/* =============================================================================
   styles.css
   -----------------------------------------------------------------------------
   Thiết kế: một tấm "thiệp đố vui" ấm áp, cá nhân — không phải giao diện thi
   cử nghiêm túc. Bảng màu lấy cảm hứng từ giấy note và bút dạ quang: nền kem
   dịu, một tông xanh mực đậm cho chữ, và một màu cam san hô làm điểm nhấn duy
   nhất (nút bấm, đáp án đúng, thanh tiến trình).

   Token hệ thống:
   - Màu:   --color-paper (nền), --color-ink (chữ chính), --color-accent (cam),
            --color-accent-soft (nền nhấn nhẹ), --color-line (viền/đường kẻ)
   - Chữ:   --font-display (tiêu đề, có cá tính) + --font-body (nội dung, dễ đọc)
   - Bố cục: các "card" giấy bo góc nhẹ, đổ bóng mềm, xếp dọc giữa trang.
============================================================================= */

@import url("https://fonts.googleapis.com/css2?family=Fraunces:ital,wght@0,600;0,700;1,600&family=Karla:wght@400;500;700&display=swap");

:root {
  /* Màu sắc */
  --color-paper: #faf6ee;
  --color-card: #ffffff;
  --color-ink: #2b2621;
  --color-ink-soft: #6b6258;
  --color-accent: #e8703a;
  --color-accent-dark: #c85a28;
  --color-accent-soft: #fbe4d4;
  --color-correct: #4b8b5f;
  --color-correct-soft: #e2f0e4;
  --color-error: #c85252;
  --color-error-soft: #fbe6e6;
  --color-line: #e8ddcd;

  /* Kiểu chữ */
  --font-display: "Fraunces", Georgia, serif;
  --font-body: "Karla", -apple-system, BlinkMacSystemFont, sans-serif;

  /* Bố cục */
  --radius-lg: 20px;
  --radius-md: 12px;
  --radius-sm: 8px;
  --shadow-card: 0 4px 24px rgba(43, 38, 33, 0.08);
  --max-width: 640px;
  --transition-fast: 150ms ease;
}

* {
  box-sizing: border-box;
}

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

body {
  margin: 0;
  min-height: 100vh;
  background-color: var(--color-paper);
  background-image:
    radial-gradient(circle at 15% 20%, rgba(232, 112, 58, 0.06) 0%, transparent 45%),
    radial-gradient(circle at 85% 75%, rgba(75, 139, 95, 0.05) 0%, transparent 40%);
  color: var(--color-ink);
  font-family: var(--font-body);
  line-height: 1.5;
  padding: 24px 16px 48px;
}

h1, h2, h3 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.2;
  margin: 0 0 8px;
}

p {
  margin: 0 0 16px;
  color: var(--color-ink-soft);
}

button {
  font-family: inherit;
  cursor: pointer;
}

input:focus-visible,
button:focus-visible,
label:has(input:focus-visible) {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

.app-container {
  max-width: var(--max-width);
  margin: 0 auto;
}

.card {
  background-color: var(--color-card);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-card);
  padding: 32px 28px;
}

@media (max-width: 480px) {
  .card {
    padding: 24px 20px;
    border-radius: var(--radius-md);
  }
}

.hidden {
  display: none !important;
}

/* =============================================================================
   Header chung: nhãn nhỏ + tiêu đề, dùng ở đầu mỗi màn hình.
============================================================================= */

.screen-header {
  text-align: center;
  margin-bottom: 28px;
}

.screen-header__eyebrow {
  display: inline-block;
  font-family: var(--font-body);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-accent-dark);
  background-color: var(--color-accent-soft);
  padding: 4px 12px;
  border-radius: 999px;
  margin-bottom: 12px;
}

.screen-header__title {
  font-size: clamp(24px, 5vw, 32px);
}

.screen-header__subtitle {
  margin-bottom: 0;
}

/* =============================================================================
   Màn hình chào / đăng nhập
============================================================================= */

.login-form {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.form-field {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.form-field label {
  font-size: 14px;
  font-weight: 700;
  color: var(--color-ink);
}

.form-field input {
  font-family: var(--font-body);
  font-size: 16px;
  padding: 12px 14px;
  border: 1.5px solid var(--color-line);
  border-radius: var(--radius-sm);
  background-color: var(--color-paper);
  color: var(--color-ink);
  transition: border-color var(--transition-fast);
}

.form-field input::placeholder {
  color: #b3a996;
}

.form-field input:focus {
  border-color: var(--color-accent);
}

.primary-button {
  font-size: 16px;
  font-weight: 700;
  color: #fff;
  background-color: var(--color-accent);
  border: none;
  border-radius: var(--radius-sm);
  padding: 14px 20px;
  transition: background-color var(--transition-fast), transform var(--transition-fast);
}

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

.primary-button:active:not(:disabled) {
  transform: scale(0.98);
}

.primary-button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.secondary-button {
  font-size: 15px;
  font-weight: 700;
  color: var(--color-ink);
  background-color: transparent;
  border: 1.5px solid var(--color-line);
  border-radius: var(--radius-sm);
  padding: 12px 18px;
  transition: border-color var(--transition-fast), background-color var(--transition-fast);
}

.secondary-button:hover {
  border-color: var(--color-accent);
  background-color: var(--color-accent-soft);
}

.error-message {
  font-size: 14px;
  font-weight: 500;
  color: var(--color-error);
  background-color: var(--color-error-soft);
  border-radius: var(--radius-sm);
  padding: 10px 14px;
}

/* =============================================================================
   Màn hình quiz
============================================================================= */

.quiz-toolbar {
  position: sticky;
  top: 12px;
  z-index: 10;
  display: flex;
  align-items: center;
  gap: 16px;
  background-color: var(--color-card);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-card);
  padding: 14px 18px;
  margin-bottom: 24px;
}

.timer-display {
  font-family: var(--font-display);
  font-size: 22px;
  font-weight: 700;
  color: var(--color-ink);
  min-width: 64px;
  text-align: center;
}

.timer-display.timer--warning {
  color: var(--color-error);
}

.progress-wrapper {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.progress-text {
  font-size: 12px;
  font-weight: 700;
  color: var(--color-ink-soft);
}

.progress-bar-track {
  height: 8px;
  background-color: var(--color-line);
  border-radius: 999px;
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  background-color: var(--color-accent);
  border-radius: 999px;
  width: 0%;
  transition: width 200ms ease;
}

.question-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-bottom: 24px;
}

.question-card {
  background-color: var(--color-card);
  border: 1.5px solid var(--color-line);
  border-radius: var(--radius-md);
  padding: 20px;
  margin: 0;
  transition: border-color var(--transition-fast);
}

.question-card--answered {
  border-color: var(--color-accent-soft);
}

.question-card__title {
  font-family: var(--font-body);
  font-size: 17px;
  font-weight: 700;
  color: var(--color-ink);
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-bottom: 14px;
}

.question-card__number {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-accent-dark);
}

.answer-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.answer-option {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 14px;
  border: 1.5px solid var(--color-line);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: border-color var(--transition-fast), background-color var(--transition-fast);
}

.answer-option:hover {
  border-color: var(--color-accent);
  background-color: var(--color-accent-soft);
}

.answer-option:has(.answer-option__input:checked) {
  border-color: var(--color-accent);
  background-color: var(--color-accent-soft);
}

.answer-option__input {
  width: 18px;
  height: 18px;
  accent-color: var(--color-accent);
  flex-shrink: 0;
}

.answer-option__text {
  font-size: 15px;
  color: var(--color-ink);
  display: flex;
  align-items: baseline;
  gap: 8px;
}

.answer-option__label {
  font-weight: 700;
  color: var(--color-accent-dark);
}

.quiz-footer {
  display: flex;
  justify-content: center;
}

/* =============================================================================
   Màn hình kết quả
============================================================================= */

.result-summary {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-bottom: 24px;
}

.result-stat {
  text-align: center;
  background-color: var(--color-paper);
  border-radius: var(--radius-md);
  padding: 18px 10px;
}

.result-stat__value {
  display: block;
  font-family: var(--font-display);
  font-size: 28px;
  font-weight: 700;
  color: var(--color-accent-dark);
}

.result-stat__label {
  font-size: 12px;
  font-weight: 700;
  color: var(--color-ink-soft);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.save-status {
  text-align: center;
  font-size: 14px;
  font-weight: 500;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  margin-bottom: 20px;
}

.save-status--saving {
  color: var(--color-ink-soft);
  background-color: var(--color-paper);
}

.save-status--success {
  color: var(--color-correct);
  background-color: var(--color-correct-soft);
}

.save-status--error {
  color: var(--color-error);
  background-color: var(--color-error-soft);
}

.result-actions {
  display: flex;
  justify-content: center;
}

/* =============================================================================
   Màn hình bảng xếp hạng
============================================================================= */

.leaderboard-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  margin-bottom: 20px;
}

.leaderboard-state {
  text-align: center;
  padding: 32px 16px;
  color: var(--color-ink-soft);
}

.leaderboard-state--error {
  color: var(--color-error);
}

.leaderboard-table-wrapper {
  overflow-x: auto;
  border-radius: var(--radius-md);
  border: 1.5px solid var(--color-line);
}

.leaderboard-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
  min-width: 520px;
}

.leaderboard-table thead {
  background-color: var(--color-paper);
}

.leaderboard-table th {
  text-align: left;
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--color-ink-soft);
  padding: 12px 14px;
  border-bottom: 1.5px solid var(--color-line);
}

.leaderboard-cell {
  padding: 12px 14px;
  border-bottom: 1px solid var(--color-line);
  color: var(--color-ink);
  white-space: nowrap;
}

.leaderboard-cell--rank {
  font-weight: 700;
  text-align: center;
}

.leaderboard-cell--name {
  font-weight: 700;
  white-space: normal;
}

.leaderboard-cell--date {
  color: var(--color-ink-soft);
}

.leaderboard-row--top {
  background-color: var(--color-accent-soft);
}

.leaderboard-table tbody tr:last-child .leaderboard-cell {
  border-bottom: none;
}

/* =============================================================================
   Responsive
============================================================================= */

@media (max-width: 480px) {
  .result-summary {
    grid-template-columns: 1fr;
  }

  .quiz-toolbar {
    flex-wrap: wrap;
    top: 8px;
  }

  .leaderboard-toolbar {
    flex-direction: column;
    align-items: stretch;
  }
}

/* Tôn trọng người dùng bật "giảm thiểu hiệu ứng chuyển động" trong hệ điều hành */
@media (prefers-reduced-motion: reduce) {
  * {
    transition: none !important;
    scroll-behavior: auto !important;
  }
}