* {
  box-sizing: border-box;
}

:root {
  font-family:
    Inter,
    ui-sans-serif,
    system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;

  color: #172033;
  background: #f5f7fb;
}

body {
  margin: 0;
  min-height: 100vh;
}

button,
input {
  font: inherit;
}

button {
  border: 0;
  border-radius: 11px;
  padding: 13px 18px;

  background: #2637d8;
  color: white;

  font-weight: 750;
  cursor: pointer;
}

button.secondary {
  background: #eef1ff;
  color: #2637d8;
}

button.danger {
  background: #b42318;
}

button:disabled {
  opacity: .45;
  cursor: not-allowed;
}

input {
  width: 100%;
  padding: 14px;

  border:
    1px solid #d7dce7;

  border-radius: 11px;

  background: white;
}

.topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;

  padding: 15px 22px;

  background: white;
  border-bottom:
    1px solid #e5e9f1;
}

.topbar span {
  color: #7b8493;
  font-size: .82rem;
}

.shell {
  width:
    min(
      850px,
      calc(100% - 28px)
    );

  margin: 55px auto;
}

.card {
  padding: 26px;

  background: white;

  border:
    1px solid #e5e9f1;

  border-radius: 17px;

  box-shadow:
    0 10px 30px
    rgba(30, 42, 80, .06);
}

.center {
  text-align: center;
}

.role-tabs {
  display: flex;
  gap: 8px;

  margin-bottom: 28px;
}

.role-tabs button {
  flex: 1;
}

.student-box,
.teacher-box {
  max-width: 540px;
  margin: 0 auto;
}

.code-input {
  margin: 12px 0;

  font-size: 2rem;
  letter-spacing: .18em;
  text-align: center;
}

.session-code {
  font-size: 2.8rem;
  letter-spacing: .16em;
  font-weight: 900;

  margin: 18px 0;
}

.nickname {
  font-size: 1.8rem;
  font-weight: 900;

  margin: 20px 0;
}

.status {
  margin: 18px 0;
  padding: 13px;

  border-radius: 11px;

  background: #f5f7fb;
}

.message {
  min-height: 24px;
  margin-top: 12px;

  color: #a12626;
}

.player-list {
  display: grid;
  gap: 9px;

  margin: 20px 0;
}

.player {
  padding: 12px 14px;

  border:
    1px solid #e5e9f1;

  border-radius: 11px;

  background: #fafbfc;

  font-weight: 700;
}

.actions {
  display: flex;
  gap: 10px;

  margin-top: 22px;
}

.actions button {
  flex: 1;
}

.muted {
  color: #7b8493;
}

.ok {
  color: #187448;
}

@media (max-width: 600px) {
  .shell {
    margin-top: 24px;
  }

  .actions,
  .role-tabs {
    flex-direction: column;
  }

  .topbar span {
    display: none;
  }
}