@import "tailwindcss";

/* Class-based dark mode (toggled on <html> by the theme script). */
@custom-variant dark (&:where(.dark, .dark *));

@theme {
  /* Navy-tinted neutral scale — sampled from the app icon. ---------------- */
  --color-frost-50: #f5f8fd;
  --color-frost-100: #eaf0fa;
  --color-frost-200: #d9e3f3;
  --color-frost-300: #c2cfe4;
  --color-frost-400: #92a3c0;
  --color-frost-500: #6a7c9b;
  --color-frost-600: #4e5f7d;
  --color-frost-700: #3c4b66;
  --color-frost-800: #2b3752;
  --color-frost-900: #1d2740;
  --color-frost-950: #0e1526;

  /* Accent: the icon's snowflake blue. ------------------------------------ */
  --color-accent-50: #eff7ff;
  --color-accent-100: #dbecff;
  --color-accent-200: #bcdcff;
  --color-accent-300: #8fc6ff;
  --color-accent-400: #59a8f7;
  --color-accent-500: #3f95ea;
  --color-accent-600: #2478d2;
  --color-accent-700: #1d61ab;
  --color-accent-800: #1c518b;
  --color-accent-900: #1b4473;

  /* Aurora hues used only for the frosted backdrop wash. ----------------- */
  --color-aurora-mint: #9fe3d0;
  --color-aurora-sky: #9ccdf5;
  --color-aurora-lilac: #c3b6f0;
  --color-aurora-peach: #f6cdb4;

  --font-sans: -apple-system, BlinkMacSystemFont, ui-sans-serif, system-ui,
    "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif,
    "Apple Color Emoji", "Segoe UI Emoji", "Noto Color Emoji";

  --shadow-frost: 0 14px 34px -22px rgb(13 13 13 / 0.28);
  --shadow-lift: 0 4px 14px -8px rgb(13 13 13 / 0.18);
  --shadow-hairline: 0 1px 0 0 rgb(13 13 13 / 0.04);

  --animate-float: float 11s ease-in-out infinite;
  --animate-pop: pop 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
  --animate-wiggle: wiggle 0.4s ease-in-out;
  --animate-rise: rise 0.4s cubic-bezier(0.22, 1, 0.36, 1) both;
  --animate-sheet: sheet 0.32s cubic-bezier(0.22, 1, 0.36, 1) both;
}

@keyframes float {
  0%, 100% { transform: translate3d(0, 0, 0) scale(1) }
  50% { transform: translate3d(0, -18px, 0) scale(1.04) }
}
@keyframes pop {
  0% { transform: scale(0.92) }
  60% { transform: scale(1.02) }
  100% { transform: scale(1) }
}
@keyframes wiggle {
  0%, 100% { transform: translateX(0) }
  25% { transform: translateX(-5px) }
  75% { transform: translateX(5px) }
}
@keyframes rise {
  from { opacity: 0; transform: translateY(10px) }
  to { opacity: 1; transform: translateY(0) }
}
@keyframes sheet {
  from { opacity: 0; transform: translateY(24px) }
  to { opacity: 1; transform: translateY(0) }
}

/* ---------------------------------------------------------------------------
   Theme tokens.
   Light: ChatGPT-ish neutral (page #ffffff, sidebar #f9f9f9, border #e5e5e5).
   Dark:  page #212121, sidebar #171717, surfaces #2f2f2f, borders rgba(255,255,255,.1).
   Text tiers are picked to clear WCAG AA (4.5:1) on their own background.
   --------------------------------------------------------------------------- */
:root {
  color-scheme: light;
  --page: #f4f7fd;
  --sidebar: #e9eff9;
  --surface: #ffffff;
  --surface-raised: #ffffff;
  --surface-strong: #edf2fa;
  --card-hover-bg: #f7faff;
  --surface-sunken: rgb(14 21 40 / 0.05);
  --hairline: #dce4f1;
  --card-border: #d7e0ef;
  --sidebar-divider: #d7e0ef;
  --hairline-soft: rgb(14 21 40 / 0.07);
  --glass-tint: rgb(255 255 255 / 0.55);
  --text: #0e1526;          /* 16.9:1 on #f4f7fd */
  --text-muted: #4d5c78;    /* 6.3:1  */
  --text-subtle: #5a6a86;   /* 5.1:1  */
  --hover: rgb(14 21 40 / 0.05);
  --sidebar-top: #eef3fb;
  --sidebar-bottom: #e5edf9;
  --sidebar-edge: 0 1px 0 var(--sidebar-divider), 6px 0 18px -12px rgb(14 21 40 / 0.35);
  /* API-key gate: cool near-white stage with soft blue glows, tinted input. */
  --gate-base: #eef3fb;
  --gate-glow-a: rgb(90 150 240 / 0.25);
  --gate-glow-b: rgb(140 150 240 / 0.2);
  --gate-card: #ffffff;
  --gate-card-border: #dde5f2;
  --gate-callout-bg: #eef3fa;
  --gate-callout-border: #c9d5e8;
  --field: #eef2f9;
  --field-border: #dbe3f0;
  --shadow-gate: 0 28px 70px -36px rgb(14 21 40 / 0.3), 0 1px 2px rgb(14 21 40 / 0.05);
  /* Install sheet: light variant (dark is the default, see .dark). */
  --install-sheet: #ffffff;
  --install-card: #f7f7f8;
  --install-chip: #f2f2f2;
  --install-border: #e0e0e0;
  --shadow-card: 0 1px 2px rgb(14 21 40 / 0.06), 0 1px 3px rgb(14 21 40 / 0.04);
  --card-shadow: 0 1px 2px rgb(14 21 40 / 0.05), 0 5px 14px -6px rgb(14 21 40 / 0.12);
  --shadow-card-hover: 0 12px 30px -12px rgb(14 21 40 / 0.2), 0 2px 6px rgb(14 21 40 / 0.07);
}

.dark {
  color-scheme: dark;
  --page: #0e1424;
  --sidebar: #0a0f1c;
  --surface: #171f33;
  --surface-raised: #1e2740;
  --surface-strong: #202a42;
  --card-hover-bg: #1e2740;
  --surface-sunken: rgb(255 255 255 / 0.07);
  --hairline: rgb(255 255 255 / 0.12);
  --card-border: rgb(255 255 255 / 0.12);
  --sidebar-divider: rgb(255 255 255 / 0.1);
  --hairline-soft: rgb(255 255 255 / 0.08);
  --glass-tint: rgb(255 255 255 / 0.06);
  --text: #e9eefb;          /* 15.4:1 on #0e1424 */
  --text-muted: #b7c3dc;    /* 10.4:1 */
  --text-subtle: #94a4c2;   /* 7.3:1  */
  --hover: rgb(255 255 255 / 0.07);
  --sidebar-top: #0b1120;
  --sidebar-bottom: #080d18;
  --sidebar-edge: 0 1px 0 var(--hairline), 6px 0 16px -14px rgb(0 0 0 / 0.75);
  /* API-key gate: navy stage with the icon's blue glows, raised input. */
  --gate-base: #0a0f1c;
  --gate-glow-a: rgb(70 140 235 / 0.2);
  --gate-glow-b: rgb(120 120 235 / 0.14);
  --gate-card: #131a2c;
  --gate-card-border: rgb(255 255 255 / 0.1);
  --gate-callout-bg: rgb(255 255 255 / 0.06);
  --gate-callout-border: rgb(255 255 255 / 0.2);
  --field: #1b2438;
  --field-border: rgb(255 255 255 / 0.1);
  --shadow-gate: 0 30px 80px -40px rgb(0 0 0 / 0.85), 0 1px 2px rgb(0 0 0 / 0.4);
  /* Install sheet: layered dark surfaces (default theme for the sheet). */
  --install-sheet: #1c1c1e;
  --install-card: #2c2c2e;
  --install-chip: #3a3a3c;
  --install-border: rgb(255 255 255 / 0.08);
  --shadow-card: 0 1px 2px rgb(0 0 0 / 0.25);
  --card-shadow: var(--shadow-card);
  --shadow-card-hover: 0 10px 28px -16px rgb(0 0 0 / 0.55), 0 1px 2px rgb(0 0 0 / 0.3);
}

/* Backdrop: the icon's navy base and blue wash, seen through frosted glass. */
:root {
  --bd-sky: rgb(110 175 245 / 0.2);
  --bd-lilac: rgb(145 145 240 / 0.14);
  --bd-mint: rgb(110 210 230 / 0.12);
  --bd-top: #f8fafe;
  --bd-mid: #f2f6fd;
  --bd-bottom: #ecf1fb;
}
.dark {
  --bd-sky: rgb(60 130 230 / 0.14);
  --bd-lilac: rgb(110 115 235 / 0.1);
  --bd-mint: rgb(70 180 215 / 0.08);
  --bd-top: #111a2e;
  --bd-mid: #0e1424;
  --bd-bottom: #0a101d;
}

html,
body {
  height: 100%;
  overscroll-behavior: none;
}

body {
  font-family: var(--font-sans);
  -webkit-tap-highlight-color: transparent;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  /* Matches the backdrop so iOS rubber-banding never shows a seam. */
  background-color: var(--page);
  color: var(--text);
  overscroll-behavior-y: none;
}

.dark body {
  color: var(--color-frost-100);
}

/* The page backdrop now lives in ONE viewport-fixed layer (see .app-backdrop)
   so it can never stretch, scroll or be clipped by a content column.
   `.frost-bg` stays as a transparent wrapper for pages that used it. */
.frost-bg {
  background: transparent;
}

/* API-key gate stage: two big blurred blobs (top-right + bottom-left) over a
   near-black (dark) or near-white (light) base. Real blurred elements read as
   atmosphere; a flat radial gradient was too faint. Both blobs are decorative,
   non-interactive and sit behind the card (z-index 0 vs the card's z-10). */
.gate-bg {
  background: var(--gate-base);
}
.gate-bg::before,
.gate-bg::after {
  content: "";
  position: absolute;
  z-index: 0;
  width: 48rem;
  height: 48rem;
  border-radius: 9999px;
  filter: blur(120px);
  pointer-events: none;
}
.gate-bg::before {
  top: -20rem;
  right: -16rem;
  background: var(--gate-glow-a);
}
.gate-bg::after {
  bottom: -20rem;
  left: -16rem;
  background: var(--gate-glow-b);
}

.app-backdrop {
  position: fixed;
  inset: 0;
  z-index: -10;
  overflow: hidden;
  pointer-events: none;
  background:
    radial-gradient(135vw 110vh at 4% -30%, var(--bd-sky) 0%, transparent 72%),
    radial-gradient(125vw 105vh at 104% -18%, var(--bd-lilac) 0%, transparent 70%),
    radial-gradient(135vw 105vh at 38% 128%, var(--bd-mint) 0%, transparent 72%),
    linear-gradient(180deg, var(--bd-top) 0%, var(--bd-mid) 50%, var(--bd-bottom) 100%);
}

/* Two slow, very soft blobs for a little life behind the glass. */
.app-backdrop::before,
.app-backdrop::after {
  content: "";
  position: absolute;
  border-radius: 50%;
  filter: blur(110px);
  opacity: 0.22;
}
.app-backdrop::before {
  width: 52vw;
  height: 52vw;
  min-width: 24rem;
  min-height: 24rem;
  top: -26vh;
  left: -18vw;
  background: radial-gradient(circle, var(--bd-sky), transparent 66%);
  animation: float 16s ease-in-out infinite;
}
.app-backdrop::after {
  width: 46vw;
  height: 46vw;
  min-width: 22rem;
  min-height: 22rem;
  bottom: -28vh;
  right: -14vw;
  background: radial-gradient(circle, var(--bd-mint), transparent 66%);
  animation: float 20s ease-in-out infinite reverse;
}
.dark .app-backdrop::before,
.dark .app-backdrop::after {
  opacity: 0.3;
}

@layer components {
/* Glass primitives ------------------------------------------------------ */
.glass-panel {
  @apply backdrop-blur-xl backdrop-saturate-150;
  background: color-mix(in oklab, var(--surface) 82%, transparent);
  border: 1px solid var(--hairline);
  box-shadow: var(--shadow-card);
}

.glass-chip {
  @apply backdrop-blur-md;
  background: var(--surface-sunken);
  border: 1px solid transparent;
}
.glass-chip:hover {
  background: var(--hover);
}

.glass {
  /* Tailwind emits both the prefixed and standard properties; hand-written
     backdrop-filter gets minified down to -webkit- only, which paints nothing. */
  @apply backdrop-blur-xl backdrop-saturate-150;
  background: color-mix(in oklab, var(--surface) 70%, transparent);
  border-bottom: 1px solid var(--hairline);
}

/* Study-feed chrome (progress header + bottom pager): the same neutral
   surface as the cards, with a neutral border and shadow. */
.study-chrome {
  @apply backdrop-blur-xl backdrop-saturate-150;
  background: color-mix(in oklab, var(--surface) 88%, transparent);
  border: 1px solid var(--hairline);
  box-shadow: var(--shadow-card);
}
.dark .study-chrome {
  border-color: var(--hairline-soft);
}

.card {
  border-radius: 1.125rem;               /* 18px */
  @apply backdrop-blur-xl backdrop-saturate-150;
  background: color-mix(in oklab, var(--surface) 78%, transparent);
  border: 1px solid var(--card-border);
  box-shadow: var(--card-shadow);
}

/* Opt-in hover lift for interactive cards (deck cards). Pointer devices only,
   so touch screens never get sticky hover states. */
.card-hover {
  transition: background-color 180ms ease, box-shadow 180ms ease, border-color 180ms ease, transform 180ms ease;
}
@media (hover: hover) and (pointer: fine) {
  .card-hover:hover {
    background: var(--card-hover-bg);
    border-color: color-mix(in oklab, var(--hairline) 45%, var(--text) 20%);
    box-shadow: var(--shadow-card-hover);
  }
  :root:not(.dark) .card-hover:hover {
    transform: translateY(-2px);
  }
}
.card-hover:active {
  transform: translateY(0);
}

/* Inset grouped list ---------------------------------------------------- */
.list-group {
  border-radius: 1rem;
  @apply backdrop-blur-lg backdrop-saturate-150;
  background: color-mix(in oklab, var(--surface) 82%, transparent);
  border: 1px solid var(--hairline);
  overflow: hidden;
}
.list-group > * + * {
  border-top: 1px solid var(--hairline-soft);
}

/* iOS segmented control ------------------------------------------------- */
.segmented {
  display: flex;
  gap: 2px;
  padding: 3px;
  border-radius: 0.95rem;
  @apply backdrop-blur-sm;
  background: var(--surface-sunken);
  border: 1px solid var(--hairline);
}
.segmented > button {
  flex: 1;
  border-radius: 0.75rem;
  padding: 0.42rem 0.5rem;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-frost-700);
  transition: background-color 0.18s ease, color 0.18s ease, box-shadow 0.18s ease;
}
.dark .segmented > button {
  color: var(--color-frost-300);
}
.segmented > button[aria-pressed="true"],
.segmented > button[aria-checked="true"] {
  background: var(--surface-strong);
  color: var(--text);
  box-shadow: 0 1px 2px rgb(13 13 13 / 0.12);
}
.dark .segmented > button[aria-pressed="true"],
.dark .segmented > button[aria-checked="true"] {
  background: var(--surface-raised);
  color: #fff;
}

/* Sheet grabber --------------------------------------------------------- */
.sheet-grabber {
  width: 36px;
  height: 5px;
  border-radius: 999px;
  background: var(--hairline-soft);
  margin: 0 auto 0.75rem;
}

.tabbar {
  @apply backdrop-blur-xl;
  background: color-mix(in oklab, var(--page) 88%, transparent);
  border-top: 1px solid var(--hairline);
}

/* Soft tinted chip for activity types (a hint of colour, not a rainbow) -- */
.tint-sky { background: linear-gradient(140deg, rgb(156 205 245 / 0.34), rgb(156 205 245 / 0.14)); color: #1c4e72 }
.tint-mint { background: linear-gradient(140deg, rgb(159 227 208 / 0.4), rgb(159 227 208 / 0.16)); color: #1d5c4c }
.tint-lilac { background: linear-gradient(140deg, rgb(195 182 240 / 0.4), rgb(195 182 240 / 0.16)); color: #47397f }
.tint-peach { background: linear-gradient(140deg, rgb(246 205 180 / 0.45), rgb(246 205 180 / 0.18)); color: #7d4522 }
.tint-rose { background: linear-gradient(140deg, rgb(246 178 190 / 0.4), rgb(246 178 190 / 0.16)); color: #7c2b3d }
.dark .tint-sky { background: linear-gradient(140deg, rgb(74 164 220 / 0.26), rgb(74 164 220 / 0.1)); color: #bfe2fb }
.dark .tint-mint { background: linear-gradient(140deg, rgb(88 201 173 / 0.26), rgb(88 201 173 / 0.1)); color: #bdf0e2 }
.dark .tint-lilac { background: linear-gradient(140deg, rgb(160 140 235 / 0.26), rgb(160 140 235 / 0.1)); color: #ddd5fb }
.dark .tint-peach { background: linear-gradient(140deg, rgb(230 160 118 / 0.26), rgb(230 160 118 / 0.1)); color: #fadfc9 }
.dark .tint-rose { background: linear-gradient(140deg, rgb(230 130 150 / 0.26), rgb(230 130 150 / 0.1)); color: #fbd5dd }

/* Sidebar surface: frosted navy glass with a real edge. */
.sidebar-surface {
  @apply backdrop-blur-xl backdrop-saturate-150;
  background: linear-gradient(
    180deg,
    color-mix(in oklab, var(--sidebar-top) 84%, transparent),
    color-mix(in oklab, var(--sidebar-bottom) 84%, transparent)
  );
  border-right: 1px solid var(--sidebar-divider);
  box-shadow: var(--sidebar-edge);
}

/* Sidebar nav rows */
.nav-row {
  display: flex;
  align-items: center;
  gap: 0.625rem;
  width: 100%;
  border-radius: 0.625rem;
  padding: 0.5rem 0.625rem;
  font-size: 13.5px;
  font-weight: 500;
  color: var(--text-muted);
  transition: background-color 140ms ease, color 140ms ease;
}
.nav-row:hover {
  background: var(--hover);
  color: var(--text);
}
.nav-row[aria-current="page"],
.nav-row[aria-pressed="true"] {
  background: var(--surface-sunken);
  color: var(--text);
}

/* Shared CTA language: the icon's blue, with a deeper fill in light mode. */
.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  border-radius: 999px;
  background: #1d61ab;
  color: #ffffff;
  font-weight: 500;
  box-shadow: 0 1px 2px rgb(14 21 40 / 0.22);
  transition: background-color 160ms ease, transform 160ms ease, box-shadow 160ms ease;
}
.btn-primary:hover { background: #2478d2; }
.btn-primary:active { transform: scale(0.985); }
.dark .btn-primary {
  background: #59a8f7;
  color: #081020;
  box-shadow: none;
}
.dark .btn-primary:hover { background: #7bbaff; }

.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  border-radius: 999px;
  background: transparent;
  color: var(--text);
  border: 1px solid var(--hairline);
  font-weight: 500;
  transition: background-color 160ms ease, border-color 160ms ease, transform 160ms ease;
}
.btn-secondary:hover { background: var(--hover); border-color: color-mix(in oklab, var(--hairline) 70%, var(--text) 12%); }
.btn-secondary:active { transform: scale(0.985); }

.btn-ghost {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  border-radius: 0.75rem;
  background: transparent;
  color: var(--text-muted);
  font-weight: 500;
  transition: background-color 160ms ease, color 160ms ease;
}
.btn-ghost:hover { background: var(--hover); color: var(--text); }

/* Difficulty: neutral pill, colour lives in the text only. */
.diff-easy { color: #16714f; }
.diff-medium { color: #7a5300; }
.diff-hard { color: #b4342f; }
.dark .diff-easy { color: #6fd3a8; }
.dark .diff-medium { color: #e3b341; }
.dark .diff-hard { color: #f08a84; }

/* Loading skeleton */
.skeleton {
  position: relative;
  overflow: hidden;
  background: var(--surface-sunken);
  border-radius: 0.75rem;
}
.skeleton::after {
  content: "";
  position: absolute;
  inset: 0;
  transform: translateX(-100%);
  background: linear-gradient(90deg, transparent, rgb(255 255 255 / 0.45), transparent);
  animation: shimmer 1.6s infinite;
}
.dark .skeleton::after {
  background: linear-gradient(90deg, transparent, rgb(255 255 255 / 0.06), transparent);
}
@keyframes shimmer {
  100% { transform: translateX(100%); }
}

.text-balance {
  text-wrap: balance;
}

/* Focus rings ------------------------------------------------------------ */
:where(button, a, input, textarea, [tabindex]):focus-visible {
  outline: 2.5px solid var(--color-accent-500);
  outline-offset: 2px;
  border-radius: 0.75rem;
}

/* Scrollbars ------------------------------------------------------------- */
.thin-scroll {
  scrollbar-width: thin;
  scrollbar-color: color-mix(in oklab, var(--color-frost-400) 55%, transparent) transparent;
}
.thin-scroll::-webkit-scrollbar { width: 8px; height: 8px }
.thin-scroll::-webkit-scrollbar-thumb {
  background: color-mix(in oklab, var(--color-frost-400) 45%, transparent);
  border-radius: 999px;
}
.no-scrollbar::-webkit-scrollbar { display: none }
.no-scrollbar { -ms-overflow-style: none; scrollbar-width: none }

/* Mobile safe areas ------------------------------------------------------ */
.pt-safe { padding-top: max(env(safe-area-inset-top), 0.75rem) }
.pb-safe { padding-bottom: max(env(safe-area-inset-bottom), 0.75rem) }
.pb-tabbar { padding-bottom: calc(env(safe-area-inset-bottom, 0px) + 5.25rem) }
.pb-cta { padding-bottom: calc(env(safe-area-inset-bottom, 0px) + 9rem) }

@media (display-mode: standalone) {
  .standalone-hide { display: none }
}
}

/* Mobile form fields ----------------------------------------------------- */
/* iOS Safari zooms the whole page when a focused field's text is under 16px
   (it ignores user-scalable=no for that). Deliberately unlayered so it wins
   over the per-component Tailwind sizes, and only on phone-sized screens. */
@media (max-width: 639px) {
  input:not([type="checkbox"]):not([type="radio"]):not([type="range"]),
  textarea,
  select {
    font-size: 16px;
  }
}

/* Reduced motion --------------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}