/* ==================== CSS CUSTOM PROPERTIES ==================== */
:root {
  /* Color Palette */
  --clr-bg-primary: hsl(0, 0%, 12%);
  --clr-bg-secondary: hsl(0, 0%, 13%);
  --clr-bg-button: hsl(0, 0%, 20%);
  --clr-bg-operator: hsl(28, 100%, 50%);
  --clr-bg-equals: hsl(35, 77%, 65%);
  --clr-bg-clear: hsl(0, 0%, 96%);

  --clr-text-primary: hsl(0, 0%, 100%);
  --clr-text-secondary: hsl(0, 0%, 20%);
  --clr-text-display: hsl(0, 27%, 98%);

  /* Spacing */
  --space-xs: 0.625rem;
  --space-sm: 1.25rem;
  --space-md: 1.25rem;

  /* Sizing */
  --button-size: clamp(3.75rem, 15vw, 5rem);
  --button-font: clamp(1.5rem, 6vw, 2rem);
  --display-font: clamp(1.75rem, 8vw, 2.5rem);
  --clear-font: clamp(1.125rem, 5vw, 1.5rem);

  /* Border Radius */
  --radius-sm: 1.25rem;
  --radius-md: 1.5625rem;
  --radius-full: 50%;

  /* Shadows */
  --shadow-inset: inset 0 0 0.625rem hsl(0, 0%, 0%, 0.5);
  --shadow-outer: 0 0.3125rem 0.9375rem hsl(0, 0%, 0%, 0.3);
  --shadow-button: 0 0.25rem 0.5rem hsl(0, 0%, 0%, 0.2);

  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 200ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* ==================== RESET & BASE STYLES ==================== */
*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-block-size: 90vh;
  padding-block: 1.25rem;
  padding-inline: 1.25rem;

  display: grid;
  place-items: center;

  font-family: 'Ubuntu Mono', monospace;
  color: var(--clr-text-primary);
  background-color: var(--clr-bg-primary);

  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ==================== CALCULATOR CONTAINER ==================== */
.calculator {
  inline-size: min(calc(100vw - 2.5rem), 23.75rem);
  padding-block: var(--space-md);
  padding-inline: var(--space-md);

  background-color: var(--clr-bg-secondary);
  border-radius: var(--space-md);
  box-shadow: var(--shadow-inset), var(--shadow-outer);

  container-type: inline-size;
}

/* ==================== DISPLAY ==================== */
#display {
  display: flex;
  align-items: center;
  justify-content: flex-end;

  min-block-size: 3.75rem;
  margin-block-start: 0;
  margin-block-end: var(--space-xs);
  padding-block-end: var(--space-xs);
  padding-inline: 0.5rem;

  font-size: var(--display-font);
  color: var(--clr-text-display);
  border-block-end: 0.125rem solid var(--clr-bg-primary);

  word-break: break-all;
  overflow-wrap: anywhere;
  overflow-x: auto;
  overflow-y: hidden;

  /* Smooth scrollbar styling */
  scrollbar-width: thin;
  scrollbar-color: var(--clr-bg-button) transparent;

  &::-webkit-scrollbar {
    block-size: 0.25rem;
  }

  &::-webkit-scrollbar-track {
    background: transparent;
  }

  &::-webkit-scrollbar-thumb {
    background-color: var(--clr-bg-button);
    border-radius: 0.125rem;
  }
}

/* ==================== BUTTON ROWS ==================== */
p {
  display: flex;
  gap: var(--space-xs);
  margin-block: 0;
  margin-block-end: var(--space-xs);
  margin-inline: 0;
}

/* ==================== BUTTONS ==================== */
button {
  flex: 1;
  min-block-size: var(--button-size);
  aspect-ratio: 1;

  font-family: inherit;
  font-size: var(--button-font);
  color: var(--clr-text-primary);

  background-color: var(--clr-bg-button);
  border: none;
  border-radius: var(--radius-full);
  cursor: pointer;

  transition:
    transform var(--transition-fast),
    box-shadow var(--transition-fast),
    filter var(--transition-base);

  user-select: none;
  -webkit-tap-highlight-color: transparent;

  &:where(:hover, :focus-visible) {
    filter: brightness(1.2);
    box-shadow: var(--shadow-button);
  }

  &:active {
    transform: scale(0.95);
    filter: brightness(0.9);
  }

  &:focus-visible {
    outline: 0.125rem solid var(--clr-bg-operator);
    outline-offset: 0.125rem;
  }
}

/* ==================== OPERATOR BUTTONS ==================== */
.operator {
  background-color: var(--clr-bg-operator);
  font-weight: 500;

  &:where(:hover, :focus-visible) {
    filter: brightness(1.15) saturate(1.1);
  }
}

/* ==================== EQUALS BUTTON ==================== */
#equals {
  background-color: var(--clr-bg-equals);
  color: var(--clr-text-secondary);
  font-weight: 500;
}

/* ==================== CLEAR BUTTON ==================== */
.clear-button {
  display: flex;
  align-items: center;
  justify-content: center;

  inline-size: min(38%, 10rem);
  min-block-size: 3.125rem;
  aspect-ratio: auto;
  margin-block-start: var(--space-md);
  margin-inline: auto;

  font-weight: 700;
  font-size: var(--clear-font);
  color: var(--clr-text-secondary);

  background-color: var(--clr-bg-clear);
  border-radius: var(--radius-md);

  &:where(:hover, :focus-visible) {
    filter: brightness(0.95);
  }

  &:active {
    filter: brightness(0.85);
  }
}

/* ==================== ACCESSIBILITY ==================== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* ==================== PRINT STYLES ==================== */
@media print {
  body {
    background-color: white;
    color: black;
  }

  .calculator {
    box-shadow: none;
    border: 0.0625rem solid black;
  }
}