/* =============================================================================
   Expense & Budget Visualizer — style.css
   Mobile-first responsive layout • 320px – 1920px
   Requirements: 2.2, 6.1
   ============================================================================= */

/* -----------------------------------------------------------------------------
   1. CSS Custom Properties
   ----------------------------------------------------------------------------- */
:root {
  /* Colour palette */
  --color-bg:           #f0f2f5;
  --color-surface:      #ffffff;
  --color-border:       #e0e4ea;
  --color-header-bg:    #1a2637;
  --color-header-text:  #ffffff;
  --color-primary:      #3b82f6;
  --color-primary-dark: #2563eb;
  --color-danger:       #ef4444;
  --color-danger-dark:  #dc2626;
  --color-text:         #1e293b;
  --color-text-muted:   #64748b;
  --color-success-bg:   #f0fdf4;

  /* Category badge colours */
  --color-food:       #fdba74;
  --color-food-text:  #7c2d12;
  --color-transport:  #93c5fd;
  --color-transport-text: #1e3a5f;
  --color-fun:        #c4b5fd;
  --color-fun-text:   #3b0764;

  /* Typography */
  --font-base: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen,
               Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
  --font-size-xs:   0.75rem;   /* 12px */
  --font-size-sm:   0.875rem;  /* 14px */
  --font-size-base: 1rem;      /* 16px */
  --font-size-lg:   1.125rem;  /* 18px */
  --font-size-xl:   1.25rem;   /* 20px */
  --font-size-2xl:  1.5rem;    /* 24px */
  --font-size-3xl:  2rem;      /* 32px */
  --font-size-4xl:  2.5rem;    /* 40px */

  /* Spacing scale */
  --space-1:  0.25rem;
  --space-2:  0.5rem;
  --space-3:  0.75rem;
  --space-4:  1rem;
  --space-5:  1.25rem;
  --space-6:  1.5rem;
  --space-8:  2rem;
  --space-10: 2.5rem;

  /* Borders & shadows */
  --radius-sm:  4px;
  --radius-md:  8px;
  --radius-lg:  12px;
  --radius-pill: 9999px;
  --shadow-sm:  0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md:  0 4px 12px rgba(0, 0, 0, 0.10);

  /* Layout */
  --header-height: 72px;
  --container-max: 1280px;
  --list-max-height-mobile: 320px;
  --list-max-height-desktop: 420px;
}

/* -----------------------------------------------------------------------------
   2. CSS Reset & Base
   ----------------------------------------------------------------------------- */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  /* Prevent horizontal scroll at any viewport width */
  overflow-x: hidden;
  /* Smooth font rendering */
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

body {
  font-family: var(--font-base);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  min-height: 100dvh;
  /* Prevent horizontal overflow caused by any child element */
  overflow-x: hidden;
}

/* -----------------------------------------------------------------------------
   3. Typography helpers
   ----------------------------------------------------------------------------- */
h1, h2, h3 {
  line-height: 1.3;
  font-weight: 700;
}

/* -----------------------------------------------------------------------------
   4. Header / Balance Display
   ----------------------------------------------------------------------------- */
header {
  background-color: var(--color-header-bg);
  color: var(--color-header-text);
  height: 100px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0 var(--space-6);
  padding-bottom: 10px;
  padding-top: 5px;
  position: sticky;
  top: 0;
  z-index: 200;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.20);
}

.balance-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding-top: 10px;
}

.balance-label {
    font-size: 20px;
    font-weight: 300;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: rgba(255,255,255,0.65);
    /* margin-bottom: var(--space-1); */
}

@media (min-width: 480px) {
  header::before {
    display: inline;
  }
}

#balance {
  font-size: clamp(var(--font-size-2xl), 5vw, var(--font-size-4xl));
  font-weight: 800;
  letter-spacing: -0.02em;
  font-variant-numeric: tabular-nums;
  /* Prevent the number from clipping on tiny viewports */
  max-width: 100%;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  padding-top: 0px;
  
}

/* -----------------------------------------------------------------------------
   5. Main grid container
   ----------------------------------------------------------------------------- */
main {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: var(--space-6) var(--space-4);

  /* Mobile: single column stacked */
  display: grid;
  grid-template-columns: 1fr;
  grid-template-areas:
    "form"
    "list"
    "chart";
  gap: var(--space-6);
}

/* -----------------------------------------------------------------------------
   6. Shared section card style
   ----------------------------------------------------------------------------- */
.form-section,
.list-section,
.chart-section {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  /* Prevent children from breaking out of the card */
  overflow: hidden;
  min-width: 0;  /* Required for grid children to respect text-overflow */
}

.form-section {
  grid-area: form;
  padding: var(--space-6);
}

.list-section {
  grid-area: list;
  padding: var(--space-6);
  /* Flex column so the list can fill remaining space and scroll */
  display: flex;
  flex-direction: column;
}

.chart-section {
  grid-area: chart;
  padding: var(--space-6);
}

.list-section h2,
.chart-section h2 {
  font-size: var(--font-size-xl);
  color: var(--color-text);
  margin-bottom: var(--space-4);
  flex-shrink: 0;
}

/* -----------------------------------------------------------------------------
   7. Input Form
   ----------------------------------------------------------------------------- */
#input-form {
  display: flex;
  flex-direction: column;
  gap: var(--space-5);
}

.form-section h2 {
  font-size: var(--font-size-xl);
  margin-bottom: var(--space-5);
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}

.form-group label {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-text-muted);
  letter-spacing: 0.03em;
}

.form-group input,
.form-group select {
  padding: var(--space-3) var(--space-4);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-md);
  font-size: var(--font-size-base);
  font-family: inherit;
  color: var(--color-text);
  background-color: var(--color-surface);
  transition: border-color 0.18s ease, box-shadow 0.18s ease;
  /* Prevent inputs from exceeding their container on small screens */
  width: 100%;
  min-width: 0;
}

.form-group input:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.18);
}

.form-group input::placeholder {
  color: #b0bac5;
}

/* Inline validation error messages */
.error-msg {
  font-size: var(--font-size-xs);
  color: var(--color-danger);
  font-weight: 500;
  min-height: 1.2em;  /* Reserve space so the form doesn't jump */
  display: block;
  line-height: 1.4;
}

/* Submit button */
#add-btn {
  margin-top: var(--space-2);
  padding: var(--space-3) var(--space-6);
  background-color: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: var(--radius-md);
  font-size: var(--font-size-base);
  font-family: inherit;
  font-weight: 700;
  letter-spacing: 0.02em;
  cursor: pointer;
  transition: background-color 0.18s ease, transform 0.1s ease;
  width: 100%;
}

#add-btn:hover {
  background-color: var(--color-primary-dark);
}

#add-btn:active {
  transform: scale(0.98);
}

#add-btn:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 2px;
}

/* -----------------------------------------------------------------------------
   8. Storage Error Banner  (#storage-error)
   ----------------------------------------------------------------------------- */
#storage-error {
  margin-top: var(--space-4);
  background-color: #fff5f5;
  border: 1.5px solid var(--color-danger);
  border-radius: var(--radius-md);
  padding: var(--space-3) var(--space-4);
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: var(--space-3);
}

#storage-error p {
  margin: 0;
  font-size: var(--font-size-sm);
  color: var(--color-danger-dark);
  line-height: 1.5;
}

.dismiss-btn {
  flex-shrink: 0;
  background: none;
  border: none;
  font-size: var(--font-size-xl);
  line-height: 1;
  color: var(--color-danger);
  cursor: pointer;
  padding: 0;
  transition: color 0.15s;
}

.dismiss-btn:hover {
  color: var(--color-danger-dark);
}

/* Backwards-compat: .error-banner is the class on the element in HTML */
.error-banner {
  /* Same rules as #storage-error — covered above via ID selector */
}

/* -----------------------------------------------------------------------------
   9. Transaction List  — Requirement 2.2, 6.1
   ----------------------------------------------------------------------------- */

/* The <ul> is the scrollable region.
   max-height + overflow-y: auto fulfils Requirement 2.2:
   list scrolls without affecting balance / chart / form layout.            */

   .list-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-4);
  gap: var(--space-3);
  
}

#sort {
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-md);
  width: 150px;
  padding: 5px
}

#transaction-list {
  list-style: none;
  flex: 1 1 auto;                  /* Grow within the flex .list-section */
  max-height: var(--list-max-height-mobile);
  overflow-y: auto;
  overflow-x: hidden;
  /* Subtle inset shadow to signal scrollability */
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-md);
  /* Custom scrollbar (webkit) */
  scrollbar-width: thin;
  scrollbar-color: var(--color-border) transparent;
}

#transaction-list::-webkit-scrollbar {
  width: 6px;
}

#transaction-list::-webkit-scrollbar-track {
  background: transparent;
}

#transaction-list::-webkit-scrollbar-thumb {
  background-color: var(--color-border);
  border-radius: var(--radius-pill);
}

/* Empty state placeholder */
#empty-msg {
  color: var(--color-text-muted);
  text-align: center;
  padding: var(--space-8) var(--space-4);
  font-size: var(--font-size-sm);
  font-style: italic;
}

/* Individual transaction row */
.transaction-item {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  border-bottom: 1px solid var(--color-border);
  /* Prevent row content from overflowing the container */
  min-width: 0;
  overflow: hidden;
  transition: background-color 0.12s;
}

.transaction-item:last-child {
  border-bottom: none;
}

.transaction-item:hover {
  background-color: #f8fafc;
}

/* ---
   .tx-name — Requirement 2.1 + design spec:
   overflow:hidden + white-space:nowrap + text-overflow:ellipsis
   max-width: 100ch enforces 100-char visual truncation.
   flex:1 + min-width:0 lets the text shrink without pushing other columns.
--- */
.tx-name {
  flex: 1 1 auto;
  min-width: 0;                  /* Critical: allows flex child to shrink */
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;
  max-width: 100ch;              /* Enforces ~100-character visual limit */
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-text);
}

/* Amount column — fixed width so it never wraps or shrinks away */
.tx-amount {
  flex: 0 0 auto;
  min-width: 72px;
  text-align: right;
  font-size: var(--font-size-sm);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  color: var(--color-text);
  white-space: nowrap;
}

/* Category badge */
.tx-category {
  flex: 0 0 auto;
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-pill);
  font-size: var(--font-size-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  white-space: nowrap;
  /* Default colours (overridden per category below) */
  background-color: var(--color-border);
  color: var(--color-text-muted);
}

/* Per-category colour overrides */
.tx-category[data-category="Food"],
.tx-category:not([data-category]) /* text-based fallback */ {
  /* applied via JS class or text content — use attribute selectors */
}

/* Text-content–based category colouring
   (app.js sets textContent = tx.category, no extra attribute needed)   */
li.transaction-item:has(.tx-category) .tx-category {
  /* Base reset — colour assigned by specific rules below */
}

/* Specific category colours via :has or general sibling trick.
   Since the category text is set dynamically, we rely on the text value.
   The safest cross-browser approach for text content is data attributes,
   but app.js does not set them. We use the more-compatible workaround of
   a dedicated class or we scope the badge colour by text content heuristic.
   Best approach: target via :not / attribute selectors won't work for text
   content in CSS — so we provide a visually distinct neutral badge and let
   JS add a modifier class. Since task.md says we must NOT modify app.js in
   this task, we provide a neutral badge plus document the hook.             */

/* --------------------------------------------------------------------------
   NOTE: If app.js ever adds class="tx-category food" / "transport" / "fun",
   the following rules will activate automatically.
   -------------------------------------------------------------------------- */
.tx-category.food,
span.tx-category[class*="food"] {
  background-color: var(--color-food);
  color: var(--color-food-text);
}

.tx-category.transport,
span.tx-category[class*="transport"] {
  background-color: var(--color-transport);
  color: var(--color-transport-text);
}

.tx-category.fun,
span.tx-category[class*="fun"] {
  background-color: var(--color-fun);
  color: var(--color-fun-text);
}

/* Delete button */
.delete-btn {
  flex: 0 0 auto;
  padding: var(--space-1) var(--space-3);
  background-color: transparent;
  color: var(--color-danger);
  border: 1.5px solid var(--color-danger);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-xs);
  font-family: inherit;
  font-weight: 700;
  letter-spacing: 0.02em;
  cursor: pointer;
  white-space: nowrap;
  transition: background-color 0.15s, color 0.15s;
}

.delete-btn:hover {
  background-color: var(--color-danger);
  color: #fff;
}

.delete-btn:focus-visible {
  outline: 3px solid var(--color-danger);
  outline-offset: 2px;
}

/* -----------------------------------------------------------------------------
   10. Chart Section
   ----------------------------------------------------------------------------- */
.chart-container {
  position: relative;
  width: 100%;
  /* Fixed aspect-ratio container prevents layout thrash */
  aspect-ratio: 1 / 1;
  max-height: 320px;
  display: flex;
  justify-content: center;
  align-items: center;
}

#chart-canvas {
  display: block;
  max-width: 100%;
  max-height: 100%;
}

#chart-placeholder {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-muted);
  font-size: var(--font-size-sm);
  font-style: italic;
  text-align: center;
  padding: var(--space-4);
}

/* When Chart.js hides the canvas, hidden attribute is set */
#chart-canvas[hidden],
#chart-canvas[style*="display: none"] {
  display: none !important;
}

/* When placeholder is hidden (hidden attribute set by renderChart) */
#chart-placeholder[hidden] {
  display: none;
}

/* -----------------------------------------------------------------------------
   11. Responsive Breakpoints — mobile-first
   ----------------------------------------------------------------------------- */

/* --- 480px: slightly larger phones / landscape phones ---------------------- */
@media (min-width: 480px) {
  main {
    padding: var(--space-6) var(--space-6);
  }

  #transaction-list {
    max-height: 360px;
  }
}

/* --- 640px: large phones / small tablets ---------------------------------- */
@media (min-width: 640px) {
  main {
    padding: var(--space-8) var(--space-6);
    gap: var(--space-8);
  }

  .transaction-item {
    gap: var(--space-4);
    padding: var(--space-4) var(--space-5);
  }

  .tx-name {
    font-size: var(--font-size-base);
  }

  .tx-amount {
    font-size: var(--font-size-base);
    min-width: 88px;
  }

  .tx-category {
    font-size: var(--font-size-xs);
    padding: var(--space-1) var(--space-4);
  }
}

/* --- 768px: tablets — two-column layout: form | list, chart full-width ---- */
main {
  max-width: 900px;
  margin: 0 auto;
  padding: var(--space-6) var(--space-4);

  display: grid;
  grid-template-columns: 1fr;
  grid-template-areas:
    "form"
    "list"
    "chart";

  gap: var(--space-6);
}


/* --- 1280px: wide desktops — more breathing room -------------------------- */
@media (min-width: 1280px) {
  main {
    padding: var(--space-8) var(--space-10);
    gap: var(--space-8);
  }
}

/* --- 1536px: ultra-wide — cap container, increase padding ----------------- */
@media (min-width: 1536px) {
  main {
    padding: var(--space-10) var(--space-8);
  }
}

/* --- 1920px: 4K / very wide monitors ------------------------------------- */
@media (min-width: 1920px) {
  :root {
    --container-max: 1440px;
  }
}

/* -----------------------------------------------------------------------------
   12. Accessibility — focus & motion
   ----------------------------------------------------------------------------- */
:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 2px;
}

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

/* Skip-link (if added in future) */
.skip-link {
  position: absolute;
  top: -9999px;
  left: var(--space-4);
  z-index: 9999;
  background: var(--color-primary);
  color: #fff;
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-sm);
  font-weight: 600;
  text-decoration: none;
}

.skip-link:focus {
  top: var(--space-2);
}

/* -----------------------------------------------------------------------------
   13. Utility — visually hidden (screen-reader only)
   ----------------------------------------------------------------------------- */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.large-expense {
    border-left: 6px solid red;
    background: #fff2f2;
}

#theme-toggle {
    position: absolute;
    right: 20px;

    background: transparent;
    border: none;
    color: white;
    font-size: 1.4rem;
    cursor: pointer;
}

body.dark {
    --color-bg: #111827;
    --color-surface: #1f2937;
    --color-border: #374151;
    --color-text: #f9fafb;
    --color-text-muted: #d1d5db;
    --color-header-bg: #030712;
}

body.dark .large-expense {
    background: #3b1d1d;
    border-left: 6px solid #ef4444;
}




/* -----------------------------------------------------------------------------
   End of style.css
   ============================================================================= */