* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: 'Segoe UI', Arial, sans-serif;
  background: linear-gradient(135deg, #0f2027, #203a43, #2c5364);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  padding: 24px 12px;
}

.container {
  width: 100%;
  max-width: 480px;
}

.header {
  text-align: center;
  color: #fff;
  margin-bottom: 20px;
}

.header h1 {
  margin: 0 0 6px;
  font-size: 26px;
}

.header p {
  margin: 0;
  opacity: 0.8;
  font-size: 14px;
}

.card {
  background: #fff;
  border-radius: 14px;
  padding: 20px;
  margin-bottom: 16px;
  box-shadow: 0 8px 24px rgba(0,0,0,0.2);
}

.card h2 {
  margin-top: 0;
  font-size: 17px;
  color: #203a43;
}

.hidden { display: none !important; }

select, input[type="text"] {
  width: 100%;
  padding: 12px;
  border-radius: 8px;
  border: 1px solid #ccc;
  font-size: 15px;
  margin-bottom: 10px;
}

.student-list {
  max-height: 320px;
  overflow-y: auto;
}

.student-item {
  padding: 12px 14px;
  border-radius: 8px;
  border: 1px solid #e2e2e2;
  margin-bottom: 8px;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: background 0.15s;
}

.student-item:hover {
  background: #f2f7ff;
}

.student-item.selected {
  background: #2c5364;
  color: #fff;
  border-color: #2c5364;
}

.badge {
  font-size: 11px;
  padding: 3px 8px;
  border-radius: 20px;
  background: #d4f8d4;
  color: #227722;
}

.confirm-box {
  text-align: center;
}

.confirm-box p {
  font-size: 16px;
}

.checkbox-label {
  display: block;
  margin: 16px 0;
  font-size: 14px;
  color: #444;
}

button#btn-submit {
  width: 100%;
  padding: 14px;
  border: none;
  border-radius: 8px;
  background: #2c5364;
  color: #fff;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: opacity 0.2s;
}

button#btn-submit:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.alert {
  padding: 14px;
  border-radius: 10px;
  text-align: center;
  font-weight: 600;
  margin-bottom: 16px;
}

.alert.success {
  background: #d4f8d4;
  color: #1c6b1c;
}

.alert.error {
  background: #ffd9d9;
  color: #a41616;
}

.admin-link {
  display: block;
  text-align: center;
  color: #fff;
  opacity: 0.7;
  font-size: 13px;
  margin-top: 20px;
  text-decoration: none;
}

.admin-link:hover { opacity: 1; }