:root {
  color-scheme: light;
  --ink: #152033;
  --muted: #647084;
  --line: rgba(34, 55, 83, 0.12);
  --paper: #ffffff;
  --soft: #f3f8fb;
  --blue: #2377ff;
  --cyan: #34c4d7;
  --green: #1bbf8d;
  --orange: #ff9e43;
  --shadow: 0 24px 70px rgba(28, 65, 106, 0.18);
  font-family: "PingFang SC", "Microsoft YaHei", "Segoe UI", Arial, sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: #f7fbfd;
}

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

.site-header {
  position: fixed;
  top: 16px;
  left: 50%;
  z-index: 20;
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  width: min(1120px, calc(100% - 32px));
  height: 64px;
  padding: 0 10px 0 16px;
  border: 1px solid rgba(255, 255, 255, 0.62);
  border-radius: 32px;
  background: rgba(255, 255, 255, 0.72);
  box-shadow: 0 18px 50px rgba(35, 77, 120, 0.12);
  backdrop-filter: blur(18px);
  transform: translateX(-50%);
}

.site-header.is-solid {
  background: rgba(255, 255, 255, 0.94);
  border-color: var(--line);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-width: 0;
  font-weight: 800;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border-radius: 13px;
  color: #fff;
  background: linear-gradient(135deg, var(--blue), var(--green));
  box-shadow: 0 10px 26px rgba(35, 119, 255, 0.24);
}

.brand-text {
  white-space: nowrap;
}

.site-nav {
  justify-self: center;
  display: flex;
  gap: 28px;
  color: #425169;
  font-size: 15px;
}

.site-nav a {
  transition: color 0.2s ease;
}

.site-nav a:hover {
  color: var(--blue);
}

.header-action,
.primary-action,
.secondary-action {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 20px;
  border-radius: 999px;
  font-weight: 700;
  white-space: nowrap;
}

.header-action,
.primary-action {
  color: #fff;
  background: linear-gradient(135deg, #176cff, #13bfa5);
  box-shadow: 0 14px 34px rgba(35, 119, 255, 0.24);
}

.secondary-action {
  border: 1px solid var(--line);
  color: #20304a;
  background: rgba(255, 255, 255, 0.72);
}

.section-band {
  position: relative;
  overflow: hidden;
}

.hero {
  min-height: 760px;
  padding: 128px 24px 64px;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.78), rgba(247, 251, 253, 0.92)),
    url("./assets/campus-bg.png") center top / cover no-repeat;
}

.hero-media {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 82% 18%, rgba(255, 214, 102, 0.34), transparent 26%),
    radial-gradient(circle at 22% 78%, rgba(19, 191, 165, 0.18), transparent 30%);
  pointer-events: none;
}

.hero-inner {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1fr) 520px;
  gap: 54px;
  align-items: center;
  width: min(1120px, 100%);
  margin: 0 auto;
}

.eyebrow {
  margin: 0 0 14px;
  color: var(--blue);
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0;
  text-transform: uppercase;
}

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

h1 {
  margin-bottom: 20px;
  font-size: clamp(54px, 8vw, 104px);
  line-height: 0.98;
  letter-spacing: 0;
}

h2 {
  margin-bottom: 16px;
  font-size: clamp(32px, 4vw, 54px);
  line-height: 1.08;
  letter-spacing: 0;
}

h3 {
  margin-bottom: 10px;
  font-size: 22px;
  line-height: 1.25;
  letter-spacing: 0;
}

.hero-lead {
  max-width: 610px;
  color: #40506a;
  font-size: 22px;
  line-height: 1.65;
}

.hero-actions,
.contact-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 34px;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 132px));
  gap: 16px;
  margin: 42px 0 0;
}

.hero-stats div {
  padding: 18px;
  border: 1px solid rgba(255, 255, 255, 0.72);
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.66);
  box-shadow: 0 14px 36px rgba(42, 84, 125, 0.1);
}

.hero-stats dt {
  font-size: 26px;
  font-weight: 900;
}

.hero-stats dd {
  margin: 4px 0 0;
  color: var(--muted);
  font-size: 14px;
}

.phone-stage {
  position: relative;
  min-height: 590px;
}

.phone {
  position: absolute;
  border: 10px solid #152033;
  border-radius: 44px;
  background: #152033;
  box-shadow: var(--shadow);
}

.phone-main {
  right: 96px;
  top: 0;
  width: 310px;
  height: 626px;
}

.phone-side {
  right: 0;
  top: 92px;
  width: 250px;
  height: 500px;
  opacity: 0.92;
}

.phone-screen {
  position: relative;
  overflow: hidden;
  width: 100%;
  height: 100%;
  border-radius: 34px;
  background: #eef7ff url("./assets/card-bg.png") center top / cover no-repeat;
}

.app-hero {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 34px 18px 18px;
  color: #fff;
}

.app-hero span,
.app-hero strong {
  display: block;
}

.app-hero span {
  font-size: 13px;
  opacity: 0.86;
}

.app-hero strong {
  margin-top: 5px;
  font-size: 21px;
}

.app-hero button {
  width: 34px;
  height: 34px;
  border: 0;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.82);
}

.post-card {
  margin: 12px 14px;
  padding: 16px;
  border-radius: 22px;
  background: rgba(255, 255, 255, 0.92);
  box-shadow: 0 16px 38px rgba(34, 72, 106, 0.12);
}

.post-author {
  display: flex;
  align-items: center;
  gap: 10px;
}

.post-author strong,
.post-author small,
.message-row strong,
.message-row small {
  display: block;
}

.post-author small,
.message-row small {
  margin-top: 4px;
  color: var(--muted);
  font-size: 12px;
}

.avatar {
  flex: 0 0 auto;
  width: 38px;
  height: 38px;
  border-radius: 50%;
}

.avatar-blue {
  background: linear-gradient(135deg, #4384ff, #65d7ff);
}

.avatar-green {
  background: linear-gradient(135deg, #23c48f, #92e0ba);
}

.avatar-purple {
  background: linear-gradient(135deg, #7c67ff, #c3a9ff);
}

.avatar-orange {
  background: linear-gradient(135deg, #ff9f45, #ffd166);
}

.featured-post p {
  margin: 16px 0 12px;
  color: #33445b;
  line-height: 1.55;
}

.post-image {
  height: 118px;
  border-radius: 18px;
  background:
    linear-gradient(135deg, rgba(35, 119, 255, 0.32), rgba(27, 191, 141, 0.2)),
    url("./assets/campus-bg.png") center / cover no-repeat;
}

.post-actions {
  display: flex;
  justify-content: space-between;
  margin-top: 14px;
  color: #6c7788;
  font-size: 12px;
}

.compact-post {
  display: grid;
  gap: 8px;
}

.tag {
  width: fit-content;
  padding: 5px 10px;
  border-radius: 999px;
  color: #0e7b67;
  background: #dff8ef;
  font-size: 12px;
  font-weight: 800;
}

.tab-bar {
  position: absolute;
  left: 14px;
  right: 14px;
  bottom: 14px;
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  align-items: center;
  height: 62px;
  padding: 0 10px;
  border-radius: 24px;
  background: rgba(246, 252, 255, 0.94);
  box-shadow: 0 12px 30px rgba(23, 63, 96, 0.15);
}

.tab-bar img {
  width: 25px;
  height: 25px;
  justify-self: center;
  object-fit: contain;
}

.publish-dot {
  display: grid;
  place-items: center;
  justify-self: center;
  width: 46px;
  height: 46px;
  border-radius: 50%;
  color: #fff;
  background: linear-gradient(135deg, var(--blue), var(--green));
  font-size: 27px;
  font-weight: 300;
}

.chat-screen {
  padding: 34px 14px;
  background: #f0f8fd;
}

.chat-title {
  margin: 2px 4px 18px;
  font-size: 24px;
  font-weight: 900;
}

.message-row {
  display: flex;
  align-items: center;
  gap: 11px;
  margin-bottom: 12px;
  padding: 12px;
  border-radius: 18px;
  background: #fff;
}

.message-row.active {
  background: #e5f3ff;
}

.section {
  width: min(1120px, calc(100% - 40px));
  margin: 0 auto;
  padding: 92px 0;
}

.section-heading {
  max-width: 740px;
  margin-bottom: 34px;
}

.section-heading p,
.scene-copy p,
.security-panel p,
.contact-card p {
  color: var(--muted);
  font-size: 18px;
  line-height: 1.7;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
}

.feature-card {
  min-height: 292px;
  padding: 28px;
  border: 1px solid var(--line);
  border-radius: 24px;
  background: var(--paper);
  box-shadow: 0 18px 46px rgba(30, 72, 105, 0.08);
}

.feature-card p {
  color: var(--muted);
  line-height: 1.7;
}

.feature-icon {
  display: grid;
  place-items: center;
  width: 54px;
  height: 54px;
  margin-bottom: 24px;
  border-radius: 18px;
  background: #eef7ff;
}

.feature-icon::before {
  content: "";
  width: 28px;
  height: 28px;
  background: center / contain no-repeat;
}

.square-icon::before {
  background-image: url("./assets/tab-square-active.png");
}

.alumni-icon::before {
  background-image: url("./assets/tab-alumni-active.png");
}

.message-icon::before {
  background-image: url("./assets/tab-message-active.png");
}

.profile-icon::before {
  background-image: url("./assets/tab-profile-active.png");
}

.scene-section {
  display: grid;
  grid-template-columns: 0.8fr 1.2fr;
  gap: 42px;
  align-items: start;
}

.scene-list {
  display: grid;
  gap: 14px;
}

.scene-list article {
  display: grid;
  grid-template-columns: 70px 1fr;
  gap: 0 18px;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: 24px;
  background: #fff;
}

.scene-list span {
  grid-row: span 2;
  color: rgba(35, 119, 255, 0.34);
  font-size: 38px;
  font-weight: 900;
}

.scene-list p {
  margin-bottom: 0;
  color: var(--muted);
  line-height: 1.7;
}

.security {
  width: 100%;
  padding: 92px 20px;
  background:
    linear-gradient(90deg, rgba(7, 29, 56, 0.88), rgba(16, 91, 95, 0.78)),
    url("./assets/card-bg.png") center / cover no-repeat;
}

.security-panel {
  display: grid;
  grid-template-columns: 1fr 0.88fr;
  gap: 48px;
  align-items: center;
  width: min(1120px, 100%);
  margin: 0 auto;
  color: #fff;
}

.security-panel p {
  color: rgba(255, 255, 255, 0.76);
}

.security .eyebrow {
  color: #8cf0d7;
}

.check-list {
  display: grid;
  gap: 14px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.check-list li {
  position: relative;
  padding: 18px 18px 18px 48px;
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.12);
}

.check-list li::before {
  content: "";
  position: absolute;
  left: 19px;
  top: 22px;
  width: 13px;
  height: 8px;
  border-left: 2px solid #8cf0d7;
  border-bottom: 2px solid #8cf0d7;
  transform: rotate(-45deg);
}

.contact-section {
  padding-bottom: 96px;
}

.contact-card {
  padding: 52px;
  border: 1px solid rgba(35, 119, 255, 0.18);
  border-radius: 30px;
  background:
    linear-gradient(135deg, rgba(255, 255, 255, 0.94), rgba(237, 249, 246, 0.94)),
    url("./assets/campus-bg.png") right bottom / 58% auto no-repeat;
  box-shadow: var(--shadow);
}

.site-footer {
  display: flex;
  justify-content: space-between;
  width: min(1120px, calc(100% - 40px));
  margin: 0 auto;
  padding: 26px 0 42px;
  color: var(--muted);
  border-top: 1px solid var(--line);
}

@media (max-width: 980px) {
  .site-header {
    grid-template-columns: auto auto;
  }

  .site-nav {
    display: none;
  }

  .header-action {
    justify-self: end;
  }

  .hero {
    padding-top: 118px;
  }

  .hero-inner,
  .scene-section,
  .security-panel {
    grid-template-columns: 1fr;
  }

  .phone-stage {
    min-height: 620px;
  }

  .phone-main {
    left: 50%;
    right: auto;
    transform: translateX(-62%);
  }

  .phone-side {
    left: 50%;
    right: auto;
    transform: translateX(14%);
  }

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

@media (max-width: 640px) {
  .site-header {
    top: 10px;
    width: calc(100% - 20px);
    height: 58px;
    padding-left: 10px;
  }

  .brand-mark {
    width: 38px;
    height: 38px;
  }

  .brand-text {
    max-width: 120px;
    overflow: hidden;
    text-overflow: ellipsis;
  }

  .header-action {
    min-height: 38px;
    padding: 0 14px;
    font-size: 14px;
  }

  .hero {
    min-height: auto;
    padding: 94px 18px 34px;
  }

  .hero-lead {
    font-size: 18px;
  }

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

  .hero-actions .primary-action,
  .hero-actions .secondary-action {
    padding: 0 12px;
  }

  .hero-stats {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 8px;
    margin-top: 26px;
  }

  .hero-stats div {
    padding: 14px 10px;
  }

  .hero-stats dt {
    font-size: 21px;
  }

  .phone-stage {
    min-height: 350px;
    overflow: hidden;
  }

  .phone-main {
    left: 50%;
    width: 284px;
    height: 574px;
    transform: translateX(-54%) scale(0.66);
    transform-origin: top center;
  }

  .phone-side {
    left: 62%;
    top: 72px;
    width: 220px;
    height: 442px;
    opacity: 0.58;
    transform: translateX(0) scale(0.66);
    transform-origin: top left;
  }

  .section {
    width: calc(100% - 32px);
    padding: 68px 0;
  }

  .feature-grid {
    grid-template-columns: 1fr;
  }

  .feature-card {
    min-height: auto;
  }

  .scene-list article {
    grid-template-columns: 1fr;
  }

  .scene-list span {
    grid-row: auto;
    margin-bottom: 12px;
  }

  .security {
    padding: 68px 16px;
  }

  .contact-card {
    padding: 32px 22px;
    background:
      linear-gradient(135deg, rgba(255, 255, 255, 0.94), rgba(237, 249, 246, 0.94)),
      url("./assets/campus-bg.png") right bottom / 96% auto no-repeat;
  }

  .contact-actions {
    flex-direction: column;
  }

  .site-footer {
    display: grid;
    gap: 8px;
    width: calc(100% - 32px);
  }
}