/* Echo Flip 스타일시트. 빌드 도구 없이 이 파일 하나로 끝난다.
   색·둥근 정도 같은 디자인 토큰은 CSS 변수로 두고, 다크 모드는
   prefers-color-scheme에서 변수만 바꾼다. */

:root {
  --bg: #fafafa;
  --fg: #171717;
  --surface: #ffffff;
  --border: #e5e5e5;
  --muted: #737373;
  --faint: #a3a3a3;
  --primary: #2563eb;
  --primary-fg: #ffffff;
  --primary-soft: #eff6ff;
  --primary-soft-border: #bfdbfe;
  --amber-soft: #fffbeb;
  --amber-border: #fde68a;
  --amber: #f59e0b;
  --amber-strong: #b45309;
  --green: #16a34a;
  --green-soft-border: #86efac;
  --red: #ef4444;
  --answer-bg: #eff6ff;
  --answer-border: #bfdbfe;
  --radius: 0.75rem;
  --radius-lg: 1rem;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0a0a0a;
    --fg: #f5f5f5;
    --surface: #171717;
    --border: #262626;
    --muted: #a3a3a3;
    --faint: #737373;
    --primary-soft: rgba(37, 99, 235, 0.15);
    --primary-soft-border: #1e3a8a;
    --amber-soft: rgba(245, 158, 11, 0.12);
    --amber-border: #78350f;
    --amber-strong: #fbbf24;
    --green-soft-border: #166534;
    --answer-bg: rgba(37, 99, 235, 0.12);
    --answer-border: #1e3a8a;
  }
}

* {
  box-sizing: border-box;
}

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

body {
  margin: 0;
  min-height: 100dvh;
  background: var(--bg);
  color: var(--fg);
  font-family:
    "Pretendard Variable", Pretendard, -apple-system, BlinkMacSystemFont,
    "Apple SD Gothic Neo", "Noto Sans KR", "Segoe UI", Roboto, sans-serif;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
}

h1 {
  font-size: 1.25rem;
  margin: 0;
}

h2 {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--muted);
  margin: 0;
}

svg.icon {
  width: 1.25em;
  height: 1.25em;
  flex-shrink: 0;
  vertical-align: -0.25em;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

/* ---------- 앱 프레임: 상단 바 · 본문 · 하단 탭 ---------- */

.frame {
  max-width: 32rem;
  margin: 0 auto;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 3rem;
  padding: 0 1rem;
  border-bottom: 1px solid var(--border);
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-weight: 700;
  font-size: 0.875rem;
}

.topbar-user {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  min-width: 0;
  font-size: 0.75rem;
  color: var(--muted);
}

.topbar-user .email {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

main {
  flex: 1;
  padding: 1.5rem 1rem 2.5rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

main.with-nav {
  padding-bottom: 6rem;
}

.bottomnav {
  position: fixed;
  inset: auto 0 0 0;
  z-index: 40;
  border-top: 1px solid var(--border);
  background: color-mix(in srgb, var(--bg) 95%, transparent);
  backdrop-filter: blur(8px);
}

.bottomnav div {
  max-width: 32rem;
  margin: 0 auto;
  display: flex;
  justify-content: space-around;
}

.bottomnav a {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.125rem;
  padding: 0.625rem 1rem;
  font-size: 0.75rem;
  color: var(--muted);
}

.bottomnav a.active {
  color: var(--primary);
}

#offline-banner {
  display: none;
  background: var(--amber);
  color: #fff;
  text-align: center;
  font-size: 0.875rem;
  padding: 0.375rem 1rem;
}

#offline-banner.show {
  display: block;
}

/* ---------- 토스트(플래시 메시지) ---------- */

.toast {
  position: fixed;
  inset: auto 0 5rem 0;
  z-index: 50;
  display: flex;
  justify-content: center;
  padding: 0 1rem;
  pointer-events: none;
}

.toast div {
  background: #262626;
  color: #fff;
  font-size: 0.875rem;
  border-radius: 0.5rem;
  padding: 0.5rem 1rem;
  box-shadow: 0 10px 15px -3px rgb(0 0 0 / 0.2);
  animation: toast-out 0.4s ease 2.6s forwards;
}

.toast div.error {
  background: #dc2626;
}

@keyframes toast-out {
  to {
    opacity: 0;
    transform: translateY(0.5rem);
  }
}

/* ---------- 버튼 ---------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.375rem;
  border: 1px solid transparent;
  border-radius: 0.5rem;
  padding: 0.5rem 0.75rem;
  font: inherit;
  font-size: 0.875rem;
  font-weight: 500;
  color: inherit;
  background: none;
  cursor: pointer;
}

.btn:disabled {
  opacity: 0.5;
  cursor: default;
}

.btn:active {
  transform: scale(0.98);
}

.btn-primary {
  background: var(--primary);
  color: var(--primary-fg);
}

.btn-outline {
  border-color: var(--border);
}

.btn-big {
  border-radius: var(--radius);
  padding: 0.875rem 1.5rem;
  font-weight: 600;
  width: 100%;
}

.btn-green {
  background: var(--green);
  color: #fff;
}

.btn-red {
  background: var(--red);
  color: #fff;
}

.btn-amber {
  background: var(--amber);
  color: #fff;
}

.btn-icon {
  padding: 0.375rem;
  color: var(--faint);
}

.btn-share-ok {
  border-color: var(--green-soft-border);
  color: var(--green);
}

.btn-danger-outline {
  border-color: color-mix(in srgb, var(--red) 40%, var(--border));
  color: var(--red);
}

.link {
  color: var(--primary);
  font-size: 0.875rem;
}

/* ---------- 타일(목록 항목)과 섹션 ---------- */

.stack {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.stack-lg {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.row {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.row-between {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
}

.tile {
  display: block;
  border: 1px solid var(--border);
  background: var(--surface);
  border-radius: var(--radius);
  padding: 0.875rem 1rem;
}

.tile-blue {
  border-color: var(--primary-soft-border);
  background: var(--primary-soft);
}

.tile-amber {
  border-color: var(--amber-border);
  background: var(--amber-soft);
}

.tile-dashed {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  border: 1px dashed var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  color: var(--muted);
}

.hero {
  border-radius: var(--radius-lg);
  background: var(--primary);
  color: #fff;
  padding: 1.25rem;
}

.hero .count {
  font-size: 1.875rem;
  font-weight: 700;
  margin: 0.25rem 0 0;
}

.hero .btn-big {
  margin-top: 1rem;
  background: #fff;
  color: var(--primary);
}

.hero p {
  margin: 0;
}

.hero .sub {
  font-size: 0.875rem;
  opacity: 0.8;
}

.pill {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  border-radius: 9999px;
  padding: 0.125rem 0.625rem;
  font-size: 0.75rem;
  font-weight: 500;
}

.pill-streak {
  background: var(--amber-soft);
  color: var(--amber-strong);
  padding: 0.25rem 0.75rem;
  font-size: 0.875rem;
}

.pill-muted {
  background: color-mix(in srgb, var(--fg) 7%, transparent);
  color: var(--muted);
}

.pill-blue {
  background: var(--primary-soft);
  color: var(--primary);
}

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

.faint {
  color: var(--faint);
}

.small {
  font-size: 0.875rem;
}

.tiny {
  font-size: 0.75rem;
}

.center {
  text-align: center;
}

.empty {
  padding: 2rem 0;
  text-align: center;
  font-size: 0.875rem;
  color: var(--muted);
}

.truncate {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* ---------- 폼 ---------- */

input,
textarea,
select {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 0.5rem;
  background: var(--surface);
  color: inherit;
  font: inherit;
  font-size: 0.875rem;
  padding: 0.625rem 0.75rem;
}

input:focus,
textarea:focus {
  outline: none;
  border-color: var(--primary);
}

input[type="range"] {
  padding: 0;
  border: none;
  background: transparent;
  accent-color: var(--primary);
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.375rem;
}

.field > span {
  font-size: 0.875rem;
  font-weight: 500;
}

form {
  margin: 0;
}

/* 카드 종류 선택: 라디오 버튼을 알약 모양으로 */

.type-pills {
  display: flex;
  gap: 0.5rem;
}

.type-pills input {
  position: absolute;
  opacity: 0;
  width: 0;
}

.type-pills span {
  display: inline-block;
  border-radius: 9999px;
  padding: 0.375rem 1rem;
  font-size: 0.875rem;
  background: color-mix(in srgb, var(--fg) 7%, transparent);
  color: var(--muted);
  cursor: pointer;
}

.type-pills input:checked + span {
  background: var(--primary);
  color: var(--primary-fg);
}

/* 새 덱 만들기: details/summary로 자바스크립트 없이 펼친다 */

details.reveal > summary {
  list-style: none;
  cursor: pointer;
}

details.reveal > summary::-webkit-details-marker {
  display: none;
}

details.reveal[open] > summary {
  display: none;
}

/* ---------- 학습(플래시카드) ---------- */

.study-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.875rem;
  color: var(--muted);
}

.progress {
  height: 0.375rem;
  border-radius: 9999px;
  overflow: hidden;
  background: color-mix(in srgb, var(--fg) 12%, transparent);
}

.progress div {
  height: 100%;
  border-radius: 9999px;
  background: var(--primary);
  transition: width 0.3s;
}

/* 뒤집기: 숨긴 체크박스가 상태, CSS가 애니메이션. 자바스크립트 없음. */

.reveal-toggle {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.flip-scene {
  display: block;
  perspective: 1200px;
  min-height: 18rem;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  user-select: none;
}

.flip-inner {
  position: relative;
  width: 100%;
  min-height: 18rem;
  transform-style: preserve-3d;
  transition: transform 0.45s cubic-bezier(0.4, 0, 0.2, 1);
}

.reveal-toggle:checked ~ .flip-scene .flip-inner {
  transform: rotateY(180deg);
}

.reveal-toggle:checked ~ .flip-scene .hint {
  visibility: hidden;
}

.flip-face {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  border: 1px solid var(--border);
  background: var(--surface);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  box-shadow: 0 1px 2px rgb(0 0 0 / 0.05);
}

.flip-back {
  transform: rotateY(180deg);
  border-color: var(--answer-border);
  background: var(--answer-bg);
}

.flip-face .face-center {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 1rem 0;
  text-align: center;
}

.question {
  font-size: 1.5rem;
  font-weight: 600;
  line-height: 1.35;
  margin: 0;
  white-space: pre-line;
}

.answer {
  font-size: 1.125rem;
  font-weight: 500;
  line-height: 1.6;
  margin: 0;
  white-space: pre-line;
}

.example {
  font-style: italic;
  font-size: 0.875rem;
  color: var(--muted);
  margin: 0;
  white-space: pre-line;
}

.tts {
  border: none;
  background: none;
  border-radius: 9999px;
  padding: 0.5rem;
  color: var(--primary);
  cursor: pointer;
}

.tts:hover {
  background: var(--primary-soft);
}

/* 정답을 보기 전에는 채점 버튼을 숨긴다 */

.grade-grid {
  display: none;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}

.reveal-toggle:checked ~ .grade-grid {
  display: grid;
}

.reveal-btn {
  display: block;
}

.reveal-toggle:checked ~ .reveal-btn {
  display: none;
}

.finish-icon {
  color: var(--amber);
}

.stat-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.75rem;
  text-align: center;
}

.stat-3 .box {
  border: 1px solid var(--border);
  background: var(--surface);
  border-radius: var(--radius);
  padding: 1rem 0;
}

.stat-3 .num {
  font-size: 1.125rem;
  font-weight: 700;
}

.stat-3 .label {
  font-size: 0.75rem;
  color: var(--muted);
  margin-top: 0.125rem;
}

/* ---------- 통계 ---------- */

.chart {
  display: flex;
  align-items: flex-end;
  gap: 3px;
  height: 8rem;
}

.chart .day {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  gap: 1px;
  height: 100%;
}

.chart .correct {
  width: 100%;
  border-radius: 2px 2px 0 0;
  background: color-mix(in srgb, var(--primary) 90%, transparent);
}

.chart .wrong {
  width: 100%;
  background: color-mix(in srgb, var(--red) 80%, transparent);
}

.meter {
  height: 0.5rem;
  border-radius: 9999px;
  overflow: hidden;
  background: color-mix(in srgb, var(--fg) 12%, transparent);
  margin-top: 0.5rem;
}

.meter div {
  height: 100%;
  border-radius: 9999px;
  background: var(--green);
}

/* ---------- 로그인 ---------- */

.login {
  max-width: 24rem;
  margin: 0 auto;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2.5rem;
  padding: 0 1.5rem;
  text-align: center;
}

.login h1 {
  font-size: 1.875rem;
  margin-top: 1rem;
}

.login .buttons {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.login .google {
  background: #fff;
  color: #262626;
  border-color: #d4d4d4;
}

.login .github {
  background: #171717;
  color: #fff;
}

/* 공유 링크 복사 버튼: 복사 성공 시 라벨 교체 */

[data-copy] .after {
  display: none;
}

[data-copy][data-done] .before {
  display: none;
}

[data-copy][data-done] .after {
  display: inline;
}