body {
  font-family: "Segoe UI", "Meiryo", sans-serif;
  background: #f8fbff;
  color: #23344d;
  margin: 0;
  padding: 0;
}
main {
  max-width: 680px;
  margin: 40px auto 60px auto;
  background: #fff;
  padding: 40px 30px 60px 30px;
  border-radius: 32px;
  box-shadow: 0 8px 32px #bcdcff2a;
}
h1, h2, h3 {
  color: #387bee;
  margin-top: 0.5em;
}
.subtitle {
  color: #7691c6;
  font-size: 1.1em;
  margin-bottom: 1em;
}
.explain-block, .drill-block, .scene-examples, .vocab-block {
  background: #f2f8ff;
  border-radius: 18px;
  padding: 18px 24px;
  margin: 28px 0 34px 0;
  box-shadow: 0 3px 12px #cde6fb13;
}
.expression-table {
  overflow-x: auto;
  margin-bottom: 18px;
}
.expression-table table {
  border-collapse: collapse;
  width: 100%;
  background: #fff;
  font-size: 1em;
}
.expression-table th, .expression-table td {
  border: 1px solid #ddeaff;
  padding: 10px 14px;
  text-align: left;
}
.expression-table th {
  background: #e6f0ff;
  color: #2b3e64;
}
.highlight.hello   { color: #1679cc; font-weight: bold; }
.highlight.hi      { color: #40b28d; font-weight: bold; }
.highlight.hey     { color: #e47f26; font-weight: bold; }
.highlight.morning { color: #a16ce8; font-weight: bold; }
.highlight.casual  { color: #d16ea5; font-weight: bold; }

.card-btn, .vocab-btn {
  display: inline-block;
  font-size: 1.05em;
  color: #fff;
  background: linear-gradient(90deg, #5ab3ff, #6dc1d1 90%);
  padding: 0.57em 1.8em;
  border: none;
  border-radius: 22px;
  cursor: pointer;
  margin: 0 0.6em 10px 0;
  transition: background 0.2s;
  box-shadow: 0 2px 8px #c2e2ff34;
  outline: none;
}
.card-btn:hover, .vocab-btn:hover {
  background: linear-gradient(90deg, #1e86d2, #25acac 90%);
}
.warn {
  color: #ff5722;
  font-size: 0.98em;
  margin-left: 8px;
}
.note {
  color: #69c;
  font-size: 0.97em;
  margin-left: 8px;
}
.scene-label {
  display: inline-block;
  color: #4e7cc2;
  background: #e7f1ff;
  border-radius: 8px;
  padding: 3px 12px;
  font-weight: bold;
  font-size: 1.06em;
  margin-bottom: 4px;
}
.q {
  color: #336;
  font-weight: bold;
}
.a {
  color: #258e70;
}
ul { padding-left: 1.3em; }
@media (max-width: 600px) {
  main { padding: 16px 4vw; }
  .expression-table th, .expression-table td { font-size: 0.98em; padding: 7px 4vw; }
}