:root {
  --bg: #0d1117;
  --fg: #e6edf3;
  --muted: #8b949e;
  --card: #161b22;
  --accent: #58a6ff;
  --danger: #ff5555;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: system-ui, sans-serif;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.6;
}

header {
  min-height: 100vh;
  display: grid;
  place-items: center;
  text-align: center;
  padding: 2rem;
}

.hero {
  max-width: 760px;
}

.photo {
  width: 180px;
  height: 180px;
  border-radius: 50%;
  object-fit: cover;
  border: 4px solid var(--accent);
  box-shadow: 0 0 35px #58a6ff55;
}

h1 {
  font-size: clamp(2.5rem, 7vw, 5rem);
  margin: 1rem 0 0.5rem;
}

.subtitle {
  color: var(--muted);
  font-size: 1.2rem;
}

section {
  max-width: 900px;
  margin: auto;
  padding: 5rem 2rem;
}

.card {
  background: var(--card);
  border: 1px solid #30363d;
  border-radius: 18px;
  padding: 2rem;
  box-shadow: 0 10px 40px #0008;
}

.langs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.8rem;
  margin-top: 1rem;
}

.lang {
  background: #21262d;
  color: var(--fg);
  border: 1px solid #30363d;
  padding: 0.6rem 1rem;
  border-radius: 999px;
  font-family: monospace;
}

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

form {
  display: grid;
  gap: 1rem;
  margin-top: 1rem;
}

label {
  display: grid;
  gap: 0.3rem;
}

input, select, button {
  font: inherit;
  padding: 0.8rem;
  border-radius: 10px;
  border: 1px solid #30363d;
  background: #0d1117;
  color: var(--fg);
}

button {
  background: var(--accent);
  color: #00111f;
  border: none;
  cursor: pointer;
  font-weight: bold;
}

button:hover {
  filter: brightness(1.1);
}

.overlay {
  position: fixed;
  inset: 0;
  background: #0009;
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  padding: 1rem;
}

.popup {
  background: #111827;
  border: 1px solid #374151;
  border-radius: 16px;
  padding: 2rem;
  max-width: 420px;
  width: 100%;
  text-align: center;
  box-shadow: 0 20px 80px #000;
  animation: pop 0.2s ease-out;
}

.popup h2 {
  color: var(--danger);
  margin-top: 0;
}

.close {
  margin-top: 1rem;
  background: #30363d;
  color: var(--fg);
}

@keyframes pop {
  from {
    transform: scale(0.92);
    opacity: 0;
  }
  to {
    transform: scale(1);
    opacity: 1;
  }
}

.calculator-window {
  width: 320px;
  background: #202020;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 30px 100px #000;
  border: 1px solid #444;
  color: white;
  font-family: "Segoe UI", system-ui, sans-serif;
}

.calc-titlebar {
  background: #2b2b2b;
  padding: 0.6rem 0.8rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.9rem;
}

.calc-close {
  color: #ff7777;
  cursor: pointer;
  font-weight: bold;
}

.calc-display {
  padding: 1.5rem 1rem;
  text-align: right;
  font-size: 2rem;
  background: #1b1b1b;
  min-height: 80px;
}

.calc-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: #111;
}

.calc-key {
  padding: 1rem;
  text-align: center;
  background: #333;
  cursor: pointer;
  user-select: none;
}

.calc-key:hover {
  background: #444;
}

.calc-key.op {
  background: #3a3a3a;
  color: #58a6ff;
}

footer {
  text-align: center;
  color: var(--muted);
  padding: 3rem 1rem;
}