:root {
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --primary-light: #818cf8;
  --accent: #10b981;
  --bg-gradient-start: #0f172a;
  --bg-gradient-end: #1e1b4b;
  --surface: #ffffff;
  --surface-alt: #f8fafc;
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --text-muted: #94a3b8;
  --border: #e2e8f0;
  --border-focus: #6366f1;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md:
    0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg:
    0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
  font-family:
    "Inter",
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    Roboto,
    sans-serif;
  background: linear-gradient(
    135deg,
    var(--bg-gradient-start) 0%,
    var(--bg-gradient-end) 100%
  );
  min-height: 100vh;
  color: var(--text-primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 3rem 1.5rem;
}

/* Header */
.header {
  text-align: center;
  margin-bottom: 2.5rem;
  animation: fadeInDown 0.6s ease-out;
}

.header-icon {
  width: 64px;
  height: 64px;
  margin: 0 auto 1.25rem;
  background: linear-gradient(
    135deg,
    var(--primary) 0%,
    var(--primary-dark) 100%
  );
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-lg);
}

.header-icon svg {
  width: 32px;
  height: 32px;
  color: #fff;
}

#title {
  font-size: 2.5rem;
  font-weight: 700;
  color: #fff;
  letter-spacing: -0.02em;
  margin-bottom: 0.5rem;
}

#description {
  font-size: 1.125rem;
  color: rgba(255, 255, 255, 0.7);
  font-weight: 300;
}

/* Form */
#survey-form {
  background: var(--surface);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  padding: 2.5rem;
  animation: fadeInUp 0.6s ease-out 0.1s both;
}

.form-section {
  margin-bottom: 2.5rem;
}

.form-section:last-of-type {
  margin-bottom: 2rem;
}

.section-title {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-primary);
  padding-bottom: 0.75rem;
  margin-bottom: 1.5rem;
  border-bottom: 2px solid var(--border);
  position: relative;
}

.section-title::after {
  content: "";
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 48px;
  height: 2px;
  background: linear-gradient(
    90deg,
    var(--primary) 0%,
    var(--primary-light) 100%
  );
}

.form-group {
  margin-bottom: 1.5rem;
}

.form-group:last-child {
  margin-bottom: 0;
}

/* Labels */
label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

/* Inputs */
input[type="text"],
input[type="email"],
input[type="number"],
select,
textarea {
  width: 100%;
  padding: 0.75rem 1rem;
  font-size: 0.9375rem;
  font-family: inherit;
  color: var(--text-primary);
  background: var(--surface-alt);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  transition: var(--transition);
  outline: none;
}

input[type="text"]:hover,
input[type="email"]:hover,
input[type="number"]:hover,
select:hover,
textarea:hover {
  border-color: var(--text-muted);
}

input[type="text"]:focus,
input[type="email"]:focus,
input[type="number"]:focus,
select:focus,
textarea:focus {
  border-color: var(--border-focus);
  background: #fff;
  box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.1);
}

input::placeholder,
textarea::placeholder {
  color: var(--text-muted);
}

/* Select */
select {
  appearance: none;
  -webkit-appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 1rem center;
  padding-right: 2.5rem;
  cursor: pointer;
}

/* Choice groups (radio & checkbox) */
.choice-group {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-top: 0.5rem;
}

.choice-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 1rem;
  background: var(--surface-alt);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition);
  margin-bottom: 0;
}

.choice-item:hover {
  border-color: var(--primary-light);
  background: #f5f5ff;
}

.choice-item input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.choice-text {
  font-size: 0.9375rem;
  font-weight: 400;
  color: var(--text-primary);
  user-select: none;
}

/* Custom radio */
.radio-custom {
  width: 20px;
  height: 20px;
  border: 2px solid var(--border);
  border-radius: 50%;
  position: relative;
  flex-shrink: 0;
  transition: var(--transition);
}

.choice-item input:checked + .radio-custom {
  border-color: var(--primary);
}

.choice-item input:checked + .radio-custom::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--primary);
  animation: popIn 0.2s ease-out;
}

.choice-item input:focus-visible + .radio-custom {
  box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.1);
}

/* Custom checkbox */
.checkbox-custom {
  width: 20px;
  height: 20px;
  border: 2px solid var(--border);
  border-radius: 6px;
  position: relative;
  flex-shrink: 0;
  transition: var(--transition);
}

.choice-item input:checked + .checkbox-custom {
  background: var(--primary);
  border-color: var(--primary);
}

.choice-item input:checked + .checkbox-custom::after {
  content: "";
  position: absolute;
  top: 40%;
  left: 50%;
  transform: translate(-50%, -50%) rotate(45deg);
  width: 5px;
  height: 10px;
  border: solid #fff;
  border-width: 0 2px 2px 0;
  animation: popIn 0.2s ease-out;
}

.choice-item input:focus-visible + .checkbox-custom {
  box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.1);
}

.choice-item:has(input:checked) {
  border-color: var(--primary);
  background: #f5f5ff;
}

/* Textarea */
textarea {
  resize: vertical;
  min-height: 120px;
  line-height: 1.5;
}

/* Submit button */
#submit {
  width: 100%;
  padding: 0.875rem 1.5rem;
  font-size: 1rem;
  font-weight: 600;
  font-family: inherit;
  color: #fff;
  background: linear-gradient(
    135deg,
    var(--primary) 0%,
    var(--primary-dark) 100%
  );
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  transition: var(--transition);
  box-shadow: var(--shadow-md);
}

#submit svg {
  width: 18px;
  height: 18px;
}

#submit:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(99, 102, 241, 0.35);
}

#submit:active {
  transform: translateY(0);
  box-shadow: var(--shadow-sm);
}

#submit:focus-visible {
  outline: none;
  box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.3);
}

/* Footer */
.footer {
  text-align: center;
  padding: 2rem 0 0;
  color: rgba(255, 255, 255, 0.5);
  font-size: 0.875rem;
}

.footer a {
  color: rgba(255, 255, 255, 0.8);
  text-decoration: none;
  font-weight: 500;
  transition: var(--transition);
}

.footer a:hover {
  color: var(--primary-light);
}

/* Animations */
@keyframes fadeInDown {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

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

@keyframes popIn {
  from {
    transform: translate(-50%, -50%) scale(0);
  }
  to {
    transform: translate(-50%, -50%) scale(1);
  }
}

/* Responsive */
@media (max-width: 640px) {
  .container {
    padding: 1.5rem 1rem;
  }

  #survey-form {
    padding: 1.5rem;
    border-radius: var(--radius-md);
  }

  #title {
    font-size: 2rem;
  }

  .header-icon {
    width: 56px;
    height: 56px;
  }

  .header-icon svg {
    width: 28px;
    height: 28px;
  }
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}