:root {
  --bg: #0a0e17;
  --bg-card: #111827;
  --bg-elevated: #1a2234;
  --border: rgba(255, 255, 255, 0.08);
  --text: #f1f5f9;
  --text-muted: #94a3b8;
  --accent: #ef0027;
  --accent-hover: #ff1a3d;
  --accent-glow: rgba(239, 0, 39, 0.25);
  --success: #22c55e;
  --warning: #f59e0b;
  --radius: 12px;
  --radius-lg: 20px;
  --font: "Inter", "PingFang SC", "Microsoft YaHei", sans-serif;
  --mono: "JetBrains Mono", "SF Mono", monospace;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 50% at 50% -20%, rgba(239, 0, 39, 0.15), transparent),
    radial-gradient(ellipse 60% 40% at 100% 50%, rgba(59, 130, 246, 0.08), transparent);
  pointer-events: none;
  z-index: 0;
}

.container {
  width: min(1120px, 92vw);
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

/* Header */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(16px);
  background: rgba(10, 14, 23, 0.85);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 0;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-weight: 700;
  font-size: 1.15rem;
  text-decoration: none;
  color: var(--text);
}

.logo-icon {
  width: 36px;
  height: 36px;
  background: linear-gradient(135deg, var(--accent), #ff6b35);
  border-radius: 10px;
  display: grid;
  place-items: center;
  font-size: 1.1rem;
}

.nav {
  display: flex;
  gap: 1.5rem;
}

.nav a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.9rem;
  transition: color 0.2s;
}

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

.lang-switcher {
  display: flex;
  gap: 0.25rem;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.2rem;
}

.lang-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.35rem 0.55rem;
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.2s;
  line-height: 1;
}

.lang-btn:hover {
  color: var(--text);
  background: rgba(255, 255, 255, 0.05);
}

.lang-btn.active {
  background: var(--accent);
  color: #fff;
}

.modal-receive-addr {
  font-size: 0.75rem;
  word-break: break-all;
  max-width: 60%;
  text-align: right;
}

/* Hero */
.hero {
  padding: 4rem 0 3rem;
  text-align: center;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.35rem 0.9rem;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 999px;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 1.5rem;
}

.hero-badge .dot {
  width: 6px;
  height: 6px;
  background: var(--success);
  border-radius: 50%;
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 3.2rem);
  font-weight: 800;
  line-height: 1.15;
  margin-bottom: 1rem;
  background: linear-gradient(to right, #fff 30%, #94a3b8);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  color: var(--text-muted);
  font-size: 1.1rem;
  max-width: 560px;
  margin: 0 auto 2rem;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 2.5rem;
  flex-wrap: wrap;
  margin-top: 2.5rem;
}

.stat {
  text-align: center;
}

.stat-value {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--accent);
}

.stat-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 0.2rem;
}

/* Sections */
.section {
  padding: 3rem 0;
}

.section-title {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.section-desc {
  color: var(--text-muted);
  margin-bottom: 2rem;
  font-size: 0.95rem;
}

/* Package cards */
.packages {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
}

.package-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  cursor: pointer;
  transition: all 0.25s;
  position: relative;
}

.package-card:hover {
  border-color: rgba(239, 0, 39, 0.4);
  transform: translateY(-2px);
}

.package-card.selected {
  border-color: var(--accent);
  box-shadow: 0 0 0 1px var(--accent), 0 8px 32px var(--accent-glow);
}

.package-card.popular {
  position: relative;
}

.package-popular {
  position: absolute;
  top: -10px;
  right: 16px;
  background: var(--accent);
  color: #fff;
  font-size: 0.7rem;
  font-weight: 600;
  padding: 0.2rem 0.6rem;
  border-radius: 999px;
}

.package-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.package-energy {
  font-size: 1.6rem;
  font-weight: 700;
  margin: 0.5rem 0 0.2rem;
}

.package-energy span {
  font-size: 0.85rem;
  font-weight: 400;
  color: var(--text-muted);
}

.package-price {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--accent);
  margin-bottom: 0.75rem;
}

.package-original {
  font-size: 0.8rem;
  font-weight: 400;
  color: var(--text-muted);
  text-decoration: line-through;
  margin-left: 0.4rem;
}

.package-discount {
  font-size: 0.75rem;
  color: var(--success);
  margin-top: -0.5rem;
  margin-bottom: 0.5rem;
}

.package-meta {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* Order form */
.order-panel {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 2rem;
  max-width: 640px;
  margin: 0 auto;
}

.form-group {
  margin-bottom: 1.25rem;
}

.form-group label {
  display: block;
  font-size: 0.85rem;
  font-weight: 500;
  margin-bottom: 0.5rem;
  color: var(--text-muted);
}

.form-group input {
  width: 100%;
  padding: 0.85rem 1rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  font-size: 0.95rem;
  font-family: var(--mono);
  transition: border-color 0.2s;
}

.form-group input:focus {
  outline: none;
  border-color: var(--accent);
}

.form-group input.error {
  border-color: var(--accent);
}

.form-hint {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 0.4rem;
}

.form-error {
  font-size: 0.75rem;
  color: var(--accent);
  margin-top: 0.4rem;
  display: none;
}

.form-error.show {
  display: block;
}

.order-summary {
  background: var(--bg-elevated);
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  margin: 1.5rem 0;
  display: grid;
  gap: 0.5rem;
}

.summary-row {
  display: flex;
  justify-content: space-between;
  font-size: 0.9rem;
}

.summary-row.total {
  font-weight: 700;
  font-size: 1.05rem;
  padding-top: 0.5rem;
  border-top: 1px solid var(--border);
  margin-top: 0.25rem;
}

.summary-row.total .value {
  color: var(--accent);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.9rem 1.75rem;
  border: none;
  border-radius: var(--radius);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  width: 100%;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
}

.btn-primary:hover {
  background: var(--accent-hover);
  box-shadow: 0 4px 20px var(--accent-glow);
}

.btn-primary:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn-outline {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
  width: auto;
}

.btn-outline:hover {
  border-color: var(--text-muted);
}

/* Payment modal */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.7);
  backdrop-filter: blur(4px);
  z-index: 200;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 1rem;
}

.modal-overlay.open {
  display: flex;
}

.modal {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 2rem;
  max-width: 480px;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
  animation: slideUp 0.3s ease;
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
}

.modal-header h3 {
  font-size: 1.2rem;
}

.modal-close {
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 1.5rem;
  cursor: pointer;
  line-height: 1;
  padding: 0.25rem;
}

.modal-close:hover {
  color: var(--text);
}

.qr-wrap {
  display: flex;
  justify-content: center;
  margin: 0 auto;
  padding: 1rem;
  background: #fff;
  border-radius: var(--radius);
  width: fit-content;
}

.qr-wrap img,
.qr-wrap canvas {
  display: block;
}

.payment-qr-block,
.payment-address-block {
  margin-bottom: 1.25rem;
}

.payment-qr-block {
  text-align: center;
}

.payment-block-label {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 0.6rem;
  text-align: center;
}

.payment-address-block .address-box {
  margin-bottom: 0;
}

.payment-address-block code {
  font-size: 0.82rem;
  line-height: 1.5;
}

.payment-amount {
  text-align: center;
  margin-bottom: 1.5rem;
}

.payment-amount .amount {
  font-size: 2rem;
  font-weight: 800;
  color: var(--accent);
}

.payment-amount .label {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.address-box {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.85rem 1rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.address-box code {
  flex: 1;
  font-family: var(--mono);
  font-size: 0.78rem;
  word-break: break-all;
  color: var(--text-muted);
}

.copy-btn {
  flex-shrink: 0;
  padding: 0.4rem 0.75rem;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  font-size: 0.75rem;
  cursor: pointer;
  transition: all 0.2s;
}

.copy-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.copy-btn.copied {
  border-color: var(--success);
  color: var(--success);
}

.payment-steps {
  list-style: none;
  margin-top: 1.5rem;
}

.payment-steps li {
  display: flex;
  gap: 0.75rem;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}

.step-num {
  flex-shrink: 0;
  width: 22px;
  height: 22px;
  background: var(--bg-elevated);
  border-radius: 50%;
  display: grid;
  place-items: center;
  font-size: 0.7rem;
  font-weight: 600;
  color: var(--accent);
}

.payment-warning {
  background: rgba(245, 158, 11, 0.1);
  border: 1px solid rgba(245, 158, 11, 0.3);
  border-radius: var(--radius);
  padding: 0.85rem 1rem;
  font-size: 0.8rem;
  color: var(--warning);
  margin-top: 1rem;
}

/* How it works */
.steps-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.25rem;
}

.step-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
}

.step-card .step-icon {
  width: 44px;
  height: 44px;
  background: var(--bg-elevated);
  border-radius: 12px;
  display: grid;
  place-items: center;
  font-size: 1.3rem;
  margin-bottom: 1rem;
}

.step-card h4 {
  font-size: 1rem;
  margin-bottom: 0.5rem;
}

.step-card p {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* FAQ */
.faq-list {
  max-width: 720px;
  margin: 0 auto;
}

.faq-item {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 0.75rem;
  overflow: hidden;
}

.faq-question {
  width: 100%;
  background: var(--bg-card);
  border: none;
  color: var(--text);
  padding: 1rem 1.25rem;
  text-align: left;
  font-size: 0.95rem;
  font-weight: 500;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.faq-question:hover {
  background: var(--bg-elevated);
}

.faq-question .arrow {
  transition: transform 0.2s;
  color: var(--text-muted);
}

.faq-item.open .faq-question .arrow {
  transform: rotate(180deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
}

.faq-item.open .faq-answer {
  max-height: 200px;
}

.faq-answer p {
  padding: 0 1.25rem 1rem;
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.7;
}

/* Footer */
.footer {
  border-top: 1px solid var(--border);
  padding: 2rem 0;
  margin-top: 2rem;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

.footer p {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.footer-links {
  display: flex;
  gap: 1.25rem;
}

.footer-links a {
  font-size: 0.8rem;
  color: var(--text-muted);
  text-decoration: none;
}

.footer-links a:hover {
  color: var(--text);
}

/* Toast */
.toast {
  position: fixed;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 0.75rem 1.5rem;
  border-radius: 999px;
  font-size: 0.85rem;
  z-index: 300;
  opacity: 0;
  transition: all 0.3s;
  pointer-events: none;
}

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

/* Responsive */
@media (max-width: 640px) {
  .nav {
    display: none;
  }

  .lang-switcher {
    margin-left: auto;
  }

  .hero {
    padding: 2.5rem 0 2rem;
  }

  .hero-stats {
    gap: 1.5rem;
  }

  .order-panel {
    padding: 1.25rem;
  }

  .footer-inner {
    flex-direction: column;
    text-align: center;
  }
}