:root {
  --primary: #0077FF;
  --primary-dark: #005FCC;
  --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --surface: rgba(255, 255, 255, 0.85);
  --surface-solid: #ffffff;
  --text: #1a1a2e;
  --text-light: #555;
  --shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
  --radius: 20px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: var(--bg-gradient);
  min-height: 100vh;
  color: var(--text);
  display: flex;
  justify-content: center;
  align-items: flex-start;
  padding: 20px;
  backdrop-filter: blur(10px);
}

#app {
  width: 100%;
  max-width: 700px;
  background: var(--surface);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-radius: 30px;
  box-shadow: var(--shadow), 0 0 0 1px rgba(255,255,255,0.2);
  overflow: hidden;
  padding: 20px;
  margin: 20px 0;
}

.header { text-align: center; margin-bottom: 30px; padding-bottom: 20px; border-bottom: 1px solid rgba(0,0,0,0.05); }
.header h1 { font-size: 2.2rem; font-weight: 700; background: linear-gradient(135deg, #667eea, #0077FF); -webkit-background-clip: text; -webkit-text-fill-color: transparent; margin-bottom: 5px; }
.subtitle { font-size: 0.9rem; color: #888; }

.card {
  background: var(--surface-solid);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 20px;
  box-shadow: var(--shadow);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  transition: transform var(--transition), box-shadow var(--transition);
}
.card:hover { transform: translateY(-2px); box-shadow: 0 10px 30px rgba(0,0,0,0.1); }

.form-group { margin-bottom: 15px; }
.input-field {
  width: 100%; padding: 12px 16px; border: 2px solid #e0e0e0; border-radius: 14px;
  font-size: 1rem; outline: none; transition: border-color var(--transition);
  background: #f9f9ff; color: var(--text);
}
.input-field:focus { border-color: var(--primary); }
.textarea { resize: vertical; }

.image-upload-group { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.btn-icon {
  background: none; border: 2px dashed #ccc; border-radius: 12px; padding: 8px 12px;
  cursor: pointer; display: flex; align-items: center; color: #888; transition: all var(--transition);
}
.btn-icon:hover { border-color: var(--primary); color: var(--primary); }
.image-name { font-size: 0.85rem; color: #666; max-width: 150px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.image-preview { max-width: 100px; max-height: 100px; border-radius: 8px; object-fit: cover; margin-top: 8px; }

.btn-primary {
  background: linear-gradient(135deg, #0077FF, #005FCC);
  color: white; border: none; padding: 12px 24px; border-radius: 14px;
  font-size: 1rem; font-weight: 600; cursor: pointer; width: 100%;
  transition: transform var(--transition), box-shadow var(--transition);
  box-shadow: 0 4px 15px rgba(0,119,255,0.3); letter-spacing: 0.5px;
}
.btn-primary:hover { transform: scale(1.02); box-shadow: 0 6px 20px rgba(0,119,255,0.4); }
.btn-primary:active { transform: scale(0.98); }
.status-message { margin-top: 10px; font-size: 0.9rem; text-align: center; color: #ff4d4f; }

.post-item { transition: all var(--transition); }
.post-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 10px; }
.nickname { font-weight: 600; color: var(--primary); }
.post-date { font-size: 0.8rem; color: #999; }
.post-content { margin-bottom: 10px; word-break: break-word; white-space: pre-wrap; }
.post-image { max-width: 100%; max-height: 400px; border-radius: 12px; margin-top: 10px; object-fit: cover; cursor: pointer; }
.post-actions { display: flex; gap: 20px; margin-top: 15px; align-items: center; border-top: 1px solid #f0f0f0; padding-top: 15px; }
.action-btn { display: inline-flex; align-items: center; gap: 5px; background: none; border: none; cursor: pointer; color: #666; font-size: 0.95rem; transition: color var(--transition); }
.action-btn.liked { color: #ff3366; }
.action-btn:hover { color: var(--primary); }

.comments-section { margin-top: 15px; border-top: 1px solid #f0f0f0; padding-top: 15px; }
.comment-item { background: #f8f9ff; border-radius: 10px; padding: 8px 12px; margin-bottom: 8px; }
.comment-nickname { font-weight: 600; font-size: 0.85rem; color: var(--primary-dark); margin-right: 6px; }
.comment-content { font-size: 0.9rem; color: #333; }
.comment-date { font-size: 0.75rem; color: #aaa; margin-left: 8px; }
.comment-form { display: flex; gap: 8px; margin-top: 10px; }
.comment-form input { flex: 1; padding: 8px 12px; border-radius: 10px; border: 1px solid #ddd; outline: none; font-size: 0.9rem; }
.comment-form button { padding: 8px 16px; background: var(--primary); color: white; border: none; border-radius: 10px; cursor: pointer; font-weight: 600; }

.loading { text-align: center; padding: 20px; color: #888; }
.btn-secondary { display: block; margin: 10px auto; background: transparent; border: 1px solid var(--primary); color: var(--primary); padding: 8px 20px; border-radius: 20px; cursor: pointer; transition: all var(--transition); }
.btn-secondary:hover { background: var(--primary); color: white; }
footer { text-align: center; margin-top: 20px; color: #aaa; font-size: 0.8rem; }

@media (max-width: 600px) {
  body { padding: 10px; }
  #app { margin: 10px 0; padding: 15px; border-radius: 20px; }
  .header h1 { font-size: 1.8rem; }
  .post-actions { gap: 10px; }
}