:root[data-theme='light'] {
  --bg: #f3f4f6;
  --bg-soft: #e5e7eb;

  --text: #111827;
  --text-muted: #6b7280;

  --header-text: #f3f4f6;
  --header-text-hover: #1d4ed8;

  --card: #ffffff;

  --button-base: #2563eb;

  --accent: #2563eb;
  --accent50: #2564eb80;
  --accent-strong: #1d4ed8;
  --accent-text: #fff;

  --border: rgba(0,0,0,0.08);
  --border-strong: rgba(0,0,0,0.15);

  --shadow-soft: 0 8px 22px rgba(0,0,0,0.2);
  --shadow-medium: 0 0 20px rgba(0, 0, 0, 0.4);

  --title-gradient: linear-gradient(
      to right,
      rgba(0,0,0,0.12),
      rgba(255,255,255,0.2) 45%,
      rgba(0,0,0,0.12)
  );
}

:root[data-theme='dark'] {
  --bg: #020617;
  --bg-soft: #0f172a;

  --text: #eef0f3;
  --text-muted: #c5c4c4;

  --header-text: #f3f4f6;
  --header-text-hover: #1d4ed8;

  --card: #031b53;

  --button-base: #1e4fd6;

  --accent: #f3f4f6;
  --accent50: #f3f4f680;
  --accent-strong: #ffffff;
  --accent-text: #061944;

  --border: rgba(255,255,255,0.12);
  --border-strong: rgba(255,255,255,0.22);

  --shadow-soft: 0 10px 35px rgba(245, 242, 242, 0.1);
  --shadow-medium: 0 0 30px rgba(243, 240, 240, 0.7);

  --title-gradient: linear-gradient(
      to right,
      rgba(255,255,255,0.08),
      rgba(255,255,255,0.25) 50%,
      rgba(255,255,255,0.08)
  );
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', sans-serif;
  background:
    radial-gradient(circle at top, rgba(37,99,235,0.16), transparent 60%),
    radial-gradient(circle at bottom, rgba(15,23,42,0.20), transparent 65%),
    var(--bg);
  color: var(--text);
  line-height: 1.65;
  transition: 0.35s ease, color 0.35s ease;
}

img {
  max-width: 100%;
  display: block;
  border-radius: 10px;
}

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

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

h1, h2, h3 {
  font-weight: 700;
  letter-spacing: -0.03em;
}

/* Header & Navigation */

header {
  background: rgba(15,23,42,0.85);
  backdrop-filter: blur(14px);
  padding: 18px 0;
  position: sticky;
  top: 0;
  z-index: 50;
  border-bottom: 1px solid var(--border);
}

.logo-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--header-text);
  padding-left: 12px;
  position: relative;
}

.nav-list {
  list-style: none;
  display: flex;
  gap: 22px;
  align-items: center;
}

.nav-list a {
  padding: 6px 10px;
  border-radius: 6px;
  font-weight: 500;
  color: var(--header-text);
  transition: 0.18s ease, color 0.18s ease;
}

.nav-list a:hover {
  background: rgba(255, 255, 255, 0.8);
  color: var(--header-text-hover);
}

/* Hamburger */

.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
}

.hamburger span {
  width: 25px;
  height: 2.5px;
  border-radius: 3px;
  background: var(--header-text);
}

.hamburger-navmenu {
  background: rgba(15,23,42,0.99);
  border: 1px solid rgba(255, 255, 255, 0.3);
  box-shadow: 0 0px 20px rgba(160, 159, 159, 0.55) ;
}

/* Mobile menu */

@media (max-width: 780px) {
  nav {
    display: none;
    position: absolute;
    right: 20px;
    top: 72px;
    background: var(--card);
    padding: 16px;
    width: calc(100% - 40px);
    border-radius: 14px;
    border: 1px solid var(--border);
    box-shadow: var(--shadow-medium);
  }

  nav.active {
    display: block;
  }

  .nav-list {
    flex-direction: column;
    gap: 14px;
    align-items: flex-start;
  }

  .hamburger {
    display: flex;
  }
}

/* Footer */

footer {
  text-align: center;
  padding: 30px 20px;
  font-size: 0.9rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border);
  margin-top: 60px;
}

footer a {
  color: var(--accent);
}

/* Icon */

.nav-list .icon {
  width: 24px;
  height: 24px;
  stroke: var(--header-text);
  cursor: pointer;
}

.hidden {
  display: none;
}