*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
    :root {
      --green:       #3BB54A;
      --green-light: #EBF7ED;
      --green-dark:  #267A31;
      --text:        #1a1a1a;
      --muted:       #5a6472;
      --border:      #dde6e0;
      --surface:     #f7faf8;
      --error:       #c0392b;
    }
    body {
      font-family: 'Inter', sans-serif;
      background: var(--surface);
      color: var(--text);
      min-height: 100vh;
      display: flex;
      align-items: center;
      justify-content: center;
      padding: 2rem;
      -webkit-font-smoothing: antialiased;
    }
    .card {
      background: #fff;
      border-radius: 20px;
      border: 1px solid var(--border);
      padding: 2.5rem 2rem;
      max-width: 420px;
      width: 100%;
      text-align: center;
    }
    .logo {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      margin-bottom: 2rem;
      text-decoration: none;
    }
    .logo svg { width: 28px; height: 28px; }
    .logo-text {
      font-size: 22px;
      font-weight: 700;
      color: var(--text);
    }
    .logo-text span { color: var(--green); }
    h1 { font-size: 22px; font-weight: 500; margin-bottom: 0.4rem; }
    p { font-size: 14px; color: var(--muted); line-height: 1.6; margin-bottom: 1.5rem; }
    .code-input {
      width: 100%;
      padding: 14px 18px;
      font-size: 20px;
      font-family: 'SF Mono', 'Fira Code', monospace;
      font-weight: 600;
      letter-spacing: .12em;
      text-align: center;
      text-transform: uppercase;
      border: 2px solid var(--border);
      border-radius: 12px;
      outline: none;
      color: var(--text);
      background: var(--surface);
      transition: border-color 0.15s, box-shadow 0.15s;
      margin-bottom: 1rem;
    }
    .code-input:focus {
      border-color: var(--green);
      box-shadow: 0 0 0 3px rgba(59,181,74,0.12);
      background: #fff;
    }
    .error-msg {
      background: #fdf2f2;
      border: 1px solid rgba(192,57,43,0.2);
      border-radius: 8px;
      padding: 10px 14px;
      font-size: 13px;
      color: var(--error);
      margin-bottom: 1rem;
    }
    .btn {
      width: 100%;
      padding: 14px;
      background: var(--green);
      color: #fff;
      font-size: 16px;
      font-weight: 500;
      border: none;
      border-radius: 100px;
      cursor: pointer;
      transition: background 0.15s;
    }
    .btn:hover { background: var(--green-dark); }