/* ============================================
   Design Kit — Mobile App Design System
   ============================================ */

/* --- Font Import --- */
@import url('https://fonts.googleapis.com/css2?family=Science+Gothic:wght@400;500;600;700&display=swap');

/* --- CSS Custom Properties (Design Tokens) --- */
:root {
  /* Colors */
  --color-primary: #000000;
  --color-secondary-purple: #AF85E9;
  --color-secondary-yellow: #EECB57;
  --color-neutral: #FFFFFF;
  --color-accent: #DC3045;
  
  /* Semantic colors */
  --color-bg: var(--color-primary);
  --color-bg-card: rgba(255, 255, 255, 0.06);
  --color-bg-input: rgba(255, 255, 255, 0.08);
  --color-text: var(--color-neutral);
  --color-text-muted: rgba(255, 255, 255, 0.6);
  --color-text-placeholder: rgba(255, 255, 255, 0.4);
  --color-border: rgba(255, 255, 255, 0.2);
  --color-border-focus: var(--color-secondary-purple);
  --color-error: var(--color-accent);
  --color-success: #22c55e;
  
  /* Typography */
  --font-family-heading: 'Science Gothic', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-family-body: -apple-system, BlinkMacSystemFont, 'SF Pro Text', 'SF Pro Display', 'Segoe UI', system-ui, sans-serif;
  --font-size-xs: 0.75rem;    /* 12px */
  --font-size-sm: 0.875rem;   /* 14px */
  --font-size-base: 1rem;     /* 16px */
  --font-size-lg: 1.125rem;   /* 18px */
  --font-size-xl: 1.25rem;   /* 20px */
  --font-size-2xl: 1.5rem;   /* 24px */
  --font-size-3xl: 2rem;      /* 32px */
  --font-size-4xl: 2.5rem;    /* 40px */
  --font-weight-regular: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  --line-height-tight: 1.2;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.6;
  
  /* Spacing */
  --space-xs: 0.25rem;   /* 4px */
  --space-sm: 0.5rem;    /* 8px */
  --space-md: 1rem;      /* 16px */
  --space-lg: 1.5rem;    /* 24px */
  --space-xl: 2rem;      /* 32px */
  --space-2xl: 3rem;     /* 48px */
  
  /* Border Radius */
  --radius-button: 8px;
  --radius-card: 10px;
  --radius-input: 8px;
  --radius-badge: 8px;
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 200ms ease;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.5);
}

/* --- Base Styles --- */
*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: var(--font-family-body);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-regular);
  line-height: var(--line-height-normal);
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  margin: 0 0 var(--space-md);
  font-family: var(--font-family-heading);
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
}

h1 {
  font-size: var(--font-size-3xl);
  letter-spacing: -0.02em;
}

h2 {
  font-size: var(--font-size-2xl);
  letter-spacing: -0.01em;
}

h3 {
  font-size: var(--font-size-xl);
}

h4 {
  font-size: var(--font-size-lg);
}

p {
  margin: 0 0 var(--space-md);
  font-size: var(--font-size-base);
  line-height: var(--line-height-relaxed);
}

.caption {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
}

.label {
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-medium);
  color: var(--color-text);
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  font-family: var(--font-family-body);
  font-weight: var(--font-weight-semibold);
  text-decoration: none;
  border: none;
  border-radius: var(--radius-button);
  cursor: pointer;
  transition: opacity var(--transition-fast), transform var(--transition-fast);
  -webkit-tap-highlight-color: transparent;
}

.btn:active {
  transform: scale(0.98);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

/* Button sizes */
.btn-sm {
  padding: var(--space-sm) var(--space-md);
  font-size: var(--font-size-sm);
  min-height: 36px;
}

.btn-md {
  padding: var(--space-md) var(--space-lg);
  font-size: var(--font-size-base);
  min-height: 48px;
}

.btn-lg {
  padding: var(--space-md) var(--space-xl);
  font-size: var(--font-size-lg);
  min-height: 56px;
}

/* Primary button (yellow) */
.btn-primary {
  background-color: var(--color-secondary-yellow);
  color: var(--color-primary);
}

.btn-primary:hover:not(:disabled) {
  opacity: 0.9;
}

/* Outline button (purple border) */
.btn-outline {
  background-color: transparent;
  color: var(--color-neutral);
  border: 2px solid var(--color-secondary-purple);
}

.btn-outline:hover:not(:disabled) {
  background-color: rgba(175, 133, 233, 0.15);
}

/* Accent button */
.btn-accent {
  background-color: var(--color-accent);
  color: var(--color-neutral);
}

.btn-accent:hover:not(:disabled) {
  opacity: 0.9;
}

/* Icon button */
.btn-icon {
  padding: var(--space-sm);
  min-width: 48px;
  min-height: 48px;
}

.btn-icon.btn-sm {
  min-width: 36px;
  min-height: 36px;
  padding: var(--space-xs);
}

/* Full width */
.btn-block {
  width: 100%;
}

/* --- Forms --- */
.form-group {
  margin-bottom: var(--space-lg);
}

.form-label {
  display: block;
  margin-bottom: var(--space-xs);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-regular);
  color: var(--color-text);
}

.form-label.error {
  color: var(--color-error);
}

.form-input,
.form-select,
.form-textarea {
  width: 100%;
  padding: var(--space-sm) 0 var(--space-md);
  font-family: var(--font-family-body);
  font-size: var(--font-size-base);
  color: var(--color-text);
  background-color: transparent;
  border: none;
  border-bottom: 1px solid var(--color-border);
  border-radius: 0;
  transition: border-color var(--transition-fast);
  -webkit-appearance: none;
  appearance: none;
}

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

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
  outline: none;
  border-bottom-color: var(--color-border-focus);
  box-shadow: none;
}

.form-input.error,
.form-textarea.error {
  border-bottom-color: var(--color-error);
}

.form-input.error:focus,
.form-textarea.error:focus {
  border-bottom-color: var(--color-error);
}

.form-helper {
  margin-top: var(--space-xs);
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
}

.form-error {
  margin-top: var(--space-xs);
  font-size: var(--font-size-xs);
  color: var(--color-error);
}

/* Select with custom arrow */
.form-select {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%23FFFFFF' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0 center;
  padding-right: 1.5rem;
}

/* Textarea */
.form-textarea {
  min-height: 100px;
  resize: vertical;
  padding-bottom: var(--space-md);
}

/* Checkbox */
.form-checkbox {
  display: flex;
  align-items: flex-start;
  gap: var(--space-md);
  cursor: pointer;
}

.form-checkbox input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.form-checkbox .checkbox-box {
  flex-shrink: 0;
  width: 24px;
  height: 24px;
  border: 2px solid var(--color-border);
  border-radius: 4px;
  background-color: var(--color-bg-input);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: border-color var(--transition-fast), background-color var(--transition-fast);
}

.form-checkbox input:checked + .checkbox-box {
  background-color: var(--color-primary);
  border-color: var(--color-neutral);
}

.form-checkbox input:checked + .checkbox-box svg {
  opacity: 1;
}

.form-checkbox input:focus + .checkbox-box {
  box-shadow: 0 0 0 2px rgba(175, 133, 233, 0.3);
}

.form-checkbox .checkbox-box svg {
  width: 14px;
  height: 14px;
  color: var(--color-neutral);
  opacity: 0;
  transition: opacity var(--transition-fast);
}

/* Slider */
.form-slider {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 8px;
  background: var(--color-border);
  border-radius: 4px;
  outline: none;
}

.form-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 24px;
  height: 24px;
  background: var(--color-secondary-purple);
  border-radius: 50%;
  cursor: pointer;
  transition: transform var(--transition-fast);
}

.form-slider::-webkit-slider-thumb:hover {
  transform: scale(1.1);
}

.form-slider::-moz-range-thumb {
  width: 24px;
  height: 24px;
  background: var(--color-secondary-purple);
  border: none;
  border-radius: 50%;
  cursor: pointer;
}

.slider-labels {
  display: flex;
  justify-content: space-between;
  margin-top: var(--space-sm);
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
}

/* --- Cards --- */
.card {
  background-color: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-card);
  padding: var(--space-lg);
  transition: border-color var(--transition-fast);
}

.card:hover {
  border-color: rgba(255, 255, 255, 0.3);
}

.card-header {
  margin-bottom: var(--space-md);
  padding-bottom: var(--space-md);
  border-bottom: 1px solid var(--color-border);
}

.card-title {
  margin: 0;
  font-family: var(--font-family-heading);
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-bold);
}

.card-body {
  margin: 0;
}

/* Card variants */
.card-highlight {
  border-color: var(--color-secondary-purple);
  background-color: rgba(175, 133, 233, 0.1);
}

/* --- Badges --- */
.badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-xs) var(--space-sm);
  font-size: var(--font-size-xs);
  font-weight: var(--font-weight-semibold);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  border-radius: var(--radius-badge);
  white-space: nowrap;
}

.badge-default {
  background-color: var(--color-neutral);
  color: var(--color-primary);
}

.badge-purple {
  background-color: rgba(175, 133, 233, 0.3);
  color: var(--color-secondary-purple);
  border: 1px solid var(--color-secondary-purple);
}

.badge-yellow {
  background-color: rgba(238, 203, 87, 0.3);
  color: var(--color-secondary-yellow);
  border: 1px solid var(--color-secondary-yellow);
}

.badge-accent {
  background-color: rgba(220, 48, 69, 0.3);
  color: var(--color-accent);
  border: 1px solid var(--color-accent);
}

/* --- Icons --- */
.icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  flex-shrink: 0;
}

.icon-sm {
  width: 20px;
  height: 20px;
}

.icon-lg {
  width: 32px;
  height: 32px;
}

.icon svg {
  width: 100%;
  height: 100%;
  fill: none;
  stroke: currentColor;
  stroke-linecap: round;
  stroke-linejoin: round;
}

/* --- Progress / Steps --- */
.progress-bar {
  display: flex;
  gap: var(--space-xs);
  margin-bottom: var(--space-md);
}

.progress-step {
  flex: 1;
  height: 4px;
  background-color: var(--color-border);
  border-radius: 2px;
  transition: background-color var(--transition-fast);
}

.progress-step.active {
  background-color: var(--color-neutral);
}

.progress-step.completed {
  background-color: var(--color-secondary-purple);
}

/* --- Section spacing for showcase --- */
.dk-section {
  margin-bottom: var(--space-2xl);
}

.dk-section-title {
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-sm);
  font-family: var(--font-family-heading);
  font-size: var(--font-size-xl);
  font-weight: var(--font-weight-bold);
  color: var(--color-text);
  border-bottom: 1px solid var(--color-border);
}

.dk-grid {
  display: grid;
  gap: var(--space-lg);
}

@media (min-width: 640px) {
  :root {
    --font-size-3xl: 2.25rem;
    --font-size-4xl: 3rem;
  }
  
  .dk-grid-2 {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .dk-grid-3 {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (min-width: 768px) {
  .dk-grid-4 {
    grid-template-columns: repeat(4, 1fr);
  }
}