/* ============================================================
   BuildCertificates — Design System
   Dark premium theme matching Build ecosystem
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&display=swap');

/* ── CSS Variables ── */
:root {
  --bg-primary: #0a0b14;
  --bg-secondary: #12131f;
  --bg-card: rgba(255,255,255,0.03);
  --bg-card-hover: rgba(255,255,255,0.06);
  --border: rgba(255,255,255,0.08);
  --border-focus: rgba(196,165,90,0.5);
  --text-primary: #f0f0f5;
  --text-secondary: #a0a0b8;
  --text-muted: #666680;
  --accent: #C5A55A;
  --accent-hover: #D4B76A;
  --accent-glow: rgba(197,165,90,0.15);
  --gradient-start: #C5A55A;
  --gradient-end: #8B6F2E;
  --navy: #1B365D;
  --success: #22c55e;
  --error: #ef4444;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 4px 24px rgba(0,0,0,0.3);
}

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

body {
  font-family: 'Inter', -apple-system, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--accent-hover); }

/* ── Navbar ── */
.navbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 2rem;
  background: rgba(10,11,20,0.9);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.navbar-brand {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 8px;
}

.navbar-brand:hover { color: var(--accent); }

.navbar-links { display: flex; gap: 1.5rem; }
.navbar-links a {
  color: var(--text-secondary);
  font-size: 0.875rem;
  font-weight: 500;
  transition: color 0.2s;
}
.navbar-links a:hover { color: var(--accent); }

/* ── Hero ── */
.hero-banner {
  text-align: center;
  padding: 3rem 2rem 2rem;
  background: linear-gradient(135deg, rgba(197,165,90,0.08), rgba(27,54,93,0.08));
}

.hero-banner h1 {
  font-size: 2.2rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--gradient-start), #f0e68c);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 0.5rem;
}

.hero-banner p {
  color: var(--text-secondary);
  font-size: 1.05rem;
  max-width: 600px;
  margin: 0 auto;
}

/* ── Tab Bar ── */
.tab-bar {
  display: flex;
  justify-content: center;
  gap: 0;
  padding: 1rem 2rem 0;
}

.tab-btn {
  padding: 0.6rem 1.5rem;
  background: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border);
  font-family: inherit;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
}

.tab-btn:first-child { border-radius: var(--radius-sm) 0 0 var(--radius-sm); }
.tab-btn:last-child { border-radius: 0 var(--radius-sm) var(--radius-sm) 0; }

.tab-btn.active {
  background: var(--accent);
  color: #0a0b14;
  border-color: var(--accent);
}

/* ── App Container ── */
.app-container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  padding: 1.5rem 2rem 3rem;
  max-width: 1400px;
  margin: 0 auto;
}

/* ── Form Panel ── */
.form-panel {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.form-section {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
}

.form-section-header h3 {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 0.75rem;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
  margin-bottom: 0.75rem;
}

.form-row:last-child { margin-bottom: 0; }
.form-row.full { grid-template-columns: 1fr; }
.form-row.triple { grid-template-columns: 1fr 1fr 1fr; }

.form-group label {
  display: block;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-muted);
  margin-bottom: 0.3rem;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.form-group input,
.form-group select,
.form-group textarea {
  width: 100%;
  padding: 0.55rem 0.75rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-family: inherit;
  font-size: 0.875rem;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.form-group select {
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%23666680' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 10px center;
  padding-right: 30px;
}

.color-row {
  display: flex;
  gap: 0.5rem;
  align-items: center;
}

.color-row input[type="color"] {
  width: 42px;
  height: 36px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  padding: 2px;
  background: var(--bg-secondary);
}

/* ── Buttons ── */
.btn-download {
  width: 100%;
  padding: 0.85rem;
  background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
  color: #0a0b14;
  border: none;
  border-radius: var(--radius);
  font-family: inherit;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.3s;
  box-shadow: 0 4px 20px rgba(197,165,90,0.25);
}

.btn-download:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 28px rgba(197,165,90,0.35);
}

.btn-download:active { transform: translateY(0); }

/* ── Bulk Upload Area ── */
.bulk-panel { display: none; }
.bulk-panel.active { display: block; }
.single-panel.active { display: flex; flex-direction: column; gap: 1rem; }

.csv-upload-area {
  background: var(--bg-card);
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  padding: 2rem;
  text-align: center;
  cursor: pointer;
  transition: all 0.3s;
}

.csv-upload-area:hover {
  border-color: var(--accent);
  background: var(--accent-glow);
}

.csv-upload-area h3 { color: var(--accent); margin-bottom: 0.5rem; }
.csv-upload-area p { color: var(--text-muted); font-size: 0.85rem; }

.csv-preview {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem;
  max-height: 200px;
  overflow-y: auto;
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.csv-preview table {
  width: 100%;
  border-collapse: collapse;
}

.csv-preview th, .csv-preview td {
  padding: 0.3rem 0.5rem;
  border-bottom: 1px solid var(--border);
  text-align: left;
}

.csv-preview th { color: var(--accent); font-weight: 600; }

/* ── Preview Panel ── */
.preview-panel {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  position: sticky;
  top: 80px;
  max-height: calc(100vh - 100px);
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

.preview-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border);
}

.preview-header h3 {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.preview-body {
  flex: 1;
  padding: 1rem;
  overflow-y: auto;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #f8f6f2;
  min-height: 400px;
}

.preview-cert {
  width: 100%;
  aspect-ratio: 11 / 8.5;
  background: #ffffff;
  border-radius: 4px;
  box-shadow: 0 2px 12px rgba(0,0,0,0.15);
  padding: 24px;
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.preview-cert .border-frame {
  position: absolute;
  inset: 8px;
  border: 2px solid var(--accent);
  border-radius: 2px;
  pointer-events: none;
}

.preview-cert .inner-frame {
  position: absolute;
  inset: 14px;
  border: 1px solid var(--accent);
  border-radius: 1px;
  pointer-events: none;
}

.preview-cert .cert-ornament {
  font-size: 14px;
  color: var(--accent);
  margin-bottom: 6px;
}

.preview-cert .cert-title {
  font-size: 16px;
  font-weight: 700;
  letter-spacing: 3px;
  color: #1B365D;
  margin-bottom: 4px;
}

.preview-cert .cert-divider {
  width: 120px;
  height: 1px;
  background: var(--accent);
  margin: 8px 0;
}

.preview-cert .cert-presented {
  font-size: 9px;
  color: #888;
  margin-bottom: 8px;
}

.preview-cert .cert-recipient {
  font-size: 24px;
  font-weight: 700;
  color: #1B365D;
  margin-bottom: 4px;
  text-align: center;
  padding: 0 20px;
}

.preview-cert .cert-name-line {
  width: 200px;
  height: 1px;
  background: var(--accent);
  margin-bottom: 10px;
}

.preview-cert .cert-course {
  font-size: 10px;
  color: #555;
  text-align: center;
  padding: 0 30px;
  margin-bottom: 10px;
}

.preview-cert .cert-date {
  font-size: 9px;
  color: #888;
  margin-bottom: 12px;
}

.preview-cert .cert-footer {
  display: flex;
  justify-content: center;
  align-items: flex-end;
  gap: 40px;
  width: 80%;
}

.preview-cert .cert-issuer {
  text-align: center;
}

.preview-cert .cert-sig-line {
  width: 100px;
  height: 1px;
  background: #999;
  margin-bottom: 4px;
}

.preview-cert .cert-issuer-name {
  font-size: 9px;
  font-weight: 600;
  color: #333;
}

.preview-cert .cert-issuer-title {
  font-size: 7px;
  color: #888;
}

/* ── Toast ── */
.toast {
  position: fixed;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  font-weight: 500;
  opacity: 0;
  transition: all 0.3s;
  z-index: 1000;
  pointer-events: none;
}

.toast.show {
  transform: translateX(-50%) translateY(0);
  opacity: 1;
}

.toast.success { background: var(--success); color: #fff; }
.toast.error { background: var(--error); color: #fff; }

/* ── Footer ── */
.site-footer {
  text-align: center;
  padding: 2rem;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 0.8rem;
}

.site-footer a { color: var(--text-secondary); }
.site-footer a:hover { color: var(--accent); }

/* ── Responsive ── */
@media (max-width: 900px) {
  .app-container {
    grid-template-columns: 1fr;
    padding: 1rem;
  }
  .preview-panel {
    position: static;
    max-height: 500px;
  }
  .hero-banner h1 { font-size: 1.6rem; }
  .navbar { padding: 0.75rem 1rem; }
  .tab-bar { padding: 0.75rem 1rem 0; }
}

@media (max-width: 600px) {
  .form-row { grid-template-columns: 1fr; }
  .form-row.triple { grid-template-columns: 1fr; }
  .navbar-links { gap: 1rem; }
  .navbar-links a { font-size: 0.8rem; }
}