: 13px;
}

.ai-edit-panel textarea {
  min-height: 86px;
}

.ai-edit-actions {
  display: flex;
  gap: 8px;
  justify-content: flex-end;
  margin-top: 10px;
}

.ai-edit-actions button {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  color: var(--ink);
  padding: 8px 12px;
  font-weight: 800;
  cursor: pointer;
}

.ai-edit-actions button:first-child {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.status-message {
  min-height: 24px;
  padding: 0 24px 22px;
  color: var(--muted);
  font-size: 13px;
}

.status-message.error {
  color: #b2374f;
}

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

.history-panel {
  margin-top: 22px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
}

.history-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 10px;
}

.history-header h2 {
  font-size: 15px;
}

.history-header button {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  color: var(--muted);
  padding: 5px 9px;
  font-size: 12px;
  font-weight: 800;
  cursor: pointer;
}

.history-list {
  display: grid;
  gap: 8px;
}

.history-item {
  display: grid;
  gap: 3px;
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fbfcfd;
  color: var(--ink);
  padding: 10px;
  text-align: left;
  cursor: pointer;
}

.history-item:hover {
  border-color: var(--accent);
}

.history-title {
  font-size: 13px;
  font-weight: 800;
}

.history-meta,
.history-empty {
  color: var(--muted);
  font-size: 12px;
}

.auth-bar {
  margin-bottom: 16px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--line);
}

.user-info {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

.user-email {
  font-size: 12px;
  color: var(--muted);
  flex: 1;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.usage-badge {
  font-size: 12px;
  font-weight: 700;
  color: var(--accent-dark);
  background: rgba(13, 124, 115, 0.1);
  border-radius: 99px;
  padding: 3px 8px;
  white-space: nowrap;
}

.usage-badge.usage-warn {
  color: #b2374f;
  background: rgba(178, 55, 79, 0.1);
}

.upgrade-button {
  border: 1px solid var(--accent);
  border-radius: 8px;
  background: #fff;
  color: var(--accent-dark);
  padding: 4px 9px;
  font-size: 12px;
  font-weight: 800;
  cursor: pointer;
  white-space: nowrap;
}

.upgrade-button:hover {
  background: var(--accent);
  color: #fff;
}

.logout-button {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  color: var(--muted);
  padding: 4px 9px;
  font-size: 12px;
  font-weight: 800;
  cursor: pointer;
  white-space: nowrap;
}

.login-button {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  color: var(--ink);
  padding: 10px;
  font-size: 13px;
  font-weight: 800;
  cursor: pointer;
  text-align: center;
}

.login-button:hover {
  border-color: var(--accent);
  color: var(--accent-dark);
}

.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(23, 32, 38, 0.55);
  align-items: center;
  justify-content: center;
  z-index: 100;
}

.modal-overlay:not(.hidden) {
  display: flex;
}

.modal {
  background: #fff;
  border-radius: 12px;
  padding: 32px;
  max-width: 400px;
  width: calc(100% - 40px);
  box-shadow: var(--shadow);
}

.modal h2 {
  font-size: 20px;
  margin-bottom: 12px;
}

.modal p {
  color: var(--muted);
  font-size: 14px;
  line-height: 1.7;
  margin-bottom: 20px;
}

.modal-actions {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.modal-cancel {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  color: var(--muted);
  padding: 10px;
  font-weight: 700;
  cursor: pointer;
}

@media (max-width: 900px) {
  .app-shell {
    padding: 14px;
  }

  .workspace {
    grid-template-columns: 1fr;
  }

  .builder-panel {
    position: static;
  }
}

@media (max-width: 560px) {
  .lesson-form,
  fieldset {
    grid-template-columns: 1fr;
  }

  .output-header {
    align-items: flex-start;
    flex-direction: column;
  }

  .actions {
    justify-content: flex-start;
    max-width: 100%;
  }
}

@media print {
  @page {
    margin: 14mm;
  }

  html,
  body {
    background: #fff;
    margin: 0;
    padding: 0;
  }

  .app-shell {
    width: 100%;
    padding: 0;
    margin: 0;
  }

  .workspace {
    display: block;
    min-height: 0;
    margin: 0;
  }

  .builder-panel,
  .actions,
  .tabs,
  #teacher,
  .status-message {
    display: none;
  }

  #student {
    display: block;
  }

  .output-area {
    border: 0;
    box-shadow: none;
    border-radius: 0;
    overflow: visible;
  }

  .output-header {
    padding: 0 0 14px;
    border-bottom: 2px solid #172026;
  }

  .output-header h2 {
    font-size: 22px;
  }

  .eyebrow {
    color: #65717a;
  }

  .result-panel {
    padding: 10px 0 0;
    display: block;
  }

  .material-card {
    border: 0;
    padding: 0;
    page-break-inside: auto;
    break-inside: auto;
  }

  .prompt-box {
    background: #fff;
    color: #172026;
    border: 1px solid #d7dee5;
  }
}

.site-footer {
  text-align: center;
  padding: 16px;
  font-size: 13px;
  color: #65717a;
}

.site-footer a {
  color: #65717a;
  text-decoration: none;
  margin: 0 12px;
}

.site-footer a:hover {
  text-decoration: underline;
}