:root {
  color-scheme: light;
  --bg: #f5f7f3;
  --panel: #ffffff;
  --ink: #1b2421;
  --muted: #5e6964;
  --line: #d9dfd8;
  --accent: #12685d;
  --accent-strong: #0a4d44;
  --warn: #9a5200;
  --bad: #b42318;
  --good: #087443;
  --focus: #e4f2ef;
  --soft: #fbfcfa;
  --shadow: 0 18px 38px rgba(28, 40, 36, 0.1);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.6;
}

button,
input,
select {
  font: inherit;
}

button {
  cursor: pointer;
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.58;
}

a {
  color: var(--accent-strong);
}

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

h1 {
  margin-bottom: 0;
  font-size: clamp(1.55rem, 3vw, 2.4rem);
  letter-spacing: 0;
}

h2 {
  font-size: 1.14rem;
  margin-bottom: 8px;
}

h3 {
  font-size: 1rem;
  margin-bottom: 8px;
}

.hidden {
  display: none !important;
}

.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 28px clamp(18px, 4vw, 56px) 18px;
  border-bottom: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.78);
  backdrop-filter: blur(12px);
}

.eyebrow {
  margin: 0 0 4px;
  color: var(--accent);
  font-size: 0.82rem;
  font-weight: 700;
}

.home-shell {
  display: grid;
  grid-template-columns: minmax(320px, 480px) minmax(280px, 1fr);
  gap: 18px;
  padding: 24px clamp(18px, 4vw, 56px) 40px;
  align-items: start;
}

.control-panel,
.home-summary,
.quiz-area,
.exam-status,
.result-shell {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: var(--shadow);
}

.control-panel,
.home-summary,
.result-shell {
  padding: 20px;
}

.panel-title p,
.source-note,
.question-meta,
.explanation,
.result-note,
.mode-card small {
  color: var(--muted);
}

.mode-grid {
  display: grid;
  gap: 10px;
  margin: 16px 0;
}

.mode-card {
  display: grid;
  grid-template-columns: auto 1fr;
  column-gap: 10px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--soft);
}

.mode-card:has(input:checked) {
  border-color: var(--accent);
  background: #eef8f5;
}

.mode-card input {
  margin-top: 5px;
}

.mode-card span {
  font-weight: 700;
}

.mode-card small {
  grid-column: 2;
}

.select-row,
.settings-row label {
  display: grid;
  gap: 6px;
}

.select-row span,
.settings-row span {
  color: var(--muted);
  font-size: 0.86rem;
  font-weight: 700;
}

select,
input[type="number"] {
  width: 100%;
  min-height: 42px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #fff;
  padding: 8px 10px;
}

.settings-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 14px;
}

.toggle-row {
  grid-column: 1 / -1;
  display: flex !important;
  grid-template-columns: none !important;
  align-items: center;
  gap: 10px;
}

.primary-button,
.ghost-button,
.answer-button,
.nav-button {
  border-radius: 6px;
  border: 1px solid transparent;
  min-height: 42px;
  padding: 8px 14px;
  font-weight: 700;
}

.primary-button {
  width: 100%;
  margin-top: 16px;
  background: var(--accent);
  color: white;
}

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

.ghost-button,
.nav-button {
  background: white;
  border-color: var(--line);
  color: var(--ink);
}

.availability-note {
  color: var(--warn);
  font-size: 0.86rem;
  margin: 10px 0 0;
}

.summary-grid,
.result-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  margin: 16px 0;
}

.summary-grid div,
.result-grid div {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 14px;
  background: var(--soft);
}

.metric-label {
  display: block;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 700;
}

.home-summary ul {
  padding-left: 18px;
}

.home-summary li {
  margin-bottom: 8px;
}

.source-note {
  border-top: 1px solid var(--line);
  padding-top: 14px;
  font-size: 0.85rem;
}

.exam-page {
  min-height: 100vh;
}

.exam-shell {
  width: min(980px, calc(100% - 32px));
  margin: 0 auto;
  padding: 18px 0 34px;
}

.exam-status {
  display: grid;
  grid-template-columns: repeat(3, 1fr) auto;
  gap: 1px;
  overflow: hidden;
  margin-bottom: 14px;
}

.exam-status div {
  padding: 12px 14px;
  background: #fff;
}

.exam-status .ghost-button {
  align-self: center;
  margin: 10px 12px;
}

.quiz-area {
  min-height: 560px;
  padding: clamp(16px, 3vw, 28px);
}

.progress-line {
  height: 8px;
  border-radius: 999px;
  background: #e8ece8;
  overflow: hidden;
  margin-bottom: 18px;
}

.progress-line span {
  display: block;
  height: 100%;
  width: 0%;
  background: var(--accent);
}

.question-card h2 {
  font-size: 1.28rem;
  line-height: 1.55;
  margin-bottom: 16px;
}

.question-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 14px;
  font-size: 0.86rem;
}

.tag {
  display: inline-flex;
  align-items: center;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 3px 9px;
  background: var(--soft);
}

.answers {
  display: grid;
  gap: 10px;
  margin: 18px 0;
}

.answer-button {
  width: 100%;
  text-align: left;
  background: white;
  border-color: var(--line);
  font-weight: 600;
  line-height: 1.55;
}

.answer-button:hover,
.answer-button:focus {
  background: var(--focus);
  outline: none;
}

.answer-button.selected {
  border-color: var(--accent);
  background: #eef8f5;
}

.answer-button.correct {
  border-color: var(--good);
  background: #eef8f3;
}

.answer-button.incorrect {
  border-color: var(--bad);
  background: #fff2f1;
}

.feedback {
  border-left: 4px solid var(--accent);
  background: #f7fbfa;
  padding: 14px;
  margin: 16px 0;
}

.feedback.bad {
  border-left-color: var(--bad);
  background: #fff8f7;
}

.nav-row {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  margin-top: 18px;
}

.nav-row .primary-button {
  width: auto;
  margin-top: 0;
}

.result-page {
  min-height: 100vh;
  padding: 24px clamp(16px, 4vw, 56px) 40px;
}

.result-shell {
  width: min(980px, 100%);
  margin: 0 auto;
}

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

.review-list {
  display: grid;
  gap: 14px;
  margin-top: 20px;
}

.review-item {
  border-top: 1px solid var(--line);
  padding-top: 14px;
}

@media (max-width: 900px) {
  .home-shell,
  .exam-status,
  .result-grid {
    grid-template-columns: 1fr;
  }

  .exam-status .ghost-button {
    width: calc(100% - 24px);
  }
}

@media (max-width: 640px) {
  .app-header {
    align-items: flex-start;
    flex-direction: column;
  }

  .settings-row,
  .summary-grid {
    grid-template-columns: 1fr;
  }

  .nav-row {
    flex-direction: column;
  }

  .nav-row .primary-button,
  .nav-row .ghost-button,
  .nav-row .nav-button {
    width: 100%;
  }
}