:root {
    --color-bg: #ffffff;
    --color-text: #111;
    --color-accent: #333;
    --color-light-gray: #f0f0f0;
    --color-border: #e0e0e0;
    --bard-color-brand-text-gradient-stop-1: #8ec5fc;
    --bard-color-brand-text-gradient-2: #e0c3fc;
    --bard-color-brand-text-gradient-stop-3: #ff9a9e;
    --gem-sys-color--surface: #ffffff;
    --logo-gradient-stop-4: #d96570;
    --logo-gradient-stop-5: #fad0c4;
  }
  @media (prefers-color-scheme: dark) {
    :root {
      --color-bg: #101215;
      --color-text: #cdcdcd;
      --color-border: #333;
      --color-accent: #eee;
      --color-light-gray: #2c2c2c;
      --bard-color-brand-text-gradient-stop-1: #9ec9e7;
      --bard-color-brand-text-gradient-stop-2: #b592e3;
      --bard-color-brand-text-gradient-stop-3: #ffabae;
      --gem-sys-color--surface: #cccccc;
      --logo-gradient-stop-4: #eb8c92;
      --logo-gradient-stop-5: #ffdfd4;
    }
    .card-front, .card-back {
      background-color: #2c2c2c;
    }
    .card-back {
      color: #ececec;
    }
    .download-btn {
      background-color: #555;
      color: #fff;
    }
    .download-btn:hover {
      background-color: #666;
    }
  }
  * {
    box-sizing: border-box;
  }
  body {
    margin: 0;
    font-family: 'Inter', sans-serif;
    background: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
  }
  header {
    border-bottom: 1px solid var(--color-border);
    padding: 1.5rem 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
  }
    .logo {
      font-size: 1.5rem;
      text-decoration: none;
      padding: 0.5rem 1rem;
      font-family: "Poppins", sans-serif;
      font-weight: 400;
      background: linear-gradient(74deg,
        var(--bard-color-brand-text-gradient-stop-1) 0%,
        var(--bard-color-brand-text-gradient-stop-2) 9%,
        var(--bard-color-brand-text-gradient-stop-3) 20%,
        var(--logo-gradient-stop-4) 24%,
        var(--bard-color-brand-text-gradient-stop-2) 35%,
        var(--bard-color-brand-text-gradient-stop-1) 44%,
        var(--bard-color-brand-text-gradient-stop-2) 50%,
        var(--bard-color-brand-text-gradient-stop-3) 56%,
        var(--gem-sys-color--surface) 75%,
        var(--gem-sys-color--surface) 100%
      );
      background-size: 400% 400%;
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      animation: gradientMovement 30s ease-in-out infinite;
  }
  nav {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 0.8rem;
  }
  nav a {
    text-decoration: none;
    color: var(--color-text);
    transition: color 0.2s;
    padding: 0.25rem 0.25rem;
    font-family: "Poppins", sans-serif;
    font-weight: 200;
    font-style: normal;
    font-size: 0.85rem;
  }
  nav a:hover {
    color: var(--color-accent);
  }
  main {
    max-width: 960px;
    margin: 3rem auto;
    padding: 0 1rem;
    text-align: center;
  }
  .app-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
    padding: 0 1rem;
  }

  /* --- Card Flip Styles --- */
  .card {
    background-color: transparent;
    aspect-ratio: 1200 / 630;
    perspective: 1000px;
    cursor: pointer;
  }
  .card-inner {
    position: relative;
    width: 100%;
    height: 100%;
    transition: transform 0.6s;
    transform-style: preserve-3d;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
    border-radius: 12px;
  }
  .card.is-flipped .card-inner {
    transform: rotateY(180deg);
  }
  .card-front, .card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
    border-radius: 12px;
    overflow: hidden;
    background: var(--color-light-gray);
  }
  .card-front {
    color: white;
    display: flex;
    z-index: 2;
    align-items: flex-end; /* 텍스트를 하단에 정렬 */
  }
  .card-front img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    z-index: 1; /* 이미지가 뒤에 오도록 */
  }
  .card-front-text {
      position: relative;
      width: 100%;
      padding: 1rem;
      z-index: 2; /* 텍스트가 이미지 위에 오도록 */
      background: linear-gradient(to top, rgba(0,0,0,0.7) 0%, rgba(0,0,0,0.4) 40%, transparent 100%);
      text-align: left;
  }
  .card-front-text h3 {
      margin: 0 0 0 0;
      font-size: 1rem;
  }
  .card-front-text p {
      margin: 0;
      font-size: 0.85rem;
      opacity: 0.9;
  }
  .card-back {
    transform: rotateY(180deg);
    z-index: 1;
    padding: 2rem;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
  }
  .card-back h3 {
      margin: 1rem 0 0.5rem 0;
      font-size: 1.2rem;
  }
  .card-back p {
      margin: 0 0 1.5rem 0;
      font-size: 0.8rem;
      flex-grow: 1;
  }
  .download-buttons {
      display: flex;
      gap: 0.75rem;
      margin: 0 0 1rem 0;
  }
  .download-btn {
      display: inline-block;
      padding: 0.6rem 1rem;
      border-radius: 8px;
      background-color: #3d3d3d;
      color: white;
      text-decoration: none;
      font-weight: 600;
      font-size: 0.7rem;
      transition: background-color 0.2s, transform 0.2s;
  }

  .detail-btn{
    background-color: #484848;
    color: rgb(255, 255, 255);
  }
  .download-btn:hover {
      background-color: #000;
      transform: translateY(-2px);
  }
  
  /* --- End Card Flip Styles --- */

  footer {
    margin-top: 5rem;
    text-align: center;
    padding: 2rem;
    font-size: 0.75rem;
    color: #999;
    border-top: 1px solid var(--color-border);
  }
  .back-to-top {
    display: block;
    margin-top: 3rem;
    text-align: center;
    font-size: 0.9rem;
    color: #999;
    text-decoration: none;
  }
  .menu-toggle {
    display: none;
    font-size: 1.5rem;
    cursor: pointer;
    background: none;
    border: none;
    color: var(--color-text);
  }
  @media (max-width: 800px) {
    .menu-toggle { display: block; }
    nav { display: none; flex-direction: column; align-items: center; width: 100%; order: 1; }
    nav.show { display: flex; }
  }

  @keyframes gradientMovement {
    0%   { background-position: 10% 40%; }
    15%  { background-position: 60% 30%; }
    30%  { background-position: 30% 70%; }
    45%  { background-position: 90% 60%; }
    60%  { background-position: 20% 20%; }
    75%  { background-position: 70% 90%; }
    90%  { background-position: 40% 50%; }
    100% { background-position: 10% 40%; }
  }