@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

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

:root {
  --bg-primary: #ffffff;
  --bg-secondary: #f5f5f7;
  --bg-card: #ffffff;
  --text-primary: #1d1d1f;
  --text-secondary: #6e6e73;
  --accent: #0071e3;
  --accent-hover: #0077ed;
  --border: #d2d2d7;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.08);
  --shadow-hover: 0 8px 32px rgba(0, 0, 0, 0.14);
  --toggle-bg: #e5e5ea;
  --toggle-knob: #ffffff;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
  --bg-primary: #000000;
  --bg-secondary: #1c1c1e;
  --bg-card: #2c2c2e;
  --text-primary: #f5f5f7;
  --text-secondary: #98989d;
  --accent: #2997ff;
  --accent-hover: #409cff;
  --border: #38383a;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
  --shadow-hover: 0 8px 32px rgba(0, 0, 0, 0.6);
  --toggle-bg: #48484a;
  --toggle-knob: #f5f5f7;
}

html {
  transition: background-color var(--transition), color var(--transition);
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  transition: background-color var(--transition), color var(--transition);
}

/* Header */
header {
  width: 100%;
  max-width: 900px;
  padding: 20px 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 18px;
  font-weight: 600;
  color: var(--text-primary);
  letter-spacing: -0.3px;
}

/* Theme Toggle */
.theme-toggle {
  display: flex;
  align-items: center;
  gap: 10px;
  cursor: pointer;
  user-select: none;
}

.theme-toggle-label {
  font-size: 13px;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color var(--transition);
}

.toggle-switch {
  position: relative;
  width: 52px;
  height: 28px;
  background-color: var(--toggle-bg);
  border-radius: 14px;
  transition: background-color var(--transition);
  cursor: pointer;
  border: none;
  outline: none;
  padding: 0;
}

.toggle-switch:focus-visible {
  box-shadow: 0 0 0 3px var(--accent);
}

.toggle-knob {
  position: absolute;
  top: 3px;
  left: 3px;
  width: 22px;
  height: 22px;
  background-color: var(--toggle-knob);
  border-radius: 50%;
  transition: transform var(--transition), background-color var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.2);
  pointer-events: none;
}

[data-theme="dark"] .toggle-knob {
  transform: translateX(24px);
}

.toggle-icon {
  font-size: 12px;
  line-height: 1;
}

/* Main Content */
main {
  flex: 1;
  width: 100%;
  max-width: 900px;
  padding: 40px 24px 80px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 48px;
}

/* Hero */
.hero {
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}

.hero-tag {
  display: inline-block;
  padding: 6px 14px;
  background-color: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 20px;
  font-size: 12px;
  font-weight: 500;
  color: var(--text-secondary);
  letter-spacing: 0.5px;
  text-transform: uppercase;
  transition: background-color var(--transition), border-color var(--transition);
}

.hero h1 {
  font-size: clamp(36px, 6vw, 64px);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -1.5px;
  color: var(--text-primary);
  transition: color var(--transition);
}

.hero h1 span {
  background: linear-gradient(135deg, var(--accent), #30d158);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 18px;
  color: var(--text-secondary);
  max-width: 480px;
  line-height: 1.6;
  font-weight: 400;
  transition: color var(--transition);
}

/* Cards */
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 20px;
  width: 100%;
}

.card {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 28px;
  box-shadow: var(--shadow);
  transition: background-color var(--transition), border-color var(--transition),
              box-shadow var(--transition), transform var(--transition);
  cursor: default;
}

.card:hover {
  box-shadow: var(--shadow-hover);
  transform: translateY(-2px);
}

.card-icon {
  font-size: 28px;
  margin-bottom: 16px;
  display: block;
}

.card h3 {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
  transition: color var(--transition);
}

.card p {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.6;
  transition: color var(--transition);
}

/* CTA Button */
.cta-group {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 28px;
  border-radius: 980px;
  font-size: 15px;
  font-weight: 500;
  cursor: pointer;
  border: none;
  transition: background-color var(--transition), color var(--transition),
              transform 0.15s ease, box-shadow var(--transition);
  text-decoration: none;
  font-family: inherit;
}

.btn:active {
  transform: scale(0.97);
}

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

.btn-primary:hover {
  background-color: var(--accent-hover);
  box-shadow: 0 4px 16px rgba(0, 113, 227, 0.35);
}

.btn-secondary {
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background-color: var(--border);
}

/* Toast notification */
.toast {
  position: fixed;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%) translateY(80px);
  background-color: var(--bg-card);
  color: var(--text-primary);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 12px 20px;
  font-size: 14px;
  font-weight: 500;
  box-shadow: var(--shadow-hover);
  transition: transform 0.35s cubic-bezier(0.34, 1.56, 0.64, 1), opacity 0.35s ease;
  opacity: 0;
  pointer-events: none;
  white-space: nowrap;
  z-index: 1000;
}

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

/* Contact Form */
.contact-section {
  width: 100%;
  max-width: 600px;
  display: flex;
  flex-direction: column;
  gap: 28px;
}

.contact-header {
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.contact-header h2 {
  font-size: 30px;
  font-weight: 700;
  letter-spacing: -0.6px;
  color: var(--text-primary);
  transition: color var(--transition);
}

.contact-header p {
  font-size: 15px;
  color: var(--text-secondary);
  line-height: 1.6;
  transition: color var(--transition);
}

.contact-form {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 32px;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  gap: 18px;
  transition: background-color var(--transition), border-color var(--transition);
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 7px;
}

.form-group label {
  font-size: 13px;
  font-weight: 500;
  color: var(--text-primary);
  transition: color var(--transition);
}

.required { color: #ff453a; }

.form-group input,
.form-group textarea {
  background-color: var(--bg-secondary);
  border: 1.5px solid var(--border);
  border-radius: 10px;
  padding: 11px 13px;
  font-size: 14px;
  font-family: inherit;
  color: var(--text-primary);
  outline: none;
  resize: vertical;
  transition: border-color var(--transition), background-color var(--transition),
              box-shadow var(--transition), color var(--transition);
}

.form-group input::placeholder,
.form-group textarea::placeholder {
  color: var(--text-secondary);
  opacity: 0.6;
}

.form-group input:focus,
.form-group textarea:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 15%, transparent);
  background-color: var(--bg-primary);
}

.btn-full {
  width: 100%;
  justify-content: center;
  padding: 14px;
  font-size: 15px;
  border-radius: 12px;
  margin-top: 4px;
}

.btn-primary:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

@media (max-width: 600px) {
  .form-row { grid-template-columns: 1fr; }
  .contact-form { padding: 24px 20px; }
}

/* Comments Section */
.comments-section {
  width: 100%;
  max-width: 760px;
  display: flex;
  flex-direction: column;
  gap: 28px;
}

.comments-header {
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.comments-header h2 {
  font-size: 30px;
  font-weight: 700;
  letter-spacing: -0.6px;
  color: var(--text-primary);
  transition: color var(--transition);
}

.comments-header p {
  font-size: 15px;
  color: var(--text-secondary);
  line-height: 1.6;
  transition: color var(--transition);
}

.comments-wrapper {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 32px;
  box-shadow: var(--shadow);
  transition: background-color var(--transition), border-color var(--transition);
  min-height: 120px;
}

/* Footer */
footer {
  width: 100%;
  padding: 20px 24px;
  text-align: center;
  border-top: 1px solid var(--border);
  color: var(--text-secondary);
  font-size: 13px;
  transition: border-color var(--transition), color var(--transition);
}

@media (max-width: 600px) {
  .cards {
    grid-template-columns: 1fr;
  }

  .hero h1 {
    font-size: 36px;
  }

  .hero p {
    font-size: 16px;
  }
}