/* ---------- MODERN PREMIUM THEME FOR FORMULA VIEWER ---------- */

:root {
  --bg-main: #070d18;
  --bg-card: #0f1c2e;
  --bg-element: #16263f;
  --border-color: rgba(255, 255, 255, 0.08);
  --accent-blue: #3aa0ff;
  --accent-gradient: linear-gradient(135deg, #00d2ff, #0072ff);
  --text-main: #f1f5f9;
  --text-muted: #8a99ad;
}

body {
  margin: 0;
  background: var(--bg-main);
  color: var(--text-main);
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  -webkit-tap-highlight-color: transparent;
  -webkit-touch-callout: none;
  -webkit-user-select: none;
  user-select: none;
}

input, textarea {
  -webkit-user-select: text;
  user-select: text;
}

/* ---------- TOPBAR ---------- */
.topbar {
  background: rgba(15, 28, 46, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  padding: 16px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
}

.topbar h2 {
  font-size: 1.1rem;
  margin: 0;
  font-weight: 700;
  letter-spacing: 0.5px;
}

.back {
  color: #fff;
  text-decoration: none;
  background: var(--accent-gradient);
  padding: 8px 14px;
  border-radius: 8px;
  font-size: 0.85rem;
  font-weight: 600;
  box-shadow: 0 4px 12px rgba(0, 210, 255, 0.25);
  transition: transform 0.2s ease;
}

.back:active {
  transform: scale(0.95);
}

main {
  padding: 16px;
  max-width: 700px;
  margin: 0 auto;
}

/* ---------- FILTERS (Uniform Grid Layout) ---------- */
.filters {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
  margin-bottom: 20px;
}

@media (min-width: 600px) {
  .filters {
    grid-template-columns: repeat(5, 1fr);
  }
}

select, .filters button {
  width: 100%;
  padding: 12px;
  border-radius: 10px;
  border: 1px solid var(--border-color);
  background: var(--bg-card);
  color: var(--text-main);
  font-size: 0.9rem;
  outline: none;
  box-sizing: border-box;
  text-align: center;
  transition: all 0.2s ease;
}

select:focus, select:hover {
  border-color: var(--accent-blue);
  background: var(--bg-element);
}

.filters button {
  cursor: pointer;
  background: var(--accent-gradient);
  font-weight: 700;
  grid-column: span 2;
  box-shadow: 0 4px 15px rgba(0, 114, 255, 0.3);
}

@media (min-width: 600px) {
  .filters button {
    grid-column: span 1;
  }
}

.filters button:active {
  transform: scale(0.97);
}

/* ---------- FORMULA LIST & CARDS ---------- */
.formula-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.formula-card {
  background: var(--bg-card);
  padding: 14px 16px;
  border-radius: 14px;
  border: 1px solid var(--border-color);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.3);
  transition: transform 0.2s ease, border-color 0.2s ease;
}

.formula-card:hover {
  border-color: rgba(0, 210, 255, 0.3);
}

.formula-head {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-bottom: 10px;
  font-weight: 600;
  letter-spacing: 0.5px;
  text-transform: uppercase;
}

/* ---------- TEXT FORMULA CARD ---------- */
.formula-text {
  background: var(--bg-element);
  padding: 12px 14px;
  border-radius: 10px;
  font-size: 0.95rem;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  border: 1px solid transparent;
  transition: 0.2s ease;
}

.formula-text:hover {
  border-color: rgba(58, 160, 255, 0.4);
  background: #1a2d4a;
}

.click-hint {
  font-size: 0.75rem;
  color: var(--accent-blue);
  font-weight: 600;
  background: rgba(58, 160, 255, 0.1);
  padding: 4px 8px;
  border-radius: 6px;
  white-space: nowrap;
}

/* ---------- IMAGE & MEDIA BUTTON ---------- */
.formula-media-box {
  background: var(--bg-element);
  padding: 14px;
  border-radius: 10px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 12px;
  border: 1px dashed rgba(58, 160, 255, 0.4);
  font-weight: 600;
  font-size: 0.9rem;
  transition: 0.2s ease;
}

.formula-media-box:hover {
  background: #1a2d4a;
  border-color: var(--accent-blue);
}

/* ---------- PDF BUTTON ---------- */
.pdf-btn {
  margin-top: 4px;
  display: block;
  background: linear-gradient(135deg, #ff5e62, #ff9966);
  padding: 12px 16px;
  border-radius: 10px;
  color: #fff;
  border: none;
  width: 100%;
  text-align: left;
  font-weight: 700;
  font-size: 0.9rem;
  cursor: pointer;
  box-shadow: 0 4px 15px rgba(255, 94, 98, 0.3);
  transition: transform 0.2s ease;
}

.pdf-btn:active {
  transform: scale(0.98);
}

/* ---------- TEXT MODAL POPUP STYLES ---------- */
.text-modal-overlay {
  display: none;
  position: fixed;
  top: 0; left: 0; width: 100%; height: 100%;
  background: rgba(5, 10, 18, 0.85);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  justify-content: center;
  align-items: center;
  z-index: 999;
  padding: 16px;
  box-sizing: border-box;
}

.text-modal-card {
  background: var(--bg-card);
  border-radius: 16px;
  width: 100%;
  max-width: 500px;
  padding: 20px;
  border: 1px solid var(--border-color);
  box-shadow: 0 15px 35px rgba(0, 0, 0, 0.6);
  animation: modalScale 0.25s ease;
}

@keyframes modalScale {
  from { transform: scale(0.9); opacity: 0; }
  to { transform: scale(1); opacity: 1; }
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-weight: 700;
  font-size: 1rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 12px;
  margin-bottom: 14px;
}

.modal-header button {
  background: rgba(255, 255, 255, 0.05);
  border: none;
  color: var(--text-muted);
  font-size: 14px;
  padding: 6px 10px;
  border-radius: 8px;
  cursor: pointer;
  transition: 0.2s;
}

.modal-header button:hover {
  background: rgba(255, 255, 255, 0.1);
  color: #fff;
}

.modal-body {
  background: var(--bg-element);
  padding: 16px;
  border-radius: 10px;
  font-size: 1rem;
  line-height: 1.6;
  white-space: pre-wrap;
  word-break: break-word;
  max-height: 60vh;
  overflow-y: auto;
  color: #e2e8f0;
}