/* ═══════════════════════════════════════════════════════════
   DryDive — App Shell & SPA Styles
   Aesthetic: deep ocean, dark navy, teal/amber accents
   ═══════════════════════════════════════════════════════════ */

/* ── AMBIENT GLOW ORB (behind header) ── */
.app-header::before {
  content: '';
  position: fixed;
  top: -80px;
  right: -100px;
  width: 360px;
  height: 360px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(0, 196, 167, 0.08) 0%, transparent 70%);
  pointer-events: none;
  z-index: -1;
}

/* ── APP HEADER ── */
.app-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  padding: 0.875rem 2rem;
  background: rgba(8, 28, 44, 0.92);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
}
.app-header-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 44px;
}
.app-header .wordmark {
  font-family: var(--font-display);
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--teal);
  text-decoration: none;
  letter-spacing: -0.02em;
  filter: drop-shadow(0 0 8px rgba(0, 196, 167, 0.4));
}

/* ── NAV ── */
.app-nav {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}
.app-nav a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.8rem;
  font-weight: 400;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 0.4rem 1rem;
  border-radius: 8px;
  border: 1px solid transparent;
  transition: all 0.25s ease;
}
.app-nav a:hover {
  color: var(--text);
  background: rgba(255, 255, 255, 0.06);
  border-color: var(--border);
}
.app-nav a.active {
  color: var(--teal);
  background: var(--teal-dim);
  border-color: rgba(0, 196, 167, 0.3);
}

/* ── HAMBURGER (mobile) ── */
.nav-hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 36px;
  height: 36px;
  background: none;
  border: 1px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
  padding: 8px;
  transition: border-color 0.2s;
}
.nav-hamburger:hover { border-color: var(--teal); }
.nav-hamburger span {
  display: block;
  height: 1.5px;
  background: var(--text-muted);
  border-radius: 2px;
  transition: all 0.25s ease;
}
.nav-hamburger.open span:nth-child(1) { transform: translateY(6.5px) rotate(45deg); }
.nav-hamburger.open span:nth-child(2) { opacity: 0; transform: scaleX(0); }
.nav-hamburger.open span:nth-child(3) { transform: translateY(-6.5px) rotate(-45deg); }

/* ── APP CONTAINER ── */
.app-container {
  max-width: 960px;
  margin: 0 auto;
  padding: 7rem 2rem 5rem;
  min-height: 100vh;
}

/* ── APP FOOTER ── */
.app-footer {
  border-top: 1px solid var(--border);
  padding: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.25rem;
  background: rgba(6, 19, 36, 0.5);
}
.app-footer .wordmark-sm {
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 700;
  color: var(--teal);
}
.app-footer .footer-tagline {
  font-size: 0.8rem;
  color: var(--text-dim);
  letter-spacing: 0.04em;
}
.app-footer::before {
  content: '';
  position: fixed;
  bottom: -60px;
  left: -60px;
  width: 280px;
  height: 280px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(245, 166, 35, 0.05) 0%, transparent 70%);
  pointer-events: none;
}

/* ══════════════════════════════════════
   HUB VIEW
   ══════════════════════════════════════ */

.hub-header {
  margin-bottom: 3rem;
}
.hub-header h1 {
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 4vw, 2.5rem);
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.02em;
  line-height: 1.15;
}
.hub-header p {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-top: 0.5rem;
}

/* Hub grid */
.hub-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  margin-bottom: 3rem;
}

/* Hub card base */
.hub-card {
  position: relative;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 2rem;
  cursor: pointer;
  transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  overflow: hidden;
}
.hub-card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: 18px;
  padding: 1px;
  background: linear-gradient(135deg, rgba(0, 196, 167, 0.3), transparent 60%);
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: destination-out;
  mask-composite: exclude;
  opacity: 0;
  transition: opacity 0.3s;
}
.hub-card:hover {
  transform: translateY(-4px);
  border-color: var(--teal);
  box-shadow:
    0 20px 40px rgba(0, 0, 0, 0.3),
    0 0 30px rgba(0, 196, 167, 0.08);
}
.hub-card:hover::before { opacity: 1; }

.co2-card:hover {
  border-color: var(--amber);
  box-shadow:
    0 20px 40px rgba(0, 0, 0, 0.3),
    0 0 30px rgba(245, 166, 35, 0.08);
}
.co2-card:hover::before {
  background: linear-gradient(135deg, rgba(245, 166, 35, 0.3), transparent 60%);
}

/* Card icon */
.card-icon {
  width: 52px;
  height: 52px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.5rem;
  position: relative;
}
.co2-card .card-icon { background: var(--amber-dim); }
.o2-card .card-icon { background: var(--teal-dim); }
.card-icon::after {
  content: '';
  position: absolute;
  inset: -1px;
  border-radius: 14px;
  background: linear-gradient(135deg, rgba(255,255,255,0.1), transparent);
  pointer-events: none;
}
.card-icon svg { display: block; }

/* Card tag */
.card-tag {
  display: inline-flex;
  align-items: center;
  font-size: 0.65rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  font-weight: 500;
  padding: 0.25rem 0.65rem;
  border-radius: 6px;
  margin-bottom: 0.875rem;
  border: 1px solid;
}
.co2-card .card-tag {
  color: var(--amber);
  border-color: rgba(245, 166, 35, 0.4);
  background: var(--amber-dim);
}
.o2-card .card-tag {
  color: var(--teal);
  border-color: rgba(0, 196, 167, 0.4);
  background: var(--teal-dim);
}

/* Card title */
.hub-card h2 {
  font-family: var(--font-display);
  font-size: 1.35rem;
  font-weight: 600;
  margin-bottom: 0.625rem;
  color: var(--text);
  letter-spacing: -0.01em;
}
.hub-card p {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.65;
}

/* Card footer stats */
.card-stats {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  margin-top: 1.5rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--border);
}
.stat {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}
.stat-label {
  font-size: 0.65rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-dim);
  font-weight: 500;
}
.stat-value {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 600;
}
.co2-card .stat-value { color: var(--amber); }
.o2-card .stat-value { color: var(--teal); }

/* Card CTA arrow */
.card-cta {
  position: absolute;
  bottom: 1.75rem;
  right: 1.75rem;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--border);
  color: var(--text-dim);
  transition: all 0.25s;
}
.hub-card:hover .card-cta {
  border-color: var(--teal);
  color: var(--teal);
  transform: translateX(3px);
}
.co2-card:hover .card-cta {
  border-color: var(--amber);
  color: var(--amber);
}

/* ── EXERCISE SECTION ── */
.exercise-section {
  margin-top: 2.5rem;
}
.exercise-section > h2 {
  font-family: var(--font-display);
  font-size: 1.6rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 1.5rem;
  letter-spacing: -0.01em;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}
.exercise-section > h2::before {
  content: '';
  display: block;
  width: 4px;
  height: 1.4em;
  background: var(--teal);
  border-radius: 2px;
  box-shadow: 0 0 8px rgba(0, 196, 167, 0.5);
}

.exercise-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1.25rem;
}

.exercise-card {
  position: relative;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 1.75rem;
  cursor: pointer;
  transition: all 0.25s ease;
  overflow: hidden;
}
.exercise-card::after {
  content: '';
  position: absolute;
  top: 0;
  right: 0;
  width: 80px;
  height: 80px;
  background: radial-gradient(circle at top right, rgba(0, 196, 167, 0.06), transparent 70%);
  pointer-events: none;
  transition: opacity 0.3s;
}
.exercise-card:hover {
  border-color: var(--teal);
  transform: translateY(-3px);
  box-shadow:
    0 12px 30px rgba(0, 0, 0, 0.25),
    0 0 20px rgba(0, 196, 167, 0.06);
}
.exercise-card:hover::after { opacity: 1.5; }

.ex-tag {
  display: inline-flex;
  align-items: center;
  font-size: 0.63rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--teal);
  border: 1px solid rgba(0, 196, 167, 0.4);
  background: var(--teal-dim);
  border-radius: 6px;
  padding: 0.2rem 0.55rem;
  margin-bottom: 0.875rem;
  font-weight: 500;
}
.exercise-card h3 {
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  color: var(--text);
}
.exercise-card p {
  font-size: 0.825rem;
  color: var(--text-muted);
  line-height: 1.6;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.exercise-card .ex-duration {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.75rem;
  color: var(--text-dim);
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
}
.exercise-card .ex-duration svg { color: var(--teal); }

/* ══════════════════════════════════════
   ONBOARDING (PB SETUP)
   ══════════════════════════════════════ */

.onboard-wrap {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: calc(100vh - 9rem);
  padding: 2rem 0;
}

.onboard-card {
  position: relative;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 24px;
  padding: 3.5rem;
  max-width: 580px;
  width: 100%;
  overflow: hidden;
}
/* Top-right glow */
.onboard-card::before {
  content: '';
  position: absolute;
  top: -60px;
  right: -60px;
  width: 220px;
  height: 220px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(0, 196, 167, 0.07) 0%, transparent 70%);
  pointer-events: none;
}

.onboard-eyebrow {
  font-size: 0.68rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--teal);
  font-weight: 500;
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.onboard-eyebrow::before {
  content: '';
  display: block;
  width: 20px;
  height: 1px;
  background: var(--teal);
  box-shadow: 0 0 6px rgba(0, 196, 167, 0.6);
}

.onboard-heading {
  font-family: var(--font-display);
  font-size: 2.2rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 0.75rem;
  letter-spacing: -0.02em;
  line-height: 1.2;
}
.onboard-sub {
  font-size: 0.95rem;
  color: var(--text-muted);
  line-height: 1.7;
  margin-bottom: 3rem;
}

/* PB fields */
.pb-fields { display: flex; flex-direction: column; gap: 2rem; margin-bottom: 2.5rem; }

.pb-field label {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 0.875rem;
  font-weight: 400;
  letter-spacing: 0.02em;
}

.label-tag {
  font-size: 0.63rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-weight: 600;
  padding: 0.25rem 0.55rem;
  border-radius: 6px;
  border: 1px solid;
}
.label-tag.co2 {
  color: var(--amber);
  border-color: rgba(245, 166, 35, 0.4);
  background: var(--amber-dim);
}
.label-tag.o2 {
  color: var(--teal);
  border-color: rgba(0, 196, 167, 0.4);
  background: var(--teal-dim);
}

.input-row {
  display: flex;
  align-items: center;
  gap: 1rem;
}

/* Styled inputs */
.styled-input {
  background: rgba(6, 19, 36, 0.6);
  border: 1px solid var(--border);
  border-radius: 12px;
  color: var(--text);
  font-family: var(--font-display);
  font-size: 2rem;
  font-weight: 700;
  padding: 0.875rem 1.25rem;
  width: 140px;
  text-align: center;
  outline: none;
  transition: all 0.25s ease;
  letter-spacing: -0.02em;
  caret-color: var(--teal);
}
.styled-input::placeholder { color: var(--text-dim); font-weight: 300; }
.styled-input:focus {
  border-color: var(--teal);
  box-shadow: 0 0 0 3px rgba(0, 196, 167, 0.12), 0 0 20px rgba(0, 196, 167, 0.1);
}
.co2-field .styled-input:focus {
  border-color: var(--amber);
  box-shadow: 0 0 0 3px rgba(245, 166, 35, 0.12), 0 0 20px rgba(245, 166, 35, 0.1);
}

.input-unit {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 400;
}

.pb-hint {
  font-size: 0.78rem;
  color: var(--text-dim);
  margin-top: 0.625rem;
  line-height: 1.5;
  padding-left: 0.25rem;
}

/* ── PRIMARY BUTTON ── */
.btn-primary {
  position: relative;
  background: var(--teal);
  color: var(--bg);
  border: none;
  border-radius: 12px;
  font-family: var(--font-body);
  font-size: 1.05rem;
  font-weight: 500;
  padding: 1rem 2rem;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.625rem;
  transition: all 0.25s ease;
  overflow: hidden;
  width: 100%;
  justify-content: center;
  letter-spacing: 0.01em;
}
.btn-primary::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(255,255,255,0.12), transparent 50%);
  pointer-events: none;
}
.btn-primary:hover {
  background: #00d9bf;
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(0, 196, 167, 0.35), 0 0 0 1px rgba(0, 196, 167, 0.2);
}
.btn-primary:active { transform: translateY(0); }
.btn-primary .btn-arrow { transition: transform 0.2s; }
.btn-primary:hover .btn-arrow { transform: translateX(4px); }

/* ── INFO NOTE ── */
.onboard-note {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  font-size: 0.78rem;
  color: var(--text-dim);
  margin-top: 1.75rem;
  line-height: 1.55;
  padding: 1rem 1.25rem;
  background: rgba(0, 196, 167, 0.04);
  border: 1px solid rgba(0, 196, 167, 0.1);
  border-radius: 10px;
}
.onboard-note svg { flex-shrink: 0; margin-top: 1px; color: var(--teal); }

/* ══════════════════════════════════════
   TIMER VIEW
   ══════════════════════════════════════ */

.timer-wrap {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  position: relative;
}

/* Ambient glow behind timer */
.timer-wrap::before {
  content: '';
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -60%);
  width: 500px;
  height: 500px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(0, 196, 167, 0.04) 0%, transparent 65%);
  pointer-events: none;
  z-index: -1;
}

.timer-nav {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 3rem;
  align-self: flex-start;
  max-width: 960px;
  width: 100%;
  padding: 0 2rem;
}
.timer-nav a {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.825rem;
  transition: color 0.2s;
}
.timer-nav a:hover { color: var(--teal); }
.timer-nav .sep { color: var(--text-dim); }
.timer-nav .view-title {
  margin-left: auto;
  font-family: var(--font-display);
  font-size: 0.95rem;
  color: var(--text-dim);
  font-weight: 600;
  letter-spacing: -0.01em;
}

.timer-type-label {
  font-size: 0.68rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  font-weight: 500;
  padding: 0.3rem 0.85rem;
  border-radius: 6px;
  display: inline-block;
  margin-bottom: 1.25rem;
  border: 1px solid;
}
.timer-type-label.co2 {
  color: var(--amber);
  border-color: rgba(245, 166, 35, 0.4);
  background: var(--amber-dim);
}
.timer-type-label.o2 {
  color: var(--teal);
  border-color: rgba(0, 196, 167, 0.4);
  background: var(--teal-dim);
}

.timer-phase {
  font-size: 0.8rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 2rem;
}

/* Timer circle */
.timer-circle-wrap {
  position: relative;
  display: inline-block;
  margin-bottom: 2rem;
}

.timer-circle {
  width: 300px;
  height: 300px;
  border-radius: 50%;
  border: 2px solid var(--border);
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-card);
  transition: all 0.4s ease;
}
.timer-circle.active {
  border-color: var(--teal);
  box-shadow:
    0 0 0 1px rgba(0, 196, 167, 0.2),
    0 0 60px rgba(0, 196, 167, 0.15),
    inset 0 0 40px rgba(0, 196, 167, 0.04);
}
.timer-circle.rest {
  border-color: var(--amber);
  box-shadow:
    0 0 0 1px rgba(245, 166, 35, 0.2),
    0 0 60px rgba(245, 166, 35, 0.12),
    inset 0 0 40px rgba(245, 166, 35, 0.03);
}

/* Animated progress ring */
.progress-ring {
  position: absolute;
  inset: -3px;
  border-radius: 50%;
  transition: background 0.3s;
}
.progress-ring.rest { background: conic-gradient(var(--amber) 0deg, transparent 0deg); }

/* Timer inner */
.timer-inner {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
}
.timer-time {
  font-family: var(--font-display);
  font-size: 4rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.04em;
  line-height: 1;
}
.timer-time.co2 { color: var(--amber); }
.timer-time.o2 { color: var(--teal); }
.timer-sublabel {
  font-size: 0.73rem;
  color: var(--text-dim);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

/* Controls */
.timer-controls {
  display: flex;
  gap: 1rem;
  margin-bottom: 2.5rem;
}
.btn-timer {
  border-radius: 12px;
  font-family: var(--font-body);
  font-size: 0.95rem;
  font-weight: 500;
  padding: 0.8rem 2rem;
  cursor: pointer;
  border: 1px solid;
  transition: all 0.25s ease;
  letter-spacing: 0.01em;
}
.btn-start {
  background: var(--teal);
  color: var(--bg);
  border-color: var(--teal);
  box-shadow: 0 4px 15px rgba(0, 196, 167, 0.25);
}
.btn-start:hover {
  background: #00d9bf;
  box-shadow: 0 6px 20px rgba(0, 196, 167, 0.4);
  transform: translateY(-1px);
}
.btn-start:active { transform: translateY(0); }
.btn-pause {
  background: var(--bg-alt);
  color: var(--text);
  border-color: var(--border);
}
.btn-pause:hover {
  border-color: var(--teal);
  color: var(--teal);
}
.btn-reset {
  background: transparent;
  color: var(--text-muted);
  border-color: var(--border);
}
.btn-reset:hover {
  color: var(--text);
  border-color: var(--text-muted);
}

/* Timer table */
.timer-table {
  width: 100%;
  max-width: 500px;
  margin-top: 2rem;
}
.timer-table table {
  width: 100%;
  border-collapse: collapse;
}
.timer-table th {
  font-size: 0.63rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-dim);
  text-align: left;
  padding: 0.75rem 1.25rem;
  border-bottom: 1px solid var(--border);
  font-weight: 500;
}
.timer-table td {
  font-size: 0.875rem;
  color: var(--text-muted);
  padding: 0.7rem 1.25rem;
  border-bottom: 1px solid rgba(0, 196, 167, 0.06);
  font-family: var(--font-body);
  font-weight: 400;
}
.timer-table td:first-child {
  color: var(--text-dim);
  font-size: 0.8rem;
  width: 60px;
}
.timer-table td.hold { color: var(--amber); font-weight: 500; }
.timer-table td.rest { color: var(--teal); font-weight: 500; }
.timer-table tr.current td {
  color: var(--text);
  background: rgba(0, 196, 167, 0.06);
  border-radius: 8px;
}
.timer-table tr.current td.hold { color: var(--amber); }
.timer-table tr.current td.rest { color: var(--teal); }

/* Table complete screen */
.table-complete {
  text-align: center;
  padding: 3rem 0;
}
.table-complete-icon {
  font-size: 4rem;
  margin-bottom: 1.5rem;
  display: block;
  filter: drop-shadow(0 0 20px rgba(0, 196, 167, 0.4));
}
.table-complete h2 {
  font-family: var(--font-display);
  font-size: 2rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 0.625rem;
  letter-spacing: -0.02em;
}
.table-complete p {
  color: var(--text-muted);
  margin-bottom: 2.5rem;
  font-size: 0.95rem;
}
.complete-actions { display: flex; gap: 1rem; justify-content: center; }

/* ══════════════════════════════════════
   EXERCISE VIEW
   ══════════════════════════════════════ */

.exercise-view {
  max-width: 640px;
  margin: 0 auto;
}
.exercise-view .back-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.825rem;
  margin-bottom: 2.5rem;
  transition: color 0.2s;
  padding: 0.4rem 0.75rem;
  border-radius: 8px;
  border: 1px solid transparent;
}
.exercise-view .back-btn:hover {
  color: var(--teal);
  background: var(--teal-dim);
  border-color: rgba(0, 196, 167, 0.2);
}

.exercise-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  margin-bottom: 1.75rem;
}
.exercise-title {
  font-family: var(--font-display);
  font-size: 2.25rem;
  font-weight: 600;
  color: var(--text);
  letter-spacing: -0.02em;
  line-height: 1.2;
}
.exercise-meta {
  font-size: 0.8rem;
  color: var(--text-dim);
  margin-top: 0.5rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.exercise-description {
  font-size: 0.95rem;
  color: var(--text-muted);
  line-height: 1.75;
  margin-bottom: 2rem;
}

/* Steps card */
.ex-steps {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 2rem;
  margin-bottom: 1.75rem;
  position: relative;
  overflow: hidden;
}
.ex-steps::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--teal), transparent);
  opacity: 0.4;
}
.ex-steps h3 {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 1.5rem;
}
.ex-steps ol {
  padding-left: 1.75rem;
  counter-reset: steps;
}
.ex-steps li {
  font-size: 0.95rem;
  color: var(--text-muted);
  line-height: 1.7;
  margin-bottom: 0.875rem;
  counter-increment: steps;
  position: relative;
  padding-left: 0.5rem;
}
.ex-steps li::marker {
  color: var(--teal);
  font-weight: 600;
}

/* Exercise timer card */
.ex-timer {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 2.5rem 2rem;
  text-align: center;
  margin-bottom: 1.75rem;
  position: relative;
}
.ex-timer::before {
  content: '';
  position: absolute;
  inset: -1px;
  border-radius: 16px;
  background: conic-gradient(from 180deg, var(--teal), var(--amber), transparent 60%);
  opacity: 0.15;
  z-index: -1;
}
.ex-timer-display {
  font-family: var(--font-display);
  font-size: 3.5rem;
  font-weight: 700;
  color: var(--teal);
  margin-bottom: 0.5rem;
  letter-spacing: -0.04em;
  line-height: 1;
  transition: color 0.3s;
}
.ex-timer-label {
  font-size: 0.78rem;
  color: var(--text-dim);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

/* Exercise start button */
.btn-ex-start {
  width: 100%;
  background: var(--teal);
  color: var(--bg);
  border: none;
  border-radius: 14px;
  font-family: var(--font-body);
  font-size: 1.05rem;
  font-weight: 500;
  padding: 1.125rem;
  cursor: pointer;
  transition: all 0.25s ease;
  letter-spacing: 0.01em;
  position: relative;
  overflow: hidden;
}
.btn-ex-start::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(255,255,255,0.12), transparent 50%);
  pointer-events: none;
}
.btn-ex-start:hover {
  background: #00d9bf;
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(0, 196, 167, 0.35);
}
.btn-ex-start:active { transform: translateY(0); }

/* ── LOADING ── */
.loading {
  text-align: center;
  padding: 5rem 0;
  color: var(--text-muted);
  font-size: 1rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
}
.loading::after {
  content: '';
  width: 40px;
  height: 40px;
  border: 2px solid var(--border);
  border-top-color: var(--teal);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ── RESPONSIVE ── */
@media (max-width: 768px) {
  .app-container { padding: 6rem 1.5rem 4rem; }

  .app-nav {
    display: none;
    position: fixed;
    top: 60px;
    left: 1rem;
    right: 1rem;
    background: rgba(8, 28, 44, 0.98);
    backdrop-filter: blur(16px);
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 1rem;
    flex-direction: column;
    gap: 0.25rem;
    z-index: 99;
    box-shadow: 0 20px 40px rgba(0,0,0,0.4);
  }
  .app-nav.open { display: flex; }
  .app-nav a { padding: 0.75rem 1rem; text-align: center; }

  .nav-hamburger { display: flex; }

  .hub-grid { grid-template-columns: 1fr; }
  .exercise-grid { grid-template-columns: 1fr; }

  .onboard-card { padding: 2.5rem 1.75rem; }
  .onboard-heading { font-size: 1.75rem; }
  .styled-input { font-size: 1.5rem; width: 120px; }

  .timer-circle { width: 240px; height: 240px; }
  .timer-time { font-size: 3rem; }
  .timer-nav { padding: 0 0; }
  .timer-nav .view-title { display: none; }
  .timer-table { max-width: 100%; }

  .exercise-title { font-size: 1.75rem; }
}

@media (max-width: 480px) {
  .timer-circle { width: 200px; height: 200px; }
  .timer-time { font-size: 2.5rem; }
  .btn-timer { padding: 0.7rem 1.5rem; font-size: 0.9rem; }
  .hub-card { padding: 1.75rem 1.5rem; }
}