:root {
  --bg: #ffffff;
  --panel: #ffffff;
  --text: #0f172a;
  --muted: #6b7280;
  --accent: #ef4444; /* red */
  --accent-2: #f59e0b; /* warm secondary */
  --border: #e5e7eb;
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Ubuntu, Cantarell, "Fira Sans", "Droid Sans", "Helvetica Neue", Arial, "Apple Color Emoji", "Segoe UI Emoji";
  background: #fafafa;
  color: var(--text);
}

.nav {
  backdrop-filter: saturate(180%) blur(8px);
  background: rgba(255, 255, 255, 0.8);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}
.nav-inner { max-width: 1100px; margin: 0 auto; padding: 12px 16px; display: flex; align-items: center; justify-content: space-between; }
.brand { display: flex; align-items: center; gap: 8px; font-weight: 700; color: var(--text); }
.brand-heart { color: var(--accent); font-size: 22px; }
.nav-actions { display: flex; gap: 16px; }
.nav-link { color: var(--text); text-decoration: none; font-weight: 600; }
.nav-link:hover { color: var(--accent); }

.hero { background: linear-gradient(180deg, #fff, #fef2f2); border-bottom: 1px solid var(--border); }
.hero-inner { max-width: 1100px; margin: 0 auto; padding: 48px 16px; text-align: center; }
.hero h1 { font-size: 40px; margin: 0 0 12px; }
.hero p { color: var(--muted); margin: 0 0 16px; }
.primary-btn { display:inline-block; background: var(--accent); color: white; padding: 12px 18px; border-radius: 8px; text-decoration:none; font-weight:700; box-shadow: 0 10px 25px rgba(239,68,68,0.3); }
.primary-btn:hover { filter: brightness(1.05); }

header {
  padding: 24px;
  text-align: center;
}
header h1 { margin: 0 0 4px; font-size: 28px; }
header p { margin: 0; color: var(--muted); }

main { max-width: 1100px; margin: 0 auto; padding: 24px 16px; }

.features { margin-bottom: 20px; }
.features-grid { display: grid; grid-template-columns: repeat(4, minmax(0,1fr)); gap: 16px; }
.feature-card { display:block; text-decoration:none; color:inherit; background: #fff; border: 1px solid var(--border); border-radius: 14px; padding: 18px; text-align: center; cursor: pointer; box-shadow: 0 4px 20px rgba(0,0,0,0.05); transition: transform 0.12s ease, box-shadow 0.12s ease; }
.feature-card:hover { transform: translateY(-2px); box-shadow: 0 10px 30px rgba(0,0,0,0.08); }
.feature-icon { font-size: 28px; }
.feature-title { font-weight: 700; margin-top: 8px; }
.feature-desc { color: var(--muted); margin-top: 4px; }

@media (max-width: 900px) { .features-grid { grid-template-columns: repeat(2, minmax(0,1fr)); } }
@media (max-width: 560px) { .features-grid { grid-template-columns: 1fr; } }

.uploader, .controls, .progress, .result { background: var(--panel); border-radius: 12px; padding: 16px; margin-bottom: 16px; box-shadow: 0 6px 22px rgba(0,0,0,0.08); border: 1px solid var(--border); }

.file-label { display: block; margin-bottom: 8px; }
#file-input { width: 100%; display:none; }

.dropzone { border: 2px dashed var(--border); border-radius: 12px; background: #fff; cursor: pointer; }
.dropzone-inner { display:flex; align-items:center; justify-content:center; gap: 10px; padding: 24px; color: var(--muted); }
.dropzone.dragover { border-color: var(--accent); background: #fff5f5; color: var(--text); }
.drop-icon { font-size: 20px; }
.drop-text { font-weight: 600; }

.control-row {
  display: flex;
  gap: 12px;
  align-items: center;
  margin-bottom: 12px;
}
.control-row label { width: 160px; color: var(--muted); }
.control-row select { flex:1; padding:8px; border-radius:8px; border: 1px solid var(--border); background:#fff; color: var(--text); }

button#convert-btn { padding: 10px 16px; border-radius: 10px; border: none; background: var(--accent); color: white; font-weight: 700; cursor: pointer; box-shadow: 0 10px 25px rgba(239,68,68,0.25); }
button#convert-btn[disabled] { filter: grayscale(0.6); opacity: 0.6; cursor: not-allowed; }

.progress-bar { width:100%; height:10px; background:#f3f4f6; border-radius:999px; overflow:hidden; margin-top:8px; border:1px solid var(--border); }
#progress-bar-fill { height:100%; width:0; background: var(--accent); transition: width 0.2s ease; }

#result-section a { display:inline-block; margin-top:8px; color:white; text-decoration:none; background: var(--accent); padding: 8px 12px; border-radius:8px; font-weight:700; }

footer { text-align:center; color: var(--muted); padding:24px; }