* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family:
    -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background-color: #f5f5f5;
  color: #333;
}

a {
  text-decoration: none;
  color: inherit;
}

button {
  font: inherit;
}

.header {
  background: #fff;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.nav-container {
  max-width: 1400px;
  margin: 0 auto;
  height: 72px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
}

.nav-left {
  display: flex;
  align-items: center;
  gap: 56px;
}

.logo-image {
  height: 40px;
  display: block;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 56px;
}

.nav-menu a {
  font-size: 18px;
  color: #333;
  position: relative;
  transition: color 0.3s;
}

.nav-menu a:hover,
.nav-menu a.active {
  color: #1e5bb8;
}

.nav-menu a.active::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: -22px;
  width: 24px;
  height: 3px;
  background: #1e5bb8;
  transform: translateX(-50%);
}

.nav-right {
  display: flex;
  align-items: center;
  gap: 18px;
}

.search-icon {
  width: 24px;
  height: 24px;
  cursor: pointer;
  color: #1e5bb8;
}

.login-btn {
  padding: 12px 28px;
  background: #1f56b1;
  color: #fff;
  border-radius: 24px;
  font-size: 14px;
  line-height: 1;
  transition: background 0.3s;
}

.login-btn:hover {
  background: #163f87;
}

.logout-form {
  display: inline-flex;
}

.logout-link {
  border: 0;
  background: transparent;
  color: #1e5bb8;
  cursor: pointer;
}

.flash-wrap {
  max-width: 1400px;
  margin: 14px auto 0;
  padding: 0 24px;
}

.flash {
  padding: 12px 18px;
  border-radius: 10px;
  font-size: 14px;
}

.flash-success {
  background: #e8f6ed;
  color: #227445;
}

.flash-error {
  background: #fdebec;
  color: #a73b41;
}

.banner {
  height: 516px;
  position: relative;
  overflow: hidden;
}

.banner-slide {
  display: none;
  position: absolute;
  inset: 0;
}

.banner-slide.active {
  display: block;
}

.banner-slide.theme-live {
  background:
    radial-gradient(circle at 78% 24%, rgba(255, 255, 255, 0.28), transparent 14%),
    radial-gradient(circle at 12% 48%, rgba(140, 255, 244, 0.28), transparent 12%),
    radial-gradient(circle at 96% 54%, rgba(255, 255, 255, 0.18), transparent 10%),
    linear-gradient(90deg, #58a8ff 0%, #57a6f8 24%, #3f8eef 52%, #58a8ff 100%);
}

.banner-slide.theme-video {
  background:
    radial-gradient(circle at 14% 70%, rgba(255, 255, 255, 0.55), transparent 22%),
    linear-gradient(120deg, #edf7ff 0%, #d4ebff 36%, #b8dafc 100%);
}

.banner-slide.theme-package {
  background:
    linear-gradient(90deg, rgba(26, 82, 218, 0.16), rgba(26, 82, 218, 0) 50%),
    linear-gradient(135deg, #1f58d4 0%, #2f7bff 100%);
}

.banner-content {
  max-width: 1400px;
  margin: 0 auto;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 74px;
  position: relative;
}

.banner-left {
  color: #fff;
  max-width: 760px;
}

.theme-video .banner-left {
  color: #2755ad;
}

.banner-brand {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 18px;
}

.brand-logo-image {
  height: 52px;
  display: block;
  filter: brightness(0) invert(1);
}

.theme-video .brand-logo-image {
  filter: none;
}

.brand-divider {
  font-size: 28px;
  color: rgba(255, 255, 255, 0.6);
}

.theme-video .brand-divider {
  color: rgba(39, 85, 173, 0.42);
}

.brand-sinorock {
  font-size: 34px;
  letter-spacing: 1px;
  color: rgba(255, 255, 255, 0.85);
}

.theme-video .brand-sinorock {
  color: rgba(39, 85, 173, 0.8);
}

.banner-title {
  font-size: 78px;
  font-weight: 700;
  line-height: 1.08;
  letter-spacing: 2px;
  margin-bottom: 26px;
  text-shadow: 0 4px 16px rgba(8, 39, 107, 0.18);
}

.theme-video .banner-title {
  text-shadow: 0 4px 14px rgba(255, 255, 255, 0.55);
}

.banner-subtitle {
  display: inline-flex;
  align-items: center;
  min-height: 64px;
  padding: 0 32px;
  border-radius: 34px;
  background: rgba(32, 74, 190, 0.95);
  color: #fff;
  font-size: 24px;
  box-shadow: 0 12px 24px rgba(30, 91, 184, 0.24);
}

.theme-video .banner-subtitle {
  background: rgba(39, 85, 173, 0.92);
}

.banner-right {
  position: relative;
  flex: 0 0 430px;
  height: 360px;
}

.banner-mascot {
  width: 280px;
  height: 280px;
  background: linear-gradient(135deg, #ffd93d 0%, #ffb800 100%);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  position: absolute;
  right: 40px;
  top: 18px;
}

.mascot-face {
  width: 200px;
  height: 200px;
  background: #fff;
  border-radius: 50%;
  position: relative;
}

.mascot-eyes {
  position: absolute;
  top: 60px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 30px;
}

.mascot-eye {
  width: 24px;
  height: 30px;
  background: #333;
  border-radius: 50%;
}

.mascot-nose {
  position: absolute;
  top: 95px;
  left: 50%;
  transform: translateX(-50%);
  width: 20px;
  height: 16px;
  background: #ffb800;
  border-radius: 50%;
}

.mascot-mouth {
  position: absolute;
  top: 115px;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 30px;
  border: 3px solid #333;
  border-top: none;
  border-radius: 0 0 60px 60px;
}

.mascot-ears {
  position: absolute;
  top: -20px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 100px;
}

.mascot-ear {
  width: 40px;
  height: 60px;
  background: #ffb800;
  border-radius: 50%;
}

.mascot-hat {
  position: absolute;
  top: -40px;
  left: 50%;
  transform: translateX(-50%);
  width: 80px;
  height: 50px;
  background: #1e5bb8;
  border-radius: 40px 40px 0 0;
}

.mascot-hat::after {
  content: "R";
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: #fff;
  font-weight: bold;
  font-size: 24px;
}

.video-cube {
  position: absolute;
  right: 12px;
  top: 12px;
  width: 320px;
  height: 320px;
  border-radius: 72px;
  background: linear-gradient(135deg, rgba(59, 140, 255, 0.92), rgba(38, 90, 220, 0.98));
  box-shadow: 0 40px 70px rgba(60, 125, 241, 0.22);
}

.video-cube::before,
.video-cube::after {
  content: "";
  position: absolute;
  border-radius: 68px;
  inset: 12px;
  border: 5px solid rgba(255, 255, 255, 0.2);
}

.video-cube::after {
  inset: 30px;
  border-radius: 54px;
  border-color: rgba(255, 255, 255, 0.3);
}

.video-cube-play {
  position: absolute;
  left: 50%;
  top: 50%;
  width: 116px;
  height: 116px;
  background: rgba(255, 255, 255, 0.2);
  border-radius: 36px;
  transform: translate(-50%, -50%);
}

.video-cube-play::before {
  content: "";
  position: absolute;
  left: 46px;
  top: 32px;
  border-top: 24px solid transparent;
  border-bottom: 24px solid transparent;
  border-left: 36px solid #fff;
}

.video-cube-orbit {
  position: absolute;
  border: 2px solid rgba(46, 110, 255, 0.72);
  border-radius: 50%;
}

.orbit-a {
  width: 360px;
  height: 180px;
  left: -20px;
  top: 72px;
  transform: rotate(16deg);
}

.orbit-b {
  width: 340px;
  height: 164px;
  left: -4px;
  top: 90px;
  transform: rotate(-22deg);
}

.video-cube-eye {
  position: absolute;
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: rgba(80, 131, 255, 0.95);
  border: 10px solid rgba(230, 245, 255, 0.92);
}

.eye-a {
  right: 72px;
  top: -18px;
}

.eye-b {
  right: 2px;
  top: 24px;
}

.study-stage {
  position: absolute;
  right: 0;
  bottom: 16px;
  width: 420px;
  height: 330px;
}

.stage-base {
  position: absolute;
  left: 48px;
  right: 0;
  bottom: 0;
  height: 118px;
  border-radius: 38px;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.32), rgba(135, 210, 255, 0.42));
  box-shadow: inset 0 -8px 0 rgba(70, 229, 255, 0.58);
}

.stage-laptop {
  position: absolute;
  left: 126px;
  top: 108px;
  width: 224px;
  height: 142px;
  border-radius: 22px;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.94), rgba(215, 238, 255, 0.8));
  transform: rotate(-8deg);
  box-shadow: 0 18px 44px rgba(16, 58, 149, 0.22);
}

.stage-laptop::before {
  content: "";
  position: absolute;
  left: -40px;
  top: 86px;
  width: 304px;
  height: 22px;
  border-radius: 0 0 22px 22px;
  background: rgba(219, 240, 255, 0.95);
}

.stage-book {
  position: absolute;
  left: 174px;
  top: 12px;
  width: 158px;
  height: 168px;
  border-radius: 34px 34px 18px 18px;
  background: rgba(255, 255, 255, 0.95);
  box-shadow: 0 16px 36px rgba(16, 58, 149, 0.24);
}

.stage-book::before,
.stage-book::after {
  content: "";
  position: absolute;
  top: 18px;
  width: 66px;
  height: 128px;
  border-radius: 18px;
  background: rgba(224, 239, 255, 0.95);
}

.stage-book::before {
  left: 10px;
}

.stage-book::after {
  right: 10px;
}

.stage-pen {
  position: absolute;
  right: 92px;
  top: 14px;
  width: 18px;
  height: 172px;
  border-radius: 12px;
  background: linear-gradient(180deg, #88ceff, #2b73ff);
  transform: rotate(14deg);
}

.banner-arrow {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 48px;
  height: 48px;
  border: 0;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.18);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: background 0.3s;
  color: #fff;
  font-size: 34px;
}

.banner-arrow:hover {
  background: rgba(255, 255, 255, 0.3);
}

.banner-arrow.prev {
  left: 24px;
}

.banner-arrow.next {
  right: 24px;
}

.theme-video .banner-arrow {
  background: rgba(31, 86, 177, 0.14);
  color: #1f56b1;
}

.theme-video .banner-arrow:hover {
  background: rgba(31, 86, 177, 0.24);
}

.banner-dots {
  position: absolute;
  bottom: 18px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 10px;
}

.banner-dot {
  width: 14px;
  height: 14px;
  border: 0;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.35);
  cursor: pointer;
  transition: width 0.3s, background 0.3s;
}

.banner-dot.active {
  width: 34px;
  background: #fff;
}

.section {
  max-width: 1400px;
  margin: 0 auto;
  padding: 52px 24px;
}

.section-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 36px;
}

.section-title {
  display: flex;
  align-items: baseline;
  gap: 12px;
}

.section-title h2 {
  font-size: 36px;
  font-weight: 600;
  color: #333;
}

.section-title span {
  font-size: 12px;
  color: #999;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.view-more {
  min-width: 144px;
  height: 52px;
  border: 1px solid #d7d7d7;
  border-radius: 26px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  font-size: 16px;
  color: #666;
  transition: 0.3s;
}

.view-more:hover {
  color: #1e5bb8;
  border-color: #1e5bb8;
}

.course-grid,
.public-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px 54px;
}

.course-card,
.public-card {
  background: #fff;
  overflow: hidden;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
  border: 1px solid #ececec;
  transition:
    transform 0.3s,
    box-shadow 0.3s;
}

.course-card:hover,
.public-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 28px rgba(0, 0, 0, 0.12);
}

.course-cover {
  height: 242px;
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.course-cover::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    repeating-linear-gradient(
      -45deg,
      rgba(255, 255, 255, 0.14) 0 14px,
      rgba(0, 0, 0, 0.55) 14px 28px
    );
  opacity: 0.7;
}

.course-cover.add {
  background: linear-gradient(135deg, #2955aa 0%, #224a96 100%);
}

.course-cover.yellow {
  background: linear-gradient(135deg, #ffc800 0%, #ffcc1f 100%);
}

.course-cover.blue {
  background: linear-gradient(135deg, #10b2df 0%, #20abd9 100%);
}

.course-cover.green {
  background: linear-gradient(135deg, #b7df4b 0%, #b0dc4a 100%);
}

.course-cover.add::after,
.course-cover.yellow::after,
.course-cover.blue::after,
.course-cover.green::after {
  content: "";
  position: absolute;
  inset: 14px 16px 18px;
  border-radius: 18px;
  background: rgba(36, 91, 186, 0.9);
}

.course-cover.yellow::after {
  background: #ffca14;
}

.course-cover.blue::after {
  background: #1ab0d9;
}

.course-cover.green::after {
  background: #b2dc4e;
}

.add-icon,
.course-tag {
  position: relative;
  z-index: 1;
}

.add-icon {
  font-size: 78px;
  color: #fff;
}

.course-tag {
  width: 100%;
  text-align: center;
  color: #fff;
  padding: 0 32px;
}

.course-tag-icon {
  position: absolute;
  left: 28px;
  top: -52px;
  font-size: 28px;
  font-weight: 700;
  color: rgba(255, 255, 255, 0.96);
}

.course-tag-title {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 250px;
  min-height: 54px;
  padding: 0 28px;
  background: #fff;
  border: 3px solid #222;
  border-radius: 999px;
  font-size: 30px;
  font-weight: 700;
  color: #0d67a8;
}

.course-cover.yellow .course-tag-title {
  color: #1b2d5d;
}

.course-cover.green .course-tag-title {
  color: #41622a;
}

.course-tag-subtitle {
  font-size: 46px;
  font-weight: 700;
  font-style: italic;
  line-height: 1.25;
  margin-top: 22px;
}

.course-info,
.public-info {
  padding: 22px 24px 24px;
}

.course-name,
.public-title {
  font-size: 18px;
  font-weight: 600;
  color: #333;
  margin-bottom: 14px;
  line-height: 1.5;
}

.course-meta,
.public-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
}

.course-desc,
.public-views {
  font-size: 14px;
  color: #777;
}

.course-arrow {
  width: 58px;
  height: 58px;
  border-radius: 50%;
  background: #1e5bb8;
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 42px;
  line-height: 1;
}

.course-views,
.public-views {
  display: flex;
  align-items: center;
  gap: 6px;
}

.public-section {
  background: #fff;
}

.public-cover {
  min-height: 260px;
  background:
    radial-gradient(circle at 88% 12%, rgba(255, 227, 97, 0.52), transparent 18%),
    linear-gradient(135deg, #f7f2da 0%, #efe6bc 100%);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 28px 24px;
}

.public-cover-content {
  flex: 1;
}

.public-cover-badge {
  display: inline-flex;
  align-items: center;
  min-height: 30px;
  padding: 0 12px;
  background: #1e5bb8;
  color: #fff;
  font-size: 12px;
  border-radius: 4px;
  margin-bottom: 14px;
}

.public-cover-title {
  font-size: 34px;
  line-height: 1.3;
  font-weight: 700;
  color: #111;
  margin-bottom: 12px;
}

.public-cover-summary {
  font-size: 14px;
  line-height: 1.7;
  color: #444;
}

.public-cover-teacher {
  width: 118px;
  min-height: 152px;
  border-radius: 12px;
  background: linear-gradient(135deg, #4a9eff 0%, #1e5bb8 100%);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 12px;
  font-size: 18px;
  font-weight: 600;
  line-height: 1.4;
}

.public-free {
  font-size: 16px;
  color: #1e5bb8;
  font-weight: 600;
}

.footer {
  background: #071a39;
  color: #fff;
  padding: 52px 0 24px;
}

.footer-content {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 36px;
}

.footer-left {
  display: flex;
  align-items: center;
  gap: 84px;
}

.footer-logo-image {
  height: 48px;
  display: block;
  filter: brightness(0) invert(1);
}

.footer-links {
  display: flex;
  gap: 42px;
  font-size: 18px;
}

.footer-center {
  text-align: center;
}

.footer-label {
  font-size: 18px;
  margin-bottom: 10px;
}

.footer-phone {
  font-size: 30px;
  font-weight: 500;
}

.footer-right {
  display: flex;
  gap: 26px;
}

.qr-code-wrap {
  width: 116px;
  height: 116px;
  padding: 8px;
  background: #fff;
}

.qr-code-image {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.footer-bottom {
  max-width: 1400px;
  margin: 46px auto 0;
  padding: 26px 24px 0;
  border-top: 1px solid rgba(255, 255, 255, 0.12);
  text-align: center;
  color: rgba(255, 255, 255, 0.72);
  font-size: 14px;
}

.float-buttons {
  position: fixed;
  right: 24px;
  bottom: 54px;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 16px;
  z-index: 1001;
}

.float-btn {
  width: 80px;
  height: 80px;
  border: 0;
  border-radius: 50%;
  background: #fff;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.12);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
}

.float-btn-icon {
  font-size: 30px;
  color: #333;
}

.float-qrs {
  width: 160px;
  padding: 14px;
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.98);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.12);
}

.float-qr-card + .float-qr-card {
  margin-top: 14px;
}

.float-qr-card img {
  display: block;
  width: 100%;
  background: #fff;
}

.float-qr-card span {
  display: block;
  margin-top: 8px;
  text-align: center;
  font-size: 14px;
  color: #333;
}

.empty-state {
  grid-column: 1 / -1;
  padding: 48px 0;
  text-align: center;
  color: #999;
  font-size: 16px;
}

@media (max-width: 1200px) {
  .nav-container,
  .banner-content,
  .section,
  .footer-content,
  .footer-bottom {
    max-width: 100%;
  }

  .banner-title {
    font-size: 58px;
  }

  .course-grid,
  .public-grid {
    gap: 24px;
  }

  .course-tag-subtitle {
    font-size: 34px;
  }
}

@media (max-width: 900px) {
  .nav-container,
  .nav-left,
  .nav-menu,
  .footer-content,
  .footer-left {
    flex-wrap: wrap;
  }

  .nav-container {
    height: auto;
    padding-top: 18px;
    padding-bottom: 18px;
  }

  .nav-menu {
    gap: 24px;
  }

  .nav-menu a.active::after {
    bottom: -10px;
  }

  .banner {
    height: auto;
  }

  .banner-slide,
  .banner-slide.active {
    position: relative;
    min-height: 440px;
  }

  .banner-content {
    flex-direction: column;
    justify-content: center;
    gap: 24px;
    padding: 48px 24px 64px;
  }

  .banner-right {
    flex: initial;
    width: 100%;
    max-width: 360px;
    height: 280px;
  }

  .banner-title {
    font-size: 42px;
  }

  .banner-subtitle {
    font-size: 18px;
    min-height: 52px;
    padding: 0 22px;
  }

  .brand-sinorock {
    font-size: 24px;
  }

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

  .section-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 18px;
  }

  .footer-content {
    flex-direction: column;
    align-items: flex-start;
  }

  .footer-right {
    justify-content: flex-start;
  }
}