:root {
  --color-white: #ffffff;
  --color-light-gray: #f5f5f5;
  --color-gray: #9e9e9e;
  --color-dark-gray: #2c3e50;
  --color-darker-gray: #1a252f;
  --shadow-soft: 0 4px 12px rgba(0, 0, 0, 0.08);
  --shadow-medium: 0 6px 20px rgba(0, 0, 0, 0.12);
  --transition-smooth: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --border-radius: 12px;
  --border-radius-small: 8px;
}

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

body {
  font-family:
    "Montserrat",
    "Segoe UI",
    system-ui,
    -apple-system,
    sans-serif;
  background: linear-gradient(135deg, var(--color-light-gray) 0%, #e8e8e8 100%);
  color: var(--color-darker-gray);
  font-size: clamp(14px, 1.1vw, 16px);
  margin: 0;
  line-height: 1.6;
  min-height: 100vh;
  padding: 20px;
}

/* === Компоненты === */
.link {
  color: var(--color-dark-gray);
  text-decoration: none;
  font-weight: 600;
  position: relative;
  transition: var(--transition-smooth);
  padding: 2px 4px;
  border-radius: 4px;
}

.link::after {
  content: "";
  position: absolute;
  width: 0;
  height: 2px;
  bottom: 0;
  left: 0;
  background-color: var(--color-dark-gray);
  transition: width 0.3s ease;
}

.link:hover {
  color: var(--color-darker-gray);
  background-color: rgba(44, 62, 80, 0.05);
}

.link:hover::after {
  width: 100%;
}

/* === Контейнеры === */
.shell {
  max-width: 1200px;
  margin: 0 auto;
  padding: 20px;
  animation: fadeIn 0.8s ease-out;
}

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

/* === Сетка формы === */
.form-layout {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: 40px;
  align-items: start;
}

@media (max-width: 768px) {
  .form-layout {
    grid-template-columns: 1fr;
    gap: 30px;
  }
}

/* === Боковая панель === */
.form-aside {
  background: var(--color-white);
  padding: 30px;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-soft);
  border: 1px solid rgba(0, 0, 0, 0.05);
  transition: var(--transition-smooth);
  position: sticky;
  top: 30px;
}

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

.section-title {
  font-size: 1.8rem;
  margin-bottom: 20px;
  color: var(--color-darker-gray);
  position: relative;
  padding-bottom: 10px;
}

.section-title::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 60px;
  height: 3px;
  background: linear-gradient(
    to right,
    var(--color-gray),
    var(--color-dark-gray)
  );
  border-radius: 2px;
}

.text-muted {
  color: var(--color-gray);
  margin-bottom: 20px;
  line-height: 1.7;
}

.list {
  list-style: none;
  padding: 0;
}

.list li {
  display: flex;
  align-items: center;
  margin-bottom: 12px;
  padding-left: 24px;
  position: relative;
  transition: var(--transition-smooth);
}

.list li:hover {
  transform: translateX(5px);
  color: var(--color-dark-gray);
}

.list li::before {
  content: "•";
  position: absolute;
  left: 0;
  color: var(--color-gray);
  font-size: 1.5em;
}

/* === Карточка формы === */
.form-card {
  background: var(--color-white);
  padding: 40px;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-soft);
  border: 1px solid rgba(0, 0, 0, 0.05);
  transition: var(--transition-smooth);
  animation: slideIn 0.6s ease-out 0.2s both;
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateX(30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

.form-card:hover {
  box-shadow: var(--shadow-medium);
}

/* === Поля формы === */
.field {
  margin-bottom: 28px;
  position: relative;
}

.field label {
  display: block;
  margin-bottom: 10px;
  font-weight: 600;
  color: var(--color-dark-gray);
  font-size: 0.95rem;
  letter-spacing: 0.3px;
}

.field input,
.field textarea {
  width: 100%;
  padding: 16px;
  border: 2px solid var(--color-light-gray);
  border-radius: var(--border-radius-small);
  font-size: 1rem;
  font-family: inherit;
  background-color: var(--color-white);
  transition: var(--transition-smooth);
  color: var(--color-darker-gray);
}

.field input:focus,
.field textarea:focus {
  outline: none;
  border-color: var(--color-gray);
  box-shadow: 0 0 0 3px rgba(158, 158, 158, 0.1);
  transform: translateY(-1px);
}

.field input:hover,
.field textarea:hover {
  border-color: var(--color-gray);
}

.field textarea {
  resize: vertical;
  min-height: 120px;
  line-height: 1.5;
}

/* === Радио кнопки === */
.contact-preference-group {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 20px;
  margin: 15px 0 25px 0;
}

.radio-label {
  background: var(--color-light-gray);
  padding: 20px;
  border-radius: var(--border-radius-small);
  cursor: pointer;
  user-select: none;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  transition: var(--transition-smooth);
  border: 2px solid transparent;
  text-align: center;
}

.radio-label:hover {
  background: var(--color-white);
  border-color: var(--color-gray);
  transform: translateY(-3px);
  box-shadow: var(--shadow-soft);
}

.radio-label input[type="radio"] {
  margin: 0 0 12px 0;
  width: 20px;
  height: 20px;
  cursor: pointer;
  position: relative;
}

.radio-label input[type="radio"]:checked::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 15px;
  height: 15px;
  background: var(--color-darker-gray);
  border-radius: 50%;
}

.radio-label input[type="radio"] {
  appearance: none;
  border: 2px solid var(--color-gray);
  border-radius: 50%;
  background: var(--color-white);
  transition: var(--transition-smooth);
}

.radio-label input[type="radio"]:checked {
  border-color: var(--color-darker-gray);
}

/* === Кнопки === */
.btn {
  display: inline-block;
  padding: 16px 32px;
  background: linear-gradient(
    135deg,
    var(--color-dark-gray) 0%,
    var(--color-darker-gray) 100%
  );
  color: var(--color-white);
  text-align: center;
  border: none;
  border-radius: var(--border-radius-small);
  cursor: pointer;
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: 0.5px;
  transition: var(--transition-smooth);
  position: relative;
  overflow: hidden;
  min-width: 160px;
}

.btn::before {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 50%;
  transform: translate(-50%, -50%);
  transition:
    width 0.6s,
    height 0.6s;
}

.btn:hover::before {
  width: 300px;
  height: 300px;
}

.btn:hover {
  transform: translateY(-3px);
  box-shadow: 0 10px 25px rgba(44, 62, 80, 0.2);
}

.btn:active {
  transform: translateY(-1px);
}

/* === Сообщения === */
.message {
  padding: 20px;
  margin-bottom: 25px;
  background: var(--color-light-gray);
  border: 1px solid var(--color-gray);
  border-radius: var(--border-radius-small);
  color: var(--color-darker-gray);
  animation: slideDown 0.4s ease-out;
  display: flex;
  align-items: center;
  gap: 12px;
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.message::before {
  content: "✓";
  background: var(--color-dark-gray);
  color: var(--color-white);
  width: 24px;
  height: 24px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
}

/* === Кнопка "Назад" === */
.back-to-main {
  background: linear-gradient(
    135deg,
    var(--color-dark-gray) 0%,
    var(--color-darker-gray) 100%
  );
  padding: 12px 0;
  border-radius: var(--border-radius);
  margin-bottom: 25px;
  text-align: center;
  display: inline-block;
  min-width: 200px;
  transition: var(--transition-smooth);
  box-shadow: var(--shadow-soft);
}

.back-to-main:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-medium);
}

.back-link {
  color: var(--color-white);
  text-decoration: none;
  font-weight: 600;
  font-size: 1rem;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  transition: var(--transition-smooth);
}

.back-link::before {
  content: "←";
  transition: transform 0.3s ease;
}

.back-link:hover {
  letter-spacing: 0.5px;
}

.back-link:hover::before {
  transform: translateX(-5px);
}

/* === Адаптивность === */
@media (max-width: 480px) {
  body {
    padding: 10px;
  }

  .shell {
    padding: 10px;
  }

  .form-card,
  .form-aside {
    padding: 25px 20px;
  }

  .contact-preference-group {
    grid-template-columns: 1fr;
  }

  .section-title {
    font-size: 1.5rem;
  }
}

/* === Эффекты загрузки === */
@media (prefers-reduced-motion: no-preference) {
  .form-card,
  .form-aside,
  .field,
  .btn {
    will-change: transform;
  }
}

/* === Фокус-состояния для доступности === */
*:focus-visible {
  outline: 2px solid var(--color-dark-gray);
  outline-offset: 2px;
}

/* Улучшенный скроллбар */
::-webkit-scrollbar {
  width: 8px;
}

::-webkit-scrollbar-track {
  background: var(--color-light-gray);
}

::-webkit-scrollbar-thumb {
  background: var(--color-gray);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--color-dark-gray);
}

/* ======================================== */

/* Стили кнопки "Наверх" */
.back-to-top {
  position: fixed;
  bottom: 40px;
  right: -100px; /* Начальное положение за пределами экрана */
  width: 50px;
  height: 50px;
  background: #6c757d; /* Серый фон */
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  border: none;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
  transition: all 0.4s cubic-bezier(0.68, -0.55, 0.265, 1.55);
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
}

.back-to-top.show {
  right: 40px;
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  background: #5a6268; /* Темнее при наведении */
  transform: translateY(-3px);
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.2);
}

.back-to-top:active {
  transform: translateY(-1px);
}

/* Стрелка вверх */
.arrow {
  width: 15px;
  height: 15px;
  border: solid white;
  border-width: 0 3px 3px 0;
  transform: rotate(-135deg);
  transition: transform 0.3s;
}

.back-to-top:hover .arrow {
  transform: rotate(-135deg) translate(2px, 2px);
}

/* Адаптивность */
@media (max-width: 768px) {
  .back-to-top {
    width: 45px;
    height: 45px;
    bottom: 25px;
  }

  .back-to-top.show {
    right: 25px;
  }
}

@media (max-width: 480px) {
  .back-to-top {
    display: none;
  }

  .back-to-top.show {
    display: none;
  }

  .arrow {
    display: none;
  }
}