:root {
  --color-primary: #1e4e79;
  --color-secondary: #4682b4;
  --color-background: #ffffff;
  --color-surface: #f7f9fc;
  --color-surface-strong: #eef4f9;
  --color-text: #1f2937;
  --color-text-muted: #5b6573;
  --color-title: #0f172a;
  --color-white: #ffffff;
  --color-border: rgba(15, 23, 42, 0.15);
  --color-border-strong: rgba(30, 78, 121, 0.3);
  --color-success: #16803c;
  --color-error: #b42318;
  --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.06);
  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 10px;
  --space-2xs: 8px;
  --space-xs: 10px;
  --space-s: 13px;
  --space-m: 16px;
  --space-l: 20px;
  --space-xl: 25px;
  --space-2xl: 31px;
  --space-3xl: 39px;
  --space-4xl: 49px;
  --content-width: 1120px;
  --reading-width: 760px;
  --header-space: var(--space-s);
  --btn-space: var(--space-xs) var(--space-s);
  --card-space: var(--space-s);
  --footer-space: var(--space-s) var(--space-m);
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 80px;
}

body {
  margin: 0;
  min-width: 320px;
  background:
    radial-gradient(
      circle at top center,
      rgba(70, 130, 180, 0.18),
      transparent 55%
    ),
    var(--color-background);
  color: var(--color-text);
  font-family:
    "Google Sans",
    "Google Sans Text",
    Arial,
    sans-serif;
  font-size: 16px;
  line-height: 1.5;
}

img {
  display: block;
  max-width: 100%;
  height: auto;
}

a {
  color: var(--color-primary);
  text-underline-offset: 3px;
}

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

a:focus-visible,
button:focus-visible,
input:focus-visible,
textarea:focus-visible {
  outline: 3px solid rgba(42, 159, 214, 0.35);
  outline-offset: 2px;
}

h1,
h2,
h3 {
  margin-top: 0;
  color: var(--color-title);
  font-weight: 600;
}

h1 {
  margin-bottom: var(--space-m);
  font-size: clamp(2.25rem, 5vw, 3.5rem);
  line-height: 1.1;
  letter-spacing: -0.025em;
}

h2 {
  margin-bottom: var(--space-l);
  font-size: clamp(1.75rem, 3vw, 2.5rem);
  line-height: 1.2;
  letter-spacing: -0.015em;
}

h3 {
  margin-bottom: var(--space-s);
  font-size: clamp(1.35rem, 2vw, 1.75rem);
  line-height: 1.3;
}

p {
  max-width: var(--reading-width);
  margin-top: 0;
  margin-bottom: var(--space-m);
}

.lead {
  max-width: 680px;
  color: var(--color-text-muted);
  font-size: 1.125rem;
}

strong {
  color: var(--color-title);
}

main,
header > *,
footer > * {
  width: min(calc(100% - 2 * var(--space-m)), var(--content-width));
  margin-inline: auto;
}

main {
  overflow: hidden;
}

section {
  padding-block: var(--space-3xl);
  border-top: 1px solid var(--color-border);
}

section:first-child {
  border-top: 0;
}

section > :last-child {
  margin-bottom: 0;
}

article {
  padding: var(--card-space);
  background: rgba(255, 255, 255, 0.86);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
}

aside {
  padding: var(--space-m);
  background: var(--color-surface);
  border-left: 3px solid var(--color-secondary);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

ul {
  padding-left: 1.25rem;
}

li + li {
  margin-top: var(--space-2xs);
}

header {
  position: relative;
  border-bottom: 1px solid var(--color-border);
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(10px);
}

header > * {
  padding-block: var(--header-space);
}

header nav ul {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs) var(--space-m);
  margin: 0;
  padding: 0;
  list-style: none;
}

header nav li {
  margin: 0;
}

header nav a {
  font-weight: 500;
  text-decoration: none;
}

header nav a:hover {
  text-decoration: underline;
}

.hero {
  position: relative;
  padding-block: clamp(var(--space-3xl), 8vw, var(--space-4xl));
}

.hero > * {
  position: relative;
  z-index: 1;
}

.hero .tagline {
  margin-bottom: var(--space-l);
  color: var(--color-secondary);
  font-size: 1.125rem;
  font-weight: 500;
}

figure {
  margin: var(--space-xl) 0;
}

figure img {
  width: min(100%, 320px);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background: var(--color-surface);
}

figcaption {
  max-width: 320px;
  margin-top: var(--space-xs);
  color: var(--color-text-muted);
  font-size: 0.875rem;
}

.projects,
.skills {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-m);
}

.projects > article,
.skills > article {
  height: 100%;
}

button {
  display: inline-block;
  padding: var(--btn-space);
  border: 1px solid var(--color-primary);
  border-radius: var(--radius-sm);
  background: var(--color-primary);
  color: var(--color-white);
  font: inherit;
  font-weight: 500;
  line-height: 1.2;
  text-align: center;
  text-decoration: none;
  cursor: pointer;
  transition:
    background-color 160ms ease,
    border-color 160ms ease,
    transform 160ms ease;
}

button:hover {
  background: #173e60;
  border-color: #173e60;
  color: var(--color-white);
}

button:active {
  transform: translateY(1px);
}

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

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

form {
  max-width: 720px;
}

fieldset {
  margin: 0;
  padding: var(--space-l);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
}

legend {
  padding-inline: var(--space-2xs);
  color: var(--color-title);
  font-weight: 600;
}

label {
  display: block;
  margin-bottom: var(--space-2xs);
  color: var(--color-title);
  font-weight: 500;
}

input,
textarea {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--color-border-strong);
  border-radius: var(--radius-sm);
  background: var(--color-white);
  color: var(--color-text);
  font: inherit;
  line-height: 1.4;
}

input::placeholder,
textarea::placeholder {
  color: #7a8491;
}

textarea {
  min-height: 140px;
  resize: vertical;
}

.form-group + .form-group {
  margin-top: var(--space-m);
}

.form-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-s);
  margin-top: var(--space-l);
}

input:invalid:not(:placeholder-shown),
textarea:invalid:not(:placeholder-shown) {
  border-color: var(--color-error);
}

input:valid:not(:placeholder-shown),
textarea:valid:not(:placeholder-shown) {
  border-color: var(--color-success);
}

time {
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

footer {
  margin-top: var(--space-3xl);
  border-top: 1px solid var(--color-border);
  background: var(--color-surface);
}

footer > * {
  padding-block: var(--footer-space);
}

footer p {
  margin-bottom: var(--space-2xs);
}

footer p:last-child {
  margin-bottom: 0;
}

@media (max-width: 720px) {
  :root {
    --space-3xl: 34px;
    --space-4xl: 44px;
  }

  header > *,
  main,
  footer > * {
    width: min(calc(100% - 2 * var(--space-s)), var(--content-width));
  }

  section {
    padding-block: var(--space-2xl);
  }

  .projects,
  .skills {
    grid-template-columns: 1fr;
  }

  .hero {
    padding-block: var(--space-3xl);
  }

  .form-actions {
    align-items: stretch;
    flex-direction: column;
  }

  .form-actions button {
    width: 100%;
  }

  header nav ul {
    gap: var(--space-xs) var(--space-s);
  }

  fieldset {
    padding: var(--space-m);
  }
}

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

  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
  }
}