/* ==========================================================================
   디자인 시스템: 변수 및 기본 설정
   ========================================================================== */

/**
 * 색상 팔레트 (Color Palette)
 *
 * :root에서 CSS 변수를 선언하여 전체 사이트의 색상 스킴을 중앙에서 관리합니다.
 * 이를 통해 디자인의 일관성을 유지하고, 색상 변경이 필요할 때 한 곳에서만 수정하면 됩니다.
 *
 * 사용 예:
 * .some-element {
 *     color: var(--color-primary);
 *     background-color: var(--color-background);
 * }
 */
:root {
    --color-primary: #007BFF;          /* 주 색상 (예: 링크, 버튼) */
    --color-primary-hover: #005BDD;    /* 주 색상 Hover */
    --color-secondary: #00a100;        /* 보조 색상 (예: 성공, 강조) */
    --color-secondary-hover: #006e00;  /* 보조 색상 Hover */
    --color-accent: #aa0000;           /* 강조 색상 (예: 경고, 삭제) */
    --color-accent-hover: #6e0000;    /* 강조 색상 Hover */
    --color-text: #000;             /* 기본 텍스트 색상 */
    --color-text-light: #555;      /* 연한 텍스트 색상 (예: 부가 정보) */
    --color-background: #ffffff;       /* 기본 배경색 */
    --color-background-alt: #f8f9fa;  /* 대체 배경색 (예: 카드, 섹션) */
    --color-border: #dddddd;           /* 테두리 색상 */

    /* 알림(Alert) 색상 */
    --color-success-text: #006a2c;
    --color-success-bg: #00ef38;
    --color-success-border: #00b62a;
    --color-warning-text: #665a00;
    --color-warning-bg: #ffdd00;
    --color-warning-border: #b69e00;
    --color-danger-text: #ffffff;
    --color-danger-bg: #df0013;
    --color-danger-border: #b2000f;
}

/**
 * 타이포그래피 (Typography)
 *
 * 폰트 패밀리, 크기, 라인 높이 등을 변수로 정의합니다.
 * 폰트 관련 스타일을 일관되게 적용하고, 가독성을 높입니다.
 */
:root {
    --font-family-base: 'Noto Sans KR', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-size-base: 1.5rem; /* 24px */
    --line-height-base: 1.6;

    --font-size-h1: 1.875rem;   /* 30px */
    --font-size-h2: 1.5rem;     /* 24px */
    --font-size-h3: 1.25rem;    /* 20px */
    --font-size-h4: 1rem;       /* 16px */
    --font-size-h5: 0.875rem;   /* 14px */
    --font-size-h6: 0.75rem;    /* 12px */
}

/**
 * 간격 및 레이아웃 (Spacing & Layout)
 *
 * 여백(margin, padding), 컨테이너 너비 등 레이아웃 관련 값을 변수화합니다.
 * 일관된 간격 시스템은 시각적 안정감을 줍니다.
 */
:root {
    --spacing-unit: 1rem; /* 16px */
    --container-max-width: 1140px;
    --border-radius: 20px;
}


/* ==========================================================================
   기본 스타일 초기화 (Reset)
   ========================================================================== */

/**
 * Box-sizing을 border-box로 설정하여 패딩과 테두리를 너비/높이에 포함시킵니다.
 * 이는 예측 가능한 레이아웃 계산을 가능하게 합니다.
 */
*,
*::before,
*::after {
    box-sizing: border-box;
}

/**
 * 브라우저 기본 마진과 패딩을 제거하여 스타일 충돌을 방지합니다.
 */
html, body, h1, h2, h3, h4, h5, h6, p, ol, ul {
    margin: 0;
    padding: 0;
}


/* ==========================================================================
   전역 스타일 (Global Styles)
   ========================================================================== */

body {
    font-family: var(--font-family-base);
    font-size: var(--font-size-base);
    line-height: var(--line-height-base);
    color: var(--color-text);
    background-color: var(--color-background);
}

h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.3;
    margin-bottom: calc(var(--spacing-unit) * 0.5);
}

h1 { font-size: var(--font-size-h1); }
h2 { font-size: var(--font-size-h2); }
h3 { font-size: var(--font-size-h3); }
h4 { font-size: var(--font-size-h4); }
h5 { font-size: var(--font-size-h5); }
h6 { font-size: var(--font-size-h6); }

p {
    margin-bottom: var(--spacing-unit);
}

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color 0.2s ease-in-out;
}

a:hover {
    text-decoration: underline;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}


/* ==========================================================================
   레이아웃 관련 클래스 (Layout Classes)
   ========================================================================== */

.container {
    max-width: var(--container-max-width);
    margin-left: auto;
    margin-right: auto;
    padding-left: calc(var(--spacing-unit) * 1.5);
    padding-right: calc(var(--spacing-unit) * 1.5);
}


/* ==========================================================================
   사이트 헤더 및 푸터 (Site Header & Footer)
   ========================================================================== */

.site-header,
.site-footer {
    padding: calc(var(--spacing-unit) * 2) 0;
    text-align: center;
}

.site-header {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 1rem;
}

.language-toggle {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.lang-label {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--color-text-light);
    cursor: pointer;
}

.switch {
    position: relative;
    display: inline-block;
    width: 50px;
    height: 26px;
}

.switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #ccc;
    transition: .4s;
}

.slider:before {
    position: absolute;
    content: "";
    height: 20px;
    width: 20px;
    left: 3px;
    bottom: 3px;
    background-color: white;
    transition: .4s;
}

input:checked + .slider {
    background-color: var(--color-primary);
}

input:checked + .slider:before {
    transform: translateX(24px);
}

.slider.round {
    border-radius: 34px;
}

.slider.round:before {
    border-radius: 50%;
}


.header-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-unit);
}

.header-logo {
    width: 120px;
    height: auto;
    margin-right: calc(var(--spacing-unit) * 1.25); /* 20px */
    cursor: pointer;
    border-radius: 14px;
}

.site-footer {
    border-top: 1px solid var(--color-border);
    border-bottom: none;
    margin-top: calc(var(--spacing-unit) * 3);
    color: var(--color-text-light);
}

.site-header h1 {
    margin-bottom: 0;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.5);
    font-size: 3.75rem; /* 60px */
}

.site-header p {
    color: var(--color-text-light);
    font-size: 1.1rem;
}


/* ==========================================================================
   컴포넌트 스타일 (Component Styles)
   ========================================================================== */

/**
 * 디자인 섹션 (Design Section)
 * 각 컴포넌트 그룹을 구분하는 섹션입니다.
 */
.design-section {
    margin-top: calc(var(--spacing-unit) * 3);
    margin-bottom: calc(var(--spacing-unit) * 3);
    padding-bottom: calc(var(--spacing-unit) * 2);
    border-bottom: 1px solid var(--color-border);
}

.section-title {
    margin-bottom: calc(var(--spacing-unit) * 1.5);
    padding-bottom: calc(var(--spacing-unit) * 0.5);
    display: inline-block;
    font-size: 1.3em;
    text-decoration: 5px underline var(--color-primary);
}

.component-group {
    margin-bottom: calc(var(--spacing-unit) * 1.5);
}

.component-group > * {
    margin-right: var(--spacing-unit);
    margin-bottom: var(--spacing-unit);
}


/**
 * 네비게이션 바 (Navigation Bar)
 * 사이트의 주 메뉴를 포함하는 헤더 영역입니다. 로고, 링크, 액션 버튼으로 구성됩니다.
 */
.navbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-unit) calc(var(--spacing-unit) * 1.5);
    background-color: var(--color-background-alt);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    width: 100%;
}

.navbar-brand {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-text);
}

.navbar-nav {
    display: flex;
    list-style: none;
    margin: 0;
    padding: 0;
    gap: var(--spacing-unit);
}

.nav-link {
    color: var(--color-text-light);
    font-weight: 500;
    padding: calc(var(--spacing-unit) * 0.25) calc(var(--spacing-unit) * 0.75);
    border-radius: var(--border-radius);
    transition: color 0.2s ease, background-color 0.2s ease;
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-primary);
}

.nav-link.disabled {
    color: #adb5bd;
    text-decoration: 5px line-through;
    pointer-events: none;
    cursor: not-allowed;
}


/**
 * 버튼 (Buttons)
 * .btn 클래스를 기본으로 하여, 색상과 스타일에 따라 확장 클래스를 사용합니다.
 * (예: .btn-primary, .btn-outline-secondary)
 */
.btn {
    display: inline-block;
    font-weight: 600;
    text-align: center;
    white-space: nowrap;
    vertical-align: middle;
    user-select: none;
    border: none;
    padding: calc(var(--spacing-unit) * 0.5) calc(var(--spacing-unit) * 1);
    font-size: var(--font-size-base);
    line-height: var(--line-height-base);
    border-radius: var(--border-radius);
    box-shadow: 0 4px 6px rgba(0,0,0,0.2);
    transition: background-color 0.3s ease, transform 0.1s ease, box-shadow 0.3s ease;
    cursor: pointer;
}

.btn:hover {
    text-decoration: none;
    transform: translateY(2px);
    box-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

.btn:disabled,
.btn.disabled {
    opacity: 0.65;
    cursor: not-allowed;
    transform: none;
}

/* 채워진 버튼 */
.btn-primary {
    color: #fff;
    background-color: var(--color-primary);
    border-color: var(--color-primary);
}
.btn-primary:hover {
    background-color: var(--color-primary-hover);
}

.btn-secondary {
    color: #fff;
    background-color: var(--color-secondary);
    border-color: var(--color-secondary);
}
.btn-secondary:hover {
    background-color: var(--color-secondary-hover);
}

.btn-accent {
    color: #fff;
    background-color: var(--color-accent);
    border-color: var(--color-accent);
}
.btn-accent:hover {
    background-color: var(--color-accent-hover);
}

/* 외곽선 버튼 */
.btn-outline-primary {
    color: var(--color-primary);
    background-color: transparent;
    border-color: var(--color-primary);
}
.btn-outline-primary:hover {
    color: #fff;
    background-color: var(--color-primary);
}

.btn-outline-secondary {
    color: var(--color-secondary);
    background-color: transparent;
    border-color: var(--color-secondary);
}
.btn-outline-secondary:hover {
    color: #fff;
    background-color: var(--color-secondary);
}

.btn-outline-accent {
    color: var(--color-accent);
    background-color: transparent;
    border-color: var(--color-accent);
}
.btn-outline-accent:hover {
    color: #fff;
    background-color: var(--color-accent);
}


/**
 * 카드 (Cards)
 * 이미지, 제목, 본문, 액션 버튼 등을 포함할 수 있는 유연한 컨테이너입니다.
 */
.card-group {
    display: flex;
    gap: calc(var(--spacing-unit) * 1.5);
    flex-wrap: wrap;
}

.card {
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    background-color: var(--color-background);
    overflow: hidden;
    box-shadow: 0 4px 6px rgba(0,0,0,0.2);
    transition: box-shadow 0.2s ease-in-out, transform 0.2s ease-in-out;
    flex: 1 1 300px; /* Flexbox를 사용하여 반응형으로 조절 */
    align-self: flex-start; /* 세로 높이를 제각각으로 설정 */
}

.card:hover {
    transform: translateY(-10px);
    box-shadow: 0 10px 10px rgba(0,0,0,0.2);
}

.card-img-top {
    width: 100%;
    height: auto;
}

.card-body {
    padding: calc(var(--spacing-unit) * 1.25);
}

.card-title {
    font-size: var(--font-size-h1);
    margin-bottom: calc(var(--spacing-unit) * 0.75);
}

.card-text {
    color: var(--color-text-light);
    margin-bottom: calc(var(--spacing-unit) * 1.25);
}


/**
 * 폼 요소 (Form Elements)
 * 일관된 디자인의 input, textarea, label 등을 제공합니다.
 */
.form-group {
    position: relative;
    margin-bottom: calc(var(--spacing-unit) * 2);
}

.form-group label {
    position: absolute;
    top: 50%;
    left: calc(var(--spacing-unit) * 0.75);
    transform: translateY(-50%);
    color: var(--color-text-light);
    pointer-events: none;
    transition: all 0.2s ease-in-out;
    background-color: var(--color-background);
    padding: 0 5px;
}

.form-control {
    display: block;
    width: 100%;
    padding: calc(var(--spacing-unit) * 0.5) calc(var(--spacing-unit) * 0.75);
    font-size: var(--font-size-base);
    line-height: var(--line-height-base);
    color: var(--color-text);
    background-color: var(--color-background);
    background-clip: padding-box;
    border: 3px solid var(--color-border);
    border-radius: var(--border-radius);
    transition: all 0.3s ease-in-out;
}

.form-control:focus + label,
.form-control:not(:placeholder-shown) + label {
    top: 0;
    color: var(--color-primary);
    font-weight: 600;
}

.form-control:focus {
    color: var(--color-text);
    background-color: var(--color-background);
    border-color: var(--color-primary);
    outline: 0;
}


/**
 * 추가 폼 요소 (Advanced Form Elements)
 */
.file-drop-area {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 400px;
    border: 5px dashed var(--color-border);
    border-radius: var(--border-radius);
    transition: border-color 0.3s ease, background-color 0.3s ease;
    cursor: pointer;
}

.file-drop-area:hover {
    border-color: var(--color-primary);
}

.file-drop-area.is-active {
    border-color: var(--color-primary);
    background-color: rgba(0, 123, 255, 0.05);
}

.file-drop-area.is-active .file-msg {
    color: var(--color-primary);
    transform: scale(1.05);
}

.file-msg {
    color: var(--color-text-light);
    font-size: 1.2rem;
    transition: color 0.3s ease, transform 0.7s ease;
}

.file-drop-area:hover .file-msg {
    transform: scale(1.5) rotate(360deg);
}

.file-input {
    position: absolute;
    left: 0;
    top: 0;
    height: 100%;
    width: 100%;
    cursor: pointer;
    opacity: 0;
}

.form-check {
    display: flex;
    align-items: center;
    margin-bottom: calc(var(--spacing-unit) * 0.5);
}

.form-check-input {
    width: 1.5em;
    height: 1.5em;
    margin-right: 0.5em;
    vertical-align: top;
    -webkit-appearance: none;
    appearance: none;
    background-color: var(--color-background);
    border: 1px solid var(--color-border);
    border-radius: 0.25em;
    cursor: pointer;
}

.form-check-input:checked {
    background-color: var(--color-primary);
    border-color: var(--color-primary);
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 20 20'%3e%3cpath fill='none' stroke='%23fff' stroke-linecap='round' stroke-linejoin='round' stroke-width='3' d='M6 10l3 3l6-6'/%3e%3c/svg%3e");
}

.form-select {
    display: block;
    width: 100%;
    padding: calc(var(--spacing-unit) * 0.5) calc(var(--spacing-unit) * 0.75);
    font-size: var(--font-size-base);
    font-weight: 400;
    line-height: var(--line-height-base);
    color: var(--color-text);
    background-color: var(--color-background);
    border: 3px solid var(--color-border);
    border-radius: var(--border-radius);
    appearance: none;
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16'%3e%3cpath fill='none' stroke='%23343a40' stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='M2 5l6 6 6-6'/%3e%3c/svg%3e");
    background-repeat: no-repeat;
    background-position: right 0.75rem center;
    background-size: 16px 12px;
    cursor: pointer;
}

.form-select:focus {
    border-color: var(--color-primary);
    outline: 0;
}

.form-range {
    width: 100%;
    height: 1.5rem;
    padding: 0;
    background-color: transparent;
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
}
.form-range:focus {
    outline: none;
}
.form-range::-webkit-slider-thumb {
    width: 1.5rem;
    height: 1.5rem;
    margin-top: -0.5rem;
    background-color: var(--color-primary);
    border: 0;
    border-radius: 50%;
    -webkit-appearance: none;
    appearance: none;
    cursor: pointer;
}
.form-range::-webkit-slider-runnable-track {
    width: 100%;
    height: 0.5rem;
    cursor: pointer;
    background-color: var(--color-border);
    border-radius: 1rem;
}


/**
 * 알림 (Alerts)
 * 상태(성공, 경고, 위험 등)를 나타내는 메시지 박스입니다.
 */
.alert {
    position: relative;
    padding: var(--spacing-unit) calc(var(--spacing-unit) * 1.25);
    margin-bottom: var(--spacing-unit);
    border: solid 5px transparent;
    border-radius: var(--border-radius);
}

.alert-success {
    color: var(--color-success-text);
    background-color: var(--color-success-bg);
    border-color: var(--color-success-border);
}

.alert-warning {
    color: var(--color-warning-text);
    background-color: var(--color-warning-bg);
    border-color: var(--color-warning-border);
}

.alert-danger {
    color: var(--color-danger-text);
    background-color: var(--color-danger-bg);
    border-color: var(--color-danger-border);
}


/* ==========================================================================
   모달 (Modal)
   ========================================================================== */

/**
 * 모달 (Modal)
 * 화면 위에 오버레이되어 중요한 정보나 인터랙션을 제공하는 팝업 창입니다.
 * 평소에는 숨겨져 있다가 JS를 통해 .show 클래스가 추가되면 나타납니다.
 */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    display: none;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: opacity 0.3s ease;
    z-index: 1000;
}

.modal.show {
    display: flex;
    opacity: 1;
}

.modal-dialog {
    background-color: var(--color-background);
    border-radius: var(--border-radius);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.3);
    width: 90%;
    max-width: 500px;
    transform: translateY(-50px);
    transition: transform 0.3s ease;
}

.modal.show .modal-dialog {
    transform: translateY(0);
}

.modal-content {
    display: flex;
    flex-direction: column;
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-unit);
    border-bottom: 1px solid var(--color-border);
}

.modal-title {
    font-size: var(--font-size-h1);
    margin: 0;
}

.close {
    font-size: 2.5rem;
    font-weight: 700;
    line-height: 1;
    color: #000;
    text-shadow: 0 1px 0 #fff;
    opacity: 0.5;
    background-color: transparent;
    border: 0;
    cursor: pointer;
    padding: var(--spacing-unit);
    margin: calc(-1 * var(--spacing-unit));
    transition: transform 0.7s ease;
}

.close:hover {
    transform: rotate(360deg);
}

.modal-body {
    padding: var(--spacing-unit);
}

.modal-footer {
    display: flex;
    justify-content: flex-end;
    padding: var(--spacing-unit);
    border-top: 1px solid var(--color-border);
    gap: calc(var(--spacing-unit) * 0.5);
}
.footer-link {
    color: var(--color-primary);
    text-decoration: none;
    font-weight: 600;
    transition: color 0.2s ease-in-out;
}
.footer-link:hover {
    color: var(--color-primary-hover);
}


/* ==========================================================================
   애플리케이션별 스타일 (Application-Specific Styles)
   ========================================================================== */

main > .design-section {
    padding: calc(var(--spacing-unit) * 2);
    border-radius: var(--border-radius);
    margin-bottom: calc(var(--spacing-unit) * 2);
    border-bottom: none;
}

.upload-icon {
    width: 64px;
    height: 64px;
    margin-bottom: 1rem;
    color: var(--color-primary);
}

.file-drop-area .file-msg {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.file-info.card .card-body {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.file-preview {
    flex: 1;
}

.file-preview video {
    width: 100%;
    border-radius: var(--border-radius);
}

.file-details {
    flex: 1;
}

.size-presets {
    margin-top: 1rem;
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.size-presets .preset-btn.active {
    background-color: var(--color-secondary);
    color: #fff;
    border-color: var(--color-secondary-hover);
}

.settings-section .form-group > label[for="qualityBalance"] {
    position: static;
    transform: none;
    background: none;
    padding: 0;
    margin-bottom: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-weight: 600;
    width: 100%;
    color: var(--color-text);
}

.balance-labels {
    display: flex;
    justify-content: space-between;
    gap: 1rem;
    margin-top: 1rem;
}

.balance-label {
    text-align: center;
}

.balance-label svg {
    width: 32px;
    height: 32px;
    margin-bottom: 0.5rem;
    color: var(--color-primary);
}

.balance-label span {
    display: block;
    font-weight: 600;
}

.balance-label small {
    color: var(--color-text-light);
}

#convertBtn, #downloadBtn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

#convertBtn svg, #downloadBtn svg {
    width: 20px;
    height: 20px;
}

.progress-section {
    text-align: center;
}

.spinner {
    margin: 0 auto 1rem;
    width: 60px;
    height: 60px;
    border: 4px solid var(--color-border);
    border-top-color: var(--color-primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.result-section.card {
    text-align: center;
}

.success-icon {
    width: 80px;
    height: 80px;
    color: var(--color-secondary);
    margin-bottom: 1rem;
}

.result-info {
    background: var(--color-background);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin-bottom: 2rem;
    text-align: left;
}

.result-info p {
    display: flex;
    justify-content: space-between;
    margin-bottom: 0.5rem;
}
.result-info p:last-child {
    margin-bottom: 0;
}

.result-actions {
    display: flex;
    gap: 1rem;
}

.result-actions > .btn {
    flex: 1;
}