/* =========================================================================
   Marginalia — School-Notebook Design System
   Plain CSS, framework-agnostic. Import Google Fonts and Phosphor Icons
   in the consuming HTML.
   ========================================================================= */

/* ---------- Tokens ---------- */
:root {
  /* Paper & ink palette */
  --color-paper: #f5f3dc;
  --color-paper-soft: #fbf9e8;
  --color-paper-deep: #ece9c9;
  --color-rule-blue: #3f87a6;
  --color-rule-blue-soft: #8ab6c8;
  --color-margin-red: #c73030;
  --color-margin-red-deep: #a82323;
  --color-ink-navy: #1c2a4a;
  --color-graphite: #5e6266;
  --color-graphite-soft: #9ea1a4;
  --color-highlighter: #ffd96b;
  --color-mint: #cfe3c8;
  --color-eraser-pink: #f3b6b6;

  /* Semantic surface tokens */
  --surface-page: var(--color-paper);
  --surface-card: var(--color-paper-soft);
  --surface-sunken: var(--color-paper-deep);
  --on-surface: var(--color-ink-navy);
  --on-surface-muted: var(--color-graphite);
  --border-ink: var(--color-ink-navy);
  --border-pencil: var(--color-graphite);
  --focus-ring: var(--color-margin-red);

  /* Typography */
  --font-display: "Caveat", "Comic Sans MS", cursive;
  --font-serif: "Fraunces", "Georgia", serif;
  --font-sans: "Inter", system-ui, -apple-system, "Segoe UI", sans-serif;

  --type-display-xl: clamp(3rem, 6vw, 4.5rem);
  --type-display-lg: clamp(2.25rem, 4vw, 3rem);
  --type-headline-lg: 2rem;
  --type-headline-md: 1.5rem;
  --type-headline-sm: 1.25rem;
  --type-body-lg: 1.125rem;
  --type-body-md: 1rem;
  --type-body-sm: 0.875rem;
  --type-label-sm: 0.75rem;
  --type-caption: 0.6875rem;

  --leading-rule: 1.5625rem; /* 25px ruled baseline */
  --leading-tight: 1.2;
  --leading-snug: 1.35;
  --leading-comfy: 1.5;

  /* Spacing — tuned to the 25px ruled baseline */
  --space-2xs: 0.25rem;   /* 4px */
  --space-xs: 0.5rem;     /* 8px */
  --space-sm: 0.75rem;    /* 12px */
  --space-md: 1rem;       /* 16px */
  --space-lg: 1.5625rem;  /* 25px — one rule */
  --space-xl: 2.5rem;     /* 40px */
  --space-2xl: 3.75rem;   /* 60px */
  --space-3xl: 5rem;      /* 80px */

  --gutter-page: clamp(1rem, 4vw, 2.5rem);
  --margin-axis: 12%; /* matches the red margin rule */

  /* Radii — soft sticker corners */
  --radius-none: 0;
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 10px;
  --radius-xl: 16px;
  --radius-full: 999px;

  /* Borders */
  --border-w-thin: 1px;
  --border-w-mid: 1.5px;
  --border-w-bold: 2px;
  --border-w-margin: 2px;

  /* Shadows — warm paper depth, never glassy */
  --shadow-paper: 0 1px 0 rgba(28, 42, 74, 0.08);
  --shadow-card: 0 6px 18px rgba(28, 42, 74, 0.10);
  --shadow-sticky: 6px 8px 0 rgba(28, 42, 74, 0.10), 0 14px 22px rgba(28, 42, 74, 0.12);
  --shadow-press: 2px 2px 0 var(--color-ink-navy);
  --shadow-press-red: 2px 2px 0 var(--color-margin-red-deep);

  /* Focus */
  --focus-ring-width: 3px;
  --focus-ring-offset: 2px;
}

/* ---------- Notebook background pattern ---------- */
/* Promoted from the source pattern: 25px horizontal Rule Blue rhythm
   plus a Margin Red vertical at the left axis. */
.notebook-page {
  background-color: var(--color-paper);
  background-image:
    /* horizontal rules every 25px */
    linear-gradient(
      to bottom,
      transparent 0,
      transparent calc(var(--leading-rule) - 1px),
      rgba(63, 135, 166, 0.55) calc(var(--leading-rule) - 1px),
      rgba(63, 135, 166, 0.55) var(--leading-rule)
    ),
    /* vertical margin line */
    linear-gradient(
      to right,
      transparent 0,
      transparent calc(var(--margin-axis) - 1px),
      var(--color-margin-red) calc(var(--margin-axis) - 1px),
      var(--color-margin-red) calc(var(--margin-axis) + 1px),
      transparent calc(var(--margin-axis) + 1px)
    );
  background-size: 100% var(--leading-rule), 100% 100%;
  background-repeat: repeat, no-repeat;
  background-position: 0 0, 0 0;
}

.notebook-page--no-margin {
  background-image: linear-gradient(
    to bottom,
    transparent 0,
    transparent calc(var(--leading-rule) - 1px),
    rgba(63, 135, 166, 0.55) calc(var(--leading-rule) - 1px),
    rgba(63, 135, 166, 0.55) var(--leading-rule)
  );
  background-size: 100% var(--leading-rule);
  background-repeat: repeat;
}

.grid-page {
  background-color: var(--color-paper);
  background-image:
    linear-gradient(to right, rgba(63, 135, 166, 0.25) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(63, 135, 166, 0.25) 1px, transparent 1px);
  background-size: var(--leading-rule) var(--leading-rule);
}

/* ---------- Base & reset ---------- */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  font-family: var(--font-serif);
  font-size: var(--type-body-md);
  line-height: var(--leading-rule);
  color: var(--on-surface);
  background-color: var(--surface-page);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

::selection {
  background-color: var(--color-highlighter);
  color: var(--color-ink-navy);
}

:focus-visible {
  outline: var(--focus-ring-width) dashed var(--focus-ring);
  outline-offset: var(--focus-ring-offset);
  border-radius: var(--radius-sm);
}

/* ---------- Typography ---------- */
.display-xl,
.display-lg {
  font-family: var(--font-display);
  font-weight: 700;
  color: var(--color-ink-navy);
  letter-spacing: 0;
  line-height: var(--leading-tight);
  margin: 0;
}

.display-xl { font-size: var(--type-display-xl); }
.display-lg { font-size: var(--type-display-lg); }

h1, .headline-lg,
h2, .headline-md,
h3, .headline-sm {
  font-family: var(--font-serif);
  color: var(--color-ink-navy);
  font-weight: 600;
  line-height: var(--leading-snug);
  margin: 0;
}

h1, .headline-lg { font-size: var(--type-headline-lg); }
h2, .headline-md { font-size: var(--type-headline-md); }
h3, .headline-sm { font-size: var(--type-headline-sm); font-weight: 700; }

p, .body-md {
  font-family: var(--font-serif);
  font-size: var(--type-body-md);
  line-height: var(--leading-rule);
  color: var(--on-surface);
  margin: 0 0 var(--leading-rule) 0;
}

.body-lg {
  font-family: var(--font-serif);
  font-size: var(--type-body-lg);
  line-height: var(--leading-rule);
}

.body-sm {
  font-family: var(--font-serif);
  font-size: var(--type-body-sm);
  line-height: var(--leading-comfy);
  color: var(--on-surface-muted);
}

.label-sm,
label {
  font-family: var(--font-sans);
  font-size: var(--type-label-sm);
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-graphite);
}

.caption {
  font-family: var(--font-sans);
  font-size: var(--type-caption);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-graphite);
}

.handwritten {
  font-family: var(--font-display);
  font-weight: 600;
  color: var(--color-margin-red);
}

a {
  color: var(--color-rule-blue);
  text-decoration: underline;
  text-decoration-thickness: 1.5px;
  text-underline-offset: 3px;
}
a:hover { color: var(--color-margin-red); }

/* ---------- Highlights & ink marks ---------- */
.mark-highlight {
  background-image: linear-gradient(
    to top,
    var(--color-highlighter) 0,
    var(--color-highlighter) 55%,
    transparent 55%
  );
  padding: 0 0.15em;
}

.mark-circle {
  display: inline-block;
  padding: 0.05em 0.4em;
  border: var(--border-w-mid) solid var(--color-margin-red);
  border-radius: 999px / 60%;
  transform: rotate(-1.5deg);
}

.mark-underline {
  text-decoration: underline wavy var(--color-margin-red);
  text-decoration-thickness: 1.5px;
  text-underline-offset: 4px;
}

/* ---------- Layout primitives ---------- */
.page {
  min-height: 100%;
  padding: var(--space-2xl) var(--gutter-page);
}

.container {
  max-width: 1120px;
  margin-inline: auto;
}

.stack > * + * { margin-top: var(--space-lg); }
.stack-sm > * + * { margin-top: var(--space-md); }
.stack-xs > * + * { margin-top: var(--space-xs); }

.row {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  flex-wrap: wrap;
}

.grid {
  display: grid;
  gap: var(--space-lg);
}
.grid-2 { grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); }

/* ---------- Button ---------- */
.btn {
  --btn-bg: var(--color-paper-soft);
  --btn-fg: var(--color-ink-navy);
  --btn-border: var(--color-ink-navy);
  --btn-shadow: var(--shadow-press);

  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-family: var(--font-sans);
  font-weight: 700;
  font-size: var(--type-body-sm);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  text-decoration: none;
  background: var(--btn-bg);
  color: var(--btn-fg);
  border: var(--border-w-mid) solid var(--btn-border);
  border-radius: var(--radius-sm);
  padding: 0.625rem 1.125rem;
  cursor: pointer;
  box-shadow: var(--btn-shadow);
  transform: translate(0, 0);
  transition: transform 80ms ease, box-shadow 80ms ease, background-color 120ms ease;
}

.btn:hover {
  transform: translate(-1px, -1px);
  box-shadow: 3px 3px 0 var(--btn-border);
}

.btn:active {
  transform: translate(2px, 2px);
  box-shadow: 0 0 0 var(--btn-border);
}

.btn--primary {
  --btn-bg: var(--color-margin-red);
  --btn-fg: var(--color-paper);
  --btn-border: var(--color-ink-navy);
  --btn-shadow: var(--shadow-press);
}

.btn--secondary {
  --btn-bg: var(--color-paper-soft);
  --btn-fg: var(--color-ink-navy);
  --btn-border: var(--color-ink-navy);
}

.btn--ghost {
  --btn-bg: transparent;
  --btn-fg: var(--color-rule-blue);
  --btn-border: var(--color-rule-blue);
  --btn-shadow: none;
  box-shadow: none;
}
.btn--ghost:hover {
  background-color: rgba(63, 135, 166, 0.12);
  box-shadow: none;
  transform: none;
}

.btn--highlighter {
  --btn-bg: var(--color-highlighter);
  --btn-fg: var(--color-ink-navy);
  --btn-border: var(--color-ink-navy);
}

.btn--sm { padding: 0.375rem 0.75rem; font-size: var(--type-caption); }
.btn--lg { padding: 0.875rem 1.5rem; font-size: var(--type-body-md); }

.btn[disabled],
.btn:disabled {
  cursor: not-allowed;
  opacity: 0.55;
  box-shadow: none;
  transform: none;
}

/* ---------- Input ---------- */
.field {
  display: flex;
  flex-direction: column;
  gap: var(--space-2xs);
}

.field__label {
  font-family: var(--font-sans);
  font-size: var(--type-label-sm);
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-graphite);
}

.field__hint {
  font-family: var(--font-sans);
  font-size: var(--type-caption);
  color: var(--color-graphite-soft);
}

.input {
  font-family: var(--font-serif);
  font-size: var(--type-body-md);
  line-height: var(--leading-rule);
  color: var(--color-ink-navy);
  background: transparent;
  background-image: linear-gradient(
    to bottom,
    transparent calc(var(--leading-rule) - 2px),
    var(--color-rule-blue) calc(var(--leading-rule) - 2px),
    var(--color-rule-blue) calc(var(--leading-rule) - 0.5px),
    transparent calc(var(--leading-rule) - 0.5px)
  );
  background-size: 100% var(--leading-rule);
  background-repeat: repeat-y;
  border: 0;
  border-radius: 0;
  padding: 0 0 2px 0;
  width: 100%;
  outline: none;
}

.input::placeholder {
  color: var(--color-graphite-soft);
  font-style: italic;
}

.input--boxed {
  background-image: none;
  background-color: var(--color-paper-soft);
  border: var(--border-w-mid) solid var(--color-ink-navy);
  border-radius: var(--radius-sm);
  padding: 0.625rem 0.875rem;
  box-shadow: var(--shadow-press);
}

.input--boxed:focus {
  outline: var(--focus-ring-width) dashed var(--color-margin-red);
  outline-offset: 2px;
}

textarea.input--boxed {
  min-height: calc(var(--leading-rule) * 3);
  line-height: var(--leading-rule);
  resize: vertical;
}

/* ---------- Card ---------- */
.card {
  position: relative;
  background-color: var(--color-paper-soft);
  border: var(--border-w-mid) solid var(--color-ink-navy);
  border-radius: var(--radius-lg);
  padding: var(--space-lg) var(--space-lg) var(--space-lg) calc(var(--space-lg) + 28px);
  box-shadow: var(--shadow-card);
  overflow: hidden;
}

.card::before {
  /* the red margin axis on the left */
  content: "";
  position: absolute;
  inset: 0 auto 0 22px;
  width: 2px;
  background-color: var(--color-margin-red);
  opacity: 0.95;
}

.card::after {
  /* faint ruled paper rhythm inside the card */
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image: linear-gradient(
    to bottom,
    transparent 0,
    transparent calc(var(--leading-rule) - 1px),
    rgba(63, 135, 166, 0.18) calc(var(--leading-rule) - 1px),
    rgba(63, 135, 166, 0.18) var(--leading-rule)
  );
  background-size: 100% var(--leading-rule);
  z-index: 0;
}

.card > * { position: relative; z-index: 1; }

.card__eyebrow {
  font-family: var(--font-sans);
  font-size: var(--type-caption);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-rule-blue);
  margin-bottom: var(--space-xs);
}

.card__title {
  font-family: var(--font-serif);
  font-size: var(--type-headline-md);
  font-weight: 700;
  color: var(--color-ink-navy);
  margin: 0 0 var(--space-xs);
}

.card__body { color: var(--color-ink-navy); }

.card--flat { box-shadow: none; }

.card--note {
  /* page-edge variant without the side margin offset */
  padding-left: var(--space-lg);
}
.card--note::before { display: none; }

/* ---------- Checkbox ---------- */
.checkbox {
  display: inline-flex;
  align-items: flex-start;
  gap: var(--space-sm);
  cursor: pointer;
  font-family: var(--font-serif);
  font-size: var(--type-body-md);
  color: var(--color-ink-navy);
  user-select: none;
}

.checkbox input[type="checkbox"] {
  appearance: none;
  -webkit-appearance: none;
  width: 22px;
  height: 22px;
  border: var(--border-w-mid) solid var(--color-ink-navy);
  border-radius: var(--radius-sm);
  background-color: var(--color-paper-soft);
  display: inline-grid;
  place-content: center;
  cursor: pointer;
  flex-shrink: 0;
  margin-top: 1px;
  transition: background-color 120ms ease, transform 80ms ease;
}

.checkbox input[type="checkbox"]::before {
  content: "";
  width: 14px;
  height: 14px;
  /* hand-drawn check using a Phosphor-derived stroke geometry expressed via box-shadow */
  background:
    linear-gradient(45deg, transparent 45%, var(--color-margin-red) 45%, var(--color-margin-red) 55%, transparent 55%) center / 100% 2.5px no-repeat,
    linear-gradient(-45deg, transparent 45%, var(--color-margin-red) 45%, var(--color-margin-red) 55%, transparent 55%) center / 65% 2.5px no-repeat;
  background-position: 0 0, 0 0;
  transform: scale(0) rotate(-8deg);
  transition: transform 140ms ease;
}

.checkbox input[type="checkbox"]:checked {
  background-color: var(--color-highlighter);
}

.checkbox input[type="checkbox"]:checked::before {
  transform: scale(1) rotate(-8deg);
}

.checkbox input[type="checkbox"]:focus-visible {
  outline: var(--focus-ring-width) dashed var(--color-margin-red);
  outline-offset: 2px;
}

/* ---------- Tabs (index tabs along the top) ---------- */
.tabs {
  display: flex;
  align-items: flex-end;
  gap: 6px;
  border-bottom: var(--border-w-mid) solid var(--color-ink-navy);
  padding: 0 var(--space-md);
}

.tab {
  font-family: var(--font-sans);
  font-size: var(--type-body-sm);
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--color-graphite);
  background: var(--color-paper-deep);
  border: var(--border-w-mid) solid var(--color-ink-navy);
  border-bottom: 0;
  border-radius: var(--radius-md) var(--radius-md) 0 0;
  padding: 0.5rem 1rem;
  cursor: pointer;
  position: relative;
  bottom: -1.5px;
  transition: transform 100ms ease, background-color 120ms ease, color 120ms ease;
}

.tab:hover { background-color: var(--color-mint); color: var(--color-ink-navy); }

.tab[aria-selected="true"],
.tab.is-active {
  background-color: var(--color-paper-soft);
  color: var(--color-ink-navy);
  transform: translateY(-3px);
  box-shadow: 0 -2px 0 var(--color-margin-red) inset;
}

.tabpanel {
  background-color: var(--color-paper-soft);
  border: var(--border-w-mid) solid var(--color-ink-navy);
  border-top: 0;
  border-radius: 0 0 var(--radius-lg) var(--radius-lg);
  padding: var(--space-lg);
}

/* ---------- Sticky Note (signature element) ---------- */
.sticky {
  --sticky-bg: var(--color-highlighter);
  --sticky-rotate: -2deg;

  position: relative;
  display: inline-block;
  background-color: var(--sticky-bg);
  color: var(--color-ink-navy);
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.5rem;
  line-height: 1.15;
  padding: 1rem 1.25rem 1.125rem;
  min-width: 180px;
  max-width: 280px;
  border-radius: 2px;
  transform: rotate(var(--sticky-rotate));
  box-shadow: var(--shadow-sticky);
  background-image:
    linear-gradient(180deg, rgba(28, 42, 74, 0.05) 0%, transparent 12%),
    linear-gradient(0deg, rgba(28, 42, 74, 0.04) 0%, transparent 14%);
}

.sticky::before {
  /* tape strip across the top */
  content: "";
  position: absolute;
  top: -10px;
  left: 50%;
  transform: translateX(-50%) rotate(-3deg);
  width: 64px;
  height: 18px;
  background-color: rgba(255, 255, 255, 0.55);
  border: 1px solid rgba(28, 42, 74, 0.15);
  box-shadow: 0 1px 2px rgba(28, 42, 74, 0.1);
}

.sticky--mint { --sticky-bg: var(--color-mint); --sticky-rotate: 1.5deg; }
.sticky--pink { --sticky-bg: var(--color-eraser-pink); --sticky-rotate: -1.5deg; }
.sticky--paper { --sticky-bg: var(--color-paper-soft); --sticky-rotate: 1deg; }

.sticky__title {
  display: block;
  font-family: var(--font-display);
  font-size: 1.75rem;
  margin-bottom: 0.25rem;
  color: var(--color-margin-red);
}

/* ---------- Chips / Pills / Badges ---------- */
.chip {
  display: inline-flex;
  align-items: center;
  gap: 0.375rem;
  font-family: var(--font-sans);
  font-size: var(--type-label-sm);
  font-weight: 600;
  letter-spacing: 0.04em;
  background-color: var(--color-paper-soft);
  color: var(--color-ink-navy);
  border: var(--border-w-mid) solid var(--color-ink-navy);
  border-radius: var(--radius-full);
  padding: 0.25rem 0.75rem;
}

.chip--mint { background-color: var(--color-mint); }
.chip--pink { background-color: var(--color-eraser-pink); }
.chip--yellow { background-color: var(--color-highlighter); }
.chip--blue { background-color: var(--color-rule-blue); color: var(--color-paper); border-color: var(--color-ink-navy); }

.badge-grade {
  display: inline-grid;
  place-content: center;
  width: 56px;
  height: 56px;
  border-radius: 999px;
  border: var(--border-w-mid) solid var(--color-margin-red);
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 2.25rem;
  color: var(--color-margin-red);
  transform: rotate(-6deg);
  background-color: var(--color-paper-soft);
}

/* ---------- Doodle decorators ---------- */
.divider-dashed {
  border: 0;
  border-top: 1.5px dashed var(--color-graphite);
  margin: var(--space-lg) 0;
}

.divider-rule {
  border: 0;
  border-top: 1.5px solid var(--color-rule-blue);
  margin: var(--space-lg) 0;
}

.scribble-underline {
  position: relative;
  display: inline-block;
}
.scribble-underline::after {
  content: "";
  position: absolute;
  left: -2px;
  right: -2px;
  bottom: -6px;
  height: 8px;
  background-image: radial-gradient(circle at 4px 4px, transparent 2px, var(--color-margin-red) 2px, var(--color-margin-red) 2.5px, transparent 2.6px);
  background-size: 8px 8px;
  background-repeat: repeat-x;
  opacity: 0.85;
}

/* ---------- Icon sizing (Phosphor) ---------- */
.icon,
.ph,
[class^="ph-"],
[class*=" ph-"] {
  font-size: 1.125em;
  line-height: 1;
  vertical-align: -0.125em;
  color: currentColor;
}

/* ---------- Utility helpers ---------- */
.text-ink { color: var(--color-ink-navy); }
.text-blue { color: var(--color-rule-blue); }
.text-red { color: var(--color-margin-red); }
.text-graphite { color: var(--color-graphite); }
.text-center { text-align: center; }

.bg-paper { background-color: var(--color-paper); }
.bg-paper-soft { background-color: var(--color-paper-soft); }
.bg-mint { background-color: var(--color-mint); }
.bg-pink { background-color: var(--color-eraser-pink); }
.bg-yellow { background-color: var(--color-highlighter); }

.rotate-left { transform: rotate(-2deg); }
.rotate-right { transform: rotate(2deg); }

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