:root {
  --navy: #07152f;
  --navy2: #0b2147;
  --blue: #2563eb;
  --cyan: #28d7ff;
  --ink: #0b1830;
  --muted: #6c7b91;
  --paper: #f4f7fc;
  --line: #dce5f0;
  --white: #fff;
  --font: Inter, "PingFang SC", "Microsoft YaHei", sans-serif;
}
* {
  box-sizing: border-box;
}
html {
  scroll-behavior: smooth;
}
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font);
  line-height: 1.65;
}
button,
input,
select,
textarea {
  font: inherit;
}
button {
  cursor: pointer;
}
a {
  text-decoration: none;
  color: inherit;
}
.container {
  width: min(1180px, calc(100% - 40px));
  margin: auto;
}
.header {
  position: sticky;
  top: 0;
  z-index: 50;
  height: 72px;
  background: rgba(7, 21, 47, 0.97);
  color: #fff;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(16px);
}
.nav {
  position: relative;
  height: 100%;
  display: flex;
  align-items: center;
  gap: 35px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 11px;
  font-weight: 800;
  white-space: nowrap;
}
.brand b {
  color: var(--cyan);
}
.logo {
  display: flex;
  gap: 2px;
  align-items: end;
  transform: skewX(-17deg);
}
.logo i {
  width: 7px;
  height: 20px;
  background: linear-gradient(var(--cyan), var(--blue));
  border-radius: 2px;
}
.logo i:nth-child(2) {
  height: 25px;
}
.logo i:nth-child(3) {
  height: 30px;
}
.nav nav {
  display: flex;
  align-items: center;
  gap: 4px;
  margin-left: auto;
}
.nav nav a,
.nav nav button {
  border: 0;
  background: transparent;
  padding: 8px 12px;
  color: #aebcd2;
  font-size: 14px;
}
.nav nav a:hover,
.nav nav button:hover,
.nav nav .active {
  color: #fff;
}
.nav nav .nav-login {
  margin-left: 8px;
  border-radius: 5px;
  color: #07152f;
  background: var(--cyan);
  font-weight: 700;
}
.nav nav .nav-login.logged-in {
  color: #07152f;
}
.account {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 12px;
  color: #94a8c5;
}
.small-btn,
.account a {
  border: 1px solid rgba(40, 215, 255, 0.35);
  background: transparent;
  color: var(--cyan);
  padding: 6px 10px;
  border-radius: 5px;
}
.menu-btn {
  display: none;
  color: #fff;
  background: none;
  border: 0;
  font-size: 23px;
}
.hero {
  position: relative;
  overflow: hidden;
  color: #fff;
  background:
    radial-gradient(
      circle at 82% 10%,
      rgba(40, 215, 255, 0.14),
      transparent 30%
    ),
    linear-gradient(135deg, #07152f, #0c2650);
  padding: 52px 0 42px;
}
.grid-bg {
  position: absolute;
  inset: 0;
  opacity: 0.5;
  background-image:
    linear-gradient(rgba(64, 142, 226, 0.1) 1px, transparent 1px),
    linear-gradient(90deg, rgba(64, 142, 226, 0.1) 1px, transparent 1px);
  background-size: 52px 52px;
  mask-image: linear-gradient(to right, #000, transparent);
}
.hero-inner {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 42px;
}
.eyebrow,
.section-no {
  display: block;
  color: #59dffc;
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 2.1px;
}
.hero h1 {
  font-size: clamp(42px, 6vw, 68px);
  line-height: 1.1;
  letter-spacing: -3px;
  margin: 13px 0;
}
.hero p {
  max-width: 630px;
  margin: 0;
  color: #a7b8d1;
  font-size: 17px;
}
.teacher-credentials {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  max-width: 760px;
  margin-top: 16px;
}
.teacher-credentials strong {
  margin-right: 3px;
  color: #fff;
  font-size: 13px;
}
.teacher-credentials span {
  padding: 6px 10px;
  border: 1px solid rgba(89, 223, 252, 0.22);
  border-radius: 4px;
  color: #b7c9df;
  background: rgba(255, 255, 255, 0.04);
  font-size: 11px;
}
.hero-stat {
  display: flex;
  align-items: baseline;
  gap: 7px;
  margin-top: 13px;
}
.hero-stat strong {
  font-size: 25px;
  line-height: 1;
  color: #fff;
}
.hero-stat span {
  font-size: 10px;
  color: #8ea6c6;
}
.hero-support {
  flex: 0 0 356px;
  display: grid;
  grid-template-columns: 1fr 126px;
  align-items: center;
  gap: 18px;
  padding: 15px 16px 15px 20px;
  border: 1px solid rgba(89, 223, 252, 0.22);
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.055);
  box-shadow: 0 18px 45px rgba(0, 0, 0, 0.16);
}
.support-copy > span {
  display: block;
  margin-bottom: 5px;
  color: var(--cyan);
  font-size: 8px;
  font-weight: 800;
  letter-spacing: 1.5px;
}
.support-copy > strong {
  display: block;
  color: #fff;
  font-size: 18px;
}
.support-copy > p {
  margin-top: 4px;
  color: #9db2ce;
  font-size: 11px;
  line-height: 1.6;
}
.support-qr {
  padding: 7px;
  border-radius: 7px;
  background: #fff;
}
.support-qr img {
  width: 100%;
  height: 96px;
  object-fit: contain;
}
.support-qr small {
  display: block;
  margin-top: 3px;
  color: #71839a;
  font-size: 8px;
  text-align: center;
}
.learning {
  padding: 32px 0 80px;
}
.track-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 22px;
  margin-top: -20px;
  position: relative;
  z-index: 2;
}
.track {
  position: relative;
  text-align: left;
  border: 1px solid #d9e5f2;
  background: #fff;
  padding: 24px 28px;
  border-radius: 12px;
  box-shadow: 0 18px 45px rgba(28, 64, 113, 0.08);
  overflow: hidden;
  color: var(--ink);
  transition: 0.25s;
}
.track:after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(90deg, var(--cyan), var(--blue));
  transform: scaleX(0);
  transform-origin: left;
  transition: 0.3s;
}
.track:hover,
.track.active {
  transform: translateY(-5px);
  border-color: #72b5eb;
}
.track.active:after {
  transform: scaleX(1);
}
.track.ai {
  background: linear-gradient(145deg, #0c2854, #07172f);
  border-color: #244b77;
  color: #fff;
}
.track-icon {
  position: absolute;
  right: 27px;
  top: 22px;
  font: 700 38px monospace;
  color: #dce8f5;
}
.track.ai .track-icon {
  color: #183b68;
}
.track small {
  font-weight: 800;
  letter-spacing: 1.6px;
  color: #258acb;
}
.track h2 {
  font-size: 25px;
  margin: 8px 0;
}
.track p {
  margin: 0 0 17px;
  color: var(--muted);
  max-width: 500px;
}
.track.ai p {
  color: #93a8c5;
}
.track i {
  font-style: normal;
  font-size: 12px;
  font-weight: 700;
  color: #1388d0;
}
.library-head {
  display: flex;
  align-items: end;
  justify-content: space-between;
  margin: 28px 0 18px;
}
.library-head h2 {
  font-size: 34px;
  margin: 7px 0 0;
  letter-spacing: -1px;
}
.filters {
  display: flex;
  gap: 7px;
}
.filter {
  border: 1px solid var(--line);
  background: #fff;
  color: #66778e;
  padding: 8px 14px;
  border-radius: 6px;
  font-size: 12px;
}
.filter.active {
  background: var(--navy2);
  border-color: var(--navy2);
  color: #fff;
}
.resource-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}
.resource {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 10px;
  overflow: hidden;
  transition: 0.25s;
}
.resource:hover {
  transform: translateY(-4px);
  box-shadow: 0 18px 40px rgba(23, 60, 106, 0.1);
}
.resource-cover {
  height: 175px;
  position: relative;
  display: grid;
  place-items: center;
  background: linear-gradient(145deg, #e9f2fb, #d4e4f4);
}
.resource.video .resource-cover {
  background: radial-gradient(circle, #17487d, #081b39);
}
.doc-icon {
  width: 64px;
  height: 78px;
  border-radius: 5px;
  background: #fff;
  box-shadow: 0 12px 30px rgba(21, 80, 133, 0.15);
  display: grid;
  place-items: center;
  color: #e1494b;
  font-weight: 900;
  font-size: 13px;
  position: relative;
}
.doc-icon:after {
  content: "";
  position: absolute;
  right: 0;
  top: 0;
  border-style: solid;
  border-width: 0 0 15px 15px;
  border-color: transparent transparent #d5e3ef transparent;
}
.play-icon {
  width: 68px;
  height: 68px;
  border: 1px solid rgba(40, 215, 255, 0.7);
  border-radius: 50%;
  display: grid;
  place-items: center;
  color: #07152f;
  background: var(--cyan);
  font-size: 25px;
  padding-left: 4px;
  box-shadow: 0 0 35px rgba(40, 215, 255, 0.25);
}
.access {
  position: absolute;
  left: 13px;
  top: 13px;
  background: rgba(6, 20, 43, 0.82);
  color: #d5e3f7;
  font-size: 9px;
  padding: 5px 8px;
  border-radius: 3px;
}
.type {
  position: absolute;
  right: 13px;
  bottom: 11px;
  color: #54728f;
  font: 700 10px monospace;
}
.video .type {
  color: #78a5cc;
}
.resource-info {
  padding: 20px;
}
.resource-info h3 {
  font-size: 17px;
  line-height: 1.45;
  margin: 0 0 8px;
  min-height: 49px;
}
.resource-info p {
  color: var(--muted);
  font-size: 12px;
  margin: 0;
  min-height: 39px;
}
.resource-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-top: 1px solid #edf1f6;
  margin-top: 16px;
  padding-top: 14px;
  font-size: 10px;
  color: #8b99ac;
}
.open-btn {
  border: 0;
  background: none;
  color: #137fc5;
  font-weight: 800;
}
.empty {
  text-align: center;
  border: 1px dashed #bfd0e2;
  background: #fff;
  padding: 70px 20px;
  border-radius: 10px;
  color: var(--muted);
}
.empty div {
  width: 55px;
  height: 55px;
  margin: auto;
  border-radius: 50%;
  display: grid;
  place-items: center;
  background: #eaf3fb;
  color: #1b8bcd;
  font-size: 27px;
}
.empty h3 {
  color: var(--ink);
  margin: 15px 0 2px;
}
.modal,
.viewer {
  position: fixed;
  inset: 0;
  z-index: 100;
  background: rgba(3, 12, 27, 0.76);
  backdrop-filter: blur(8px);
  display: grid;
  place-items: center;
}
.modal[hidden],
.viewer[hidden] {
  display: none;
}
.modal-card {
  position: relative;
  background: #fff;
  border-radius: 12px;
  padding: 38px;
  width: min(440px, calc(100% - 30px));
  box-shadow: 0 30px 90px rgba(0, 0, 0, 0.35);
}
.close {
  position: absolute;
  right: 17px;
  top: 13px;
  border: 0;
  background: none;
  font-size: 24px;
  color: #789;
}
.dark {
  color: #187dbd;
}
.modal-card h2 {
  font-size: 28px;
  margin: 8px 0;
}
.modal-card > p {
  font-size: 13px;
  color: var(--muted);
}
label {
  display: block;
  font-size: 12px;
  font-weight: 700;
  margin-top: 24px;
}
input,
select,
textarea {
  display: block;
  width: 100%;
  margin-top: 7px;
  border: 1px solid #ccd8e5;
  border-radius: 6px;
  padding: 11px 12px;
  background: #fff;
}
.primary {
  width: 100%;
  border: 0;
  border-radius: 6px;
  padding: 12px;
  margin-top: 18px;
  color: #06152d;
  background: linear-gradient(90deg, var(--cyan), #67a1ff);
  font-weight: 800;
}
.form-msg {
  min-height: 20px;
  color: #d33;
  font-size: 12px;
  margin-top: 7px;
}
.viewer {
  display: block;
  background: #050d1b;
}
.viewer-bar {
  height: 64px;
  color: #fff;
  background: #091a37;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 25px;
  border-bottom: 1px solid #1d3960;
}
.viewer-bar div {
  display: flex;
  align-items: center;
  gap: 12px;
}
.viewer-bar span {
  font-size: 9px;
  padding: 4px 7px;
  background: #1d4673;
  color: var(--cyan);
}
.close-viewer {
  border: 1px solid #436181;
  background: transparent;
  color: #d9e7f7;
  border-radius: 5px;
  padding: 7px 12px;
}
.viewer-body {
  height: calc(100vh - 64px);
  display: grid;
  place-items: center;
}
.viewer-body iframe,
.viewer-body video {
  width: 100%;
  height: 100%;
  border: 0;
}
.viewer-body video {
  max-width: 1200px;
  max-height: calc(100vh - 85px);
}
footer {
  background: #040e20;
  color: #8799b3;
  padding: 24px 0;
  font-size: 11px;
}
footer .container {
  display: flex;
  justify-content: space-between;
}
@media (max-width: 900px) {
  .nav nav {
    display: none;
  }
  .nav nav.open {
    position: absolute;
    top: calc(100% + 1px);
    right: 0;
    z-index: 60;
    min-width: 230px;
    display: flex;
    align-items: stretch;
    flex-direction: column;
    gap: 3px;
    padding: 14px;
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 0 0 8px 8px;
    background: #07152f;
    box-shadow: 0 18px 40px rgba(0, 0, 0, 0.24);
  }
  .nav nav.open a,
  .nav nav.open button {
    width: 100%;
    margin: 0;
    text-align: left;
  }
  .nav nav.open .nav-login {
    margin-top: 7px;
    text-align: center;
  }
  .menu-btn {
    display: block;
    margin-left: auto;
  }
  .track-grid {
    grid-template-columns: 1fr;
  }
  .resource-grid {
    grid-template-columns: 1fr 1fr;
  }
  .hero-inner {
    align-items: stretch;
    flex-direction: column;
    gap: 24px;
  }
  .hero-support {
    width: min(420px, 100%);
    flex-basis: auto;
  }
  .library-head {
    align-items: start;
    gap: 22px;
    flex-direction: column;
  }
}
@media (max-width: 600px) {
  .container {
    width: calc(100% - 28px);
  }
  .header {
    height: 64px;
  }
  .brand {
    font-size: 14px;
  }
  .logo i {
    height: 16px;
    width: 6px;
  }
  .logo i:nth-child(2) {
    height: 20px;
  }
  .logo i:nth-child(3) {
    height: 24px;
  }
  .account > span {
    display: none;
  }
  .hero {
    padding: 38px 0 32px;
  }
  .hero h1 {
    font-size: 40px;
    letter-spacing: -2px;
  }
  .hero p {
    font-size: 14px;
  }
  .hero-support {
    grid-template-columns: 1fr 112px;
    gap: 14px;
    padding: 14px;
  }
  .support-copy > p {
    font-size: 10px;
  }
  .support-qr img {
    height: 84px;
  }
  .learning {
    padding-top: 24px;
  }
  .track {
    padding: 25px 22px;
  }
  .track h2 {
    font-size: 21px;
  }
  .library-head {
    margin-top: 24px;
  }
  .teacher-credentials { gap: 6px; }
  .teacher-credentials strong { width: 100%; }
  .resource-grid {
    grid-template-columns: 1fr;
  }
  .viewer-bar {
    padding: 0 12px;
  }
  .viewer-bar strong {
    max-width: 190px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }
  footer .container {
    gap: 10px;
    flex-direction: column;
    text-align: center;
  }
}