* {
  box-sizing: border-box;
}

:root {
  font-family: Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;
  color: #172033;
  background: #eef3f8;
}

body {
  margin: 0;
  min-height: 100vh;
  background: linear-gradient(135deg, #eef3f8, #f8fbff);
}

button,
input,
select {
  font: inherit;
}

button {
  cursor: pointer;
}

.shell {
  width: min(1040px, calc(100% - 28px));
  margin: 0 auto;
  padding: 32px 0;
}

.card {
  background: #ffffff;
  border: 1px solid #dfe7ef;
  border-radius: 20px;
  box-shadow: 0 12px 40px rgba(40, 64, 92, 0.1);
  padding: 24px;
  margin-bottom: 20px;
}

.login-card {
  max-width: 480px;
  margin: 6vh auto;
}

.brand,
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand {
  justify-content: flex-start;
  margin-bottom: 28px;
}

.logo {
  display: grid;
  place-items: center;
  width: 58px;
  height: 58px;
  border-radius: 16px;
  background: #173f6b;
  color: #ffffff;
  font-weight: 800;
}

.eyebrow {
  margin: 0;
  color: #2c6ca3;
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.09em;
}

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

.brand h1,
.topbar h1 {
  margin: 4px 0 0;
}

.muted {
  color: #66758a;
}

label {
  display: grid;
  gap: 7px;
  font-weight: 700;
  color: #28384c;
}

input,
select {
  width: 100%;
  border: 1px solid #cbd7e3;
  border-radius: 12px;
  padding: 12px;
  background: #ffffff;
  color: #172033;
}

input[type="file"] {
  padding: 10px;
}

input:focus,
select:focus {
  outline: 3px solid rgba(44, 108, 163, 0.16);
  border-color: #2c6ca3;
}

form {
  display: grid;
  gap: 16px;
}

.primary,
.secondary {
  border: 0;
  border-radius: 12px;
  padding: 12px 18px;
  font-weight: 800;
}

.primary {
  background: #173f6b;
  color: #ffffff;
}

.secondary {
  background: #e9f0f7;
  color: #173f6b;
}

.primary:hover,
.secondary:hover {
  filter: brightness(0.97);
}

button:disabled {
  opacity: 0.6;
  cursor: wait;
}

.message {
  min-height: 1.5em;
  margin: 16px 0 0;
  font-weight: 700;
}

.message.error {
  color: #b42318;
}

.message.success {
  color: #087443;
}

.hidden {
  display: none !important;
}

.topbar {
  margin-bottom: 20px;
}

.form-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.full {
  grid-column: 1 / -1;
}

.grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
  margin-top: 20px;
}

.tile {
  border: 1px solid #dde6ef;
  border-radius: 16px;
  padding: 20px;
  background: #f9fbfd;
}

.tile > span {
  font-size: 2rem;
}

.tile h3 {
  margin: 10px 0 6px;
}

.lesson-list {
  display: grid;
  gap: 12px;
  margin-top: 14px;
}

.lesson-item {
  border: 1px solid #dde6ef;
  border-radius: 14px;
  padding: 14px;
  background: #ffffff;
}

.lesson-item strong {
  display: block;
  margin-bottom: 6px;
  color: #173f6b;
}

.lesson-item p {
  margin: 6px 0 10px;
}

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

.lesson-open-btn {
  width: 100%;
  margin-top: 8px;
}

#adminLessonList {
  display: grid;
  gap: 12px;
}

#adminLessonList .lesson-item {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 16px;
}

@media (max-width: 650px) {
  .shell {
    padding: 16px 0;
  }

  .card {
    padding: 18px;
  }

  .form-grid,
  .grid {
    grid-template-columns: 1fr;
  }

  .topbar {
    align-items: flex-start;
  }

  .full {
    grid-column: auto;
  }

  #adminLessonList .lesson-item {
    display: block;
  }

  #adminLessonList .row {
    margin-top: 12px;
  }
}