/* ============================================================
 * How It Works Section
 * 책임: Codex
 * 작업 명세: docs/HANDOFF.md → H-003 · How It Works Section
 * ============================================================ */

.how-it-works {
  padding-block: var(--space-12);
  border-block: calc(var(--space-1) / 4) solid var(--color-bg-muted);
  background-color: var(--color-bg-soft);
}

.how-it-works__inner {
  display: grid;
  gap: var(--space-12);
}

.how-it-works__header {
  display: grid;
  justify-items: center;
  text-align: center;
}

.how-it-works__badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  margin-block-end: var(--space-6);
  padding: var(--space-2) var(--space-3);
  border: calc(var(--space-1) / 4) solid var(--color-bg-muted);
  border-radius: var(--radius-full);
  background-color: var(--color-bg);
  color: var(--color-text-sub);
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-semibold);
  line-height: var(--line-height-tight);
}

.how-it-works__badge-dot {
  inline-size: calc(var(--space-1) + var(--space-1));
  block-size: calc(var(--space-1) + var(--space-1));
  border-radius: var(--radius-full);
  background-color: var(--color-brand-500);
}

.how-it-works__title {
  margin-block-end: var(--space-4);
  color: var(--color-text);
  font-size: var(--font-size-3xl);
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
}

.how-it-works__subtitle {
  color: var(--color-text-sub);
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-medium);
  line-height: var(--line-height-normal);
}

.how-it-works__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-4);
  margin: 0;
  padding: 0;
  list-style: none;
}

.how-it-works__card {
  display: flex;
  flex-direction: column;
  padding: var(--space-6);
  border: calc(var(--space-1) / 4) solid var(--color-bg-muted);
  border-radius: var(--radius-xl);
  background-color: var(--color-bg);
  transition:
    border-color var(--duration-normal) var(--ease-out),
    box-shadow var(--duration-normal) var(--ease-out),
    transform var(--duration-normal) var(--ease-out);
}

.how-it-works__card-number {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  margin-block-end: var(--space-3);
  color: var(--color-brand-500);
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
  letter-spacing: 0;
}

.how-it-works__card-number::after {
  content: "";
  flex: 1;
  block-size: calc(var(--space-1) / 4);
  background: linear-gradient(to right, var(--color-brand-50), transparent);
}

.how-it-works__card-title {
  margin-block-end: var(--space-3);
  color: var(--color-text);
  font-size: var(--font-size-xl);
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-snug);
}

.how-it-works__card-desc {
  margin-block-end: var(--space-8);
  color: var(--color-text-sub);
  font-size: var(--font-size-md);
  font-weight: var(--font-weight-medium);
  line-height: var(--line-height-relaxed);
}

.how-it-works__card-visual {
  display: grid;
  place-items: center;
  margin-block-start: auto;
  padding-block-start: var(--space-2);
}

.how-it-works__phone {
  inline-size: 220px; /* mini phone width — illustration geometry */
  block-size: 440px; /* mini phone height — illustration geometry */
  padding: 7px; /* mini phone bezel padding — illustration geometry */
  border-radius: 32px; /* mini phone bezel radius — illustration geometry */
  background-color: var(--color-text);
  box-shadow: var(--shadow-lg);
}

.how-it-works__phone-screen {
  position: relative;
  display: flex;
  flex-direction: column;
  inline-size: 100%;
  block-size: 100%;
  overflow: hidden;
  border-radius: 26px; /* mini screen radius — illustration geometry */
  background-color: var(--color-bg-soft);
}

.how-it-works__phone-notch {
  position: absolute;
  inset-block-start: 6px; /* mini notch top offset — illustration geometry */
  inset-inline-start: 50%;
  z-index: var(--z-base);
  inline-size: 64px; /* mini notch width — illustration geometry */
  block-size: 18px; /* mini notch height — illustration geometry */
  border-radius: 999px; /* mini notch pill radius — illustration geometry */
  background-color: var(--color-text);
  transform: translateX(-50%);
}

.how-it-works__mini-status {
  display: flex;
  align-items: center;
  justify-content: space-between;
  block-size: 32px; /* mini status bar height — illustration geometry */
  padding-inline: 16px; /* mini status side padding — illustration geometry */
  color: var(--color-text);
  font-size: 10px; /* mini status time size — illustration geometry */
  font-weight: var(--font-weight-bold);
}

.how-it-works__mini-icons {
  display: flex;
  align-items: center;
  gap: 3px; /* mini status icon gap — illustration geometry */
  color: var(--color-text);
}

.how-it-works__mini-signal {
  inline-size: 11px; /* mini signal icon width — illustration geometry */
  block-size: 7px; /* mini signal icon height — illustration geometry */
}

.how-it-works__mini-battery {
  inline-size: 16px; /* mini battery icon width — illustration geometry */
  block-size: 7px; /* mini battery icon height — illustration geometry */
}

.how-it-works__mini-app-header {
  display: grid;
  grid-template-columns: 20px 1fr 20px; /* mini app header side slots — illustration geometry */
  align-items: center;
  padding: 4px 14px 10px; /* mini app header padding — illustration geometry */
}

.how-it-works__mini-app-back {
  display: grid;
  place-items: center;
  inline-size: 20px; /* mini back button width — illustration geometry */
  block-size: 20px; /* mini back button height — illustration geometry */
  color: var(--color-text-sub);
}

.how-it-works__mini-chevron {
  inline-size: 14px; /* mini back chevron width — illustration geometry */
  block-size: 14px; /* mini back chevron height — illustration geometry */
}

.how-it-works__mini-app-title {
  color: var(--color-text);
  font-size: 12px; /* mini app title size — illustration geometry */
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
  text-align: center;
}

.how-it-works__mini-body {
  display: flex;
  flex: 1;
  flex-direction: column;
  gap: 8px; /* mini screen body gap — illustration geometry */
  overflow: hidden;
  padding: 4px 12px 12px; /* mini screen body padding — illustration geometry */
}

.how-it-works__upload-frame {
  display: flex;
  flex: 1;
  flex-direction: column;
  padding: 12px; /* upload frame padding — illustration geometry */
  border-radius: 14px; /* upload frame radius — illustration geometry */
  background-color: var(--color-bg);
}

.how-it-works__upload-drop {
  display: flex;
  flex: 1;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 10px; /* upload drop content gap — illustration geometry */
  padding: 18px 14px; /* upload drop padding — illustration geometry */
  border: 1.5px dashed var(--color-border-strong); /* upload dashed border — illustration geometry */
  border-radius: 12px; /* upload drop radius — illustration geometry */
  background-color: var(--color-bg-soft);
  text-align: center;
}

.how-it-works__upload-camera {
  display: grid;
  place-items: center;
  inline-size: 44px; /* upload camera circle width — illustration geometry */
  block-size: 44px; /* upload camera circle height — illustration geometry */
  border-radius: 50%; /* upload camera circle radius — illustration geometry */
  background-color: var(--color-brand-50);
  color: var(--color-brand-600);
}

.how-it-works__upload-camera-icon {
  inline-size: 22px; /* upload camera icon width — illustration geometry */
  block-size: 22px; /* upload camera icon height — illustration geometry */
}

.how-it-works__upload-hint {
  color: var(--color-text-sub);
  font-size: 11px; /* upload hint size — illustration geometry */
  font-weight: var(--font-weight-medium);
  line-height: 1.45; /* upload hint line-height — illustration geometry */
}

.how-it-works__upload-hint-title {
  display: block;
  margin-block-end: 4px; /* upload hint title bottom gap — illustration geometry */
  color: var(--color-text);
  font-size: 12px; /* upload hint title size — illustration geometry */
  font-weight: var(--font-weight-bold);
}

.how-it-works__upload-thumbs {
  display: flex;
  gap: 6px; /* upload thumb gap — illustration geometry */
  margin-block-start: 12px; /* upload thumb top gap — illustration geometry */
}

.how-it-works__upload-thumb {
  display: grid;
  flex: 1;
  place-items: center;
  block-size: 36px; /* upload thumb height — illustration geometry */
  border: 1px solid var(--color-bg-muted); /* upload thumb border — illustration geometry */
  border-radius: 8px; /* upload thumb radius — illustration geometry */
  background-color: var(--color-bg-soft);
  color: var(--color-text-mute);
  font-size: 11px; /* upload thumb text size — illustration geometry */
  font-style: italic;
  font-weight: var(--font-weight-medium);
  font-family: var(--font-serif);
}

.how-it-works__upload-thumb--active {
  border-color: var(--color-brand-500);
  background-color: var(--color-bg);
  box-shadow: 0 0 0 3px var(--color-brand-50); /* upload active glow — illustration geometry */
  color: var(--color-text);
}

.how-it-works__mini-button {
  display: grid;
  place-items: center;
  margin-block-start: 10px; /* mini CTA top gap — illustration geometry */
  padding: 10px; /* mini CTA padding — illustration geometry */
  border-radius: 10px; /* mini CTA radius — illustration geometry */
  background-color: var(--color-brand-500);
  color: var(--color-text-on-brand);
  font-size: 12px; /* mini CTA text size — illustration geometry */
  font-weight: var(--font-weight-bold);
}

.how-it-works__summary-card,
.how-it-works__solution-card,
.how-it-works__ai-bubble,
.how-it-works__practice-head,
.how-it-works__practice-item {
  background-color: var(--color-bg);
}

.how-it-works__summary-card {
  padding: 12px; /* summary card padding — illustration geometry */
  border-radius: 14px; /* summary card radius — illustration geometry */
}

.how-it-works__summary-title {
  margin-block-end: 8px; /* summary title bottom gap — illustration geometry */
  color: var(--color-text);
  font-size: 11px; /* summary title size — illustration geometry */
  font-weight: var(--font-weight-bold);
}

.how-it-works__analysis-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 4px; /* analysis tag gap — illustration geometry */
}

.how-it-works__analysis-tag {
  padding: 3px 8px; /* analysis tag padding — illustration geometry */
  border-radius: 6px; /* analysis tag radius — illustration geometry */
  background-color: var(--color-bg-soft);
  color: var(--color-text);
  font-size: 10px; /* analysis tag size — illustration geometry */
  font-weight: var(--font-weight-semibold);
}

.how-it-works__solution-card {
  padding: 12px; /* solution card padding — illustration geometry */
  border-radius: 14px; /* solution card radius — illustration geometry */
}

.how-it-works__solution-label {
  margin-block-end: 6px; /* solution label bottom gap — illustration geometry */
  color: var(--color-text-mute);
  font-size: 9px; /* solution label size — illustration geometry */
  font-weight: var(--font-weight-semibold);
}

.how-it-works__solution-formula {
  color: var(--color-text);
  font-family: var(--font-serif);
  font-size: 11px; /* solution formula size — illustration geometry */
  font-style: italic;
  line-height: 1.7; /* solution formula line-height — illustration geometry */
}

.how-it-works__solution-power {
  font-size: 8px; /* solution exponent size — illustration geometry */
}

.how-it-works__solution-error {
  position: relative;
  padding-inline: 2px; /* solution error inline padding — illustration geometry */
  border-radius: 2px; /* solution error radius — illustration geometry */
  background: linear-gradient(transparent 55%, color-mix(in srgb, var(--color-brand-500) 25%, transparent) 55%); /* solution highlighter band — illustration geometry */
  color: var(--color-brand-600);
  font-weight: var(--font-weight-bold);
}

.how-it-works__solution-pin {
  display: inline-block;
  margin-inline-start: 4px; /* solution pin left gap — illustration geometry */
  padding: 2px 5px; /* solution pin padding — illustration geometry */
  border-radius: 4px; /* solution pin radius — illustration geometry */
  background-color: var(--color-brand-500);
  color: var(--color-text-on-brand);
  font-family: var(--font-sans);
  font-size: 8px; /* solution pin text size — illustration geometry */
  font-style: normal;
  font-weight: var(--font-weight-bold);
  line-height: 1; /* solution pin line-height — illustration geometry */
}

.how-it-works__ai-bubble {
  display: flex;
  align-items: flex-start;
  gap: 8px; /* AI bubble gap — illustration geometry */
  padding: 10px 12px; /* AI bubble padding — illustration geometry */
  border-radius: 14px; /* AI bubble radius — illustration geometry */
}

.how-it-works__ai-avatar {
  display: grid;
  flex-shrink: 0;
  place-items: center;
  inline-size: 24px; /* AI avatar width — illustration geometry */
  block-size: 24px; /* AI avatar height — illustration geometry */
  border-radius: 50%; /* AI avatar radius — illustration geometry */
  background-color: var(--color-brand-500);
  color: var(--color-text-on-brand);
  font-size: 11px; /* AI avatar text size — illustration geometry */
  font-weight: var(--font-weight-bold);
}

.how-it-works__ai-message {
  color: var(--color-text);
  font-size: 11px; /* AI message size — illustration geometry */
  font-weight: var(--font-weight-medium);
  line-height: 1.5; /* AI message line-height — illustration geometry */
}

.how-it-works__ai-highlight {
  color: var(--color-brand-600);
  font-weight: var(--font-weight-bold);
}

.how-it-works__practice-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px; /* practice head gap — illustration geometry */
  padding: 10px 12px; /* practice head padding — illustration geometry */
  border-radius: 12px; /* practice head radius — illustration geometry */
}

.how-it-works__practice-title {
  color: var(--color-text);
  font-size: 11px; /* practice title size — illustration geometry */
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
}

.how-it-works__practice-subtitle {
  display: block;
  margin-block-start: 2px; /* practice subtitle top gap — illustration geometry */
  color: var(--color-text-mute);
  font-size: 9px; /* practice subtitle size — illustration geometry */
  font-weight: var(--font-weight-medium);
}

.how-it-works__practice-badge {
  flex-shrink: 0;
  padding: 4px 8px; /* practice badge padding — illustration geometry */
  border-radius: 999px; /* practice badge radius — illustration geometry */
  background-color: var(--color-brand-50);
  color: var(--color-brand-600);
  font-size: 9px; /* practice badge size — illustration geometry */
  font-weight: var(--font-weight-bold);
}

.how-it-works__practice-list {
  display: flex;
  flex-direction: column;
  gap: 6px; /* practice list gap — illustration geometry */
}

.how-it-works__practice-item {
  display: flex;
  align-items: center;
  gap: 10px; /* practice item gap — illustration geometry */
  padding: 10px 12px; /* practice item padding — illustration geometry */
  border-radius: 12px; /* practice item radius — illustration geometry */
}

.how-it-works__practice-item--done {
  opacity: 0.68;
}

.how-it-works__practice-number {
  display: grid;
  flex-shrink: 0;
  place-items: center;
  inline-size: 22px; /* practice number width — illustration geometry */
  block-size: 22px; /* practice number height — illustration geometry */
  border-radius: 7px; /* practice number radius — illustration geometry */
  background-color: var(--color-bg-soft);
  color: var(--color-text-sub);
  font-size: 10px; /* practice number size — illustration geometry */
  font-weight: var(--font-weight-bold);
}

.how-it-works__practice-item--active .how-it-works__practice-number {
  background-color: var(--color-brand-500);
  color: var(--color-text-on-brand);
}

.how-it-works__practice-item--done .how-it-works__practice-number {
  border: 1.5px solid var(--color-brand-500); /* practice done number border — illustration geometry */
  background-color: var(--color-bg);
  color: var(--color-brand-500);
}

.how-it-works__practice-check {
  inline-size: 11px; /* practice check width — illustration geometry */
  block-size: 11px; /* practice check height — illustration geometry */
}

.how-it-works__practice-meta {
  flex: 1;
  min-inline-size: 0;
}

.how-it-works__practice-type {
  margin-block-end: 2px; /* practice type bottom gap — illustration geometry */
  color: var(--color-text-mute);
  font-size: 9px; /* practice type size — illustration geometry */
  font-weight: var(--font-weight-semibold);
}

.how-it-works__practice-formula {
  overflow: hidden;
  color: var(--color-text);
  font-family: var(--font-serif);
  font-size: 10.5px; /* practice formula size — illustration geometry */
  font-style: italic;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.how-it-works__practice-power {
  font-size: 7px; /* practice exponent size — illustration geometry */
}

.how-it-works__practice-chevron {
  flex-shrink: 0;
  inline-size: 11px; /* practice chevron width — illustration geometry */
  block-size: 11px; /* practice chevron height — illustration geometry */
  color: var(--color-text-mute);
}

.how-it-works__practice-item--done .how-it-works__practice-chevron {
  color: var(--color-brand-500);
}

@media (min-width: 768px) {
  .how-it-works {
    padding-block: var(--space-16);
  }

  .how-it-works__grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: var(--space-4);
  }

  .how-it-works__card {
    padding: var(--space-5);
  }

  .how-it-works__card-title {
    font-size: var(--font-size-lg);
  }

  .how-it-works__card-desc {
    min-block-size: var(--space-16);
    font-size: var(--font-size-sm);
  }

  .how-it-works__phone {
    inline-size: 190px; /* mini phone tablet width — illustration geometry */
    block-size: 380px; /* mini phone tablet height — illustration geometry */
  }
}

@media (min-width: 1024px) {
  .how-it-works {
    padding-block: var(--space-20);
  }

  .how-it-works__inner {
    gap: var(--space-16);
  }

  .how-it-works__title {
    font-size: var(--font-size-4xl);
  }

  .how-it-works__grid {
    gap: var(--space-6);
  }

  .how-it-works__card {
    padding: var(--space-8);
  }

  .how-it-works__card:hover {
    border-color: var(--color-border);
    box-shadow: var(--shadow-md);
    transform: translateY(calc(var(--space-1) * -1));
  }

  .how-it-works__card-title {
    font-size: var(--font-size-xl);
  }

  .how-it-works__card-desc {
    min-block-size: var(--space-12);
    font-size: var(--font-size-md);
  }

  .how-it-works__phone {
    inline-size: 220px; /* mini phone desktop width — illustration geometry */
    block-size: 440px; /* mini phone desktop height — illustration geometry */
  }
}