:root {
  --bg: #0f1613;
  --panel: #16201c;
  --panel-2: #1c2823;
  --border: #2a3833;
  --text: #eaf2ee;
  --text-dim: #9fb3ac;
  --accent: #3fae6a;
  --accent-hover: #4fc47c;
  --danger: #d9534f;
  --radius: 10px;
}

* { box-sizing: border-box; }

/* Guarantee the `hidden` attribute always wins, no matter what display value
   a more specific rule below sets on the same element (this was the root
   cause of both the stuck-modal bug and the stuck-login-screen bug). */
[hidden] { display: none !important; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
}

h1, h2, h3 { margin: 0 0 8px; }

.screen { min-height: 100vh; }

/* Login */
#login-screen {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
}
.login-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  width: 100%;
  max-width: 360px;
  text-align: center;
}
.subtitle { color: var(--text-dim); font-size: 14px; margin-bottom: 20px; }
.login-card input {
  width: 100%;
  padding: 10px 12px;
  margin-bottom: 12px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--text);
  font-size: 15px;
}
.login-card button { width: 100%; }

/* Buttons */
.primary-btn, .ghost-btn, .danger-btn {
  padding: 9px 16px;
  border-radius: 8px;
  border: 1px solid var(--border);
  font-size: 14px;
  cursor: pointer;
  font-weight: 600;
}
.primary-btn { background: var(--accent); color: #06170d; border-color: var(--accent); }
.primary-btn:hover { background: var(--accent-hover); }
.ghost-btn { background: transparent; color: var(--text); }
.ghost-btn:hover { background: var(--panel-2); }
.danger-btn { background: transparent; color: var(--danger); border-color: var(--danger); }
.danger-btn:hover { background: rgba(217,83,79,0.12); }
.error-text { color: var(--danger); font-size: 13px; margin-top: 8px; }

/* Topbar */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 28px;
  border-bottom: 1px solid var(--border);
}
.topbar-actions { display: flex; gap: 10px; }

/* Filter bar */
.filter-bar {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 16px 28px 0;
  flex-wrap: wrap;
}
.filter-label { color: var(--text-dim); font-size: 13px; }
.tag-chips { display: flex; flex-wrap: wrap; gap: 8px; }
.tag-chip {
  background: var(--panel-2);
  border: 1px solid var(--border);
  color: var(--text-dim);
  padding: 5px 12px;
  border-radius: 999px;
  font-size: 13px;
  cursor: pointer;
}
.tag-chip.active, .tag-chip:hover { border-color: var(--accent); color: var(--text); }

/* Study grid */
.study-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 18px;
  padding: 20px 28px 60px;
}
.study-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  transition: border-color 0.15s;
}
.study-card:hover { border-color: var(--accent); }
.study-card img {
  width: 100%;
  height: 150px;
  object-fit: cover;
  background: var(--panel-2);
  display: block;
}
.study-card .no-image {
  width: 100%;
  height: 150px;
  background: var(--panel-2);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-dim);
  font-size: 13px;
}
.study-card-body { padding: 12px 14px; }
.study-card-title { font-weight: 600; font-size: 15px; margin-bottom: 6px; }
.study-card-meta { color: var(--text-dim); font-size: 12px; margin-bottom: 8px; }
.study-card .tag-chips { gap: 5px; }
.study-card .tag-chip { padding: 2px 9px; font-size: 11px; cursor: default; }

.empty-state { text-align: center; color: var(--text-dim); padding: 60px 20px; }

/* Modals */
.modal-overlay[hidden] {
  display: none;
}
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.6);
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 40px 16px;
  overflow-y: auto;
  z-index: 50;
}
.modal-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  width: 100%;
  max-width: 520px;
  position: relative;
}
.modal-card label {
  display: block;
  font-size: 13px;
  color: var(--text-dim);
  margin: 14px 0 6px;
}
.modal-card label .hint { font-weight: 400; opacity: 0.8; }
.modal-card input[type="text"],
.modal-card input[type="file"],
.modal-card textarea {
  width: 100%;
  padding: 9px 11px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--text);
  font-size: 14px;
  font-family: inherit;
  resize: vertical;
}
.modal-actions { display: flex; justify-content: flex-end; gap: 10px; margin-top: 20px; }
.close-x {
  position: absolute;
  top: 14px;
  right: 16px;
  background: none;
  border: none;
  color: var(--text-dim);
  font-size: 22px;
  cursor: pointer;
  line-height: 1;
}
.close-x:hover { color: var(--text); }

.detail-card { max-width: 640px; }
.detail-meta { color: var(--text-dim); font-size: 13px; margin-bottom: 14px; }
.detail-image {
  width: 100%;
  border-radius: 8px;
  margin-bottom: 14px;
  border: 1px solid var(--border);
}
.detail-text { white-space: pre-wrap; color: var(--text); font-size: 14px; line-height: 1.5; margin-bottom: 8px; }

@media (max-width: 600px) {
  .topbar { padding: 16px; flex-direction: column; align-items: flex-start; gap: 10px; }
  .filter-bar, .study-grid { padding-left: 16px; padding-right: 16px; }
}