:root {
  color-scheme: light;

  --bg: #f5f5f7;
  --bg-soft: #eef0f5;
  --bg-elevated: #ffffff;
  --border-subtle: rgba(15, 23, 42, 0.08);
  --text: #0f172a;
  --text-muted: #64748b;
  --accent: #2563eb;
  --accent-soft: rgba(37, 99, 235, 0.1);
  --accent-strong: #1d4ed8;
  --danger: #e11d48;
  --success: #16a34a;
  --shadow-soft: 0 18px 45px rgba(15, 23, 42, 0.12);
  --radius-lg: 1.1rem;
  --radius-md: 0.75rem;
  --radius-pill: 999px;
  --transition-fast: 150ms ease-out;
  --transition-med: 220ms ease-out;
}

:root[data-theme="dark"] {
  color-scheme: dark;

  --bg: #020617;
  --bg-soft: #020617;
  --bg-elevated: rgba(15, 23, 42, 0.95);
  --border-subtle: rgba(148, 163, 184, 0.25);
  --text: #e5e7eb;
  --text-muted: #94a3b8;
  --accent: #38bdf8;
  --accent-soft: rgba(56, 189, 248, 0.18);
  --accent-strong: #0ea5e9;
  --danger: #fb7185;
  --success: #22c55e;
  --shadow-soft: 0 24px 60px rgba(15, 23, 42, 0.9);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
}

body {
  min-height: 100vh;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;
  background:
    radial-gradient(circle at top left, rgba(56, 189, 248, 0.16), transparent 55%),
    radial-gradient(circle at bottom right, rgba(129, 140, 248, 0.2), transparent 55%),
    var(--bg);
  color: var(--text);
  display: flex;
  justify-content: center;
  align-items: stretch;
}

/* Layout */

.app-shell {
  width: 100%;
  max-width: 1040px;
  margin: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

@media (max-width: 640px) {
  .app-shell {
    margin: 0.75rem;
  }
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.9rem 1.2rem;
  border-radius: var(--radius-lg);
  background: linear-gradient(
      120deg,
      rgba(248, 250, 252, 0.35),
      rgba(248, 250, 252, 0.08)
    );
  backdrop-filter: blur(20px);
  border: 1px solid rgba(148, 163, 184, 0.3);
  box-shadow: var(--shadow-soft);
}

:root[data-theme="dark"] .topbar {
  background: linear-gradient(
      130deg,
      rgba(15, 23, 42, 0.9),
      rgba(15, 23, 42, 0.7)
    );
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  font-weight: 600;
  letter-spacing: 0.02em;
}

.brand-logo {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.65rem;
  height: 1.65rem;
  border-radius: 0.4rem;
  background: var(--accent-soft);
  color: var(--accent-strong);
  font-size: 1rem;
}

.brand-text {
  font-size: 0.97rem;
}

.theme-toggle {
  border-radius: var(--radius-pill);
  border: 1px solid var(--border-subtle);
  background: rgba(248, 250, 252, 0.85);
  padding: 0.4rem 0.85rem;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  cursor: pointer;
  font-size: 0.8rem;
  color: var(--text-muted);
  transition: background var(--transition-fast), transform var(--transition-fast),
    box-shadow var(--transition-fast), border-color var(--transition-fast);
  box-shadow: 0 10px 25px rgba(15, 23, 42, 0.12);
}

:root[data-theme="dark"] .theme-toggle {
  background: rgba(15, 23, 42, 0.9);
}

.theme-toggle:hover {
  transform: translateY(-1px);
  box-shadow: 0 14px 32px rgba(15, 23, 42, 0.16);
  border-color: rgba(148, 163, 184, 0.6);
}

.theme-toggle-icon {
  font-size: 1rem;
}

/* Main content */

.content {
  flex: 1;
}

.view {
  display: none;
}

.view.active {
  display: block;
}

.card {
  border-radius: var(--radius-lg);
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  box-shadow: var(--shadow-soft);
  padding: 1.6rem 1.8rem;
}

.card-large {
  padding: 2rem 2.1rem;
}

.card-main {
  min-height: 320px;
}

.card-side {
  min-width: 220px;
}

/* Text */

h1 {
  margin: 0 0 0.5rem;
  font-size: clamp(1.5rem, 1.4rem + 0.8vw, 2rem);
}

h2 {
  margin: 0 0 0.75rem;
  font-size: 1.05rem;
}

.lead {
  margin: 0 0 1.4rem;
  color: var(--text-muted);
  font-size: 0.95rem;
  max-width: 36rem;
}

/* Form */

.form {
  display: flex;
  flex-direction: column;
  gap: 1.4rem;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}

.field label {
  font-size: 0.88rem;
  font-weight: 500;
}

input[type="text"],
input[type="number"],
input:not([type]),
select {
  border-radius: 0.75rem;
  border: 1px solid var(--border-subtle);
  padding: 0.55rem 0.85rem;
  font-size: 0.95rem;
  background: rgba(248, 250, 252, 0.92);
  color: var(--text);
  outline: none;
  transition: border-color var(--transition-fast),
    box-shadow var(--transition-fast), background var(--transition-fast),
    transform var(--transition-fast);
}

:root[data-theme="dark"] input,
:root[data-theme="dark"] select {
  background: rgba(15, 23, 42, 0.96);
}

input:focus,
select:focus {
  border-color: var(--accent-strong);
  box-shadow: 0 0 0 1px rgba(37, 99, 235, 0.4);
  transform: translateY(-0.5px);
}

select {
  appearance: none;
  background-image: linear-gradient(45deg, transparent 50%, var(--text-muted) 50%),
    linear-gradient(135deg, var(--text-muted) 50%, transparent 50%);
  background-position:
    calc(100% - 14px) calc(50% - 2px),
    calc(100% - 10px) calc(50% - 2px);
  background-size: 6px 6px, 6px 6px;
  background-repeat: no-repeat;
}

.help {
  margin: 0;
  font-size: 0.8rem;
  color: var(--text-muted);
}

.fieldset {
  border-radius: 1rem;
  border: 1px dashed rgba(148, 163, 184, 0.7);
  padding: 1rem 1.1rem 1.1rem;
}

.fieldset legend {
  padding: 0 0.4rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-muted);
}

.field-grid {
  display: grid;
  gap: 0.9rem;
}

@media (min-width: 640px) {
  .field-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

.form-error {
  margin-top: 0.25rem;
  font-size: 0.85rem;
  color: var(--danger);
  min-height: 1.1rem;
}

/* Buttons */

.button {
  border-radius: var(--radius-pill);
  border: none;
  padding: 0.6rem 1.3rem;
  font-size: 0.92rem;
  font-weight: 500;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  background: var(--bg-soft);
  color: var(--text);
  transition: background var(--transition-med), transform var(--transition-fast),
    box-shadow var(--transition-fast), border-color var(--transition-fast);
  box-shadow: 0 12px 30px rgba(15, 23, 42, 0.16);
}

.button.primary {
  background: linear-gradient(
    135deg,
    var(--accent),
    var(--accent-strong)
  );
  color: #f9fafb;
}

.button.ghost {
  background: transparent;
  border: 1px solid var(--border-subtle);
  box-shadow: none;
}

.button:hover {
  transform: translateY(-1px);
  box-shadow: 0 16px 36px rgba(15, 23, 42, 0.22);
}

.button:active {
  transform: translateY(0);
  box-shadow: 0 8px 20px rgba(15, 23, 42, 0.2);
}

/* Trainer layout */

.layout-two {
  display: flex;
  flex-direction: column;
  gap: 1.1rem;
}

@media (min-width: 800px) {
  .layout-two {
    display: grid;
    grid-template-columns: minmax(0, 2.2fr) minmax(0, 1fr);
    align-items: flex-start;
  }
}

.session-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1.2rem;
}

.session-label {
  font-size: 0.9rem;
  font-weight: 600;
}

.session-sub {
  margin-top: 0.25rem;
  font-size: 0.8rem;
  color: var(--text-muted);
}

.session-meta {
  display: flex;
  gap: 0.4rem;
  align-items: center;
}

.badge {
  border-radius: var(--radius-pill);
  padding: 0.25rem 0.75rem;
  font-size: 0.8rem;
  font-weight: 500;
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
}

.badge.time {
  background: var(--accent-soft);
  color: var(--accent-strong);
}

.badge.score {
  background: rgba(34, 197, 94, 0.08);
  color: var(--success);
}

/* Question */

.question-block {
  border-radius: 1rem;
  padding: 1.2rem 1rem;
  margin-bottom: 1.1rem;
  background: radial-gradient(
      circle at top left,
      rgba(56, 189, 248, 0.18),
      transparent 55%
    ),
    radial-gradient(
      circle at bottom right,
      rgba(129, 140, 248, 0.2),
      transparent 55%
    ),
    var(--bg-soft);
  border: 1px solid rgba(148, 163, 184, 0.4);
}

.question-label {
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  margin-bottom: 0.4rem;
}

.question-text {
  font-size: 1.6rem;
  font-weight: 600;
}

/* Answer form */

.answer-form {
  display: flex;
  gap: 0.5rem;
  align-items: stretch;
}

.answer-form input {
  flex: 1;
}

.feedback {
  margin-top: 0.7rem;
  min-height: 1.3rem;
  font-size: 0.9rem;
  color: var(--text-muted);
}

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

.feedback.feedback-wrong {
  color: var(--danger);
}

/* Side card */

.stats {
  list-style: none;
  margin: 0 0 1rem;
  padding: 0;
  font-size: 0.9rem;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

/* Summary */

.summary-grid {
  display: grid;
  gap: 0.9rem;
  margin-top: 1rem;
}

@media (min-width: 640px) {
  .summary-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

.summary-item {
  padding: 0.85rem 0.9rem;
  border-radius: 0.9rem;
  background: var(--bg-soft);
  border: 1px solid rgba(148, 163, 184, 0.5);
}

.summary-label {
  display: block;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 0.2rem;
}

.summary-value {
  font-size: 1.15rem;
  font-weight: 600;
}

.summary-actions {
  margin-top: 1.4rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
}

/* Footer */

.footer {
  font-size: 0.78rem;
  color: var(--text-muted);
  text-align: center;
  padding-bottom: 0.5rem;
}

/* Utilities */

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