/* ============================================
   Petr Sahula — Personal Website Styles
   Minimal, clean, responsive
   Accent: Red (#DC2626)
   ============================================ */

/* CSS Custom Properties */
:root {
  --color-bg: #ffffff;
  --color-fg: #1a1a1a;
  --color-fg-muted: #666666;
  --color-fg-light: #999999;
  --color-border: #e5e5e5;
  --color-surface: #f5f5f5;
  --color-accent: #DC2626;
  --color-accent-hover: #b91c1c;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;

  --radius-sm: 4px;
  --radius-md: 8px;

  --transition: 150ms ease-out;
}

/* Dark mode via prefers-color-scheme */
@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #0f0f0f;
    --color-fg: #e5e5e5;
    --color-fg-muted: #a3a3a3;
    --color-fg-light: #737373;
    --color-border: #262626;
    --color-surface: #1a1a1a;
    --color-accent: #ef4444;
    --color-accent-hover: #f87171;
  }
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  background-color: var(--color-bg);
  color: var(--color-fg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

img, svg {
  display: block;
  max-width: 100%;
}

/* Container */
.container {
  width: 100%;
  max-width: 720px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(var(--color-bg), 0.8);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--color-border);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 3.5rem;
  max-width: 720px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.nav-logo {
  font-weight: 700;
  font-size: 1.125rem;
  color: var(--color-fg);
  letter-spacing: -0.02em;
}

.nav-logo:hover {
  color: var(--color-accent);
  transition: color var(--transition);
}

.nav-menu {
  display: flex;
  gap: 1.5rem;
  list-style: none;
}

.nav-link {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-fg-muted);
  transition: color var(--transition);
}

.nav-link:hover,
.nav-link:focus {
  color: var(--color-accent);
}

/* Mobile nav toggle */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
  position: relative;
  width: 2rem;
  height: 2rem;
}

.hamburger,
.hamburger::before,
.hamburger::after {
  display: block;
  width: 1.25rem;
  height: 2px;
  background-color: var(--color-fg);
  border-radius: var(--radius-sm);
  transition: transform 200ms ease;
}

.hamburger {
  position: relative;
}

.hamburger::before,
.hamburger::after {
  content: '';
  position: absolute;
  left: 0;
}

.hamburger::before {
  top: -6px;
}

.hamburger::after {
  top: 6px;
}

.nav-toggle[aria-expanded="true"] .hamburger {
  background-color: transparent;
}

.nav-toggle[aria-expanded="true"] .hamburger::before {
  transform: rotate(45deg);
  top: 0;
}

.nav-toggle[aria-expanded="true"] .hamburger::after {
  transform: rotate(-45deg);
  top: 0;
}

@media (max-width: 480px) {
  .nav-toggle {
    display: block;
  }

  .nav-menu {
    display: none;
    position: absolute;
    top: 3.5rem;
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    padding: 0.5rem 0;
  }

  .nav-menu.is-open {
    display: flex;
  }

  .nav-menu li {
    width: 100%;
  }

  .nav-link {
    display: block;
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
  }
}

/* Sections */
section {
  padding: 4rem 0;
}

.section-title {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 1.5rem;
  letter-spacing: -0.02em;
  line-height: 1.2;
}

/* Hero */
.hero {
  padding: 6rem 0 4rem;
  text-align: center;
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: 0.75rem;
}

.hero-tagline {
  font-size: 1.125rem;
  color: var(--color-fg-muted);
  margin-bottom: 2rem;
  max-width: 480px;
  margin-left: auto;
  margin-right: auto;
}

.hero-actions {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

/* About */
.about-text {
  font-size: 1.0625rem;
  color: var(--color-fg-muted);
  line-height: 1.7;
  max-width: 600px;
}

/* CV */
.cv-text {
  font-size: 1.0625rem;
  color: var(--color-fg-muted);
  margin-bottom: 1.5rem;
}

/* Contact */
.contact-text {
  font-size: 1.0625rem;
  color: var(--color-fg-muted);
  margin-bottom: 2rem;
}

.contact-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.contact-link {
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.625rem 0;
  font-size: 1rem;
  color: var(--color-fg);
  font-weight: 500;
  transition: color var(--transition), transform var(--transition);
}

.contact-link:hover,
.contact-link:focus {
  color: var(--color-accent);
  transform: translateX(4px);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.625rem 1.25rem;
  font-size: 0.875rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  border: 1.5px solid transparent;
  cursor: pointer;
  transition: background-color var(--transition), border-color var(--transition), color var(--transition), transform var(--transition);
  text-decoration: none;
}

.btn:hover {
  transform: translateY(-1px);
}

.btn-primary {
  background-color: var(--color-accent);
  color: #ffffff;
  border-color: var(--color-accent);
}

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

.btn-secondary {
  background-color: transparent;
  color: var(--color-fg);
  border-color: var(--color-border);
}

.btn-secondary:hover {
  background-color: var(--color-surface);
  border-color: var(--color-fg-muted);
}

.btn-large {
  padding: 0.875rem 1.5rem;
  font-size: 1rem;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--color-border);
  padding: 2rem 0;
  text-align: center;
}

.site-footer p {
  font-size: 0.8125rem;
  color: var(--color-fg-light);
}

/* Utilities */
.icon {
  display: inline-block;
  width: 1.25em;
  height: 1.25em;
  flex-shrink: 0;
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* Print */
@media print {
  .site-header,
  .site-footer,
  .btn,
  .nav-toggle {
    display: none !important;
  }

  section {
    padding: 1rem 0;
    page-break-inside: avoid;
  }
}