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

    body {
      font-family: "Noto Sans JP", sans-serif;
      min-height: 100vh;
      display: flex;
      align-items: center;
      justify-content: center;
      background: linear-gradient(135deg, #0f172a 0%, #1e3a5f 40%, #2563eb 100%);
      overflow: hidden;
      position: relative;
    }

    /* 背景の装飾円 */
    body::before,
    body::after {
      content: "";
      position: absolute;
      border-radius: 50%;
      filter: blur(80px);
      opacity: 0.15;
      pointer-events: none;
    }
    body::before {
      width: 600px; height: 600px;
      background: #60a5fa;
      top: -200px; right: -100px;
    }
    body::after {
      width: 400px; height: 400px;
      background: #a78bfa;
      bottom: -150px; left: -80px;
    }

    .card {
      position: relative;
      z-index: 1;
      width: 100%;
      max-width: 420px;
      margin-inline: 1rem;
      padding: 2.5rem 2rem 2rem;
      background: rgba(255, 255, 255, 0.07);
      backdrop-filter: blur(20px) saturate(1.4);
      -webkit-backdrop-filter: blur(20px) saturate(1.4);
      border: 1px solid rgba(255, 255, 255, 0.12);
      border-radius: 1.25rem;
      box-shadow:
        0 8px 32px rgba(0, 0, 0, 0.3),
        inset 0 1px 0 rgba(255, 255, 255, 0.1);
      text-align: center;
      color: #f1f5f9;
      animation: fadeUp 0.6s ease-out both;
    }

    @keyframes fadeUp {
      from { opacity: 0; transform: translateY(24px); }
      to   { opacity: 1; transform: translateY(0); }
    }

    .icon-circle {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      width: 64px; height: 64px;
      margin-bottom: 1.25rem;
      border-radius: 50%;
      background: linear-gradient(135deg, #3b82f6, #6366f1);
      box-shadow: 0 4px 20px rgba(99, 102, 241, 0.4);
    }
    .icon-circle .material-icons-round {
      font-size: 2rem;
      color: #fff;
    }

    h1 {
      font-size: 1.35rem;
      font-weight: 700;
      letter-spacing: 0.04em;
      margin-bottom: 0.5rem;
    }

    .desc {
      font-size: 0.85rem;
      font-weight: 300;
      color: rgba(226, 232, 240, 0.7);
      line-height: 1.7;
      margin-bottom: 1.75rem;
    }

    .form {
      display: flex;
      flex-direction: column;
      gap: 0.625rem;
      text-align: start;
    }

    label {
      font-size: 0.8rem;
      font-weight: 500;
      color: rgba(203, 213, 225, 0.85);
      letter-spacing: 0.03em;
    }

    input[type="password"] {
      width: 100%;
      padding: 0.75rem 1rem;
      font-size: 1rem;
      font-family: inherit;
      color: #f8fafc;
      background: rgba(255, 255, 255, 0.08);
      border: 1px solid rgba(255, 255, 255, 0.15);
      border-radius: 0.625rem;
      outline: none;
      transition: border-color 0.2s, box-shadow 0.2s;
    }
    input[type="password"]::placeholder {
      color: rgba(148, 163, 184, 0.5);
    }
    input[type="password"]:focus {
      border-color: #60a5fa;
      box-shadow: 0 0 0 3px rgba(96, 165, 250, 0.25);
    }

    button {
      margin-top: 0.5rem;
      padding: 0.8rem;
      font-family: inherit;
      font-size: 0.95rem;
      font-weight: 700;
      letter-spacing: 0.05em;
      color: #fff;
      background: linear-gradient(135deg, #3b82f6, #6366f1);
      border: none;
      border-radius: 0.625rem;
      cursor: pointer;
      transition: transform 0.15s, box-shadow 0.2s, opacity 0.2s;
      box-shadow: 0 4px 16px rgba(59, 130, 246, 0.35);
    }
    button:hover {
      transform: translateY(-1px);
      box-shadow: 0 6px 24px rgba(59, 130, 246, 0.45);
    }
    button:active {
      transform: translateY(0);
      opacity: 0.9;
    }
    button:focus-visible {
      outline: 2px solid #93c5fd;
      outline-offset: 2px;
    }

    .error {
      margin-bottom: 0.75rem;
      padding: 0.6rem 0.75rem;
      font-size: 0.82rem;
      color: #fca5a5;
      background: rgba(239, 68, 68, 0.15);
      border: 1px solid rgba(239, 68, 68, 0.3);
      border-radius: 0.5rem;
      text-align: center;
    }

    .footer-text {
      margin-top: 1.75rem;
      font-size: 0.72rem;
      font-weight: 300;
      color: rgba(148, 163, 184, 0.5);
      letter-spacing: 0.06em;
    }

    @media (max-width: 480px) {
      .card {
        padding: 2rem 1.5rem 1.5rem;
        border-radius: 1rem;
      }
      .icon-circle { width: 56px; height: 56px; }
      .icon-circle .material-icons-round { font-size: 1.75rem; }
      h1 { font-size: 1.2rem; }
    }