/* Ascetic Minimalist Dark Design System */
:root {
  --bg-main: #0c0c0e;
  --bg-card: #151518;
  --bg-card-hover: #1c1c20;
  --border: #26262b;
  --border-light: #36363f;
  --text-main: #f5f5f7;
  --text-muted: #8e8e93;
  --text-dim: #636366;
  --accent: #ffffff;
  --accent-blue: #2997ff;
  --accent-green: #30d158;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 9999px;
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", "Segoe UI", Roboto, sans-serif;
  --transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}

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

body {
  background-color: var(--bg-main);
  color: var(--text-main);
  font-family: var(--font);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Container */
.container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 0 24px;
  width: 100%;
}

/* Header */
header {
  border-bottom: 1px solid var(--border);
  background: rgba(12, 12, 14, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 70px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 14px;
  text-decoration: none;
  color: var(--text-main);
}

.brand-icon {
  width: 36px;
  height: 36px;
  border-radius: 9px;
  border: 1px solid var(--border);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.4);
}

.brand-name {
  font-size: 17px;
  font-weight: 600;
  letter-spacing: -0.3px;
}

.brand-tag {
  font-size: 11px;
  padding: 2px 8px;
  border-radius: var(--radius-full);
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-muted);
}

/* Nav Tabs */
nav.nav-tabs {
  display: flex;
  align-items: center;
  gap: 6px;
  background: #121215;
  padding: 4px;
  border-radius: var(--radius-full);
  border: 1px solid var(--border);
}

.nav-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  padding: 8px 16px;
  font-size: 14px;
  font-weight: 500;
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: var(--transition);
}

.nav-btn:hover {
  color: var(--text-main);
}

.nav-btn.active {
  background: var(--bg-card-hover);
  color: var(--text-main);
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.3);
}

.lang-toggle {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 13px;
  padding: 6px 12px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition);
}

.lang-toggle:hover {
  color: var(--text-main);
  border-color: var(--border-light);
}

/* Main content */
main {
  flex: 1;
  padding: 48px 0 80px;
}

.tab-pane {
  display: none;
  animation: fadeIn 0.3s ease;
}

.tab-pane.active {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Hero Section */
.hero {
  text-align: center;
  padding: 30px 0 50px;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border);
  border-radius: var(--radius-full);
  font-size: 13px;
  color: var(--text-muted);
  margin-bottom: 24px;
}

.badge-dot {
  width: 7px;
  height: 7px;
  background: var(--accent-green);
  border-radius: 50%;
}

.hero-title {
  font-size: 48px;
  font-weight: 700;
  letter-spacing: -1.2px;
  margin-bottom: 16px;
  line-height: 1.15;
}

.hero-subtitle {
  font-size: 19px;
  color: var(--text-muted);
  max-width: 600px;
  margin: 0 auto 40px;
  font-weight: 400;
}

/* Download Cards Grid */
.download-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 24px;
  margin-bottom: 60px;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 32px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.card:hover {
  border-color: var(--border-light);
  transform: translateY(-2px);
  background: var(--bg-card-hover);
}

.card-header {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 20px;
}

.os-icon {
  font-size: 34px;
  line-height: 1;
}

.card-title-group h3 {
  font-size: 20px;
  font-weight: 600;
  letter-spacing: -0.4px;
}

.card-title-group p {
  font-size: 13px;
  color: var(--text-muted);
}

.card-features {
  list-style: none;
  margin: 20px 0 28px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.card-features li {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 14px;
  color: #d1d1d6;
}

.check {
  color: var(--accent-green);
  font-size: 15px;
}

.btn-download {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  background: var(--accent);
  color: #000000;
  text-decoration: none;
  padding: 14px 20px;
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 15px;
  transition: var(--transition);
  box-shadow: 0 4px 14px rgba(255, 255, 255, 0.15);
}

.btn-download:hover {
  opacity: 0.9;
  transform: scale(0.99);
}

.btn-download.secondary {
  background: rgba(255, 255, 255, 0.1);
  color: var(--text-main);
  border: 1px solid var(--border-light);
  box-shadow: none;
}

.btn-download.secondary:hover {
  background: rgba(255, 255, 255, 0.15);
}

.card-footnote {
  text-align: center;
  font-size: 12px;
  color: var(--text-dim);
  margin-top: 12px;
}

/* How to use */
.section-title {
  font-size: 26px;
  font-weight: 700;
  letter-spacing: -0.6px;
  margin-bottom: 24px;
  text-align: center;
}

.steps-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 20px;
  margin-bottom: 40px;
}

.step-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 24px;
}

.step-number {
  display: inline-block;
  font-size: 12px;
  font-weight: 700;
  color: var(--text-muted);
  border: 1px solid var(--border);
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  margin-bottom: 14px;
}

.step-card h4 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 8px;
}

.step-card p {
  font-size: 14px;
  color: var(--text-muted);
}

/* About Tab */
.about-section {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 40px;
  margin-bottom: 30px;
}

.about-section h3 {
  font-size: 22px;
  margin-bottom: 16px;
  font-weight: 600;
}

.about-section p {
  color: #c7c7cc;
  font-size: 16px;
  margin-bottom: 20px;
  line-height: 1.6;
}

.comparison-table {
  width: 100%;
  border-collapse: collapse;
  margin: 30px 0 10px;
  font-size: 14px;
}

.comparison-table th,
.comparison-table td {
  padding: 14px 16px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

.comparison-table th {
  color: var(--text-muted);
  font-weight: 600;
  background: rgba(255, 255, 255, 0.02);
}

.comparison-table tr:hover {
  background: rgba(255, 255, 255, 0.02);
}

/* Feedback Tab */
.feedback-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 30px;
}

@media (max-width: 768px) {
  .feedback-grid {
    grid-template-columns: 1fr;
  }
}

.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  font-size: 14px;
  font-weight: 500;
  margin-bottom: 8px;
  color: #e5e5ea;
}

.form-control {
  width: 100%;
  background: #111114;
  border: 1px solid var(--border);
  color: var(--text-main);
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-family: inherit;
  transition: var(--transition);
}

.form-control:focus {
  outline: none;
  border-color: #ffffff;
  background: #16161a;
}

textarea.form-control {
  min-height: 120px;
  resize: vertical;
}

.rating-select {
  display: flex;
  gap: 10px;
}

.star-btn {
  background: #111114;
  border: 1px solid var(--border);
  color: var(--text-muted);
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-size: 14px;
  transition: var(--transition);
}

.star-btn.active, .star-btn:hover {
  background: var(--bg-card-hover);
  color: #ffcc00;
  border-color: var(--border-light);
}

.feedback-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
  max-height: 500px;
  overflow-y: auto;
  padding-right: 8px;
}

.feedback-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 18px;
}

.feedback-card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 8px;
}

.feedback-author {
  font-weight: 600;
  font-size: 15px;
}

.feedback-date {
  font-size: 12px;
  color: var(--text-dim);
}

.feedback-stars {
  color: #ffcc00;
  font-size: 13px;
  margin-bottom: 8px;
}

.feedback-text {
  font-size: 14px;
  color: #d1d1d6;
  line-height: 1.5;
}

/* FAQ Accordion */
.faq-list {
  max-width: 800px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: var(--transition);
}

.faq-question {
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  color: var(--text-main);
  padding: 18px 24px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.faq-icon {
  font-size: 18px;
  transition: transform 0.2s ease;
}

.faq-item.open .faq-icon {
  transform: rotate(45deg);
}

.faq-answer {
  display: none;
  padding: 0 24px 20px;
  color: var(--text-muted);
  font-size: 15px;
  line-height: 1.6;
}

.faq-item.open .faq-answer {
  display: block;
}

/* Footer */
footer {
  border-top: 1px solid var(--border);
  padding: 30px 0;
  font-size: 13px;
  color: var(--text-dim);
  text-align: center;
}

footer a {
  color: var(--text-muted);
  text-decoration: none;
}

footer a:hover {
  text-decoration: underline;
}

/* Donate Tab */
.donate-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
  margin-top: 30px;
}

.donate-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: var(--transition);
}

.donate-card:hover {
  border-color: var(--border-light);
  transform: translateY(-2px);
  background: var(--bg-card-hover);
}

.donate-icon {
  font-size: 32px;
  margin-bottom: 16px;
}

.donate-card h4 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 8px;
}

.donate-card p {
  font-size: 13px;
  color: var(--text-muted);
  margin-bottom: 20px;
}

.copy-box {
  background: #101013;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px 14px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 12px;
}

.copy-code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  font-size: 13px;
  color: #ffffff;
  word-break: break-all;
}

.btn-copy {
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid var(--border-light);
  color: var(--text-main);
  padding: 6px 12px;
  border-radius: var(--radius-sm);
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  white-space: nowrap;
  transition: var(--transition);
}

.btn-copy:hover {
  background: #ffffff;
  color: #000000;
}

.empty-feedback {
  text-align: center;
  padding: 40px 20px;
  color: var(--text-muted);
  background: var(--bg-card);
  border: 1px dashed var(--border);
  border-radius: var(--radius-md);
  font-size: 14px;
}

.toast-msg {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: #ffffff;
  color: #000000;
  font-weight: 600;
  font-size: 14px;
  padding: 12px 24px;
  border-radius: var(--radius-full);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
  transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1), opacity 0.3s;
  opacity: 0;
  z-index: 1000;
  pointer-events: none;
}

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

/* Interactive Launch Guides */
.guide-container {
  margin-top: 50px;
  text-align: left;
}

.guide-toggle-group {
  display: inline-flex;
  background: #121215;
  padding: 4px;
  border-radius: var(--radius-full);
  border: 1px solid var(--border);
  gap: 4px;
}

.guide-toggle-btn {
  background: transparent;
  border: 1px solid transparent;
  color: var(--text-muted);
  padding: 8px 18px;
  font-size: 14px;
  font-weight: 500;
  border-radius: var(--radius-full);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  transition: var(--transition);
}

.guide-toggle-btn:hover {
  color: var(--text-main);
}

.guide-toggle-btn.active {
  background: var(--bg-card-hover);
  color: var(--text-main);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.4);
  border-color: var(--border-light);
}

.guide-box {
  display: none;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 30px;
  margin-top: 16px;
  animation: fadeIn 0.3s ease;
}

.guide-box.active {
  display: block;
}

.guide-box-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  padding-bottom: 20px;
  margin-bottom: 24px;
  border-bottom: 1px solid var(--border);
}

.guide-os-badge {
  font-size: 18px;
  font-weight: 700;
  color: var(--text-main);
  display: flex;
  align-items: center;
  gap: 8px;
}

.guide-tag {
  font-size: 12px;
  padding: 4px 12px;
  border-radius: var(--radius-full);
  background: rgba(255, 255, 255, 0.06);
  color: var(--text-muted);
  border: 1px solid var(--border);
}

.guide-steps-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.guide-step-item {
  display: flex;
  gap: 18px;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 20px;
  transition: var(--transition);
}

.guide-step-item:hover {
  border-color: var(--border-light);
  background: rgba(255, 255, 255, 0.04);
}

.guide-step-item.highlight-step {
  border-color: rgba(255, 159, 10, 0.35);
  background: rgba(255, 159, 10, 0.04);
}

.step-badge {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: #222228;
  color: #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 14px;
  flex-shrink: 0;
  border: 1px solid var(--border-light);
}

.highlight-step .step-badge {
  background: #ff9f0a;
  color: #000000;
  border-color: #ff9f0a;
}

.step-content h4 {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-main);
  margin-bottom: 6px;
}

.step-content p {
  font-size: 14px;
  color: #c7c7cc;
  line-height: 1.6;
}

.file-pill {
  display: inline-block;
  padding: 4px 10px;
  border-radius: 6px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  font-size: 13px;
  font-weight: 600;
  margin: 6px 0;
}

.win-pill {
  background: rgba(41, 151, 255, 0.15);
  color: #5ac8fa;
  border: 1px solid rgba(41, 151, 255, 0.35);
}

.mac-pill {
  background: rgba(48, 209, 88, 0.15);
  color: #30d158;
  border: 1px solid rgba(48, 209, 88, 0.35);
}

.btn-highlight {
  color: #ff9f0a;
  font-weight: 700;
}