/* ============================================================
   Подготовка к собеседованию системного администратора
   Тема: GitHub Dark + VSCode
   ============================================================ */

/* ---------- CSS Variables ---------- */
:root {
  --bg-primary: #0d1117;
  --bg-secondary: #161b22;
  --bg-tertiary: #21262d;
  --bg-card: #1c2128;
  --border-color: #30363d;
  --border-hover: #484f58;
  --text-primary: #e6edf3;
  --text-secondary: #8b949e;
  --text-muted: #6e7681;
  --accent-blue: #58a6ff;
  --accent-green: #3fb950;
  --accent-red: #f85149;
  --accent-orange: #d2991d;
  --accent-purple: #a371f7;
  --accent-cyan: #39d353;
  --accent-pink: #db61a2;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
  --radius: 12px;
  --radius-sm: 8px;
  --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  --font-mono: 'Cascadia Code', 'Fira Code', 'JetBrains Mono', 'Consolas', monospace;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

/* ---------- Reset & Base ---------- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

/* ---------- App Container ---------- */
.app-container {
  max-width: 800px;
  margin: 0 auto;
  padding: 24px 20px;
  min-height: 100vh;
}

/* ---------- Screens ---------- */
.screen {
  display: none;
  animation: fadeSlideIn 0.4s ease;
}

.screen.active {
  display: block;
}

@keyframes fadeSlideIn {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ---------- Home Screen ---------- */
.home-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 48px 40px;
  text-align: center;
  box-shadow: var(--shadow);
  margin-top: 40px;
}

.logo-icon {
  font-size: 56px;
  margin-bottom: 20px;
  color: var(--accent-blue);
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.7; transform: scale(1.05); }
}

.home-card h1 {
  font-size: 28px;
  font-weight: 700;
  margin-bottom: 16px;
  line-height: 1.3;
  color: var(--text-primary);
}

.home-description {
  color: var(--text-secondary);
  font-size: 15px;
  max-width: 500px;
  margin: 0 auto 32px;
  line-height: 1.7;
}

/* ---------- Home Stats ---------- */
.home-stats {
  display: flex;
  gap: 16px;
  justify-content: center;
  margin-bottom: 28px;
}

.stat-card {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 16px 28px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  transition: var(--transition);
}

.stat-card:hover {
  border-color: var(--border-hover);
  transform: translateY(-2px);
}

.stat-number {
  font-size: 32px;
  font-weight: 800;
  color: var(--accent-blue);
  font-family: var(--font-mono);
}

.stat-label {
  font-size: 13px;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.8px;
}

/* ---------- Home Filters ---------- */
.home-filters {
  display: flex;
  gap: 16px;
  justify-content: center;
  margin-bottom: 28px;
  flex-wrap: wrap;
}

.filter-group {
  display: flex;
  align-items: center;
  gap: 8px;
}

.filter-group label {
  font-size: 13px;
  color: var(--text-secondary);
  white-space: nowrap;
}

.filter-group select {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  padding: 8px 14px;
  border-radius: 6px;
  font-size: 14px;
  font-family: var(--font-sans);
  cursor: pointer;
  transition: var(--transition);
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%238b949e' stroke-width='2'%3E%3Cpath d='M6 9l6 6 6-6'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 10px center;
  padding-right: 32px;
}

.filter-group select:focus {
  outline: none;
  border-color: var(--accent-blue);
  box-shadow: 0 0 0 3px rgba(88, 166, 255, 0.15);
}

/* ---------- Home Buttons ---------- */
.home-buttons {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: 8px;
  border: 1px solid transparent;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  font-family: var(--font-sans);
  text-decoration: none;
  position: relative;
  overflow: hidden;
}

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

.btn-primary {
  background: var(--accent-green);
  color: #000;
  border-color: var(--accent-green);
}

.btn-primary:hover {
  background: #46b756;
  box-shadow: 0 0 20px rgba(63, 185, 80, 0.3);
}

.btn-secondary {
  background: var(--accent-blue);
  color: #000;
  border-color: var(--accent-blue);
}

.btn-secondary:hover {
  background: #6eb6ff;
  box-shadow: 0 0 20px rgba(88, 166, 255, 0.3);
}

.btn-outline {
  background: transparent;
  border-color: var(--border-color);
  color: var(--text-secondary);
}

.btn-outline:hover {
  border-color: var(--text-secondary);
  color: var(--text-primary);
  background: var(--bg-tertiary);
}

.btn-icon {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 8px 16px;
  font-size: 14px;
  border-radius: 6px;
}

.btn-icon:hover {
  border-color: var(--text-secondary);
  color: var(--text-primary);
}

/* ---------- Quiz Screen ---------- */
.quiz-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
}

.progress-info {
  display: flex;
  gap: 12px;
  align-items: center;
  font-family: var(--font-mono);
  font-size: 14px;
}

#progress-text {
  color: var(--text-primary);
  font-weight: 600;
}

#progress-percent {
  color: var(--accent-blue);
  font-weight: 700;
}

/* ---------- Progress Bar ---------- */
.progress-bar-container {
  width: 100%;
  height: 6px;
  background: var(--bg-tertiary);
  border-radius: 3px;
  margin-bottom: 28px;
  overflow: hidden;
}

.progress-bar {
  height: 100%;
  background: linear-gradient(90deg, var(--accent-blue), var(--accent-purple));
  border-radius: 3px;
  transition: width 0.4s ease;
  width: 0%;
}

/* ---------- Quiz Card ---------- */
.quiz-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 36px;
  box-shadow: var(--shadow);
}

.quiz-topic {
  display: inline-block;
  background: rgba(88, 166, 255, 0.12);
  color: var(--accent-blue);
  padding: 4px 12px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 600;
  margin-bottom: 8px;
  letter-spacing: 0.5px;
  text-transform: uppercase;
}

.quiz-difficulty {
  display: inline-block;
  margin-left: 8px;
  padding: 4px 12px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.difficulty-easy { background: rgba(63, 185, 80, 0.12); color: var(--accent-green); }
.difficulty-medium { background: rgba(210, 153, 29, 0.12); color: var(--accent-orange); }
.difficulty-hard { background: rgba(248, 81, 73, 0.12); color: var(--accent-red); }
.difficulty-tricky { background: rgba(163, 113, 247, 0.12); color: var(--accent-purple); }

.quiz-question {
  font-size: 20px;
  font-weight: 600;
  margin: 16px 0 24px;
  line-height: 1.5;
  color: var(--text-primary);
}

/* ---------- Options ---------- */
.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.option-btn {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  width: 100%;
  padding: 16px 20px;
  background: var(--bg-tertiary);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-size: 15px;
  cursor: pointer;
  transition: var(--transition);
  text-align: left;
  font-family: var(--font-sans);
  line-height: 1.5;
}

.option-btn:hover:not(.option-correct):not(.option-incorrect):not(.option-disabled) {
  border-color: var(--accent-blue);
  background: rgba(88, 166, 255, 0.05);
}

.option-letter {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: rgba(139, 148, 158, 0.15);
  font-weight: 700;
  font-size: 13px;
  flex-shrink: 0;
  color: var(--text-secondary);
}

.option-btn:hover:not(.option-correct):not(.option-incorrect):not(.option-disabled) .option-letter {
  background: rgba(88, 166, 255, 0.2);
  color: var(--accent-blue);
}

.option-correct {
  border-color: var(--accent-green) !important;
  background: rgba(63, 185, 80, 0.08) !important;
}

.option-correct .option-letter {
  background: var(--accent-green) !important;
  color: #000 !important;
}

.option-incorrect {
  border-color: var(--accent-red) !important;
  background: rgba(248, 81, 73, 0.08) !important;
  animation: shake 0.4s ease;
}

.option-incorrect .option-letter {
  background: var(--accent-red) !important;
  color: #fff !important;
}

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

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20% { transform: translateX(-6px); }
  40% { transform: translateX(6px); }
  60% { transform: translateX(-4px); }
  80% { transform: translateX(4px); }
}

/* ---------- Feedback ---------- */
.quiz-feedback {
  margin-top: 24px;
  padding: 24px;
  border-radius: var(--radius-sm);
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  animation: fadeSlideIn 0.3s ease;
}

.feedback-icon {
  font-size: 28px;
  margin-bottom: 8px;
}

.feedback-text {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 16px;
}

.feedback-correct {
  color: var(--accent-green);
}

.feedback-incorrect {
  color: var(--accent-red);
}

.feedback-explanation {
  color: var(--text-secondary);
  line-height: 1.8;
  font-size: 14px;
  white-space: pre-line;
}

/* ---------- Result Screen ---------- */
.result-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 40px;
  text-align: center;
  box-shadow: var(--shadow);
  margin-top: 24px;
}

.result-card h2 {
  font-size: 24px;
  font-weight: 700;
  margin-bottom: 28px;
}

/* ---------- Result Circle ---------- */
.result-circle-container {
  position: relative;
  width: 180px;
  height: 180px;
  margin: 0 auto 28px;
}

.result-circle {
  width: 100%;
  height: 100%;
  transform: rotate(-90deg);
}

.result-circle-bg {
  fill: none;
  stroke: var(--bg-tertiary);
  stroke-width: 10;
}

.result-circle-fill {
  fill: none;
  stroke: var(--accent-green);
  stroke-width: 10;
  stroke-linecap: round;
  stroke-dasharray: 439.82;
  stroke-dashoffset: 439.82;
  transition: stroke-dashoffset 1.5s ease;
}

.result-circle-text {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  display: flex;
  flex-direction: column;
  align-items: center;
}

.result-percent {
  font-size: 42px;
  font-weight: 800;
  color: var(--accent-green);
}

/* ---------- Result Stats ---------- */
.result-stats {
  display: flex;
  gap: 16px;
  justify-content: center;
  margin-bottom: 28px;
  flex-wrap: wrap;
}

.result-stat {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 16px 24px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
}

.result-stat-value {
  font-size: 28px;
  font-weight: 800;
  font-family: var(--font-mono);
}

.result-stat-label {
  font-size: 12px;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.8px;
}

.correct-color { color: var(--accent-green); }
.incorrect-color { color: var(--accent-red); }

/* ---------- Assessment ---------- */
.result-assessment {
  margin: 0 auto 20px;
  max-width: 500px;
  padding: 16px 20px;
  border-radius: var(--radius-sm);
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  text-align: center;
}

.result-assessment .assessment-level {
  font-size: 13px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 4px;
}

.result-assessment .assessment-text {
  font-size: 18px;
  font-weight: 700;
}

.assessment-0-20 { color: var(--accent-red); }
.assessment-20-40 { color: var(--accent-orange); }
.assessment-40-60 { color: var(--accent-orange); }
.assessment-60-75 { color: var(--accent-blue); }
.assessment-75-90 { color: var(--accent-cyan); }
.assessment-90-100 { color: var(--accent-green); }

.result-strengths,
.result-weaknesses {
  margin: 12px auto;
  max-width: 500px;
  padding: 14px 20px;
  border-radius: var(--radius-sm);
  text-align: left;
  font-size: 14px;
  line-height: 1.6;
}

.result-strengths {
  background: rgba(63, 185, 80, 0.06);
  border: 1px solid rgba(63, 185, 80, 0.2);
}

.result-weaknesses {
  background: rgba(248, 81, 73, 0.06);
  border: 1px solid rgba(248, 81, 73, 0.2);
}

.result-strengths h4 {
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  margin-bottom: 6px;
  color: var(--accent-green);
}

.result-weaknesses h4 {
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  margin-bottom: 6px;
  color: var(--accent-red);
}

.result-strengths p,
.result-weaknesses p {
  color: var(--text-secondary);
}

/* ---------- Result Buttons ---------- */
.result-buttons {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
  margin-top: 28px;
}

/* ---------- Responsive ---------- */
@media (max-width: 640px) {
  .app-container {
    padding: 12px;
  }

  .home-card {
    padding: 28px 20px;
    margin-top: 16px;
  }

  .home-card h1 {
    font-size: 22px;
  }

  .home-stats {
    flex-direction: column;
    align-items: center;
  }

  .home-filters {
    flex-direction: column;
    align-items: center;
  }

  .quiz-card {
    padding: 20px;
  }

  .quiz-question {
    font-size: 17px;
  }

  .result-card {
    padding: 24px 16px;
  }

  .result-stats {
    flex-direction: column;
    align-items: center;
  }

  .btn {
    padding: 10px 20px;
    font-size: 14px;
  }
}