*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --primary: #009999;
  --primary-dark: #007a7a;
  --bg: #f5f7f8;
  --card-bg: #ffffff;
  --text: #1a1a1a;
  --text-muted: #666;
  --warning: #d94a00;
  --warning-bg: #fff3ed;
  --note-bg: #eef9f9;
  --radius: 16px;
}

html {
  font-size: 16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100dvh;
  display: flex;
  justify-content: center;
}

.app {
  width: 100%;
  max-width: 480px;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
}

/* Header */
.header {
  padding: 20px 20px 12px;
  background: var(--primary);
  color: white;
}

.header h1 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 14px;
  letter-spacing: -0.01em;
}

.progress-bar {
  height: 6px;
  background: rgba(255, 255, 255, 0.25);
  border-radius: 3px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: white;
  border-radius: 3px;
  transition: width 0.4s ease;
  width: 0%;
}

.progress-text {
  font-size: 0.8rem;
  margin-top: 6px;
  opacity: 0.85;
}

/* Step container */
.step-container {
  flex: 1;
  padding: 20px;
  display: flex;
  align-items: flex-start;
}

.step-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 28px 24px;
  width: 100%;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.06);
  transition: opacity 0.25s ease, transform 0.25s ease;
}

.step-card.fade-out {
  opacity: 0;
  transform: translateY(8px);
}

.step-card.fade-in {
  opacity: 0;
  transform: translateY(-8px);
}

/* Step icon */
.step-icon {
  width: 52px;
  height: 52px;
  border-radius: 14px;
  background: var(--note-bg);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 18px;
  font-size: 1.6rem;
}

/* Step content */
.step-title {
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 12px;
  letter-spacing: -0.01em;
}

.step-content {
  font-size: 1.05rem;
  line-height: 1.6;
  color: var(--text);
  white-space: pre-line;
}

/* Warning box */
.step-warning {
  margin-top: 16px;
  padding: 14px 16px;
  background: var(--warning-bg);
  border-left: 4px solid var(--warning);
  border-radius: 8px;
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--warning);
  line-height: 1.5;
}

/* Note box */
.step-note {
  margin-top: 16px;
  padding: 14px 16px;
  background: var(--note-bg);
  border-left: 4px solid var(--primary);
  border-radius: 8px;
  font-size: 0.95rem;
  color: var(--primary-dark);
  line-height: 1.5;
}

/* Checkbox */
.step-check {
  margin-top: 20px;
}

.checkbox-label {
  display: flex;
  align-items: center;
  gap: 12px;
  cursor: pointer;
  font-size: 1rem;
  font-weight: 500;
  user-select: none;
  -webkit-user-select: none;
}

.checkbox-label input[type="checkbox"] {
  display: none;
}

.checkmark {
  width: 26px;
  height: 26px;
  border: 2px solid #ccc;
  border-radius: 6px;
  flex-shrink: 0;
  position: relative;
  transition: all 0.2s ease;
}

.checkbox-label input:checked ~ .checkmark {
  background: var(--primary);
  border-color: var(--primary);
}

.checkbox-label input:checked ~ .checkmark::after {
  content: "";
  position: absolute;
  left: 8px;
  top: 4px;
  width: 6px;
  height: 12px;
  border: solid white;
  border-width: 0 2.5px 2.5px 0;
  transform: rotate(45deg);
}

/* Navigation buttons */
.nav-buttons {
  padding: 16px 20px 28px;
  display: flex;
  gap: 12px;
}

.btn {
  flex: 1;
  padding: 16px 20px;
  border: none;
  border-radius: 12px;
  font-size: 1.05rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s ease, opacity 0.2s ease, transform 0.1s ease;
  -webkit-tap-highlight-color: transparent;
}

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

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

.btn-next:hover {
  background: var(--primary-dark);
}

.btn-next:disabled {
  opacity: 0.4;
  cursor: not-allowed;
  transform: none;
}

.btn-back {
  background: #e8eaeb;
  color: var(--text);
}

.btn-back:hover {
  background: #dcdfe0;
}

.hidden {
  display: none !important;
}

/* Completion screen tweak */
.step-card .completion-icon {
  font-size: 3rem;
  text-align: center;
  margin-bottom: 8px;
}