:root {
  --g: #17684a;
  --ink: #17231e;
  --muted: #748079;
  --line: #e2e8e4;
}
* {
  box-sizing: border-box;
}
body {
  margin: 0;
  font-family: Arial, 'Microsoft YaHei';
  color: var(--ink);
  display: grid;
  grid-template-columns: 210px 1fr;
  min-height: 100vh;
  background: #f7f9f7;
}
body > aside {
  background: #fff;
  border-right: 1px solid var(--line);
  padding: 24px 16px;
  display: flex;
  flex-direction: column;
}
.logo {
  display: flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
  color: inherit;
  font-weight: bold;
}
.student-logo-mark {
  font-style: normal;
  width: 34px;
  height: 34px;
  border-radius: 9px;
  background: var(--g);
  color: #fff;
  display: grid;
  place-items: center;
}
body > aside nav {
  display: grid;
  gap: 6px;
  margin-top: 40px;
}
body > aside nav button,
body > aside nav a,
body > aside > button {
  border: 0;
  background: none;
  text-align: left;
  padding: 11px;
  border-radius: 8px;
  text-decoration: none;
  color: var(--muted);
}
.on {
  background: #e8f2ec !important;
  color: var(--g) !important;
}
body > aside > button {
  margin-top: auto;
}

body > aside nav a[href^='#'] {
  display: none !important;
}

body > aside nav button,
body > aside nav a {
  color: #607390 !important;
  background: #f3f7fd !important;
  box-shadow: none !important;
}

body > aside nav button.on {
  color: #fff !important;
  background: linear-gradient(100deg, #4263eb, #3478f6) !important;
  box-shadow: 0 8px 20px rgba(66, 99, 235, 0.18) !important;
}
main {
  padding: 40px clamp(24px, 4vw, 70px);
  max-width: none;
  width: 100%;
}
header {
  display: flex;
  justify-content: space-between;
  align-items: end;
}
header small {
  color: var(--g);
  letter-spacing: 2px;
}
header h1 {
  margin: 6px 0;
}
.view {
  display: none;
}
.view.on {
  display: block;
}
.stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  margin: 28px 0;
}
.stats article,
.course {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 11px;
  padding: 18px;
  color: var(--muted);
}
.stats b {
  display: block;
  color: var(--ink);
  font-size: 22px;
  margin-top: 10px;
}
.learning-list,
.catalog {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 13px;
}
.course h3 {
  color: var(--ink);
}
.course b {
  color: var(--g);
}
form {
  max-width: 650px;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 22px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 15px;
}
label {
  display: flex;
  flex-direction: column;
  gap: 6px;
}
input,
select,
textarea {
  padding: 10px;
  border: 1px solid var(--line);
  border-radius: 7px;
}
form button {
  grid-column: 1/-1;
  border: 0;
  background: var(--g);
  color: #fff;
  padding: 11px;
  border-radius: 8px;
}
#message {
  color: var(--g);
}
.recharge,
.tutor-setup {
  display: flex;
  gap: 12px;
  align-items: center;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 18px;
  margin: 20px 0;
}
.recharge div {
  margin-right: auto;
}
.recharge h2,
.recharge p {
  margin: 3px;
}
.recharge p,
#aiTutor > p {
  color: var(--muted);
  font-size: 12px;
}
.recharge button,
.tutor-setup button,
.secondary {
  border: 0;
  background: var(--g);
  color: #fff;
  padding: 11px 15px;
  border-radius: 8px;
}
.stagebar {
  padding: 12px;
  background: #e8f2ec;
  color: var(--g);
  border-radius: 8px;
  margin: 16px 0;
}
.chat-messages {
  min-height: 260px;
  max-height: 420px;
  overflow: auto;
  background: #fff;
  border: 1px solid var(--line);
  padding: 18px;
  border-radius: 12px;
}
.chat-messages p {
  width: fit-content;
  max-width: 78%;
  margin: 8px 0;
  padding: 10px 12px;
  border-radius: 10px;
  overflow-wrap: anywhere;
  white-space: pre-wrap;
}
.chat-messages .student {
  margin-left: auto;
  background: var(--g);
  color: #fff;
}
.chat-messages .assistant {
  margin-right: auto;
  background: #eef2ef;
}
#chatForm {
  max-width: none;
  margin-top: 12px;
  display: flex;
  padding: 12px;
}
#chatForm textarea {
  flex: 1;
  min-height: 70px;
}
#chatForm button {
  grid-column: auto;
}
.question-image-tools {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 8px 12px 0;
}
.question-image-tools small {
  color: var(--muted);
}
.question-image-button {
  display: inline-flex;
  align-items: center;
  min-height: 38px;
  padding: 0 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--g);
  cursor: pointer;
}
.question-image-preview {
  display: flex;
  align-items: center;
  gap: 8px;
  margin: 8px 12px 0;
  padding: 8px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: #f7faff;
}
.question-image-preview[hidden] {
  display: none;
}
.question-image-preview img {
  width: 54px;
  height: 54px;
  border-radius: 8px;
  object-fit: cover;
}
.question-image-preview span {
  flex: 1;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.question-image-preview button {
  color: #52657c;
  background: #e8eef7;
}
.chat-message-image {
  display: block;
  width: min(220px, 100%);
  max-height: 180px;
  margin-bottom: 7px;
  border-radius: 8px;
  object-fit: cover;
}
.secondary {
  margin-top: 12px;
  background: #33483e;
}
.secondary:disabled {
  opacity: 0.4;
}

.report-download-button {
  width: 100%;
  margin-top: 10px;
  padding: 12px;
  color: #fff;
  font-weight: 700;
  background: linear-gradient(100deg, #315fe8, #24a994);
  border: 0;
  border-radius: 9px;
}

.report-price-note {
  display: block;
  margin-top: 8px;
  color: #71819a;
  font-size: 11px;
  line-height: 1.5;
}
@media (max-width: 700px) {
  body {
    display: block;
  }
  body > aside {
    height: auto;
    flex-direction: row;
    align-items: center;
  }
  body > aside nav {
    display: flex;
    margin: 0 0 0 auto;
  }
  body > aside nav a {
    display: none;
  }
  body > aside > button {
    margin: 0;
  }
  .stats,
  .catalog,
  .learning-list {
    grid-template-columns: 1fr;
  }
  main {
    padding: 25px 18px;
  }
  form {
    grid-template-columns: 1fr;
  }
  .recharge,
  .tutor-setup {
    align-items: stretch;
    flex-direction: column;
  }
}

.logo > span:last-child {
  display: grid;
  gap: 2px;
}

.logo small {
  color: #3971e8;
  font-size: 9px;
  letter-spacing: 1.5px;
}

body > aside nav a,
body > aside nav button {
  font-size: 14px;
}

.student-dashboard-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(310px, 360px);
  gap: 24px;
  align-items: start;
}

.student-dashboard-content {
  min-width: 0;
}

.student-content-section,
.rail-card {
  margin: 0 0 22px;
  padding: 24px;
  background: #fff;
  border: 1px solid #dce6f3;
  border-radius: 18px;
  box-shadow: 0 12px 32px rgba(30, 70, 135, 0.06);
}

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

.student-section-heading h2,
.rail-card h2 {
  margin: 4px 0 0;
  color: #153668;
  font-size: 21px;
}

.student-section-heading small,
.rail-card > small {
  color: #3971e8;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 1.6px;
}

.student-section-heading a {
  color: #2f68dc;
  font-size: 13px;
  text-decoration: none;
}

.section-description {
  margin: -7px 0 18px;
  color: #6a7d99;
}

.student-dashboard-layout .catalog,
.student-dashboard-layout .learning-list {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.student-course-card {
  display: flex;
  min-height: 220px;
  flex-direction: column;
  border-radius: 15px;
}

.student-course-card .generated-course-cover {
  min-height: 120px;
  margin: -18px -18px 18px;
  border-radius: 15px 15px 0 0;
}

.student-course-card small {
  color: #53729f;
  font-size: 12px;
}

.student-course-card h3 {
  margin: 15px 0 8px;
  font-size: 19px;
}

.student-course-card p {
  line-height: 1.65;
}

.course-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-top: auto;
  padding-top: 18px;
  border-top: 1px solid #e4ebf5;
}

.course-card-footer button,
.course-purchase-button,
.rail-action {
  padding: 10px 15px;
  color: #fff;
  font-weight: 700;
  text-decoration: none;
  background: #3971e8;
  border: 0;
  border-radius: 9px;
}

.course-purchase-button {
  display: inline-block;
}

.student-dashboard-rail {
  position: sticky;
  top: 22px;
}

.rail-price-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 15px 0;
  color: #71819a;
  border-bottom: 1px solid #e4ebf5;
}

.rail-price-row b {
  color: #183a70;
}

.rail-action {
  display: block;
  margin-top: 18px;
  text-align: center;
}

.study-calendar {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 5px;
}

.study-calendar > span {
  display: grid;
  min-height: 34px;
  color: #607390;
  font-size: 12px;
  place-items: center;
  border-radius: 9px;
}

.study-calendar .calendar-weekday {
  min-height: 25px;
  color: #9aa8bb;
}

.study-calendar .calendar-day {
  background: #f3f7fd;
}

.study-calendar .today {
  color: #245dce;
  font-weight: 800;
  box-shadow: inset 0 0 0 1px #3971e8;
}

.study-calendar .has-event {
  color: #fff;
  font-weight: 800;
  background: #55bca7;
}

.calendar-help {
  color: #7b8ba2;
  font-size: 12px;
}

.calendar-help i {
  display: inline-block;
  width: 8px;
  height: 8px;
  margin-right: 5px;
  background: #55bca7;
  border-radius: 50%;
}

.upcoming-lessons {
  display: grid;
  gap: 10px;
  margin-top: 16px;
}

.upcoming-lessons article {
  display: grid;
  grid-template-columns: 58px 1fr auto;
  gap: 12px;
  align-items: center;
  padding: 12px;
  background: #f3f7fd;
  border-radius: 12px;
}

.upcoming-lessons time,
.upcoming-lessons div {
  display: grid;
  gap: 3px;
}

.upcoming-lessons time {
  color: #71819a;
  font-size: 10px;
}

.upcoming-lessons time b,
.upcoming-lessons strong {
  color: #153668;
  font-size: 13px;
}

.upcoming-lessons a {
  color: #3971e8;
  font-size: 12px;
}

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

.teacher-update-card {
  display: grid;
  grid-template-columns: 58px 1fr auto;
  gap: 14px;
  align-items: center;
  padding: 14px;
  background: #f7faff;
  border-radius: 14px;
}

.teacher-update-card img,
.teacher-avatar-placeholder {
  display: grid;
  width: 58px;
  height: 58px;
  object-fit: cover;
  color: #fff;
  font-weight: 800;
  background: #4b7dea;
  place-items: center;
  border-radius: 16px;
}

.teacher-update-card h3,
.teacher-update-card p {
  margin: 3px 0;
}

.teacher-update-card p {
  overflow: hidden;
  color: #6a7d99;
  font-size: 13px;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.teacher-update-card a {
  color: #2f68dc;
  font-size: 13px;
  text-decoration: none;
}

.empty-state {
  grid-column: 1 / -1;
  color: #71819a;
}

.lesson-materials {
  margin-top: 16px;
  padding: 20px;
  background: #f5f8ff;
  border: 1px solid #dce6f3;
  border-radius: 14px;
}

.lesson-materials h3,
.lesson-materials p {
  margin: 4px 0;
}

.lesson-materials > div:first-child small {
  color: #3971e8;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 1.4px;
}

#lessonMaterials {
  display: grid;
  gap: 10px;
  margin-top: 14px;
}

#lessonMaterials .material-preview-trigger {
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: 12px;
  align-items: center;
  padding: 14px;
  color: #17335f;
  text-decoration: none;
  background: #fff;
  border: 1px solid #dce6f3;
  border-radius: 12px;
  box-shadow: none !important;
  cursor: pointer;
}

#lessonMaterials .material-preview-trigger > span {
  padding: 7px 10px;
  color: #fff;
  font-size: 12px;
  background: #3971e8;
  border-radius: 8px;
}

#lessonMaterials .material-preview-trigger div {
  display: grid;
  gap: 3px;
}

#lessonMaterials .material-preview-trigger small {
  color: #71819a;
}

#lessonMaterials .material-preview-trigger > strong {
  color: #3971e8;
  font-size: 13px;
}

.material-preview-dialog {
  width: min(1050px, calc(100vw - 36px));
  height: min(820px, calc(100vh - 36px));
  padding: 0;
  overflow: hidden;
  background: #f5f8fc;
  border: 1px solid #d7e3f2;
  border-radius: 20px;
  box-shadow: 0 30px 80px rgba(23, 51, 95, 0.22);
}

.material-preview-dialog::backdrop {
  background: rgba(15, 35, 67, 0.58);
  backdrop-filter: blur(4px);
}

.material-preview-heading,
.material-preview-actions {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 16px 20px;
  background: #fff;
}

.material-preview-heading {
  border-bottom: 1px solid #dce6f3;
}

.material-preview-heading h2,
.material-preview-heading p {
  margin: 3px 0;
}

.material-preview-heading small {
  color: #3971e8;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 1.4px;
}

#closeMaterialPreview {
  width: 38px;
  height: 38px;
  padding: 0;
  color: #315fd5 !important;
  font-size: 25px;
  background: #edf3fc !important;
  border: 0;
  border-radius: 10px;
  box-shadow: none !important;
}

#materialPreviewFrame {
  display: block;
  width: calc(100% - 32px);
  height: calc(100% - 150px);
  margin: 16px;
  background: #fff;
  border: 1px solid #dce6f3;
  border-radius: 12px;
}

.material-preview-actions {
  border-top: 1px solid #dce6f3;
}

.material-preview-actions p {
  margin: 0;
  color: #6c7e99;
  font-size: 13px;
}

#downloadMaterialFile {
  padding: 10px 16px;
  color: #fff;
  font-weight: 700;
  text-decoration: none;
  background: #315fe8;
  border-radius: 9px;
}

@media (max-width: 1100px) {
  .student-dashboard-layout {
    grid-template-columns: 1fr;
  }

  .student-dashboard-rail {
    position: static;
  }
}

@media (max-width: 760px) {
  .student-dashboard-layout .catalog,
  .student-dashboard-layout .learning-list {
    grid-template-columns: 1fr;
  }

  .teacher-update-card {
    grid-template-columns: 50px 1fr;
  }

  .teacher-update-card a {
    grid-column: 2;
  }
}