:root {
  --bg: #fdfdfb;
  --bg-soft: #f4f4f2;
  --text: #1a1a1a;
  --text-muted: #555555;
  --accent: #2c3e50; /* Глубокий синий */
  --accent-soft: #5d6d7e; /* Серо-зелёный */
  --border: #e0e0dc;
  --container: 1200px;
  --transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  scroll-behavior: smooth;
}

body {
  background-color: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica,
    Arial, sans-serif;
  line-height: 1.7;
  font-size: 17px;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 40px;
}

.section {
  padding: 120px 0;
}

.bg-soft {
  background-color: var(--bg-soft);
}

h1,
h2,
h3,
h4 {
  font-weight: 500;
  line-height: 1.1;
  margin-bottom: 1.5rem;
}

h2 {
  font-size: 3rem;
  letter-spacing: -0.02em;
}
h3 {
  font-size: 1.8rem;
}

.text-serif {
  font-style: italic;
  font-family: Georgia, serif;
}

.label {
  font-size: 0.75rem;
  letter-spacing: 0.2em;
  color: var(--accent-soft);
  margin-bottom: 24px;
  display: block;
  font-weight: 700;
}

/* Header */
.site-header {
  height: 90px;
  position: fixed;
  top: 0;
  width: 100%;
  z-index: 1000;
  background: rgba(253, 253, 251, 0.9);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
}

.header-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
}

.logo {
  font-size: 1.5rem;
  font-weight: 800;
  text-decoration: none;
  color: var(--text);
  letter-spacing: 0.1em;
  display: flex;
  align-items: center;
  gap: 10px;
}

.logo img {
  height: 40px;
  width: auto;
}

.desktop-nav {
  display: flex;
  gap: 32px;
}

.desktop-nav a {
  text-decoration: none;
  color: var(--text-muted);
  font-size: 0.9rem;
  font-weight: 500;
  transition: var(--transition);
}

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

.nav-accent {
  color: var(--accent) !important;
  border-bottom: 1px solid var(--accent);
  padding-bottom: 2px;
}

.burger-trigger {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  color: var(--text);
}

/* Mobile Menu */
.mobile-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100vh;
  background: var(--bg);
  z-index: 1100;
  display: flex;
  align-items: center;
  justify-content: center;
  transform: translateY(-100%);
  transition: var(--transition);
}

.mobile-overlay.active {
  transform: translateY(0);
}

.mobile-nav {
  display: flex;
  flex-direction: column;
  gap: 40px;
  text-align: center;
  margin-top: 50px;
}

.mobile-nav a {
  font-size: 2rem;
  text-decoration: none;
  color: var(--text);
  font-weight: 400;
}

.burger-close {
  position: absolute;
  top: 30px;
  right: 40px;
  background: none;
  border: none;
  cursor: pointer;
}

/* Hero */
.hero-section {
  padding: 200px 0 120px;
}
.hero-grid {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 80px;
  align-items: flex-start;
}

.main-thesis {
  font-size: 4.5rem;
  margin-bottom: 40px;
}
.hero-essay p {
  margin-bottom: 24px;
  font-size: 1.2rem;
  color: var(--text-muted);
}

.hero-visual {
  height: 500px;
  background-image: url("./images/preview.jpg");
  background-size: cover;
  background-position: center;
  border: 1px solid var(--border);
  position: relative;
  overflow: hidden;
}

.arch-block {
  position: absolute;
  width: 150%;
  height: 150%;
  border: 1px solid var(--accent-soft);
  top: -25%;
  left: -25%;
  transform: rotate(15deg);
}

/* Layouts */
.split-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 80px;
  align-items: center;
}

.visual-pause {
  height: 400px;
  background-size: cover;
  background-position: center;
  border: 1px solid var(--border);
}
.visual-pause-wide {
  height: 300px;
  background-image: url("./images/algebra-curve-trigonometry-curve-graph\ \(1\).jpg");
  background-size: cover;
  background-position: center;
  border: 1px solid var(--border);
  margin-top: 40px;
}

/* Errors Grid */
.errors-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 40px;
  margin-top: 60px;
}

.error-card {
  background: var(--bg);
  padding: 60px 40px;
  border: 1px solid var(--border);
  transition: var(--transition);
}

.error-card:hover {
  transform: translateY(-10px);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.03);
  border-color: var(--accent);
}

.card-num {
  font-size: 1rem;
  color: var(--accent-soft);
  margin-bottom: 24px;
  font-family: var(--font-mono);
}

.offset-up {
  transform: translateY(-20px);
}
.offset-down {
  transform: translateY(20px);
}

/* Method */
.center {
  text-align: center;
}
.method-steps {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 40px;
  margin-top: 80px;
}

.method-item {
  border-left: 1px solid var(--border);
  padding-left: 32px;
}
.m-step {
  display: block;
  font-size: 2rem;
  color: var(--accent);
  margin-bottom: 20px;
  font-weight: 300;
}

/* Column Layout */
.one-column-grid {
  display: grid;
  grid-template-columns: 800px;
  justify-content: center;
}

/* Directions */
.directions-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 30px;
  margin-top: 60px;
}

.dir-card {
  padding: 50px;
  border: 1px solid var(--border);
  text-align: center;
  position: relative;
  transition: var(--transition);
}

.dir-card:hover {
  background-color: var(--accent);
  color: white;
}
.dir-card:hover p {
  color: rgba(255, 255, 255, 0.8);
}
.dir-card i {
  margin-top: 32px;
  width: 32px;
  height: 32px;
  opacity: 0.3;
}

/* FAQ */
.accordion {
  margin-top: 60px;
  border-top: 1px solid var(--border);
}
.accordion-item {
  border-bottom: 1px solid var(--border);
}
.accordion-trigger {
  width: 100%;
  padding: 40px 0;
  background: none;
  border: none;
  text-align: left;
  font-size: 1.4rem;
  cursor: pointer;
  color: var(--text);
  transition: var(--transition);
}
.accordion-trigger:hover {
  padding-left: 20px;
  color: var(--accent);
}
.accordion-content {
  max-height: 0;
  overflow: hidden;
  transition: var(--transition);
}
.accordion-content p {
  padding-bottom: 40px;
  color: var(--text-muted);
}
.accordion-item.active .accordion-content {
  max-height: 500px;
}

/* Form */
.thought-form {
  margin-top: 60px;
  display: flex;
  flex-direction: column;
  gap: 32px;
}
.input-wrap {
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.input-wrap label {
  font-size: 0.85rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}
.input-wrap input {
  background: transparent;
  border: none;
  border-bottom: 1px solid var(--border);
  padding: 16px 0;
  font-size: 1.1rem;
  transition: var(--transition);
  outline: none;
}
.input-wrap input:focus {
  border-bottom-color: var(--accent);
}

.checkbox-wrap {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  margin-top: 10px;
}
.checkbox-wrap label {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.4;
}
.checkbox-wrap a {
  color: var(--accent);
  text-decoration: none;
}

.btn-submit {
  background: var(--accent);
  color: white;
  border: none;
  padding: 24px 40px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  margin-top: 20px;
}
.btn-submit:hover {
  opacity: 0.9;
  transform: translateY(-2px);
}
.contact-section {
  border: 5px solid var(--border);
  margin: 20px;
}

/* Footer */
.site-footer {
  padding: 100px 0 0;
  background-color: var(--bg-soft);
  border-top: 1px solid var(--border);
}
.footer-grid {
  display: grid;
  grid-template-columns: 1fr 1.5fr 1fr;
  gap: 80px;
  margin-bottom: 80px;
}
.footer-brand .logo {
  font-size: 2rem;
  margin-bottom: 24px;
  display: inline-block;
}
.footer-contacts p {
  margin-bottom: 12px;
  color: var(--text-muted);
}
.footer-legal {
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.footer-legal a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.9rem;
  transition: var(--transition);
}
.footer-legal a:hover {
  color: var(--accent);
}
.footer-bottom {
  border-top: 1px solid var(--border);
  padding: 40px 0;
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Cookie Modal */
.cookie-modal {
  position: fixed;
  bottom: 40px;
  right: 40px;
  z-index: 2000;
  display: none;
}
.cookie-card {
  background: white;
  padding: 40px;
  border: 1px solid var(--border);
  max-width: 400px;
  box-shadow: 0 30px 60px rgba(0, 0, 0, 0.05);
}
.cookie-card h3 {
  font-size: 1.2rem;
  margin-bottom: 16px;
}
.cookie-card p {
  font-size: 0.9rem;
  margin-bottom: 24px;
  color: var(--text-muted);
}
.btn-small {
  background: var(--accent);
  color: white;
  border: none;
  padding: 12px 24px;
  cursor: pointer;
}

/* Responsive */
@media (min-width: 1025px) {
  .pc-no-wrap {
    white-space: nowrap;
  }
}

@media (max-width: 1024px) {
  .container {
    padding: 0 30px;
  }
  .hero-grid,
  .split-layout,
  .errors-grid,
  .method-steps,
  .directions-grid,
  .footer-grid {
    grid-template-columns: 1fr;
    gap: 60px;
  }
  .main-thesis {
    font-size: 2.5rem;
  }
  .form-header h2 {
    font-size: 2rem;
  }
  .offset-up,
  .offset-down {
    transform: none;
  }
  .desktop-nav {
    display: none;
  }
  .burger-trigger {
    display: block;
  }
  .one-column-grid {
    grid-template-columns: 1fr;
  }
}

.pages {
  padding: 120px 0;
}

.pages-wrap {
  max-width: 1000px;
  padding: 0 20px;
  margin: 0 auto 20px;
}

.pages h1 {
  font-size: 40px;
  font-weight: 900;
  color: var(--accent);
  margin-bottom: 40px;
  text-align: center;
}

.text-wrapper {
  background: #f8fafc;
  padding: 50px 40px;
  border-radius: 20px;
  line-height: 1.8;
}

.text-wrapper h2 {
  font-size: 28px;
  font-weight: 700;
  color: #1e293b;
  margin-top: 40px;
  margin-bottom: 15px;
  border-bottom: 2px solid rgba(99, 102, 241, 0.2);
  padding-bottom: 5px;
}

.text-wrapper h3 {
  color: #000000;
  margin-bottom: 20px;
}

.text-wrapper p {
  color: #64748b;
  margin-bottom: 20px;
}

.text-wrapper ul {
  list-style-type: none;
  padding-left: 0;
  margin-bottom: 20px;
}

.text-wrapper ul li {
  position: relative;
  padding-left: 25px;
  margin-bottom: 15px;
  color: #1e293b;
}

.text-wrapper ul li::before {
  content: "•";
  position: absolute;
  left: 0;
  font-size: 20px;
  line-height: 1;
  color: var(--primary);
  top: 0;
}

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

.text-wrapper a {
  color: #001eff;
  text-decoration: underline;
  font-weight: 600;
}

.text-wrapper ol {
  display: flex;
  flex-direction: column;
  padding: 20px;
  color: #000000;
}

.margin {
  margin: 120px 0 50px;
  font-size: 40px;
}

@media (max-width: 768px) {
  .pages {
    padding: 100px 0 60px;
  }
  .pages h1 {
    font-size: 28px;
    margin-bottom: 30px;
  }
  .text-wrapper {
    padding: 30px 20px;
  }
  .text-wrapper h2 {
    font-size: 24px;
    margin-top: 30px;
  }
  .margin {
    margin: 80px 0 30px;
    font-size: 28px;
  }
}