:root {
  --bg: #f7fafc;
  --card: #ffffff;
  --text: #0f172a;
  --muted: #6b7280;
  --primary: #0f62ff;
  --accent: #00b894;
  --danger: #ff4d4f;
  --glass: rgba(255, 255, 255, 0.6);
  --radius: 12px;
  --container: 1100px;
  font-family: "Inter", system-ui, -apple-system, "Segoe UI", Roboto,
    "Helvetica Neue", Arial;
}

* {
  box-sizing: border-box;
}
html,
body {
  height: 100%;
}

body {
  margin: 0;
  background: linear-gradient(180deg, #f8fafc 0%, #eef2ff 100%);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  line-height: 1.45;
  font-size: 16px;
}

/* container */
.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 2rem;
}

/* Header */
.site-header {
  backdrop-filter: blur(6px);
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.8);
  border-bottom: 1px solid rgba(15, 23, 42, 0.04);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}
.logo {
  display: flex;
  align-items: center;
  text-decoration: none;
  font-weight: 700;
  font-size: 1.2rem;
  color: #0f172a; /* dark blue */
  height: 70px; /* adjust size */
  width: auto;
  margin-right: 8px;
}

.logo .material-icons {
  background: linear-gradient(90deg, var(--primary), #6c5ce7);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.main-nav a {
  margin-left: 1rem;
  text-decoration: none;
  color: var(--muted);
  font-weight: 600;
}
.main-nav a.btn-ghost {
  background: none;
  padding: 0.4rem 0.7rem;
  border-radius: 8px;
  border: 1px solid rgba(15, 23, 42, 0.05);
  color: var(--text);
}

/* Hero */
.hero {
  padding: 3rem 0;
}
.hero-grid {
  display: grid;
  grid-template-columns: 1fr 480px;
  gap: 2rem;
  align-items: center;
}
.hero-content h1 {
  font-size: clamp(1.6rem, 2.6vw, 2.4rem);
  margin: 0 0 0.6rem;
}

.lead {
  color: var(--muted);
  margin-bottom: 1rem;
}

.hero-ctas {
  display: flex;
  gap: 0.75rem;
  align-items: center;
  margin-bottom: 0.5rem;
}

.btn-primary {
  background: var(--primary);
  color: white;
  padding: 0.6rem 1rem;
  border-radius: 10px;
  border: 0;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 6px 18px rgba(15, 98, 255, 0.12);
}

.btn-outline {
  background: transparent;
  border: 1px solid rgba(15, 23, 42, 0.06);
  padding: 0.55rem 0.95rem;
  border-radius: 10px;
  text-decoration: none;
  color: var(--text);
}

.note {
  display: block;
  color: var(--muted);
  font-size: 0.85rem;
  margin-top: 8px;
}

.hero-media img {
  width: 100%;
  border-radius: 16px;
  box-shadow: 0 14px 40px rgba(2, 6, 23, 0.08);
}

.section {
  padding: 3rem 0;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.25rem;
  margin-top: 1rem;
}

.card {
  background: var(--card);
  padding: 1.25rem;
  border-radius: 14px;
  box-shadow: 0 8px 24px rgba(2, 6, 23, 0.04);
  min-height: 140px;
}

.card .material-icons.big {
  font-size: 36px;
  color: var(--primary);
}

.card h3 {
  margin: 0.6rem 0 0.4rem;
}

/* ------ How ------ */
.how-list {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1rem;
  list-style: none;
  padding: 0;
  margin-top: 1rem;
}

.how-list li {
  background: var(--card);
  padding: 1rem;
  border-radius: 10px;
  box-shadow: 0 6px 20px rgba(2, 6, 23, 0.03);
}

/* Wipe tool */
.wipe-grid {
  display: grid;
  grid-template-columns: 1fr 380px;
  gap: 1rem;
  align-items: start;
}

.panel {
  background: var(--card);
  padding: 1.25rem;
  border-radius: 12px;
  box-shadow: 0 8px 30px rgba(2, 6, 23, 0.04);
}

.panel label {
  display: block;
  margin-top: 0.6rem;
  font-weight: 600;
  color: var(--muted);
}

.panel select,
.panel input[type="text"],
.panel textarea {
  width: 100%;
  padding: 0.6rem;
  border-radius: 8px;
  border: 1px solid rgba(15, 23, 42, 0.06);
  margin-top: 0.35rem;
  background: #fff;
}

.checkbox {
  display: flex;
  gap: 0.5rem;
  align-items: center;
  margin-top: 0.6rem;
}

.warning {
  margin-top: 0.8rem;
  color: var(--danger);
  font-weight: 600;
  font-size: 0.95rem;
  background: rgba(255, 77, 79, 0.06);
  padding: 0.6rem;
  border-radius: 8px;
}

.form-actions {
  display: flex;
  gap: 0.6rem;
  margin-top: 1rem;
}

.btn-danger {
  background: var(--danger);
  border: 0;
  color: white;
  padding: 0.6rem 0.9rem;
  border-radius: 10px;
  font-weight: 700;
  cursor: pointer;
}

.btn-ghost {
  background: transparent;
  border: 1px solid rgba(15, 23, 42, 0.06);
  padding: 0.5rem 0.8rem;
  border-radius: 10px;
  cursor: pointer;
}

.btn-primary.small {
  padding: 0.4rem 0.6rem;
  border-radius: 8px;
}

/* status/ progress */
.status-panel h3 {
  margin-top: 0;
}

.status-placeholder {
  min-height: 160px;
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
}

.progress-wrap {
  margin-top: 0.6rem;
}

.progress-bar {
  height: 12px;
  background: rgba(15, 23, 42, 0.06);
  border-radius: 999px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--primary), #7c3aed);
  transition: width 0.3s;
}

.status-log {
  list-style: none;
  padding: 0;
  margin: 0.5rem 0 0 0;
  font-size: 0.9rem;
  color: var(--muted);
  max-height: 120px;
  overflow: auto;
}

.status-log li {
  padding: 0.25rem 0;
  border-bottom: 1px dashed rgba(15, 23, 42, 0.02);
}

/* certificate */
.certificate-area {
  margin-top: 1rem;
}

.certificate-json {
  background: #0f172a;
  color: #fff;
  padding: 1rem;
  border-radius: 8px;
  max-height: 240px;
  overflow: auto;
}

.cert-actions {
  display: flex;
  gap: 0.5rem;
  margin-top: 0.6rem;
}

/* footer */
.site-footer {
  padding: 1.2rem 0;
  background: transparent;
  border-top: 1px solid rgba(15, 23, 42, 0.04);
  margin-top: 2rem;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  align-items: center;
  font-size: 0.95rem;
  color: var(--muted);
}

/* modal */
.modal {
  position: fixed;
  inset: 0;
  display: none;
  align-items: center;
  justify-content: center;
  background: rgba(2, 6, 23, 0.45);
}

.modal[aria-hidden="false"] {
  display: flex;
}

.modal-panel {
  background: var(--card);
  padding: 1.25rem;
  border-radius: 12px;
  max-width: 520px;
  box-shadow: 0 20px 60px rgba(2, 6, 23, 0.25);
}

/* responsive */
@media (max-width: 1000px) {
  .hero-grid {
    grid-template-columns: 1fr;
  }
  .user-guide-grid {
    grid-template-columns: 1fr;
    flex-direction: column;
    overflow: hidden;
    width: 100%;
  }
  .features-grid {
    grid-template-columns: 1fr 1fr;
  }
  .how-list {
    grid-template-columns: repeat(2, 1fr);
  }
  .wipe-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 600px) {
  .main-nav a {
    display: none;
  }
  .user-guide-grid {
    grid-template-columns: 1fr;
    flex-direction: column;
    overflow: hidden;
    width: 100%;
  }
  .features-grid {
    grid-template-columns: 1fr;
  }
  .how-list {
    grid-template-columns: 1fr;
  }
  .container {
    padding: 1rem;
  }
}
#iso-section,
#ventoy-section,
#prep-section,
#usb-insert-section {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background-color: white;
  border: #0f172a;
  box-shadow: #6b7280;
  padding: 30px;
  margin-top: 1rem;
  border: 2px solid rgba(15, 23, 42, 0.06);
  border-radius: 12px;
  text-align: center;
}
#download-iso,
#download-ventoy {
  background: var(--primary);
  color: white;
  padding: 0.6rem 1rem;
  border-radius: 10px;
  border: 0;
  font-weight: 700;
  border: 2px solid #0f62ff;
  cursor: pointer;
  box-shadow: 0 6px 18px rgba(15, 98, 255, 0.12);
}

#iso-next,
#ventoy-next,
#prep-next,
#usb-insert-btn {
  background: darkblue;
  color: white;
  padding: 0.6rem 3rem;
  border-radius: 10px;
}
.user-guide-grid {
  display: flex;
  justify-content: center;

  gap: 1rem;
  margin-top: 1rem;
}

.demo {
  width: 48%;
  margin: 4px;
}
.guide {
  width: 48%;
  margin: 4px;
  display: flex;
  flex-direction: column;
}

.pdf-viewer {
  align-items: center;
  width: 80%;
  height: 80%;
  border: 1px solid rgba(15, 23, 42, 0.06);
  border-radius: 8px;
}
.download-btn {
  width: 40%;
  text-decoration: none;
  color: white;
  background: var(--primary);
  padding: 0.5rem 0.8rem;
  border-radius: 10px;
  font-weight: 700;
  border: 2px solid #0f62ff;
}

@media (max-width: 1080px) {
  #iso-section,
  #ventoy-section,
  #prep-section,
  #usb-insert-section {
    width: 90%;
    padding: 20px;
  }
  #download-iso,
  #download-ventoy {
    padding: 0.5rem 0.8rem;
    font-size: 0.9rem;
  }
  #iso-next,
  #ventoy-next,
  #prep-next,
  #usb-insert-btn {
    padding: 0.5rem 1.5rem;
    font-size: 0.9rem;
  }
  .demo,
  .guide {
    width: 80%;
    margin: 10px;
  }
  .download-btn {
    width: 70%;
    padding: 0.5 rem 0.8rem;
    font-size: 1rem;
  }
}