:root {
  --bg: #f7f9fc;
  --surface: #ffffff;
  --text: #1a1d26;
  --muted: #6b7280;
  --accent: #0061ff;
  --accent-hover: #004ecc;
  --border: #e5e7eb;
  --danger: #dc2626;
  --success: #16a34a;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.06);
  --radius: 12px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
  min-height: 100vh;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.hidden { display: none !important; }

/* Nav */
.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 32px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1.15rem;
  color: var(--text);
  cursor: pointer;
}

.logo-icon {
  width: 32px;
  height: 32px;
  background: linear-gradient(135deg, #0061ff, #00c2ff);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-size: 14px;
}

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

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 20px;
  border-radius: 8px;
  font-size: 0.95rem;
  font-weight: 500;
  cursor: pointer;
  border: none;
  transition: background 0.15s, transform 0.1s;
}

.btn:active { transform: scale(0.98); }
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: var(--accent-hover); }
.btn-ghost { background: transparent; color: var(--text); border: 1px solid var(--border); }
.btn-ghost:hover { background: var(--bg); }

/* Layout */
.page { max-width: 1100px; margin: 0 auto; padding: 48px 24px; }
.page-narrow { max-width: 420px; margin: 0 auto; padding: 64px 24px; }

.hero {
  text-align: center;
  padding: 80px 24px 64px;
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 16px;
}

.hero p {
  font-size: 1.15rem;
  color: var(--muted);
  max-width: 540px;
  margin: 0 auto 32px;
}

.hero-actions { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }

/* Cards */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  box-shadow: var(--shadow);
}

.card h2 { font-size: 1.35rem; margin-bottom: 8px; }
.card .sub { color: var(--muted); font-size: 0.9rem; margin-bottom: 24px; }

/* Forms */
.form-group { margin-bottom: 16px; }
.form-group label { display: block; font-size: 0.85rem; font-weight: 500; margin-bottom: 6px; }

.form-group input {
  width: 100%;
  padding: 11px 14px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 0.95rem;
  transition: border-color 0.15s;
}

.form-group input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(0, 97, 255, 0.12);
}

.alert {
  padding: 12px 16px;
  border-radius: 8px;
  font-size: 0.9rem;
  margin-bottom: 16px;
}

.alert-error { background: #fef2f2; color: var(--danger); border: 1px solid #fecaca; }
.alert-info { background: #eff6ff; color: #1d4ed8; border: 1px solid #bfdbfe; }

/* Upload zone */
.upload-zone {
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  padding: 48px 24px;
  text-align: center;
  cursor: pointer;
  transition: border-color 0.15s, background 0.15s;
  margin-bottom: 24px;
}

.upload-zone:hover, .upload-zone.dragover {
  border-color: var(--accent);
  background: rgba(0, 97, 255, 0.03);
}

.upload-zone svg { margin-bottom: 12px; opacity: 0.5; }
.upload-zone p { color: var(--muted); font-size: 0.95rem; }
.upload-zone .hint { font-size: 0.8rem; margin-top: 8px; }

.progress-wrap {
  background: var(--border);
  border-radius: 99px;
  height: 8px;
  overflow: hidden;
  margin: 16px 0;
}

.progress-bar {
  height: 100%;
  background: var(--accent);
  border-radius: 99px;
  width: 0%;
  transition: width 0.3s;
}

/* File list */
.file-list { margin-top: 24px; }
.file-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  border: 1px solid var(--border);
  border-radius: 8px;
  margin-bottom: 8px;
}

.file-icon {
  width: 36px;
  height: 36px;
  background: var(--bg);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
}

.file-info { flex: 1; }
.file-info .name { font-weight: 500; font-size: 0.9rem; }
.file-info .meta { font-size: 0.8rem; color: var(--muted); }

/* Features grid */
.features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 24px;
  margin-top: 48px;
}

.feature {
  padding: 24px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

.feature h3 { font-size: 1rem; margin-bottom: 8px; }
.feature p { font-size: 0.9rem; color: var(--muted); }

footer {
  text-align: center;
  padding: 32px;
  color: var(--muted);
  font-size: 0.8rem;
  border-top: 1px solid var(--border);
  margin-top: 64px;
}

@media (max-width: 600px) {
  .nav { padding: 12px 16px; }
  .nav-links .btn-ghost { display: none; }
}