@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;700;800&display=swap');

:root {
    --color-bg: #ffffff;
    --color-text-primary: #111827; /* very dark gray */
    --color-text-secondary: #6b7280; /* neutral gray */
    --color-input-bg: #f9fafb;
    --color-input-border: #d1d5db;
    --color-button-bg: #111827;
    --color-button-hover-bg: #1f2937;
    --border-radius: 0.75rem;
    --shadow-light: 0 4px 6px rgba(0,0,0,0.1);
    --spacing-base: 1rem;
    --font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
}

/* Reset & base */
* {
    box-sizing: border-box;
}

body {
    margin: 0;
    background: var(--color-bg);
    color: var(--color-text-secondary);
    font-family: var(--font-family);
    font-size: 17px;
    line-height: 1.5;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem;
}

label {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}

.feedback {
  color: red;
  margin-top: 1rem;
  text-align: center;
}

main.container {
    max-width: 400px;
    width: 100%;
    background: var(--color-bg);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-light);
    padding: 3rem 2.5rem;
    display: flex;
    flex-direction: column;
    align-items: center;
}

h1 {
    font-weight: 800;
    font-size: 48px;
    color: var(--color-text-primary);
    margin: 0 0 2rem 0;
    user-select: none;
}

form {
    width: 100%;
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

input[type="text"],
input[type="password"] {
    width: 100%;
    padding: 0.75rem 1rem;
    font-size: 16px;
    font-weight: 400;
    border: 1.8px solid var(--color-input-border);
    border-radius: var(--border-radius);
    background-color: var(--color-input-bg);
    color: var(--color-text-primary);
    outline-offset: 2px;
    transition: border-color 0.3s ease, box-shadow 0.3s ease, background-color 0.3s ease;
}

input[type="text"]::placeholder,
input[type="password"]::placeholder {
    color: var(--color-text-secondary);
    font-weight: 400;
}

input[type="text"]:focus,
input[type="password"]:focus {
    border-color: var(--color-button-bg);
    box-shadow: 0 0 5px 2px rgba(17,24,39,0.3);
}

input[type="submit"] {
    width: 100%;
    padding: 0.85rem 1rem;
    font-size: 18px;
    font-weight: 700;
    color: #fff;
    background-color: var(--color-button-bg);
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: background-color 0.3s ease, transform 0.3s ease;
    user-select: none;
}

input[type="submit"]:hover,
input[type="submit"]:focus {
    background-color: var(--color-button-hover-bg);
    transform: scale(1.03);
    outline: none;
}

input[type="submit"]:active {
    transform: scale(0.98);
    transition: transform 0.1s ease;
}

.register-link {
  margin-top: 1rem;
  text-align: center;
  color: var(--color-text-secondary);
  font-size: 15px;
}

.register-link p {
  margin: 0 0 0.5rem 0;
}

.register-button {
  display: inline-block;
  padding: 0.7rem 1.5rem;
  font-size: 16px;
  font-weight: 700;
  color: #fff;
  background-color: var(--color-button-bg);
  border-radius: var(--border-radius);
  text-decoration: none;
  transition: background-color 0.3s ease, transform 0.3s ease;
}

.register-button:hover,
.register-button:focus {
  background-color: var(--color-button-hover-bg);
  transform: scale(1.03);
}

.register-button:active {
  transform: scale(0.98);
  transition: transform 0.1s ease;
}

@media (max-width: 400px) {
  h1 {
    font-size: 36px;
  }
  main.container {
    padding: 2rem 1.5rem;
  }
}