/* CSS Variables - базовые значения */
:root {
  --color-bg: #f5f5f7;
  --color-bg-elevated: #ffffff;
  --color-text: #111827;
  --color-muted: #6b7280;
  --color-accent: #2563eb;
  --color-accent-soft: rgba(37, 99, 235, 0.1);
  --color-border: #e5e7eb;
  --radius-lg: 18px;
  --radius-md: 10px;
  --shadow-soft: 0 18px 40px rgba(15, 23, 42, 0.12);
  --shadow-hover: 0 24px 48px rgba(15, 23, 42, 0.18);
  --transition: all 0.25s ease;
}

/* Светлая тема */
:root[data-theme="light"] {
  --color-bg: #f3f4f6;
  --color-bg-elevated: #ffffff;
  --color-text: #111827;
  --color-muted: #6b7280;
  --color-accent: #2563eb;
  --color-accent-soft: rgba(37, 99, 235, 0.12);
  --color-border: #e5e7eb;
}

/* Тёмная тема */
:root[data-theme="dark"] {
  --color-bg: #020617;
  --color-bg-elevated: #0f172a;
  --color-text: #e5e7eb;
  --color-muted: #9ca3af;
  --color-accent: #38bdf8;
  --color-accent-soft: rgba(56, 189, 248, 0.2);
  --color-border: #1e293b;
}

/* Тёплая тема */
:root[data-theme="warm"] {
  --color-bg: #fdf6e3;
  --color-bg-elevated: #fffaf0;
  --color-text: #3f2a1d;
  --color-muted: #876858;
  --color-accent: #d97706;
  --color-accent-soft: rgba(217, 119, 6, 0.15);
  --color-border: #f4e0c3;
}

/* Базовые стили */
html {
  font-size: 16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background-color: var(--color-bg);
  color: var(--color-text);
  transition: background-color 0.25s, color 0.25s;
  min-height: 100vh;
}

.container {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 16px;
}

/* Header */
.site-header {
  padding: 20px 0;
  border-bottom: 1px solid var(--color-border);
  background-color: var(--color-bg-elevated);
  position: sticky;
  top: 0;
  z-index: 100;
  transition: var(--transition);
}

.header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-weight: 600;
  font-size: 1.125rem;
  color: var(--color-text);
}

.logo__icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  background: var(--color-accent);
  color: white;
  border-radius: var(--radius-md);
  font-weight: 700;
}

.main-nav {
  display: flex;
  gap: 16px;
  flex: 1;
  justify-content: center;
}

.nav__link {
  color: var(--color-muted);
  font-size: 0.9375rem;
  transition: color 0.2s;
  padding: 8px 12px;
  border-radius: var(--radius-md);
}

.nav__link:hover {
  color: var(--color-accent);
  background-color: var(--color-accent-soft);
}

.header__controls {
  display: flex;
  align-items: center;
  gap: 12px;
}

.theme-switcher {
  display: flex;
  gap: 4px;
  background-color: var(--color-bg);
  padding: 4px;
  border-radius: var(--radius-md);
}

.theme-btn {
  padding: 6px 12px;
  border-radius: var(--radius-md);
  font-size: 0.8125rem;
  color: var(--color-muted);
  transition: var(--transition);
}

.theme-btn:hover {
  color: var(--color-text);
  background-color: var(--color-accent-soft);
}

.theme-btn.is-active {
  background-color: var(--color-accent);
  color: white;
}

.lang-switcher {
  padding: 8px 16px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 500;
  transition: var(--transition);
}

.lang-switcher:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* Hero Section */
.hero {
  padding: 60px 0;
}

.hero__inner {
  display: flex;
  flex-direction: column;
  gap: 48px;
}

.hero__content {
  text-align: center;
  max-width: 800px;
  margin: 0 auto;
}

.hero h1 {
  font-size: 2.5rem;
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 16px;
}

.hero__subtitle {
  font-size: 1.125rem;
  color: var(--color-muted);
  margin-bottom: 24px;
  line-height: 1.6;
}

.hero__benefits {
  display: flex;
  justify-content: center;
  gap: 32px;
  flex-wrap: wrap;
  margin-top: 32px;
}

.hero__benefits li {
  font-size: 0.9375rem;
  color: var(--color-text);
  position: relative;
  padding-left: 20px;
}

.hero__benefits li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: var(--color-accent);
  font-weight: bold;
}

/* Converter Card */
.converter-card {
  background-color: var(--color-bg-elevated);
  border-radius: var(--radius-lg);
  padding: 32px;
  box-shadow: var(--shadow-soft);
  transition: var(--transition);
}

.converter-card__toolbar {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-bottom: 24px;
}

.converter-card__label {
  font-weight: 500;
  color: var(--color-text);
  margin-bottom: 8px;
  display: block;
}

.converter-modes {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.mode-btn {
  padding: 10px 18px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 500;
  background-color: var(--color-bg);
  color: var(--color-text);
  transition: var(--transition);
}

.mode-btn:hover {
  border-color: var(--color-accent);
  background-color: var(--color-accent-soft);
}

.mode-btn.is-active {
  background-color: var(--color-accent);
  color: white;
  border-color: var(--color-accent);
}

.converter-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.btn {
  padding: 12px 24px;
  border-radius: var(--radius-md);
  font-size: 0.9375rem;
  font-weight: 500;
  transition: var(--transition);
  cursor: pointer;
}

.btn--primary {
  background-color: var(--color-accent);
  color: white;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

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

.btn--ghost {
  background-color: transparent;
  color: var(--color-muted);
  border: 1px solid var(--color-border);
}

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

.converter-card__areas {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

.converter-card__area {
  display: flex;
  flex-direction: column;
}

.converter-card__area textarea {
  width: 100%;
  min-height: 300px;
  padding: 16px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background-color: var(--color-bg);
  color: var(--color-text);
  font-size: 1rem;
  line-height: 1.6;
  resize: vertical;
  transition: var(--transition);
  font-family: inherit;
}

.converter-card__area textarea:focus {
  outline: none;
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px var(--color-accent-soft);
}

.converter-card__area textarea::placeholder {
  color: var(--color-muted);
}

.converter-card__area--output textarea {
  background-color: var(--color-bg);
  cursor: default;
}

.area-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 8px;
  font-size: 0.8125rem;
  color: var(--color-muted);
}

.hint {
  font-size: 0.75rem;
  opacity: 0.7;
}

.btn-icon {
  width: 32px;
  height: 32px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background-color: var(--color-bg);
  cursor: pointer;
  transition: var(--transition);
  font-size: 1.125rem;
}

.btn-icon:hover {
  background-color: var(--color-accent-soft);
  border-color: var(--color-accent);
}

/* Section Styles */
section {
  padding: 80px 0;
}

section h2 {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 24px;
  text-align: center;
}

section h3 {
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: 16px;
  margin-top: 32px;
}

section p {
  font-size: 1.0625rem;
  line-height: 1.7;
  color: var(--color-text);
  margin-bottom: 16px;
}

/* How it works */
#how {
  background-color: var(--color-bg-elevated);
}

.how-steps {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 32px;
  margin-top: 48px;
}

.how-step {
  text-align: center;
  padding: 32px;
}

.how-step__number {
  width: 60px;
  height: 60px;
  border-radius: 50%;
  background-color: var(--color-accent);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  font-weight: 700;
  margin: 0 auto 16px;
}

.how-step h3 {
  margin-top: 0;
}

.how-step p {
  color: var(--color-muted);
}

/* SEO Text Section */
#seo-text {
  max-width: 900px;
  margin: 0 auto;
}

#seo-text ul {
  list-style: disc;
  margin-left: 24px;
  margin-bottom: 16px;
}

#seo-text li {
  margin-bottom: 8px;
  line-height: 1.7;
}

/* FAQ Section */
#faq {
  background-color: var(--color-bg-elevated);
}

.faq-list {
  max-width: 800px;
  margin: 48px auto 0;
}

.faq-item {
  border-bottom: 1px solid var(--color-border);
  padding: 24px 0;
}

.faq-question {
  width: 100%;
  text-align: left;
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--color-text);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 8px 0;
  transition: color 0.2s;
}

.faq-question:hover {
  color: var(--color-accent);
}

.faq-question::after {
  content: "+";
  font-size: 1.5rem;
  font-weight: 300;
  color: var(--color-accent);
  transition: transform 0.3s;
}

.faq-item.is-open .faq-question::after {
  transform: rotate(45deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
  color: var(--color-muted);
  line-height: 1.7;
  padding-top: 0;
}

.faq-item.is-open .faq-answer {
  max-height: 500px;
  padding-top: 16px;
}

/* Footer */
.site-footer {
  padding: 48px 0 24px;
  border-top: 1px solid var(--color-border);
  text-align: center;
  color: var(--color-muted);
  font-size: 0.875rem;
}

.footer__links {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin-bottom: 24px;
  flex-wrap: wrap;
}

.footer__link {
  color: var(--color-accent);
  transition: color 0.2s;
  text-decoration: underline;
}

.footer__link:hover {
  color: var(--color-text);
  text-decoration: none;
}

.site-footer p {
  margin-bottom: 16px;
}

.btn-to-top {
  margin-top: 24px;
  padding: 10px 20px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background-color: var(--color-bg);
  color: var(--color-text);
  font-size: 0.875rem;
  transition: var(--transition);
  opacity: 0;
  pointer-events: none;
}

.btn-to-top.is-visible {
  opacity: 1;
  pointer-events: auto;
}

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

/* Notification */
.notification {
  position: fixed;
  bottom: 24px;
  right: 24px;
  padding: 16px 24px;
  background-color: var(--color-bg-elevated);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-soft);
  z-index: 1000;
  transform: translateY(100px);
  opacity: 0;
  transition: all 0.3s ease;
}

.notification.is-visible {
  transform: translateY(0);
  opacity: 1;
}

/* Responsive */
@media (max-width: 768px) {
  .header__inner {
    flex-wrap: wrap;
  }

  .main-nav {
    order: 3;
    width: 100%;
    justify-content: flex-start;
    overflow-x: auto;
    padding-bottom: 8px;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .hero__subtitle {
    font-size: 1rem;
  }

  .converter-card {
    padding: 24px;
  }

  .converter-card__areas {
    grid-template-columns: 1fr;
  }

  .converter-card__toolbar {
    flex-direction: column;
  }

  .converter-actions {
    width: 100%;
  }

  .btn {
    flex: 1;
  }

  section {
    padding: 48px 0;
  }

  section h2 {
    font-size: 1.75rem;
  }
}

@media (max-width: 480px) {
  .hero {
    padding: 40px 0;
  }

  .hero h1 {
    font-size: 1.75rem;
  }

  .converter-card {
    padding: 16px;
  }

  .converter-card__area textarea {
    min-height: 200px;
  }

  .how-steps {
    grid-template-columns: 1fr;
  }
}