/* Minimalist Design System - SimuPhysics */

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

:root {
  /* Colors - Light Mode */
  --bg: #f5f5f5;
  --bg-card: #ffffff;
  --text: #0a0a0a;
  --text-secondary: #737373;
  --text-muted: #a3a3a3;
  --border: #d4d4d4;
  --border-light: #e5e5e5;
  --accent: #6366f1;
  --accent-hover: #4f46e5;
  --success: #10b981;
  --warning: #f59e0b;
  --error: #ef4444;
}

html.dark {
  /* Colors - Dark Mode */
  --bg: #0a0a0a;
  --bg-card: #171717;
  --text: #e5e5e5;
  --text-secondary: #a3a3a3;
  --text-muted: #737373;
  --border: #262626;
  --border-light: #1a1a1a;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
  transition: background-color 150ms, color 150ms;
}

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

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }

/* Layout */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
}

.container-sm {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 1rem;
}

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

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text);
  text-decoration: none;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 2rem;
}

.nav-link {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  text-decoration: none;
  transition: color 150ms;
}

.nav-link:hover,
.nav-link.active {
  color: var(--text);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.theme-toggle {
  padding: 0.5rem;
  background: transparent;
  border: none;
  cursor: pointer;
  font-size: 1.25rem;
  border-radius: 0.5rem;
  transition: background 150ms;
}

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

.btn-signin {
  padding: 0.5rem 1rem;
  background: var(--accent);
  color: white;
  border: none;
  border-radius: 0.5rem;
  font-weight: 600;
  font-size: 0.875rem;
  text-decoration: none;
  cursor: pointer;
  transition: background 150ms;
}

.btn-signin:hover {
  background: var(--accent-hover);
}

/* Main Content */
main {
  min-height: calc(100vh - 128px);
  padding: 3rem 0;
}

/* Cards */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 0.75rem;
  padding: 2rem;
  margin-bottom: 1.5rem;
}

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

.form-label {
  display: block;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 0.5rem;
}

.form-input,
.form-textarea {
  width: 100%;
  padding: 0.75rem 1rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 0.5rem;
  color: var(--text);
  font-size: 1rem;
  font-family: inherit;
  transition: all 150ms;
}

.form-input:focus,
.form-textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.form-textarea {
  min-height: 150px;
  resize: vertical;
}

/* Buttons */
.btn {
  padding: 0.75rem 1.5rem;
  border: none;
  border-radius: 0.5rem;
  font-weight: 600;
  font-size: 1rem;
  cursor: pointer;
  transition: all 150ms;
  text-decoration: none;
  display: inline-block;
}

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

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

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

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

/* Footer */
.minimal-footer {
  background: var(--bg-card);
  border-top: 1px solid var(--border);
  padding: 2rem 0;
  margin-top: 4rem;
}

.footer-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.footer-links {
  display: flex;
  gap: 1.5rem;
}

.footer-link {
  color: var(--text-secondary);
  text-decoration: none;
  transition: color 150ms;
}

.footer-link:hover {
  color: var(--text);
}

/* Utilities */
.text-center { text-align: center; }
.text-muted { color: var(--text-secondary); }
.text-mono { font-family: 'JetBrains Mono', Consolas, monospace; }

.mt-4 { margin-top: 2rem; }
.mb-4 { margin-bottom: 2rem; }
.py-4 { padding-top: 2rem; padding-bottom: 2rem; }

/* Responsive */
@media (max-width: 768px) {
  .nav-links {
    display: none;
  }
  
  h1 { font-size: 2rem; }
  h2 { font-size: 1.5rem; }
  
  .card {
    padding: 1.5rem;
  }
}