:root {
  --page-bg: #f7f8fb;
  --surface: #ffffff;
  --surface-soft: #f1f3f8;
  --ink: #171923;
  --muted: #626779;
  --line: #d8dce7;
  --accent: #5d3fd3;
  --accent-strong: #4528ba;
  --success-bg: #ecf8ef;
  --coach-bg: #fff6df;
  --locked-bg: #f4efff;
  --radius-lg: 22px;
  --radius-md: 14px;
  --shadow: 0 18px 48px rgb(28 31 43 / 0.08);
  font-family: "Times New Roman", Times, serif;
}

* { box-sizing: border-box; }

html {
  min-inline-size: 320px;
  background: var(--page-bg);
  color: var(--ink);
  text-size-adjust: 100%;
}

body {
  margin: 0;
  min-block-size: 100vh;
  background: var(--page-bg);
  color: var(--ink);
  overflow-wrap: anywhere;
}

button,
input,
select {
  font: inherit;
}

button,
select {
  min-block-size: 44px;
}

button { cursor: pointer; }

button:focus-visible,
input:focus-visible,
select:focus-visible {
  outline: 3px solid rgb(93 63 211 / 0.28);
  outline-offset: 2px;
}

button:disabled,
select:disabled,
input:disabled {
  cursor: not-allowed;
  opacity: 0.62;
}

.app-shell {
  max-inline-size: 1180px;
  margin-inline: auto;
  padding-block: 20px 48px;
  padding-inline: clamp(16px, 3vw, 36px);
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding-block: 8px 22px;
}

.brand-block {
  display: flex;
  align-items: center;
  gap: 12px;
  min-inline-size: 0;
}

.brand-mark {
  display: grid;
  place-items: center;
  inline-size: 46px;
  block-size: 46px;
  flex: 0 0 46px;
  border-radius: 14px;
  background: var(--accent);
  color: white;
  font-weight: 700;
  letter-spacing: 0.02em;
}

.brand-copy {
  display: grid;
  gap: 2px;
  min-inline-size: 0;
}

.brand-copy strong { font-size: clamp(1.05rem, 2vw, 1.35rem); }
.brand-copy span { color: var(--muted); font-size: 0.94rem; }

.language-switch {
  display: flex;
  gap: 6px;
  padding: 4px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface);
  flex: 0 0 auto;
}

.lang-button {
  border: 0;
  border-radius: 999px;
  padding-inline: 14px;
  background: transparent;
  color: var(--muted);
}

.lang-button.is-active { background: var(--accent); color: white; }

.student-flow {
  display: grid;
  gap: 20px;
}

.panel {
  min-inline-size: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
  box-shadow: var(--shadow);
}

.catalog-panel {
  padding: clamp(20px, 3.6vw, 38px);
}

.catalog-heading {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(240px, 330px);
  gap: 20px;
  align-items: start;
}

.catalog-heading h1 {
  margin: 0;
  font-size: clamp(1.7rem, 4vw, 2.7rem);
  line-height: 1.12;
}

.catalog-subtitle {
  max-inline-size: 720px;
  margin-block: 10px 0;
  color: var(--muted);
  line-height: 1.55;
}

.access-card {
  display: grid;
  gap: 6px;
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--surface-soft);
}

.access-card[data-tier="free"] { background: #f2f7ff; }
.access-card[data-tier="pro"] { background: #f0ecff; border-color: #bdb0f5; }
.access-card[data-tier="locked"] { background: #f7f7f9; }
.access-card strong { font-size: 1.05rem; }
.access-card span { color: var(--ink); }
.access-card small { color: var(--muted); line-height: 1.4; }

.catalog-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
  margin-block-start: 24px;
}

.field-block {
  display: grid;
  gap: 7px;
  min-inline-size: 0;
  font-weight: 700;
}

.field-block select {
  inline-size: 100%;
  min-inline-size: 0;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding-block: 10px;
  padding-inline: 12px 36px;
  background: white;
  color: var(--ink);
}

.lesson-preview {
  margin-block-start: 18px;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--surface-soft);
}

.lesson-preview-heading,
.session-heading-row {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 16px;
}

.lesson-preview h2 { margin: 0; font-size: clamp(1.25rem, 3vw, 1.7rem); }

.tier-badge {
  display: inline-flex;
  align-items: center;
  min-block-size: 32px;
  flex: 0 0 auto;
  padding-inline: 11px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: white;
  font-size: 0.86rem;
  font-weight: 700;
}

.tier-badge[data-protected="true"] { background: var(--locked-bg); color: var(--accent-strong); border-color: #cabffc; }

.lesson-preview-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin-block: 16px 0;
}

.lesson-preview-grid > div {
  min-inline-size: 0;
  padding: 12px;
  border-radius: 12px;
  background: white;
  border: 1px solid var(--line);
}

.lesson-preview-grid dt { margin-block-end: 6px; color: var(--accent-strong); font-weight: 700; }
.lesson-preview-grid dd { margin: 0; color: var(--muted); line-height: 1.5; white-space: pre-wrap; }

.launch-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
  margin-block-start: 18px;
}

.launch-status {
  flex: 1 1 260px;
  color: var(--muted);
  line-height: 1.4;
}
.launch-status[data-tone="error"] { color: #9b1c1c; }
.launch-status[data-tone="success"] { color: #146c2e; }

.exam-coach-panel { padding: clamp(20px, 3vw, 30px); }
.exam-coach-panel h2 { margin-block-start: 0; }
.exam-coach-items { display: grid; gap: 10px; }
.exam-coach-item { padding: 14px; border: 1px solid var(--line); border-radius: 12px; background: var(--surface-soft); }
.exam-coach-item h3 { margin-block: 0 6px; }
.exam-coach-item p { margin: 0; white-space: pre-wrap; line-height: 1.5; }

.tutor-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(220px, 300px);
  gap: 20px;
  align-items: start;
}

.question-panel { padding: clamp(22px, 4vw, 42px); }
.progress-panel { padding: 22px; }
.feedback-panel { grid-column: 1 / -1; padding: clamp(20px, 3vw, 32px); }

.eyebrow {
  margin-block-end: 10px;
  color: var(--accent-strong);
  font-weight: 700;
  font-size: 0.88rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.question-text {
  margin: 0;
  font-size: clamp(1.42rem, 3.6vw, 2.25rem);
  line-height: 1.3;
  font-weight: 700;
  white-space: pre-wrap;
}

.answer-area { margin-block-start: 28px; display: grid; gap: 10px; }
.answer-area label { font-weight: 700; }

.answer-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 10px;
}

.answer-row input {
  min-inline-size: 0;
  min-block-size: 48px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding-block: 10px;
  padding-inline: 14px;
  background: white;
  color: var(--ink);
}

.primary-action,
.secondary-action,
.quiet-action,
.feedback-action {
  border-radius: 12px;
  padding-inline: 16px;
  border: 1px solid transparent;
}

.primary-action { background: var(--accent); color: white; font-weight: 700; }
.primary-action:hover { background: var(--accent-strong); }
.secondary-action,
.feedback-action { background: var(--surface-soft); border-color: var(--line); color: var(--ink); }
.quiet-action { background: transparent; border-color: var(--line); color: var(--muted); }

.primary-support-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-block-start: 18px;
}

.privacy-note { margin: 0; color: var(--muted); font-size: 0.86rem; line-height: 1.45; }
.progress-panel h2 { margin-block-start: 0; font-size: 1.1rem; }
.progress-grid { display: grid; gap: 10px; margin: 0; }

.progress-grid > div {
  display: flex;
  justify-content: space-between;
  gap: 14px;
  padding-block: 10px;
  border-block-end: 1px solid var(--line);
}
.progress-grid > div:last-child { border-block-end: 0; }
.progress-grid dt { color: var(--muted); }
.progress-grid dd { margin: 0; font-weight: 700; }

.feedback-stack {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 280px), 1fr));
  gap: 14px;
}

.feedback-card {
  min-inline-size: 0;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--surface-soft);
}
.feedback-card[data-tone="success"] { background: var(--success-bg); }
.feedback-card[data-tone="coach"] { background: var(--coach-bg); }
.feedback-card-title { margin-block: 0 8px; font-size: 1.05rem; }
.feedback-card-body { margin: 0; line-height: 1.55; white-space: pre-wrap; }
.feedback-card-body:empty { display: none; }

.math-display {
  margin-block-start: 12px;
  padding-block: 14px;
  padding-inline: 16px;
  border-radius: 12px;
  background: white;
  border: 1px solid var(--line);
  font-family: "Times New Roman", Times, serif;
  font-size: 1.15rem;
  text-align: center;
  unicode-bidi: isolate;
  direction: ltr;
  overflow-wrap: normal;
  word-break: normal;
}

.feedback-actions { display: flex; flex-wrap: wrap; gap: 8px; margin-block-start: 14px; }

[dir="rtl"] .eyebrow { letter-spacing: 0; text-transform: none; }
[dir="rtl"] .question-text,
[dir="rtl"] .feedback-card-body,
[dir="rtl"] .feedback-card-title,
[dir="rtl"] .brand-copy,
[dir="rtl"] .lesson-preview-grid dd { text-align: start; }

.visually-hidden {
  position: absolute;
  inline-size: 1px;
  block-size: 1px;
  padding: 0;
  margin: -1px;
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

@media (max-width: 900px) {
  .catalog-heading,
  .catalog-grid,
  .lesson-preview-grid,
  .tutor-layout { grid-template-columns: minmax(0, 1fr); }
  .progress-panel { order: 2; }
  .feedback-panel { grid-column: 1; order: 3; }
}

@media (max-width: 640px) {
  .app-shell { padding-block-start: 10px; padding-inline: 12px; }
  .topbar { align-items: stretch; flex-direction: column; }
  .language-switch { align-self: flex-start; }
  .lesson-preview-heading,
  .session-heading-row { flex-direction: column; align-items: stretch; }
  .answer-row { grid-template-columns: minmax(0, 1fr); }
  .launch-row { display: grid; grid-template-columns: minmax(0, 1fr); }
  .launch-status { min-inline-size: 0; }
  .primary-action,
  .secondary-action,
  .quiet-action,
  .feedback-action { inline-size: 100%; }
  .primary-support-row,
  .feedback-actions { display: grid; grid-template-columns: minmax(0, 1fr); }
}