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

:root {
  --bg-primary-light: #f0f2f5;
  --bg-secondary-light: #ffffff;
  --input-bg-light: #e0e0e0;
  --text-primary-light: #111827;
  --text-secondary-light: #374151;
  --accent-primary: #3b82f6;
  --accent-hover: #2563eb;
  --border-color-light: #d1d5db;

  --bg-primary-dark: #0f172a;
  --bg-secondary-dark: #1e293b;
  --input-bg-dark: #334155;
  --text-primary-dark: #e2e8f0;
  --text-secondary-dark: #94a3b8;
  --border-color-dark: #475569;
}

body.light-mode {
  --bg-primary: var(--bg-primary-light);
  --bg-secondary: var(--bg-secondary-light);
  --input-bg: var(--input-bg-light);
  --text-primary: var(--text-primary-light);
  --text-secondary: var(--text-secondary-light);
  --border-color: var(--border-color-light);
}

body.dark-mode {
  --bg-primary: var(--bg-primary-dark);
  --bg-secondary: var(--bg-secondary-dark);
  --input-bg: var(--input-bg-dark);
  --text-primary: var(--text-primary-dark);
  --text-secondary: var(--text-secondary-dark);
  --border-color: var(--border-color-dark);
}

body {
  font-family: 'Poppins', sans-serif;
  background: var(--bg-primary);
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  padding: 20px;
  transition: all 0.3s ease;
}

.container {
  width: 100%;
  max-width: 450px;
  background-color: var(--bg-secondary);
  padding: 35px 30px;
  border-radius: 15px;
  box-shadow: 0 8px 30px rgba(0,0,0,0.4);
  text-align: center;
}

.mode-toggle {
  display: flex;
  justify-content: flex-end;
  align-items: center;
  margin-bottom: 15px;
}

.switch {
  position: relative;
  display: inline-block;
  width: 50px;
  height: 28px;
  margin-right: 10px;
}

.switch input {
  display: none;
}

.slider {
  position: absolute;
  cursor: pointer;
  top: 0; left: 0;
  right: 0; bottom: 0;
  background-color: #ccc;
  border-radius: 28px;
  transition: 0.4s;
}

.slider:before {
  position: absolute;
  content: "";
  height: 20px; width: 20px;
  left: 4px; bottom: 4px;
  background-color: white;
  border-radius: 50%;
  transition: 0.4s;
}

input:checked + .slider {
  background-color: var(--accent-primary);
}

input:checked + .slider:before {
  transform: translateX(22px);
}

h1 {
  color: var(--text-primary);
  margin-bottom: 5px;
  font-size: 2rem;
}

.subtitle {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-bottom: 25px;
}

.form-group {
  margin-bottom: 20px;
  text-align: left;
  position: relative;
}

label {
  display: block;
  margin-bottom: 8px;
  color: var(--text-secondary);
  font-weight: 500;
}

#amount {
  width: 100%;
  font-size: 1.3rem; /* μεγαλύτερο */
  padding: 16px;
  border-radius: 8px;
  border: 1px solid var(--border-color);
  background-color: var(--input-bg);
  color: var(--text-primary);
}

.search-input {
  width: 100%;
  padding: 10px 12px;
  border-radius: 8px;
  border: 1px solid var(--border-color);
  background-color: var(--input-bg);
  color: var(--text-primary);
  font-size: 0.95rem;
  margin-bottom: 5px;
}

.currency-select {
  width: 100%;
  padding: 12px;
  border-radius: 8px;
  border: 1px solid var(--border-color);
  background-color: var(--input-bg);
  color: var(--text-primary);
  font-size: 1rem;
}

input:focus, select:focus {
  outline: none;
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
}

button {
  width: 100%;
  padding: 15px;
  border-radius: 10px;
  background: var(--accent-primary);
  color: #fff;
  border: none;
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
}

button:hover {
  background: var(--accent-hover);
  transform: translateY(-2px);
}

.powered-by {
  text-align: center;
  margin-top: 12px;
  color: var(--text-secondary);
  font-size: 0.85rem;
}

#result {
  margin-top: 25px;
  font-size: 1.2rem;
  color: var(--text-primary);
}

#loader {
  margin-top: 20px;
  color: var(--accent-primary);
  font-weight: 500;
}

.hidden {
  display: none;
}

@media(max-width: 500px) {
  .container {
    padding: 25px 20px;
  }

  h1 {
    font-size: 1.6rem;
  }

  .search-input {
    position: sticky;
    top: 0;
    z-index: 10;
  }

  .currency-select {
    font-size: 0.95rem;
  }
}