/* ==================== CSS Variables & Design System ==================== */
:root {
    /* Colors - Warm Dark Theme */
    --color-bg-primary: #001F3F;
    --color-bg-secondary: #002A54;
    --color-bg-tertiary: #00355C;
    --color-bg-glass: rgba(237, 152, 80, 0.08);
    --color-bg-glass-hover: rgba(237, 152, 80, 0.15);

    /* Accent Colors */
    --color-accent-primary: #ED9850;
    --color-accent-secondary: #F7B980;
    --color-accent-tertiary: #E6E6E6;

    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #ED9850 0%, #F7B980 100%);
    --gradient-glass: linear-gradient(135deg, rgba(237, 152, 80, 0.2) 0%, rgba(247, 185, 128, 0.2) 100%);

    /* Text Colors */
    --color-text-primary: #E6E6E6;
    --color-text-secondary: #B8C5D6;
    --color-text-tertiary: #8A9AB0;

    /* Border & Shadows */
    --color-border: rgba(230, 230, 230, 0.15);
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 32px rgba(237, 152, 80, 0.4);

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;

    /* Typography */
    --font-primary: 'Inter', 'Noto Sans KR', -apple-system, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.5rem;
    --font-size-2xl: 2rem;
    --font-size-3xl: 3rem;

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 400ms ease;

    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
}

/* ==================== Reset & Base Styles ==================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-primary);
    background: var(--color-bg-primary);
    color: var(--color-text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
}

/* Animated Background */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle at 20% 50%, rgba(237, 152, 80, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 80%, rgba(247, 185, 128, 0.1) 0%, transparent 50%);
    z-index: -1;
    animation: gradientShift 15s ease infinite;
}

@keyframes gradientShift {

    0%,
    100% {
        opacity: 1;
    }

    50% {
        opacity: 0.8;
    }
}

/* ==================== Header ==================== */
.header {
    padding: var(--spacing-md) 0;
    text-align: center;
    position: relative;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.logo {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-xs);
    animation: fadeInDown 0.8s ease;
}

.tagline {
    color: var(--color-text-secondary);
    font-size: var(--font-size-lg);
    font-weight: 300;
    animation: fadeInUp 0.8s ease;
}

/* ==================== Main App Container ==================== */
.app-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--spacing-md) var(--spacing-lg);
}

/* ==================== Upload Section ==================== */
.upload-section {
    animation: fadeIn 1s ease;
}

.upload-zone {
    background: var(--color-bg-glass);
    backdrop-filter: blur(20px);
    border: 2px dashed var(--color-border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-lg);
    text-align: center;
    transition: all var(--transition-base);
    cursor: pointer;
}

.upload-zone:hover,
.upload-zone.drag-over {
    border-color: var(--color-accent-primary);
    background: var(--color-bg-glass-hover);
    box-shadow: var(--shadow-glow);
    transform: translateY(-4px);
}

.upload-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-md);
}

.upload-icon {
    width: 60px;
    height: 60px;
    color: var(--color-accent-primary);
    stroke-width: 1.5;
    animation: float 3s ease-in-out infinite;
}

@keyframes float {

    0%,
    100% {
        transform: translateY(0);
    }

    50% {
        transform: translateY(-10px);
    }
}

.upload-zone h2 {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--color-text-primary);
}

.upload-zone p {
    color: var(--color-text-secondary);
    font-size: var(--font-size-base);
}

.file-info {
    font-size: var(--font-size-sm);
    color: var(--color-text-tertiary);
}

/* ==================== Buttons ==================== */
.btn-primary,
.btn-secondary,
.upload-button {
    padding: 7px 14px;
    border-radius: var(--radius-sm);
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
    border: none;
    font-family: var(--font-primary);
    display: inline-flex;
    align-items: center;
    gap: 5px;
}

.upload-button {
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: var(--font-size-base);
}

.btn-primary,
.upload-button {
    background: var(--gradient-primary);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover,
.upload-button:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg), var(--shadow-glow);
}

.btn-secondary {
    background: var(--color-bg-tertiary);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
}

.btn-secondary:hover {
    background: var(--color-bg-glass-hover);
    border-color: var(--color-accent-primary);
}

.btn-secondary svg,
.btn-primary svg {
    width: 15px;
    height: 15px;
}

.upload-button svg {
    width: 18px;
    height: 18px;
}

/* ==================== Photo Grid ==================== */
.photo-grid {
    margin-top: var(--spacing-xl);
    animation: fadeInUp 0.6s ease;
}

.grid-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-md);
}

.grid-header h3 {
    font-size: var(--font-size-xl);
    font-weight: 600;
}

.grid-header span {
    color: var(--color-accent-primary);
}

.grid-items {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.photo-item {
    position: relative;
    aspect-ratio: 1;
    border-radius: var(--radius-md);
    overflow: hidden;
    background: var(--color-bg-secondary);
    cursor: pointer;
    transition: all var(--transition-base);
}

.photo-item:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-lg);
}

.photo-item img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: all var(--transition-base);
}

.photo-item:hover img {
    transform: scale(1.05);
}

/* Photo Preview on Hover */
.photo-item::after {
    content: '';
    position: fixed;
    width: 300px;
    height: 300px;
    background-image: var(--preview-image);
    background-size: contain;
    background-repeat: no-repeat;
    background-position: center;
    border: 3px solid var(--color-accent-primary);
    border-radius: var(--radius-lg);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.6);
    pointer-events: none;
    z-index: 1000;
    opacity: 0;
    transform: scale(0.8);
    transition: all var(--transition-base);
    background-color: var(--color-bg-primary);
}

.photo-item:hover::after {
    opacity: 1;
    transform: scale(1);
    left: var(--mouse-x, 50%);
    top: var(--mouse-y, 50%);
    margin-left: 20px;
    margin-top: -150px;
}

/* Disable hover preview while editing date */
.photo-item.editing-date::after {
    display: none;
}

.photo-item.editing-date:hover {
    transform: none;
}

.photo-item .photo-date {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background: linear-gradient(to top, rgba(0, 0, 0, 0.8), transparent);
    padding: var(--spacing-sm);
    font-size: var(--font-size-xs);
    color: white;
}

.photo-item .date-display {
    display: block;
}

.photo-item .edit-date-btn {
    position: absolute;
    top: var(--spacing-xs);
    right: calc(var(--spacing-xs) + 36px);
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: rgba(237, 152, 80, 0.85);
    color: white;
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    opacity: 0;
    transition: all var(--transition-fast);
}

.photo-item:hover .edit-date-btn {
    opacity: 1;
}

.photo-item .edit-date-btn:hover {
    background: var(--color-accent-primary);
    transform: scale(1.1);
}

.photo-item .date-input {
    position: absolute;
    bottom: var(--spacing-sm);
    left: var(--spacing-sm);
    right: var(--spacing-sm);
    background: rgba(0, 31, 63, 0.95);
    border: 1px solid var(--color-accent-primary);
    border-radius: var(--radius-sm);
    padding: var(--spacing-xs);
    color: var(--color-text-primary);
    font-size: var(--font-size-xs);
    font-family: var(--font-primary);
}

.photo-item .date-input:focus {
    outline: none;
    border-color: var(--color-accent-secondary);
    box-shadow: 0 0 8px rgba(237, 152, 80, 0.4);
}

.photo-item .remove-photo {
    position: absolute;
    top: var(--spacing-xs);
    right: var(--spacing-xs);
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: rgba(0, 0, 0, 0.7);
    color: white;
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: all var(--transition-fast);
}

.photo-item:hover .remove-photo {
    opacity: 1;
}

.photo-item .remove-photo:hover {
    background: var(--color-accent-tertiary);
    transform: scale(1.1);
}

#createTimelineButton {
    width: 100%;
    padding: var(--spacing-md);
    font-size: var(--font-size-lg);
}

/* ==================== Timeline Section ==================== */
.timeline-section {
    animation: fadeIn 0.8s ease;
}

.timeline-controls {
    background: var(--color-bg-glass);
    backdrop-filter: blur(20px);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    padding: 8px 12px;
    margin-bottom: 12px;
    display: flex;
    flex-direction: row;
    gap: var(--spacing-md);
    align-items: flex-start;
}

.control-section {
    display: flex;
    flex-direction: column;
    gap: 3px;
    padding-right: var(--spacing-md);
    border-right: 1px solid rgba(230, 230, 230, 0.15);
    flex: 1;
    min-width: 0;
}

.control-section:last-child {
    border-right: none;
    padding-right: 0;
}

.section-label {
    font-size: 10px;
    font-weight: 600;
    color: var(--color-accent-primary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 1px;
    opacity: 0.8;
}

.control-row {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
    align-items: center;
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.control-group label {
    font-size: 11px;
    color: var(--color-text-secondary);
    font-weight: 500;
}

.drawing-status {
    margin-top: 4px;
    padding: 6px 10px;
    background: var(--gradient-glass);
    border: 1px solid var(--color-accent-primary);
    border-radius: var(--radius-sm);
    text-align: center;
}

.drawing-status p {
    color: var(--color-text-primary);
    font-weight: 500;
    font-size: 11px;
    margin: 0;
}

.toggle-group {
    display: flex;
    background: var(--color-bg-tertiary);
    border-radius: var(--radius-sm);
    padding: 2px;
}

.toggle-btn {
    padding: 5px 12px;
    border: none;
    background: transparent;
    color: var(--color-text-secondary);
    cursor: pointer;
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    gap: 5px;
    font-family: var(--font-primary);
    font-size: 12px;
}

.toggle-btn svg {
    width: 15px;
    height: 15px;
}

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

.toggle-btn:not(.active):hover {
    color: var(--color-text-primary);
}

/* ==================== Canvas Container ==================== */
.canvas-container {
    position: relative;
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    margin-bottom: 12px;
}

#timelineCanvas {
    display: block;
    width: 100%;
    height: 100%;
}

.canvas-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
}

/* ==================== Zoom Control ==================== */
.zoom-control {
    background: var(--color-bg-glass);
    backdrop-filter: blur(20px);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    padding: 8px 12px;
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.zoom-control label {
    font-size: 11px;
    color: var(--color-text-secondary);
    font-weight: 500;
    white-space: nowrap;
}

.zoom-slider-container {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    flex: 1;
}

.zoom-btn {
    width: 28px;
    height: 28px;
    border-radius: var(--radius-sm);
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    color: var(--color-text-primary);
    font-size: 18px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
    line-height: 1;
}

.zoom-btn:hover {
    background: var(--color-bg-glass-hover);
    border-color: var(--color-accent-primary);
}

#zoomSlider {
    flex: 1;
    height: 6px;
    border-radius: 3px;
    background: var(--color-bg-tertiary);
    outline: none;
    -webkit-appearance: none;
    cursor: pointer;
}

#zoomSlider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: var(--gradient-primary);
    cursor: pointer;
    box-shadow: var(--shadow-sm);
}

#zoomSlider::-moz-range-thumb {
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: var(--gradient-primary);
    cursor: pointer;
    border: none;
    box-shadow: var(--shadow-sm);
}

#zoomSlider::-webkit-slider-thumb:hover {
    box-shadow: var(--shadow-md);
}

#zoomSlider::-moz-range-thumb:hover {
    box-shadow: var(--shadow-md);
}

.zoom-value {
    font-size: 12px;
    font-weight: 600;
    color: var(--color-accent-primary);
    min-width: 45px;
    text-align: right;
}


/* ==================== Modal ==================== */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1000;
    align-items: center;
    justify-content: center;
}

.modal.active {
    display: flex;
}

.modal-backdrop {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(10px);
}

.modal-content {
    position: relative;
    max-width: 90vw;
    max-height: 90vh;
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    overflow-y: auto;
    box-shadow: var(--shadow-lg);
    animation: modalSlideIn 0.3s ease;
    display: flex;
    flex-direction: column;
}

@keyframes modalSlideIn {
    from {
        opacity: 0;
        transform: scale(0.9) translateY(20px);
    }

    to {
        opacity: 1;
        transform: scale(1) translateY(0);
    }
}

#modalImage {
    max-width: 100%;
    max-height: 50vh;
    display: block;
    object-fit: contain;
    cursor: zoom-in;
}

.modal-info {
    padding: var(--spacing-md) var(--spacing-lg);
    background: var(--color-bg-secondary);
}

.modal-info h3 {
    font-size: var(--font-size-lg);
    margin-bottom: 4px;
}

.modal-info p {
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
}

.modal-label-editor {
    margin-top: var(--spacing-md);
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--color-border);
}

.modal-label-editor label {
    display: block;
    font-size: var(--font-size-xs);
    color: var(--color-text-secondary);
    margin-bottom: 6px;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.modal-label-editor input {
    width: 100%;
    padding: 8px 12px;
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    color: var(--color-text-primary);
    font-size: var(--font-size-sm);
    font-family: var(--font-primary);
    margin-bottom: 8px;
    transition: all var(--transition-fast);
}

.modal-label-editor input:focus {
    outline: none;
    border-color: var(--color-accent-primary);
    background: var(--color-bg-secondary);
    box-shadow: 0 0 0 2px rgba(237, 152, 80, 0.15);
}

.modal-label-editor input::placeholder {
    color: var(--color-text-tertiary);
    opacity: 0.6;
}

.modal-label-editor button {
    width: 100%;
    padding: 8px 12px;
    font-size: var(--font-size-sm);
}

/* ==================== Animations ==================== */
@keyframes fadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ==================== Responsive Design ==================== */
@media (max-width: 1024px) {
    .timeline-controls {
        flex-direction: column;
    }

    .control-section {
        border-right: none;
        border-bottom: 1px solid rgba(230, 230, 230, 0.15);
        padding-right: 0;
        padding-bottom: var(--spacing-xs);
    }

    .control-section:last-child {
        border-bottom: none;
        padding-bottom: 0;
    }
}

@media (max-width: 768px) {
    .logo {
        font-size: var(--font-size-2xl);
    }

    .grid-items {
        grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
    }

    .control-row {
        flex-direction: column;
        align-items: stretch;
    }

    .control-group {
        width: 100%;
    }
}

/* ==================== Utilities ==================== */
.hidden {
    display: none !important;
}

/* ==================== Section Headers ==================== */
.section-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.step-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: var(--gradient-primary);
    color: white;
    font-size: var(--font-size-xl);
    font-weight: 700;
    box-shadow: var(--shadow-md);
}

.section-title {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--color-text-primary);
}

/* ==================== Upload Progress Indicator ==================== */
.upload-progress {
    display: none;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-xl);
    margin-top: var(--spacing-lg);
    background: var(--color-bg-glass-hover);
    border: 2px solid var(--color-accent-primary);
    border-radius: var(--radius-lg);
    animation: fadeInUp 0.4s ease;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid var(--color-bg-tertiary);
    border-top-color: var(--color-accent-secondary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

.upload-progress p {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--color-text-primary);
}

.upload-progress span {
    color: var(--color-accent-secondary);
}

/* ==================== Enhanced Timeline Button ==================== */
.create-timeline-btn {
    width: 100%;
    padding: var(--spacing-md) var(--spacing-lg);
    font-size: var(--font-size-lg);
    justify-content: center;
}

.create-timeline-btn svg {
    width: 24px;
    height: 24px;
}

/* ==================== Visual Separation ==================== */
.photo-grid {
    background: var(--color-bg-secondary);
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    border: 1px solid var(--color-border);
    box-shadow: var(--shadow-md);
}

.upload-zone h3 {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--color-text-primary);
}