:root {
      --bg: #181f2a;
      --card: #232c3b;
      --accent: #1de9b6;
      --accent2: #2979ff;
      --text: #f5f7fa;
      --text-muted: #b0b8c1;
      --border: #263043;
      --shadow: 0 6px 32px rgba(30, 41, 59, 0.18);
    }
    body {
      font-family: 'Inter', Arial, sans-serif;
      background: var(--bg);
      margin: 0;
      color: var(--text);
      min-height: 100vh;
    }
    header {
      background: var(--card);
      color: var(--text);
      padding: 1.2rem 2rem;
      display: flex;
      align-items: center;
      justify-content: space-between;
      box-shadow: var(--shadow);
      position: sticky;
      top: 0;
      z-index: 10;
    }
    header h1 {
      margin: 0;
      font-size: 2rem;
      letter-spacing: 1px;
      font-weight: 700;
      color: var(--accent);
    }
    nav a {
      color: var(--text-muted);
      text-decoration: none;
      margin-left: 2rem;
      font-weight: 600;
      font-size: 1.08rem;
      transition: color 0.2s;
      cursor: pointer;
      position: relative;
    }
    nav a.active, nav a:hover {
      color: var(--accent2);
    }
    .container {
      max-width: 1000px;
      margin: 2.5rem auto;
      background: var(--card);
      border-radius: 18px;
      box-shadow: var(--shadow);
      padding: 2.5rem 2.5rem 2rem 2.5rem;
      display: none;
      animation: fadein 0.5s;
    }
    .container.active {
      display: block;
    }
    @keyframes fadein {
      from { opacity: 0; transform: translateY(30px);}
      to { opacity: 1; transform: translateY(0);}
    }
    .hero {
      text-align: center;
      margin-bottom: 2.5rem;
    }
    .hero h2 {
      font-size: 2.3rem;
      color: var(--accent2);
      margin-bottom: 0.7rem;
      font-weight: 700;
    }
    .hero p {
      color: var(--text-muted);
      font-size: 1.15rem;
      margin-bottom: 2rem;
      font-weight: 500;
    }
    .btn {
      background: linear-gradient(90deg, var(--accent2), var(--accent));
      color: #fff;
      border: none;
      padding: 1rem 2.5rem;
      border-radius: 10px;
      font-size: 1.13rem;
      font-weight: 600;
      cursor: pointer;
      box-shadow: 0 2px 12px rgba(41,121,255,0.08);
      transition: background 0.2s, transform 0.1s;
      outline: none;
    }
    .btn:active {
      transform: scale(0.97);
    }
    .btn.secondary {
      background: var(--card);
      color: var(--accent2);
      border: 2px solid var(--accent2);
      margin-top: 1rem;
    }
    .features {
      display: flex;
      justify-content: space-between;
      margin: 2.5rem 0 1.5rem 0;
      gap: 2rem;
    }
    .feature-card {
      flex: 1;
      background: #1a2332;
      border-radius: 12px;
      padding: 1.5rem 1rem;
      text-align: center;
      box-shadow: 0 2px 12px rgba(41,121,255,0.05);
      border: 1.5px solid var(--border);
      transition: border 0.2s, box-shadow 0.2s;
    }
    .feature-card:hover {
      border: 1.5px solid var(--accent2);
      box-shadow: 0 4px 24px rgba(41,121,255,0.10);
    }
    .feature-card span {
      font-size: 2.3rem;
      display: block;
      margin-bottom: 0.7rem;
    }
    .feature-card strong {
      color: var(--accent);
      font-size: 1.13rem;
      font-weight: 700;
    }
    .feature-card p {
      color: var(--text-muted);
      font-size: 1rem;
      margin-top: 0.5rem;
    }
    /* Student Reviews */
    .reviews-section {
      margin: 2.5rem 0 1.5rem 0;
      text-align: center;
    }
    .reviews-title {
      color: var(--accent2);
      font-size: 1.5rem;
      font-weight: 700;
      margin-bottom: 1.5rem;
    }
    .reviews-list {
      display: flex;
      gap: 1.5rem;
      justify-content: center;
      flex-wrap: wrap;
    }
    .review-card {
      background: #1a2332;
      border-radius: 14px;
      padding: 1.3rem 1.1rem 1.1rem 1.1rem;
      box-shadow: 0 2px 12px rgba(41,121,255,0.05);
      border: 1.5px solid var(--border);
      width: 250px;
      text-align: left;
      display: flex;
      flex-direction: column;
      align-items: center;
      transition: border 0.2s, box-shadow 0.2s;
    }
    .review-card:hover {
      border: 1.5px solid var(--accent);
      box-shadow: 0 4px 24px rgba(29,233,182,0.10);
    }
    .review-photo {
      width: 60px;
      height: 60px;
      border-radius: 50%;
      object-fit: cover;
      margin-bottom: 0.7rem;
      border: 2.5px solid var(--accent2);
      box-shadow: 0 2px 8px rgba(41,121,255,0.10);
    }
    .review-name {
      font-weight: 700;
      color: var(--accent);
      margin-bottom: 0.3rem;
      font-size: 1.08rem;
    }
    .review-message {
      color: var(--text-muted);
      font-size: 1rem;
      margin-bottom: 0.2rem;
      text-align: center;
    }
    /* Contact Us */
    .contact-section {
      margin: 3rem 0 0 0;
      padding-top: 2rem;
      border-top: 1.5px solid var(--border);
      text-align: center;
    }
    .contact-title {
      color: var(--accent2);
      font-size: 1.4rem;
      font-weight: 700;
      margin-bottom: 1.2rem;
    }
    .contact-form {
      max-width: 400px;
      margin: 0 auto;
      display: flex;
      flex-direction: column;
      gap: 1.1rem;
      align-items: stretch;
    }
    .contact-form input, .contact-form textarea {
      padding: 0.8rem;
      border-radius: 8px;
      border: 1.5px solid var(--border);
      background: #181f2a;
      color: var(--text);
      font-size: 1.05rem;
      outline: none;
      transition: border 0.2s;
      resize: none;
    }
    .contact-form input:focus, .contact-form textarea:focus {
      border: 1.5px solid var(--accent2);
    }
    .contact-form button {
      margin-top: 0.5rem;
    }
    .contact-success {
      color: var(--accent);
      margin-top: 1rem;
      font-weight: 600;
      display: none;
    }
    /* Learning Circles */
    .circle-list {
      display: flex;
      flex-wrap: wrap;
      gap: 1.5rem;
      margin-bottom: 2rem;
      justify-content: center;
    }
    .circle-card {
      flex: 1 1 280px;
      background: #1a2332;
      border-radius: 12px;
      padding: 1.2rem 1rem;
      text-align: center;
      box-shadow: 0 2px 8px rgba(41,121,255,0.04);
      border: 1.5px solid var(--border);
      transition: border 0.2s, box-shadow 0.2s;
      position: relative;
      min-width: 260px;
      max-width: 320px;
      margin-bottom: 0.5rem;
      display: flex;
      flex-direction: column;
      justify-content: space-between;
    }
    .circle-card:hover {
      border: 1.5px solid var(--accent);
      box-shadow: 0 4px 24px rgba(29,233,182,0.10);
    }
    .circle-card h4 {
      margin: 0.5rem 0 0.2rem 0;
      color: var(--accent2);
      font-size: 1.18rem;
      font-weight: 700;
    }
    .circle-card p {
      font-size: 0.98rem;
      color: var(--text-muted);
      margin-bottom: 1.2rem;
    }
    .circle-card .circle-brief {
      font-size: 0.97rem;
      color: var(--accent);
      margin-bottom: 0.7rem;
      font-weight: 600;
    }
    .reputation {
      margin-top: 2rem;
      background: #1a2332;
      border-radius: 12px;
      padding: 1.2rem;
      text-align: center;
      border: 1.5px solid var(--border);
    }
    .badge {
      display: inline-block;
      background: linear-gradient(135deg, var(--accent2), var(--accent));
      color: #fff;
      border-radius: 50%;
      width: 52px;
      height: 52px;
      line-height: 52px;
      font-size: 1.7rem;
      margin: 0 0.7rem;
      box-shadow: 0 2px 8px rgba(29,233,182,0.10);
      border: 2px solid #fff2;
      transition: transform 0.15s;
    }
    .badge:hover {
      transform: scale(1.12) rotate(-6deg);
    }
    /* Circle Details */
    .circle-details {
      margin-top: 1rem;
    }
    .tabs {
      display: flex;
      border-bottom: 2px solid #232c3b;
      margin-bottom: 1.2rem;
    }
    .tab {
      padding: 0.8rem 1.7rem;
      cursor: pointer;
      color: var(--accent2);
      border: none;
      background: none;
      font-size: 1.13rem;
      border-bottom: 3px solid transparent;
      transition: border 0.2s, background 0.2s;
      font-weight: 600;
      outline: none;
    }
    .tab.active {
      border-bottom: 3px solid var(--accent);
      font-weight: bold;
      background: #1a2332;
      color: var(--accent);
    }
    .tab-content {
      padding: 1rem 0;
      min-height: 90px;
      animation: fadein 0.4s;
    }
    .resource-list, .discussion-list, .member-list {
      list-style: none;
      padding: 0;
      margin: 0;
    }
    .resource-list li, .discussion-list li, .member-list li {
      padding: 0.7rem 0.5rem;
      border-bottom: 1px solid #232c3b;
      color: var(--text-muted);
      font-size: 1.02rem;
    }
    .discussion-list li span {
      color: var(--accent2);
      font-weight: bold;
    }
    .member-list li {
      display: flex;
      align-items: center;
      gap: 0.7rem;
    }
    .member-avatar {
      width: 36px;
      height: 36px;
      border-radius: 50%;
      background: var(--accent2);
      color: #fff;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 1.13rem;
      font-weight: bold;
      box-shadow: 0 2px 8px rgba(41,121,255,0.10);
    }
    /* Wallet Modal */
    #walletModal {
      display:none;
      position:fixed;
      top:0;left:0;width:100vw;height:100vh;
      background:rgba(24,31,42,0.85);
      z-index:1000;
      align-items:center;
      justify-content:center;
      animation: fadein 0.3s;
    }
    #walletModal.active {
      display: flex;
      animation: fadein 0.3s;
    }
    #walletModal > div {
      background: #232c3b;
      padding:2.2rem 2.5rem 2rem 2.5rem;
      border-radius:18px;
      max-width:350px;
      margin:auto;
      box-shadow: 0 8px 32px rgba(29,233,182,0.18);
      text-align:center;
      position:relative;
      animation: popin 0.3s;
      color: var(--text);
    }
    @keyframes popin {
      from { transform: scale(0.8); opacity: 0; }
      to { transform: scale(1); opacity: 1; }
    }
    #closeModal {
      position:absolute;
      top:12px;right:16px;
      background:none;
      border:none;
      font-size:1.5rem;
      cursor:pointer;
      color:#b0b8c1;
      transition: color 0.2s;
    }
    #closeModal:hover { color: var(--accent2);}
    #walletModal img {
      border-radius:8px;
      border:1px solid #263043;
      background: #fff;
    }
    #walletModal input {
      width:90%;
      padding:0.7rem;
      border-radius:7px;
      border:1.5px solid #263043;
      margin-bottom:0.5rem;
      background: #181f2a;
      color: var(--text);
      font-size: 1.05rem;
      outline: none;
      transition: border 0.2s;
    }
    #walletModal input:focus {
      border:1.5px solid var(--accent2);
    }
    #walletModal .wallet-icons span {
      font-size:2.1rem;
      margin:0 0.6rem;
      vertical-align:middle;
      filter: grayscale(0.2);
      transition: filter 0.2s, transform 0.2s;
      cursor: pointer;
    }
    #walletModal .wallet-icons span:hover {
      filter: grayscale(0) brightness(1.2);
      transform: scale(1.15) rotate(-6deg);
    }
    #walletModal .btn {
      margin-top: 1.1rem;
    }
    /* Profile */
    .profile-header {
      display:flex;
      align-items:center;
      gap:1.5rem;
      margin-bottom: 1.5rem;
    }
    .profile-header .member-avatar {
      width:64px;height:64px;font-size:2rem;
      background: var(--accent);
      box-shadow: 0 2px 8px rgba(29,233,182,0.10);
    }
    .profile-header strong {
      color: var(--accent2);
    }
    .profile-header span {
      color: var(--text-muted);
      font-size: 1.01rem;
    }
    @media (max-width: 1100px) {
      .container { max-width: 98vw;}
    }
    @media (max-width: 900px) {
      .container { padding: 1.2rem; }
    }
    @media (max-width: 700px) {
      .features, .circle-list, .reviews-list { flex-direction: column; gap: 1.2rem;}
      .container { padding: 0.7rem;}
      .review-card { width: 100%; }
      .circle-card { min-width: 0; max-width: 100%; }
    }
    @media (max-width: 500px) {
      #walletModal > div {
        padding: 1rem 0.5rem;
        max-width: 95vw;
      }
    }