:root {
  --bg-primary: #0d1117;
  --bg-secondary: #161b22;
  --bg-card: #21262d;
  --text-main: #f0f6fc;
  --text-muted: #8b949e;
  --accent: #58a6ff;
  --accent-hover: #79c0ff;
  --accent-glow: rgba(88, 166, 255, 0.15);
  --border-color: #30363d;
  --success-bg: rgba(46, 160, 67, 0.15);
  --success-border: #2ea043;
  --success-text: #3fb950;
  --error-bg: rgba(248, 81, 73, 0.15);
  --error-border: #f85149;
  --error-text: #ff7b72;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-main);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.container {
  width: 100%;
  max-width: 1024px;
  margin: 0 auto;
  padding: 0 1.25rem;
}

/* Site Header */
.site-header {
  background-color: rgba(22, 27, 34, 0.85);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(8px);
}

.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4rem;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
  font-size: 1.125rem;
  letter-spacing: -0.01em;
}

.logo-mark {
  color: var(--accent);
  font-size: 1.35rem;
}

.nav {
  display: flex;
  gap: 1.25rem;
}

.nav-link {
  color: var(--text-muted);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.9375rem;
  transition: color 0.15s ease;
}

.nav-link:hover,
.nav-link:focus-visible {
  color: var(--accent);
}

/* Hero Section */
.hero {
  padding: 4.5rem 0 3.5rem;
  text-align: center;
  background: radial-gradient(circle at 50% 20%, rgba(88, 166, 255, 0.08), transparent 70%);
  border-bottom: 1px solid var(--border-color);
}

.hero-badge {
  display: inline-block;
  font-size: 0.875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent);
  background-color: var(--accent-glow);
  padding: 0.35rem 0.85rem;
  border-radius: 999px;
  border: 1px solid rgba(88, 166, 255, 0.3);
  margin-bottom: 1.5rem;
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.25rem);
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: -0.03em;
  margin-bottom: 1.25rem;
  max-width: 800px;
  margin-left: auto;
  margin-right: auto;
}

.hero-description {
  font-size: 1.125rem;
  color: var(--text-muted);
  max-width: 640px;
  margin: 0 auto 2rem;
}

.hero-actions {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.5rem;
  font-size: 1rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  text-decoration: none;
  cursor: pointer;
  transition: background-color 0.15s ease, border-color 0.15s ease, opacity 0.15s ease;
  border: 1px solid transparent;
}

.btn-primary, .btn-submit {
  background-color: #1f6feb;
  color: #ffffff;
}

.btn-primary:hover, .btn-submit:hover {
  background-color: #388bfd;
}

.btn-secondary {
  background-color: var(--bg-card);
  color: var(--text-main);
  border-color: var(--border-color);
}

.btn-secondary:hover {
  background-color: #30363d;
}

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

/* Schedule Section */
.schedule-section {
  padding: 4rem 0;
  border-bottom: 1px solid var(--border-color);
}

.section-title {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 2rem;
  text-align: center;
}

.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.5rem;
}

.card {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  transition: transform 0.2s ease, border-color 0.2s ease;
}

.card:hover {
  border-color: #58a6ff66;
  transform: translateY(-2px);
}

.card-time {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--accent);
  margin-bottom: 0.5rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.card-title {
  font-size: 1.125rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.card-text {
  font-size: 0.9375rem;
  color: var(--text-muted);
}

/* Feedback Section */
.feedback-section {
  padding: 4rem 0;
}

.feedback-container {
  max-width: 640px;
}

.feedback-card {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2.25rem 2rem;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.2);
}

.feedback-header {
  text-align: center;
  margin-bottom: 1.75rem;
}

.feedback-subtitle {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-top: 0.5rem;
}

/* Messages */
.message {
  padding: 0.875rem 1rem;
  border-radius: var(--radius-sm);
  margin-bottom: 1.5rem;
  font-size: 0.95rem;
  line-height: 1.5;
}

.message[hidden] {
  display: none !important;
}

.message-error {
  background-color: var(--error-bg);
  border: 1px solid var(--error-border);
  color: var(--error-text);
}

.message-success {
  background-color: var(--success-bg);
  border: 1px solid var(--success-border);
  color: var(--success-text);
}

/* Form */
.feedback-form {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.form-label {
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text-main);
}

.required {
  color: var(--error-text);
}

.field-hint {
  font-size: 0.8125rem;
  color: var(--text-muted);
}

.form-control {
  width: 100%;
  padding: 0.75rem 0.875rem;
  font-size: 1rem;
  font-family: inherit;
  color: var(--text-main);
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

.form-control:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.form-textarea {
  resize: vertical;
  min-height: 110px;
}

.form-actions {
  margin-top: 0.5rem;
}

.btn-submit {
  width: 100%;
}

/* Footer */
.site-footer {
  margin-top: auto;
  border-top: 1px solid var(--border-color);
  background-color: var(--bg-secondary);
  padding: 2rem 0;
  font-size: 0.875rem;
  color: var(--text-muted);
}

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

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

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

@media (max-width: 600px) {
  .feedback-card {
    padding: 1.5rem 1.25rem;
  }
  .hero-title {
    font-size: 1.85rem;
  }
  .header-container {
    height: 3.5rem;
  }
}