/* Base Variables & Theme */
:root {
  --primary: #4F46E5;
  --primary-hover: #4338CA;
  --secondary: #10B981;
  --bg-color: #f8fafc;
  --bg-card: #ffffff;
  --text-main: #0f172a;
  --text-muted: #64748b;
  --border-color: #e2e8f0;
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 1rem;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --transition: all 0.2s ease-in-out;
  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
}

[data-theme='dark'] {
  --bg-color: #0f172a;
  --bg-card: #1e293b;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --border-color: #334155;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.3);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.3), 0 2px 4px -2px rgb(0 0 0 / 0.3);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.4), 0 4px 6px -4px rgb(0 0 0 / 0.4);
}

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

html {
  font-family: var(--font-sans);
  line-height: 1.5;
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  background-color: var(--bg-color);
  color: var(--text-main);
  transition: background-color 0.3s, color 0.3s;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 1rem;
  color: var(--text-main);
}

h1 { font-size: 2.5rem; letter-spacing: -0.025em; }
h2 { font-size: 2rem; letter-spacing: -0.025em; }
h3 { font-size: 1.5rem; }
p { margin-bottom: 1rem; color: var(--text-muted); }

a {
  color: var(--primary);
  text-decoration: none;
  transition: var(--transition);
}

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

/* Layout Utilities */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.grid {
  display: grid;
  gap: 1.5rem;
}

.grid-cols-2 { grid-template-columns: repeat(2, 1fr); }
.grid-cols-3 { grid-template-columns: repeat(3, 1fr); }
.grid-cols-4 { grid-template-columns: repeat(4, 1fr); }

@media (max-width: 768px) {
  .grid-cols-2, .grid-cols-3, .grid-cols-4 {
    grid-template-columns: 1fr;
    gap: 1rem;
  }
}

.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.justify-center { justify-content: center; }
.gap-2 { gap: 0.5rem; }
.gap-4 { gap: 1rem; }
.gap-6 { gap: 1.5rem; }
.gap-8 { gap: 2rem; }

.mt-2 { margin-top: 0.5rem; }
.mt-4 { margin-top: 1rem; }
.mt-6 { margin-top: 1.5rem; }
.mt-8 { margin-top: 2rem; }
.mt-12 { margin-top: 3rem; }
.mb-4 { margin-bottom: 1rem; }
.mb-8 { margin-bottom: 2rem; }

.py-4 { padding-top: 1rem; padding-bottom: 1rem; }
.py-8 { padding-top: 2rem; padding-bottom: 2rem; }
.py-16 { padding-top: 4rem; padding-bottom: 4rem; }
.px-4 { padding-left: 1rem; padding-right: 1rem; }
.p-6 { padding: 1.5rem; }
.text-center { text-align: center; }
.text-lg { font-size: 1.125rem; }
.text-sm { font-size: 0.875rem; }
.font-semibold { font-weight: 600; }
.w-full { width: 100%; }
.hidden { display: none !important; }

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-md);
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: var(--transition);
  font-family: inherit;
  font-size: 1rem;
  gap: 0.5rem;
}

.btn-primary {
  background-color: var(--primary);
  color: white;
  box-shadow: var(--shadow-md);
}

.btn-primary:hover {
  background-color: var(--primary-hover);
  transform: translateY(-1px);
}

.btn-secondary {
  background-color: var(--bg-card);
  color: var(--text-main);
  border: 1px solid var(--border-color);
}

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

.btn-outline {
  background: transparent;
  color: var(--primary);
  border: 2px solid var(--primary);
}

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

/* Cards */
.card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

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

/* Header & Navigation */
.header {
  position: sticky;
  top: 0;
  z-index: 50;
  background-color: var(--bg-card);
  border-bottom: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
}

.navbar {
  height: 4.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--text-main);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.nav-links {
  display: flex;
  gap: 1.5rem;
  align-items: center;
}

.nav-links a {
  color: var(--text-muted);
  font-weight: 500;
}

.nav-links a:hover, .nav-links a.active {
  color: var(--primary);
}

.mobile-menu-btn {
  display: none;
  background: transparent;
  border: none;
  color: var(--text-main);
  cursor: pointer;
  padding: 0.5rem;
}

/* Theme Toggle */
.theme-toggle {
  background: transparent;
  border: none;
  color: var(--text-main);
  cursor: pointer;
  padding: 0.5rem;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
}

.theme-toggle:hover {
  background-color: var(--bg-color);
}

/* Footer */
.footer {
  background-color: var(--bg-card);
  border-top: 1px solid var(--border-color);
  padding: 3rem 0 1rem;
  margin-top: auto;
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 2rem;
  margin-bottom: 2rem;
}

.footer-title {
  font-size: 1.125rem;
  font-weight: 700;
  margin-bottom: 1rem;
}

.footer-links {
  list-style: none;
}

.footer-links li {
  margin-bottom: 0.5rem;
}

.footer-links a {
  color: var(--text-muted);
}

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

.footer-bottom {
  border-top: 1px solid var(--border-color);
  padding-top: 1rem;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.875rem;
}


/* Drag & Drop Upload Zone */
.upload-zone {
  border: 2px dashed var(--border-color);
  border-radius: var(--radius-lg);
  padding: 3rem 1.5rem;
  text-align: center;
  background-color: var(--bg-card);
  transition: var(--transition);
  cursor: pointer;
  position: relative;
  overflow: hidden;
}

.upload-zone:hover, .upload-zone.dragover {
  border-color: var(--primary);
  background-color: rgba(79, 70, 229, 0.05);
}

[data-theme='dark'] .upload-zone:hover, [data-theme='dark'] .upload-zone.dragover {
  background-color: rgba(79, 70, 229, 0.15);
}

.upload-icon {
  width: 48px;
  height: 48px;
  color: var(--primary);
  margin-bottom: 1rem;
}

.upload-input {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  cursor: pointer;
}

/* Tool Interface General */
.tool-workspace {
  background-color: var(--bg-card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  margin-top: 2rem;
}

.tool-header {
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
  background-color: rgba(0,0,0,0.02);
}

[data-theme='dark'] .tool-header {
  background-color: rgba(255,255,255,0.02);
}

.tool-body {
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

@media (min-width: 768px) {
  .tool-body.split-view {
    flex-direction: row;
    align-items: flex-start;
  }
  .tool-preview { flex: 1; min-width: 0; }
  .tool-controls { flex: 0 0 350px; }
}

canvas {
  max-width: 100%;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  display: block;
  margin: 0 auto;
}

/* Forms */
.form-group {
  margin-bottom: 1.25rem;
}
.form-label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 500;
  color: var(--text-main);
}
.form-input, .form-textarea, .form-select {
  width: 100%;
  padding: 0.75rem 1rem;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  background-color: var(--bg-card);
  color: var(--text-main);
  font-family: inherit;
  font-size: 1rem;
  transition: var(--transition);
}
.form-input:focus, .form-textarea:focus, .form-select:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

/* Mobile Nav */
.nav-menu {
  display: none;
}

@media (max-width: 768px) {
  .nav-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background-color: var(--bg-card);
    flex-direction: column;
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow-md);
    gap: 1rem;
  }
  .nav-menu.active {
    display: flex;
  }
  .mobile-menu-btn {
    display: block;
  }
  .nav-links {
    display: none;
  }
}