/* Shared base styles and components. See docs/07-ui-ux-spec.md. */
*,
*::before,
*::after {
  box-sizing: border-box;
}

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

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font: var(--text-body);
}

h1,
h2,
h3,
p,
dl,
dd {
  margin: 0;
}

h3 {
  font: 600 16px/22px var(--font);
  letter-spacing: -0.01em;
}

h1 {
  font: var(--text-h1);
  letter-spacing: -0.01em;
}

h2 {
  font: var(--text-h2);
  letter-spacing: -0.01em;
}

a {
  color: var(--color-link);
}

[hidden] {
  display: none !important;
}

:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}

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

.muted {
  color: var(--color-text-muted);
}

.small {
  font: var(--text-small);
}

/* Buttons: pill shaped, at least 44px tall. */
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  min-height: 44px;
  padding: 0 var(--space-5);
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  font: var(--text-body);
  font-weight: 500;
  text-decoration: none;
  cursor: pointer;
  transition:
    background-color var(--motion),
    transform var(--motion),
    opacity var(--motion);
}

.button:active {
  transform: scale(0.99);
}

.button[disabled] {
  cursor: default;
  opacity: 0.6;
}

.button--primary {
  background: var(--color-primary);
  color: var(--color-on-primary);
}

.button--primary:hover:not([disabled]) {
  background: var(--color-primary-hover);
}

/* The black button used on the sign-in card. */
.button--inverse {
  background: var(--color-inverse-bg);
  color: var(--color-inverse-text);
}

.button--inverse:hover:not([disabled]) {
  background: var(--color-text);
}

.button--secondary {
  background: var(--color-surface);
  border-color: var(--color-border);
  color: var(--color-text);
}

.button--secondary:hover:not([disabled]) {
  background: var(--color-bg-subtle);
}

/* A soft grey button for the second choice beside a primary one. */
.button--quiet {
  background: var(--tint-neutral);
  color: var(--color-text);
}

.button--quiet:hover:not([disabled]) {
  background: var(--color-hairline);
}

.button--small {
  min-height: 36px;
  padding: 0 var(--space-4);
  font: var(--text-small);
  font-weight: 500;
}

.button .icon {
  width: 18px;
  height: 18px;
}

.button--text {
  min-height: 44px;
  padding: 0 var(--space-3);
  background: none;
  color: var(--color-link);
}

.button--block {
  width: 100%;
}

.spinner {
  width: 16px;
  height: 16px;
  border: 2px solid currentColor;
  border-right-color: transparent;
  border-radius: 50%;
  animation: spin 700ms linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

/* Form fields: the label is always visible above the input. */
.field {
  display: grid;
  gap: var(--space-2);
}

.field__label {
  font: var(--text-small);
  font-weight: 500;
}

.field__control {
  position: relative;
}

.input {
  width: 100%;
  min-height: 44px;
  padding: 0 var(--space-4);
  background: var(--color-bg-subtle);
  border: 1px solid var(--color-border-control);
  border-radius: var(--radius-input);
  color: var(--color-text);
  font: var(--text-body);
  transition:
    border-color var(--motion),
    background-color var(--motion);
}

.input:hover {
  border-color: var(--color-text);
}

.input:focus-visible {
  background: var(--color-surface);
  border-color: var(--color-focus);
  outline: 2px solid var(--color-focus);
  outline-offset: 0;
}

.input[aria-invalid="true"] {
  border-color: var(--color-danger);
}

.input--with-toggle {
  padding-right: 52px;
}

.field__toggle {
  position: absolute;
  top: 0;
  right: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  background: none;
  border: 0;
  border-radius: var(--radius-input);
  color: var(--color-text-muted);
  cursor: pointer;
}

.field__toggle:hover {
  color: var(--color-text);
}

.field__help {
  color: var(--color-text-muted);
  font: var(--text-small);
}

.field__error {
  color: var(--color-danger);
  font: var(--text-small);
}

/* Page-level messages. Errors use role="alert"; status is never shown by colour alone. */
.banner {
  display: flex;
  gap: var(--space-3);
  align-items: flex-start;
  padding: var(--space-3) var(--space-4);
  background: var(--color-info-bg);
  border-left: 3px solid var(--color-text-muted);
  border-radius: var(--radius-input);
  font: var(--text-small);
}

.banner--error {
  border-left-color: var(--color-danger);
}

.banner--success {
  border-left-color: var(--color-success);
}

.banner__label {
  font-weight: 600;
}

.banner--error .banner__label {
  color: var(--color-danger);
}

.banner--success .banner__label {
  color: var(--color-success);
}

.card {
  padding: 20px;
  background: var(--color-surface);
  border-radius: var(--radius-card);
  box-shadow: var(--shadow-card);
}

.empty-state {
  display: grid;
  gap: var(--space-2);
  justify-items: start;
  color: var(--color-text-muted);
}

.badge {
  display: inline-block;
  padding: 2px var(--space-3);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  font: var(--text-caption);
}

/* ---------------------------------------------------------------------------
   Components added with the student pages (docs/07-ui-ux-spec.md section 6).
   --------------------------------------------------------------------------- */

/* Line icons come from /img/icons.svg and take the colour of the text around them. */
.icon {
  width: 20px;
  height: 20px;
  flex: none;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.7;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.icon--fill {
  fill: currentColor;
}

.eyebrow {
  color: var(--color-text-muted);
  font: var(--text-label);
  letter-spacing: 0.07em;
  text-transform: uppercase;
}

/* Fixed identifiers such as roll numbers and subject codes. */
.mono {
  font: var(--text-mono);
  letter-spacing: -0.01em;
}

.num {
  font-variant-numeric: tabular-nums;
}

/* A small labelled status or category. The word carries the meaning; colour only supports it. */
.tag {
  display: inline-flex;
  flex: none;
  gap: 6px;
  align-items: center;
  min-height: 24px;
  padding: 2px 10px;
  background: var(--tint-neutral);
  border-radius: var(--radius-pill);
  /* A little darker than the muted text colour, to keep 4.5:1 on the grey fill. */
  color: #5c5c61;
  font: var(--text-caption);
  white-space: nowrap;
}

.tag .icon {
  width: 14px;
  height: 14px;
  stroke-width: 2;
}

.tag--dot::before {
  content: "";
  width: 6px;
  height: 6px;
  background: currentColor;
  border-radius: 50%;
}

.tag--primary {
  background: var(--tint-primary);
  color: var(--on-tint-primary);
}

.tag--success {
  background: var(--tint-success);
  color: var(--on-tint-success);
}

.tag--warning {
  background: var(--tint-warning);
  color: var(--on-tint-warning);
}

.tag--danger {
  background: var(--tint-danger);
  color: var(--on-tint-danger);
}

.tag--purple {
  background: var(--tint-purple);
  color: var(--on-tint-purple);
}

.tag--orange {
  background: var(--tint-orange);
  color: var(--on-tint-orange);
}

.tag--teal {
  background: var(--tint-teal);
  color: var(--on-tint-teal);
}

.tag--solid {
  background: var(--color-primary);
  color: var(--color-on-primary);
}

/* A choice in a row of filters. The chosen one turns black. */
.pills {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.pill {
  display: inline-flex;
  gap: 6px;
  align-items: center;
  min-height: 36px;
  padding: 0 14px;
  background: var(--color-surface);
  border: 1px solid var(--color-hairline);
  border-radius: var(--radius-pill);
  color: var(--color-text);
  font: var(--text-small);
  font-weight: 500;
  cursor: pointer;
  transition:
    background-color var(--motion),
    border-color var(--motion),
    color var(--motion),
    transform var(--motion);
}

.pill:hover {
  border-color: var(--color-border-control);
}

.pill:active {
  transform: scale(0.97);
}

.pill[aria-pressed="true"] {
  background: var(--color-text);
  border-color: var(--color-text);
  color: var(--color-surface);
}

.pill__count {
  color: var(--color-text-muted);
  font-variant-numeric: tabular-nums;
}

.pill[aria-pressed="true"] .pill__count {
  color: #c7c7cc;
}

/* Two or three views of one page. A white thumb slides under the chosen one. */
.segmented {
  position: relative;
  display: inline-grid;
  grid-auto-columns: 1fr;
  grid-auto-flow: column;
  max-width: 100%;
  padding: 4px;
  background: #e8e8ed;
  border-radius: var(--radius-pill);
}

.segmented__thumb {
  position: absolute;
  top: 4px;
  bottom: 4px;
  left: 0;
  width: 0;
  background: var(--color-surface);
  border-radius: var(--radius-pill);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.12);
  transition:
    transform 320ms var(--ease),
    width 320ms var(--ease);
}

.segmented__option {
  position: relative;
  display: inline-flex;
  gap: var(--space-2);
  align-items: center;
  justify-content: center;
  min-height: 36px;
  padding: 0 var(--space-4);
  background: none;
  border: 0;
  border-radius: var(--radius-pill);
  color: var(--color-text-muted);
  font: var(--text-small);
  font-weight: 500;
  white-space: nowrap;
  cursor: pointer;
  transition: color var(--motion);
}

.segmented__option[aria-selected="true"] {
  color: var(--color-text);
}

/* On a phone the options drop their icons and the second word of a long label, so all of them
   fit on one line. */
@media (max-width: 599px) {
  .segmented__option {
    padding: 0 var(--space-3);
  }

  .segmented__option .icon,
  .segmented__more {
    display: none;
  }
}

/* Pill-shaped fields used in filter bars and short forms. */
.select,
.search__input,
.textbox {
  width: 100%;
  min-height: 44px;
  padding: 0 var(--space-4);
  background-color: var(--color-bg-subtle);
  /* The edge of a field needs 3:1 contrast, so it uses the control border colour. */
  border: 1px solid var(--color-border-control);
  border-radius: var(--radius-pill);
  color: var(--color-text);
  font: var(--text-body);
  transition:
    border-color var(--motion),
    background-color var(--motion),
    box-shadow var(--motion);
}

.select {
  padding-right: 40px;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%231d1d1f' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='m6 9 6 6 6-6'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 14px center;
  background-size: 16px;
  cursor: pointer;
}

.textbox--area {
  min-height: 160px;
  padding: var(--space-4);
  border-radius: var(--radius-card);
  resize: vertical;
}

.select:hover,
.search__input:hover,
.textbox:hover {
  border-color: var(--color-text);
}

.select:focus-visible,
.search__input:focus-visible,
.textbox:focus-visible {
  background-color: var(--color-surface);
  border-color: var(--color-focus);
  outline: 0;
  box-shadow: 0 0 0 4px rgba(0, 113, 227, 0.16);
}

.search {
  position: relative;
  display: block;
}

.search .icon {
  position: absolute;
  top: 50%;
  left: 16px;
  color: var(--color-text-muted);
  transform: translateY(-50%);
  pointer-events: none;
}

.search__input {
  padding-left: 46px;
}

.search--large .search__input {
  min-height: 56px;
  font-size: 17px;
}

/* A thin track with a coloured fill. Set --value from 0 to 100. */
.bar {
  height: 6px;
  overflow: hidden;
  background: var(--color-hairline);
  border-radius: var(--radius-pill);
}

.bar__fill {
  width: calc(var(--value, 0) * 1%);
  height: 100%;
  background: var(--color-primary);
  border-radius: inherit;
  transform-origin: left center;
  animation: bar-grow 900ms var(--ease) both;
  animation-delay: calc(var(--i, 0) * 60ms + 180ms);
}

.bar--success .bar__fill {
  background: var(--color-success);
}

.bar--warning .bar__fill {
  background: #c98a00;
}

.bar--danger .bar__fill {
  background: var(--color-danger);
}

.bar--neutral .bar__fill {
  background: var(--color-border-control);
}

@keyframes bar-grow {
  from {
    transform: scaleX(0);
  }
}

/* A circular gauge drawn by js/motion.js. */
.ring {
  position: relative;
  display: grid;
  flex: none;
  place-items: center;
}

.ring > svg {
  display: block;
  transform: rotate(-90deg);
}

.ring__track {
  fill: none;
  stroke: var(--color-hairline);
}

.ring__value {
  fill: none;
  stroke: var(--color-primary);
  stroke-linecap: round;
  transition: stroke-dashoffset 1200ms var(--ease);
}

.ring--success .ring__value {
  stroke: var(--color-success);
}

.ring--danger .ring__value {
  stroke: var(--color-danger);
}

.ring__label {
  position: absolute;
  inset: 0;
  display: grid;
  place-content: center;
  place-items: center;
  text-align: center;
}

.ring__label svg {
  transform: none;
}

/* Grey shapes shown while content is loading. */
.skeleton {
  min-height: 16px;
  background: linear-gradient(90deg, #ececf0 25%, #f6f6f8 37%, #ececf0 63%);
  background-size: 400% 100%;
  border-radius: var(--radius-input);
  animation: shimmer 1400ms ease infinite;
}

.skeleton--card {
  min-height: 180px;
  border-radius: var(--radius-card);
}

.skeleton--hero {
  min-height: 220px;
  border-radius: var(--radius-hero);
}

@keyframes shimmer {
  from {
    background-position: 100% 50%;
  }
  to {
    background-position: 0 50%;
  }
}

/* Content rises into place when it comes into view. js/motion.js adds .is-in. */
.reveal {
  opacity: 0;
  transform: translateY(18px) scale(0.985);
}

.reveal.is-in {
  opacity: 1;
  transform: none;
  transition:
    opacity 620ms var(--ease),
    transform 620ms var(--ease);
  transition-delay: calc(var(--i, 0) * 55ms);
}

/* A round button that holds one icon. */
.icon-button {
  display: inline-grid;
  flex: none;
  width: 40px;
  height: 40px;
  place-items: center;
  background: var(--color-bg-subtle);
  border: 0;
  border-radius: 50%;
  color: var(--color-text);
  cursor: pointer;
  text-decoration: none;
  transition:
    background-color var(--motion),
    color var(--motion),
    transform var(--motion);
}

.icon-button:hover {
  background: var(--color-hairline);
}

.icon-button:active {
  transform: scale(0.92);
}

.icon-button--bare {
  background: none;
  color: var(--color-text-muted);
}

.icon-button[aria-pressed="true"] {
  background: var(--tint-primary);
  color: var(--color-primary);
}

.icon-button[aria-pressed="true"] .icon {
  fill: currentColor;
  animation: pop 360ms var(--ease);
}

@keyframes pop {
  40% {
    transform: scale(1.3);
  }
}

/* "View all" style links: the arrow moves a little on hover. */
.more {
  display: inline-flex;
  gap: 2px;
  align-items: center;
  color: var(--color-link);
  font: var(--text-small);
  font-weight: 500;
  text-decoration: none;
  white-space: nowrap;
}

.more .icon {
  width: 16px;
  height: 16px;
  transition: transform var(--motion);
}

.more:hover .icon {
  transform: translateX(3px);
}

/* Dialogs use the native <dialog> element. The page behind is dimmed and blurred. */
.dialog {
  width: min(520px, calc(100vw - 32px));
  max-height: calc(100dvh - 32px);
  padding: var(--space-6) var(--space-5) var(--space-5);
  overflow-y: auto;
  background: var(--color-surface);
  border: 0;
  border-radius: 24px;
  box-shadow: var(--shadow-float);
  color: var(--color-text);
}

.dialog::backdrop {
  background: rgba(0, 0, 0, 0.32);
  backdrop-filter: blur(10px);
}

.dialog[open] {
  animation: dialog-in 320ms var(--ease);
}

.dialog[open]::backdrop {
  animation: fade-in 320ms ease-out;
}

/* A sheet slides up from the bottom edge on phones. */
.dialog--sheet {
  width: 100%;
  max-width: 640px;
  max-height: 86dvh;
  margin: auto auto 0;
  padding-bottom: calc(var(--space-5) + env(safe-area-inset-bottom));
  border-radius: 24px 24px 0 0;
}

.dialog--sheet[open] {
  animation: sheet-in 380ms var(--ease);
}

.sheet__close {
  position: sticky;
  top: 0;
  z-index: 1;
  float: right;
  margin: -8px -4px 0 var(--space-3);
}

.sheet__grab {
  width: 40px;
  height: 5px;
  margin: calc(var(--space-4) * -1) auto var(--space-4);
  background: var(--color-border);
  border-radius: var(--radius-pill);
}

@keyframes dialog-in {
  from {
    opacity: 0;
    transform: translateY(12px) scale(0.96);
  }
}

@keyframes sheet-in {
  from {
    transform: translateY(100%);
  }
}

@keyframes fade-in {
  from {
    opacity: 0;
  }
}

/* A short confirmation that appears at the bottom and leaves by itself. */
.toast {
  position: fixed;
  bottom: calc(88px + env(safe-area-inset-bottom));
  left: 50%;
  z-index: 20;
  display: inline-flex;
  gap: var(--space-2);
  align-items: center;
  padding: 10px 18px;
  background: rgba(29, 29, 31, 0.94);
  border-radius: var(--radius-pill);
  box-shadow: var(--shadow-float);
  color: #ffffff;
  font: var(--text-small);
  font-weight: 500;
  opacity: 0;
  transform: translate(-50%, 16px);
  transition:
    opacity 260ms var(--ease),
    transform 260ms var(--ease);
  pointer-events: none;
  backdrop-filter: blur(12px);
}

.toast.is-in {
  opacity: 1;
  transform: translate(-50%, 0);
}

/* Moving from one page to the next: the old content fades up and out, the new one rises in.
   Browsers without view transitions simply load the next page. */
@media (prefers-reduced-motion: no-preference) {
  @view-transition {
    navigation: auto;
  }

  ::view-transition-old(root) {
    animation: 160ms ease-out both page-out;
  }

  ::view-transition-new(root) {
    animation: 360ms var(--ease) both page-in;
  }

  /* The sidebar stays rock-solid stationary across page navigations.
     Both old and new snapshots remain visible without blinking or disappearing. */
  ::view-transition-group(sidebar) {
    animation: none;
    z-index: 3;
  }

  ::view-transition-old(sidebar),
  ::view-transition-new(sidebar) {
    animation: none;
    mix-blend-mode: normal;
  }

  /* The active highlight glides smoothly between the old and new menu items */
  ::view-transition-group(nav-active) {
    animation-duration: 240ms;
    animation-timing-function: cubic-bezier(0.2, 0, 0, 1);
    z-index: 4;
  }

  ::view-transition-old(nav-active),
  ::view-transition-new(nav-active) {
    animation: none;
    mix-blend-mode: normal;
  }
}

@keyframes page-out {
  to {
    opacity: 0;
    transform: translateY(-8px);
  }
}

@keyframes page-in {
  from {
    opacity: 0;
    transform: translateY(14px);
  }
}

@media (min-width: 600px) {
  .card {
    padding: var(--space-5);
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-delay: 0s !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    transition-delay: 0s !important;
  }
}

/* The same, when "Reduce motion" is switched on in Settings (js/preferences.js). */
:root[data-reduce-motion] *,
:root[data-reduce-motion] *::before,
:root[data-reduce-motion] *::after {
  animation-duration: 0.01ms !important;
  animation-delay: 0s !important;
  animation-iteration-count: 1 !important;
  transition-duration: 0.01ms !important;
  transition-delay: 0s !important;
}

:root[data-reduce-motion]::view-transition-old(root),
:root[data-reduce-motion]::view-transition-new(root) {
  animation: none;
}

/* A checkbox with its label beside it. */
.check {
  display: inline-flex;
  gap: var(--space-2);
  align-items: center;
  min-height: 44px;
  cursor: pointer;
}

.checkbox {
  width: 20px;
  height: 20px;
  accent-color: var(--color-primary);
}

/* The buttons at the foot of a dialog. */
.dialog__actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  justify-content: flex-end;
}