/* ==========================================================================
   Paint Studio — Core Stylesheet
   Design tokens: soft, premium, minimal. Inter typeface throughout.
   ========================================================================== */

:root {
  /* Color palette */
  --color-bg: #F5F7FA;
  --color-primary: #2563EB;
  --color-primary-hover: #1D4FD1;
  --color-primary-soft: #EEF2FF;
  --color-text: #111827;
  --color-text-muted: #6B7280;
  --color-border: #E5E7EB;
  --color-surface: #FFFFFF;
  --color-danger: #DC2626;

  /* Radius & shadow */
  --radius-lg: 16px;
  --radius-md: 12px;
  --radius-sm: 8px;
  --shadow-sm: 0 1px 2px rgba(17, 24, 39, 0.04), 0 1px 3px rgba(17, 24, 39, 0.06);
  --shadow-md: 0 4px 10px rgba(17, 24, 39, 0.05), 0 2px 4px rgba(17, 24, 39, 0.04);
  --shadow-lg: 0 12px 30px rgba(17, 24, 39, 0.08), 0 4px 10px rgba(17, 24, 39, 0.04);

  /* Motion */
  --ease: cubic-bezier(0.4, 0, 0.2, 1);
  --duration: 180ms;
}

/* ---------- Reset ---------- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background-color: var(--color-bg);
  color: var(--color-text);
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  line-height: 1.5;
}

img, svg {
  display: block;
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
  color: inherit;
}

a {
  color: inherit;
  text-decoration: none;
}

input {
  font-family: inherit;
}

/* Visible keyboard focus for accessibility */
a:focus-visible,
button:focus-visible,
input:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

/* ==========================================================================
   Header
   ========================================================================== */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(255, 255, 255, 0.92);
  backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid var(--color-border);
  transition: box-shadow var(--duration) var(--ease);
}

.site-header.is-scrolled {
  box-shadow: var(--shadow-md);
}

.header-inner {
  max-width: 1280px;
  margin: 0 auto;
  padding: 16px 32px;
  display: flex;
  align-items: center;
  gap: 40px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 18px;
  letter-spacing: -0.01em;
  flex-shrink: 0;
}

.logo-mark {
  font-size: 22px;
  line-height: 1;
}

.main-nav {
  display: flex;
  align-items: center;
  gap: 4px;
  flex: 1;
}

.nav-link {
  position: relative;
  font-size: 14.5px;
  font-weight: 500;
  color: var(--color-text-muted);
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  transition: color var(--duration) var(--ease), background-color var(--duration) var(--ease);
}

.nav-link:hover {
  color: var(--color-text);
  background-color: var(--color-bg);
}

.nav-link.is-active {
  color: var(--color-primary);
  font-weight: 600;
}

.header-contact {
  display: flex;
  align-items: center;
  gap: 20px;
  flex-shrink: 0;
}

.contact-link {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 13.5px;
  font-weight: 500;
  color: var(--color-text-muted);
  transition: color var(--duration) var(--ease);
  white-space: nowrap;
}

.contact-link:hover {
  color: var(--color-primary);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 32px;
  height: 32px;
  flex-shrink: 0;
}

.nav-toggle span {
  display: block;
  width: 100%;
  height: 2px;
  background-color: var(--color-text);
  border-radius: 2px;
  transition: transform var(--duration) var(--ease), opacity var(--duration) var(--ease);
}

/* ==========================================================================
   Main app layout
   ========================================================================== */

.app {
  max-width: 1280px;
  margin: 0 auto;
  padding: 40px 32px 64px;
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.app-intro {
  display: flex;
  flex-direction: column;
  gap: 6px;
  animation: fadeInUp 0.5s var(--ease) both;
}

.app-title {
  font-size: 28px;
  font-weight: 800;
  letter-spacing: -0.02em;
}

.app-subtitle {
  font-size: 15px;
  color: var(--color-text-muted);
}

/* ==========================================================================
   Toolbar
   ========================================================================== */

.toolbar {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 18px;
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  padding: 14px 20px;
  animation: fadeInUp 0.5s var(--ease) 0.05s both;
}

.toolbar-group {
  display: flex;
  align-items: center;
  gap: 8px;
}

.toolbar-divider {
  width: 1px;
  height: 28px;
  background-color: var(--color-border);
}

.control-label {
  font-size: 13px;
  font-weight: 500;
  color: var(--color-text-muted);
}

/* Tool buttons (Brush / Eraser) */
.tool-btn {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 9px 14px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 500;
  color: var(--color-text-muted);
  border: 1px solid transparent;
  transition: background-color var(--duration) var(--ease),
              color var(--duration) var(--ease),
              transform var(--duration) var(--ease);
}

.tool-btn:hover {
  background-color: var(--color-bg);
  color: var(--color-text);
}

.tool-btn:active {
  transform: scale(0.97);
}

.tool-btn.is-active {
  background-color: var(--color-primary-soft);
  color: var(--color-primary);
  font-weight: 600;
}

/* Icon-only buttons (Undo / Redo) */
.icon-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
  color: var(--color-text-muted);
  transition: background-color var(--duration) var(--ease),
              color var(--duration) var(--ease),
              transform var(--duration) var(--ease);
}

.icon-btn:hover:not(:disabled) {
  background-color: var(--color-bg);
  color: var(--color-text);
}

.icon-btn:active:not(:disabled) {
  transform: scale(0.94);
}

.icon-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

/* Color picker */
.toolbar-color input[type="color"] {
  width: 32px;
  height: 32px;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: 0;
  cursor: pointer;
  background: none;
  transition: transform var(--duration) var(--ease), box-shadow var(--duration) var(--ease);
}

.toolbar-color input[type="color"]:hover {
  transform: scale(1.06);
  box-shadow: var(--shadow-sm);
}

.toolbar-color input[type="color"]::-webkit-color-swatch-wrapper {
  padding: 2px;
}

.toolbar-color input[type="color"]::-webkit-color-swatch {
  border: none;
  border-radius: 5px;
}

/* Size slider */
.toolbar-size {
  min-width: 160px;
}

.toolbar-size input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100px;
  height: 4px;
  border-radius: 999px;
  background: var(--color-border);
  outline: none;
}

.toolbar-size input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--color-primary);
  border: 2px solid var(--color-surface);
  box-shadow: var(--shadow-sm);
  cursor: pointer;
  transition: transform var(--duration) var(--ease);
}

.toolbar-size input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.15);
}

.toolbar-size input[type="range"]::-moz-range-thumb {
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--color-primary);
  border: 2px solid var(--color-surface);
  box-shadow: var(--shadow-sm);
  cursor: pointer;
}

.size-value {
  font-size: 13px;
  font-weight: 600;
  color: var(--color-text);
  min-width: 32px;
}

/* Action buttons */
.toolbar-actions {
  margin-left: auto;
}

.ghost-btn {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 9px 16px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 500;
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
  transition: background-color var(--duration) var(--ease),
              color var(--duration) var(--ease),
              border-color var(--duration) var(--ease);
}

.ghost-btn:hover {
  background-color: #FEF2F2;
  color: var(--color-danger);
  border-color: #FCA5A5;
}

.primary-btn {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 9px 18px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 600;
  color: #FFFFFF;
  background-color: var(--color-primary);
  box-shadow: var(--shadow-sm);
  transition: background-color var(--duration) var(--ease), transform var(--duration) var(--ease);
}

.primary-btn:hover {
  background-color: var(--color-primary-hover);
}

.primary-btn:active {
  transform: scale(0.97);
}

/* ==========================================================================
   Canvas
   ========================================================================== */

.canvas-wrap {
  flex: 1;
  display: flex;
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  padding: 8px;
  min-height: 60vh;
  animation: fadeIn 0.6s var(--ease) 0.1s both;
}

#paintCanvas {
  width: 100%;
  height: 100%;
  min-height: 58vh;
  border-radius: var(--radius-md);
  background-color: #FFFFFF;
  cursor: crosshair;
  touch-action: none;
}

/* ==========================================================================
   Toast notification
   ========================================================================== */

.toast {
  position: fixed;
  bottom: 28px;
  left: 50%;
  transform: translate(-50%, 20px);
  display: flex;
  align-items: center;
  gap: 10px;
  background-color: var(--color-text);
  color: #FFFFFF;
  padding: 12px 20px;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  font-size: 14px;
  font-weight: 500;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s var(--ease), transform 0.25s var(--ease);
  z-index: 200;
}

.toast svg {
  color: #34D399;
  flex-shrink: 0;
}

.toast.is-visible {
  opacity: 1;
  transform: translate(-50%, 0);
}

/* ==========================================================================
   Footer
   ========================================================================== */

.site-footer {
  max-width: 1280px;
  margin: 0 auto;
  padding: 28px 32px 40px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  border-top: 1px solid var(--color-border);
  color: var(--color-text-muted);
  font-size: 13.5px;
}

.footer-credit {
  display: flex;
  align-items: center;
  gap: 4px;
}

.heart {
  font-size: 13px;
}

.footer-contact {
  display: flex;
  align-items: center;
  gap: 10px;
}

.footer-contact a {
  transition: color var(--duration) var(--ease);
}

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

.footer-dot {
  color: var(--color-border);
}

/* ==========================================================================
   Animations
   ========================================================================== */

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.001ms !important;
    transition-duration: 0.001ms !important;
  }
}