:root {
  color-scheme: light;
  --bg: #f3f6fb;
  --card: rgba(255, 255, 255, 0.92);
  --line: #d9e2f2;
  --text: #19324d;
  --muted: #5f7288;
  --primary: #356dff;
  --primary-soft: #e9f0ff;
  --success: #1f9d68;
  --shadow: 0 18px 45px rgba(39, 76, 119, 0.12);
  --radius: 22px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: linear-gradient(180deg, #eef4ff 0%, #f7f9fd 100%);
  color: var(--text);
}

button {
  border: 0;
  border-radius: 14px;
  padding: 10px 14px;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  background: #eef2f8;
  color: var(--text);
  transition: transform 0.18s ease, background 0.18s ease, color 0.18s ease;
}

button:hover {
  transform: translateY(-1px);
}

button.primary-btn {
  background: var(--primary);
  color: white;
}

.page-shell {
  max-width: 1400px;
  margin: 0 auto;
  padding: 28px;
}

.hero {
  display: grid;
  grid-template-columns: 1.7fr 1fr;
  gap: 20px;
  margin-bottom: 24px;
}

.hero,
.card {
  background: var(--card);
  border: 1px solid rgba(217, 226, 242, 0.8);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.hero {
  padding: 28px;
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--primary);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1 {
  margin: 0;
  font-size: clamp(30px, 4vw, 44px);
}

.hero-text {
  margin-top: 12px;
  max-width: 720px;
  font-size: 16px;
  line-height: 1.7;
  color: var(--muted);
}

.hero-card {
  padding: 22px;
  border-radius: 18px;
  background: linear-gradient(135deg, #356dff 0%, #5a8cff 100%);
  color: white;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 12px;
}

.hero-card-label {
  margin: 0;
  opacity: 0.8;
}

.hero-card-value {
  margin: 0;
  font-size: 24px;
  font-weight: 700;
}

.layout {
  display: grid;
  grid-template-columns: 300px 1fr;
  gap: 24px;
}

.card {
  padding: 22px;
}

.sidebar {
  position: sticky;
  top: 20px;
  align-self: start;
  max-height: calc(100vh - 40px);
  overflow: auto;
}

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

.section-heading h2,
.stat-card h2,
.essay-card h3 {
  margin: 0;
}

.badge {
  padding: 6px 10px;
  border-radius: 999px;
  background: var(--primary-soft);
  color: var(--primary);
  font-size: 12px;
  font-weight: 700;
}

.day-list {
  display: grid;
  gap: 10px;
}

.day-btn {
  width: 100%;
  text-align: left;
  padding: 14px;
  background: #f7f9fd;
  border: 1px solid transparent;
}

.day-btn strong {
  display: block;
  margin-bottom: 4px;
  font-size: 15px;
}

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

.day-btn.active {
  border-color: rgba(53, 109, 255, 0.25);
  background: var(--primary-soft);
}

.day-btn.done {
  box-shadow: inset 0 0 0 1px rgba(31, 157, 104, 0.25);
}

.content {
  display: grid;
  gap: 24px;
}

.overview-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 20px;
}

.stat-card {
  min-height: 150px;
}

.stat-label {
  margin: 0 0 10px;
  color: var(--muted);
  font-size: 13px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

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

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.word-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

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

.word-head {
  display: flex;
  align-items: start;
  justify-content: space-between;
  gap: 12px;
}

.word-title {
  margin: 0;
  font-size: 24px;
}

.word-ipa {
  margin: 6px 0 0;
  color: var(--muted);
  font-size: 14px;
}

.word-meta {
  display: grid;
  gap: 10px;
  margin-top: 16px;
}

.meaning-box {
  padding: 12px 14px;
  border-radius: 14px;
  background: #eff4fb;
  color: var(--text);
}

.hidden {
  display: none;
}

.word-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 14px;
}

.remember-btn.active {
  background: rgba(31, 157, 104, 0.14);
  color: var(--success);
}

.essay-card {
  display: grid;
  gap: 18px;
}

.essay-heading {
  align-items: flex-start;
}

.essay-panel {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
}

.essay-text {
  min-height: 180px;
  padding: 18px;
  border-radius: 18px;
  background: #f8fbff;
  border: 1px solid var(--line);
  line-height: 1.9;
}

.sentence-list {
  display: grid;
  gap: 12px;
}

.sentence-card {
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 16px;
  background: #fcfdff;
}

.sentence-card p {
  margin: 0 0 10px;
  line-height: 1.8;
}

.sentence-actions {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

@media (max-width: 1100px) {
  .layout,
  .hero,
  .overview-grid,
  .essay-panel {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: static;
    max-height: none;
  }
}

@media (max-width: 720px) {
  .page-shell {
    padding: 16px;
  }

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