/*
 * 웹 접근성 예제 스타일
 * - 고대비 색상
 * - 포커스 표시
 * - 반응형 디자인
 */

/* ============================================
   기본 스타일
   ============================================ */

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

:root {
    /* 고대비 색상 팔레트 */
    --color-primary: #0056b3;
    --color-primary-dark: #003d7a;
    --color-secondary: #495057;
    --color-success: #198754;
    --color-warning: #ffc107;
    --color-danger: #dc3545;
    --color-text: #212529;
    --color-text-muted: #6c757d;
    --color-bg: #ffffff;
    --color-bg-alt: #f8f9fa;
    --color-border: #dee2e6;

    /* 포커스 링 */
    --focus-ring: 0 0 0 3px rgba(0, 86, 179, 0.5);
    --focus-ring-offset: 2px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-bg);
}

/* ============================================
   Skip Link (건너뛰기 링크)
   ============================================ */

.skip-link {
    position: absolute;
    top: -100%;
    left: 50%;
    transform: translateX(-50%);
    background: var(--color-primary);
    color: white;
    padding: 12px 24px;
    border-radius: 0 0 8px 8px;
    text-decoration: none;
    font-weight: 600;
    z-index: 1000;
    transition: top 0.3s;
}

.skip-link:focus {
    top: 0;
    outline: none;
    box-shadow: var(--focus-ring);
}

/* ============================================
   스크린 리더 전용 텍스트
   ============================================ */

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

/* ============================================
   헤더 & 네비게이션
   ============================================ */

header {
    background: var(--color-primary);
    padding: 15px 20px;
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-list {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    justify-content: center;
    max-width: 1200px;
    margin: 0 auto;
}

.nav-list a {
    color: white;
    text-decoration: none;
    padding: 8px 16px;
    border-radius: 4px;
    transition: background 0.2s;
}

.nav-list a:hover,
.nav-list a:focus {
    background: rgba(255, 255, 255, 0.2);
    outline: none;
}

.nav-list a[aria-current="page"] {
    background: rgba(255, 255, 255, 0.3);
    font-weight: 600;
}

/* ============================================
   메인 컨텐츠
   ============================================ */

main {
    max-width: 900px;
    margin: 0 auto;
    padding: 40px 20px;
}

h1 {
    font-size: 2.2rem;
    margin-bottom: 20px;
    color: var(--color-primary-dark);
}

h2 {
    font-size: 1.6rem;
    margin: 40px 0 20px;
    padding-bottom: 10px;
    border-bottom: 3px solid var(--color-primary);
    color: var(--color-primary-dark);
}

h3 {
    font-size: 1.3rem;
    margin: 25px 0 15px;
    color: var(--color-secondary);
}

h4 {
    font-size: 1.1rem;
    margin: 15px 0 10px;
}

.intro {
    font-size: 1.1rem;
    color: var(--color-text-muted);
    margin-bottom: 30px;
}

section {
    margin-bottom: 50px;
}

article {
    margin-bottom: 30px;
}

/* ============================================
   예제 박스
   ============================================ */

.example-box {
    background: var(--color-bg-alt);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: 20px;
    margin: 15px 0;
}

pre {
    background: #2d2d2d;
    color: #f8f8f2;
    padding: 15px;
    border-radius: 4px;
    overflow-x: auto;
    font-size: 0.9rem;
}

code {
    font-family: 'Fira Code', 'Consolas', monospace;
}

/* ============================================
   이미지 예제
   ============================================ */

.image-examples {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
}

figure {
    text-align: center;
}

figcaption {
    margin-top: 10px;
    font-size: 0.9rem;
    color: var(--color-text-muted);
}

/* ============================================
   알림 & 상태 메시지
   ============================================ */

.alert {
    padding: 15px;
    border-radius: 8px;
    margin-bottom: 15px;
}

.alert-warning {
    background: #fff3cd;
    border: 1px solid #ffc107;
    color: #856404;
}

.status-message {
    padding: 10px 15px;
    background: #d4edda;
    border: 1px solid #28a745;
    border-radius: 4px;
    color: #155724;
    margin-bottom: 15px;
}

.live-region {
    padding: 15px;
    background: #e7f3ff;
    border: 2px dashed var(--color-primary);
    border-radius: 8px;
    margin-top: 10px;
    min-height: 60px;
}

/* ============================================
   아코디언
   ============================================ */

.accordion-button {
    width: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px;
    background: var(--color-primary);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    cursor: pointer;
    transition: background 0.2s;
}

.accordion-button:hover {
    background: var(--color-primary-dark);
}

.accordion-button:focus {
    outline: none;
    box-shadow: var(--focus-ring);
}

.accordion-button[aria-expanded="true"] .icon {
    transform: rotate(180deg);
}

.icon {
    transition: transform 0.3s;
}

.accordion-content {
    padding: 20px;
    background: white;
    border: 1px solid var(--color-border);
    border-top: none;
    border-radius: 0 0 8px 8px;
}

/* ============================================
   진행률 표시
   ============================================ */

.progress-demo {
    margin: 20px 0;
}

.progress-bar {
    height: 30px;
    background: var(--color-border);
    border-radius: 15px;
    overflow: hidden;
    margin-top: 10px;
}

.progress-fill {
    height: 100%;
    background: var(--color-success);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: 600;
    transition: width 0.3s;
}

/* ============================================
   탭
   ============================================ */

.tabs-demo {
    margin-top: 20px;
}

[role="tablist"] {
    display: flex;
    border-bottom: 2px solid var(--color-border);
}

[role="tab"] {
    padding: 12px 24px;
    background: transparent;
    border: none;
    border-bottom: 3px solid transparent;
    margin-bottom: -2px;
    cursor: pointer;
    font-size: 1rem;
    transition: all 0.2s;
}

[role="tab"]:hover {
    background: var(--color-bg-alt);
}

[role="tab"]:focus {
    outline: none;
    box-shadow: inset 0 0 0 2px var(--color-primary);
}

[role="tab"][aria-selected="true"] {
    border-bottom-color: var(--color-primary);
    color: var(--color-primary);
    font-weight: 600;
}

[role="tabpanel"] {
    padding: 20px;
    border: 1px solid var(--color-border);
    border-top: none;
}

[role="tabpanel"]:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: -2px;
}

/* ============================================
   폼 스타일
   ============================================ */

form {
    background: var(--color-bg-alt);
    padding: 30px;
    border-radius: 12px;
    border: 1px solid var(--color-border);
}

fieldset {
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 25px;
}

legend {
    font-weight: 600;
    color: var(--color-primary-dark);
    padding: 0 10px;
}

.form-group {
    margin-bottom: 20px;
}

label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
}

.required {
    color: var(--color-danger);
}

input[type="text"],
input[type="email"],
input[type="tel"],
input[type="search"],
select,
textarea {
    width: 100%;
    padding: 12px;
    border: 2px solid var(--color-border);
    border-radius: 6px;
    font-size: 1rem;
    transition: border-color 0.2s, box-shadow 0.2s;
}

input:focus,
select:focus,
textarea:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: var(--focus-ring);
}

input[aria-invalid="true"] {
    border-color: var(--color-danger);
}

.hint {
    display: block;
    margin-top: 5px;
    font-size: 0.85rem;
    color: var(--color-text-muted);
}

.error {
    display: block;
    margin-top: 5px;
    font-size: 0.85rem;
    color: var(--color-danger);
}

/* Radio & Checkbox */
.radio-group,
.checkbox-group {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
}

.radio-option,
.checkbox-option {
    display: flex;
    align-items: center;
    gap: 8px;
}

input[type="radio"],
input[type="checkbox"] {
    width: 20px;
    height: 20px;
    accent-color: var(--color-primary);
}

input[type="radio"]:focus,
input[type="checkbox"]:focus {
    outline: none;
    box-shadow: var(--focus-ring);
}

/* 버튼 */
.btn-primary,
.btn-secondary {
    padding: 12px 24px;
    border: none;
    border-radius: 6px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
}

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

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

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

.btn-secondary:hover {
    background: #343a40;
}

.btn-primary:focus,
.btn-secondary:focus {
    outline: none;
    box-shadow: var(--focus-ring);
}

.form-actions {
    display: flex;
    gap: 15px;
    margin-top: 20px;
}

/* ============================================
   키보드 단축키 테이블
   ============================================ */

.keyboard-shortcuts {
    width: 100%;
    border-collapse: collapse;
    margin: 15px 0;
}

.keyboard-shortcuts caption {
    text-align: left;
    font-weight: 600;
    margin-bottom: 10px;
    color: var(--color-text-muted);
}

.keyboard-shortcuts th,
.keyboard-shortcuts td {
    padding: 12px 15px;
    text-align: left;
    border: 1px solid var(--color-border);
}

.keyboard-shortcuts th {
    background: var(--color-primary);
    color: white;
}

.keyboard-shortcuts tr:nth-child(even) {
    background: var(--color-bg-alt);
}

kbd {
    display: inline-block;
    padding: 3px 8px;
    font-family: monospace;
    background: #eee;
    border: 1px solid #ccc;
    border-radius: 4px;
    box-shadow: 0 2px 0 #999;
}

/* ============================================
   커스텀 리스트박스
   ============================================ */

.custom-listbox {
    list-style: none;
    border: 2px solid var(--color-border);
    border-radius: 8px;
    overflow: hidden;
    max-width: 300px;
}

.custom-listbox:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: var(--focus-ring);
}

.custom-listbox [role="option"] {
    padding: 12px 15px;
    cursor: pointer;
    transition: background 0.2s;
}

.custom-listbox [role="option"]:hover {
    background: var(--color-bg-alt);
}

.custom-listbox [role="option"][aria-selected="true"] {
    background: var(--color-primary);
    color: white;
}

/* ============================================
   모달
   ============================================ */

.modal {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: white;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 10px 50px rgba(0, 0, 0, 0.3);
    z-index: 1001;
    max-width: 500px;
    width: 90%;
}

.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 1000;
}

.modal-content h2 {
    margin: 0 0 15px;
    border: none;
    padding: 0;
}

.modal-content p {
    margin-bottom: 20px;
}

.modal-actions {
    display: flex;
    gap: 10px;
    justify-content: flex-end;
}

/* ============================================
   포커스 트랩 영역
   ============================================ */

.focus-trap-area {
    padding: 20px;
    border: 3px dashed var(--color-primary);
    border-radius: 8px;
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
}

.focus-trap-area button,
.focus-trap-area input,
.focus-trap-area a {
    padding: 10px 20px;
}

/* ============================================
   색상 대비 예제
   ============================================ */

.contrast-examples {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

.contrast-good {
    background: #1a1a1a;
    color: #ffffff;
    padding: 20px;
    border-radius: 8px;
}

.contrast-good h3 {
    color: #ffffff;
}

.contrast-bad {
    background: #dddddd;
    color: #999999;
    padding: 20px;
    border-radius: 8px;
}

.contrast-bad h3 {
    color: #aaaaaa;
}

/* ============================================
   푸터
   ============================================ */

footer {
    background: var(--color-secondary);
    color: white;
    padding: 30px 20px;
    text-align: center;
    margin-top: 50px;
}

footer a {
    color: #a0d2ff;
}

footer a:hover {
    color: white;
}

/* ============================================
   포커스 표시 강화
   ============================================ */

/* 모든 포커스 가능한 요소에 명확한 포커스 표시 */
a:focus,
button:focus,
[tabindex]:focus {
    outline: 3px solid var(--color-primary);
    outline-offset: 2px;
}

/* ============================================
   반응형
   ============================================ */

@media (max-width: 600px) {
    h1 {
        font-size: 1.8rem;
    }

    h2 {
        font-size: 1.4rem;
    }

    .nav-list {
        flex-direction: column;
        align-items: center;
    }

    .form-actions {
        flex-direction: column;
    }

    .btn-primary,
    .btn-secondary {
        width: 100%;
    }
}

/* ============================================
   고대비 모드 지원
   ============================================ */

@media (prefers-contrast: high) {
    :root {
        --color-primary: #0000ff;
        --color-border: #000000;
    }

    * {
        border-color: #000 !important;
    }
}

/* ============================================
   모션 감소 모드
   ============================================ */

@media (prefers-reduced-motion: reduce) {
    * {
        animation: none !important;
        transition: none !important;
    }
}