* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Inter', sans-serif;
}

body {
  background-color: var(--bg-primary);
  color: var(--text-primary);
  transition: background-color 0.2s, color 0.2s;
}

:root {
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-card: #ffffff;
  --text-primary: #0f172a;
  --text-secondary: #334155;
  --border-light: #e2e8f0;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --dropzone-bg: #f1f5f9;
  --shadow: 0 10px 25px -5px rgba(0,0,0,0.05), 0 8px 10px -6px rgba(0,0,0,0.02);
}

body.dark {
  --bg-primary: #0b1120;
  --bg-secondary: #1e293b;
  --bg-card: #1e293b;
  --text-primary: #f1f5f9;
  --text-secondary: #cbd5e1;
  --border-light: #334155;
  --accent: #3b82f6;
  --dropzone-bg: #0f172a;
}

.container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 1rem 2rem;
}

.top-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 2rem;
}

.logo {
  display: flex;
  align-items: center;
  gap: 12px;
}

.logo-icon {
  width: 48px;
  height: 48px;
  background: linear-gradient(135deg, #2563eb, #7c3aed);
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.8rem;
  color: white;
  box-shadow: var(--shadow);
}

.logo-text h1 {
  font-size: 1.6rem;
  font-weight: 700;
  background: linear-gradient(135deg, #2563eb, #7c3aed);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.logo-text p {
  font-size: 0.75rem;
  color: var(--text-secondary);
}

.nav-links {
  display: flex;
  gap: 0.6rem;
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: 1rem;
}

.nav-btn {
  background: var(--bg-secondary);
  border: 1px solid var(--border-light);
  border-radius: 40px;
  padding: 0.5rem 1rem;
  font-weight: 500;
  transition: all 0.2s;
  font-size: 0.85rem;
  text-decoration: none;
  color: var(--text-primary);
  display: inline-block;
}

.nav-btn:hover,
.nav-btn.active {
  background: var(--accent);
  color: white;
  border-color: var(--accent);
}

.dark-toggle,
.donate-button {
  background: var(--bg-secondary);
  border: 1px solid var(--border-light);
  border-radius: 40px;
  padding: 0.5rem 1.2rem;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 500;
  text-decoration: none;
  color: var(--text-primary);
  transition: all 0.2s;
}

.donate-button {
  background: #ff6b6b;
  color: white;
  border: none;
}

.donate-button:hover {
  background: #ff5252;
}

.section-title {
  font-size: 1.8rem;
  font-weight: 600;
  margin: 1.5rem 0 1rem;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.5rem;
}

.card {
  background: var(--bg-card);
  border-radius: 24px;
  padding: 1.5rem;
  border: 1px solid var(--border-light);
  box-shadow: var(--shadow);
}

.card-header {
  display: flex;
  gap: 0.75rem;
  margin-bottom: 1rem;
  align-items: center;
}

.card-header i {
  font-size: 1.6rem;
  color: var(--accent);
}

.drop-zone {
  background: var(--dropzone-bg);
  border: 2px dashed var(--border-light);
  border-radius: 16px;
  padding: 1rem;
  text-align: center;
  cursor: pointer;
  margin-bottom: 0.5rem;
}

.drop-zone.dragover {
  background: var(--accent);
  opacity: 0.8;
}

.file-list {
  font-size: 0.8rem;
  max-height: 100px;
  overflow-y: auto;
  background: var(--dropzone-bg);
  border-radius: 12px;
  padding: 0.5rem;
  margin: 0.5rem 0;
}

.btn {
  background: var(--accent);
  color: white;
  border: none;
  padding: 0.6rem 1.2rem;
  border-radius: 40px;
  font-weight: 600;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  transition: background 0.2s;
  font-size: 0.9rem;
}

.btn:hover {
  background: var(--accent-hover);
}

.result-area {
  margin-top: 1rem;
  padding: 0.8rem;
  background: var(--dropzone-bg);
  border-radius: 16px;
  font-size: 0.9rem;
  word-break: break-word;
}

.format-select,
.input-group select,
.input-group input {
  width: 100%;
  padding: 0.6rem 1rem;
  border-radius: 40px;
  border: 1px solid var(--border-light);
  background: var(--bg-secondary);
  margin: 0.5rem 0;
}

.input-group {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin: 0.75rem 0;
}

.ad-universal {
  margin: 2rem 0;
  text-align: center;
  background: var(--dropzone-bg);
  border-radius: 20px;
  padding: 1rem;
  border: 1px dashed var(--accent);
  min-height: 100px;
}

footer {
  text-align: center;
  padding: 2rem;
  color: var(--text-secondary);
  margin-top: 2rem;
  border-top: 1px solid var(--border-light);
}

@media (max-width: 600px) {
  .container {
    padding: 1rem;
  }
  .top-bar {
    flex-direction: column;
    align-items: stretch;
  }
}