/* Base styles & variables */
:root {
    --color-primary: #9B1B30;
    --color-primary-dark: #7A1426;
    --color-primary-light: #B82A44;
    --color-secondary: #008080;
    --color-secondary-light: #00A0A0;
    --color-white: #FFFFFF;
    --color-gray-50: #F8F9FA;
    --color-gray-100: #F0F0F0;
    --color-gray-200: #E0E0E0;
    --color-gray-600: #666666;
    --color-gray-900: #1A1A1A;
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    --max-width: 1200px;
    --border-radius: 12px;
    --box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    background: var(--color-white);
    color: var(--color-gray-900);
    line-height: 1.6;
    margin: 0;
    padding: 0;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 2rem;
    font-size: 1rem;
    font-weight: 600;
    border: none;
    border-radius: 50px;
    cursor: pointer;
    transition: background 0.2s, transform 0.1s;
    text-decoration: none;
    text-align: center;
}

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

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

.btn-secondary {
    background: var(--color-secondary);
    color: var(--color-white);
}
.btn-secondary:hover,
.btn-secondary:focus {
    background: var(--color-secondary-light);
}

/* Header */
.header {
    background: var(--color-primary);
    color: var(--color-white);
    padding: 0.75rem 0;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 100;
}
.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.5rem;
    font-weight: 700;
}
.logo img {
    width: 40px;
    height: 40px;
}

#theme-toggle {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--color-white);
    padding: 0.25rem 0.5rem;
}

/* Hero */
.hero {
    text-align: center;
    padding: 3rem 0 1.5rem;
    background: var(--color-gray-50);
}
.hero h1 {
    font-size: 2.5rem;
    color: var(--color-primary);
    margin-bottom: 0.5rem;
}
.hero p {
    font-size: 1.2rem;
    color: var(--color-gray-600);
}

/* Upload */
.upload-section {
    padding: 2rem 0;
}
.upload-zone {
    border: 3px dashed var(--color-secondary);
    border-radius: var(--border-radius);
    padding: 3rem 2rem;
    text-align: center;
    background: var(--color-gray-50);
    transition: background 0.3s, border-color 0.3s;
    cursor: pointer;
    position: relative;
}
.upload-zone.dragover {
    background: var(--color-gray-100);
    border-color: var(--color-primary);
}
.upload-icon {
    font-size: 4rem;
    margin-bottom: 1rem;
}
.upload-zone h2 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}
.upload-zone p {
    color: var(--color-gray-600);
}
.upload-hint {
    font-size: 0.9rem;
    margin-top: 1rem;
    color: var(--color-gray-600);
}
#file-input {
    position: absolute;
    inset: 0;
    opacity: 0;
    cursor: pointer;
}

/* Processing */
.processing-section {
    padding: 2rem 0;
}
.processing-status {
    text-align: center;
    padding: 2rem;
    background: var(--color-gray-50);
    border-radius: var(--border-radius);
}
.spinner {
    border: 4px solid var(--color-gray-200);
    border-top: 4px solid var(--color-primary);
    border-radius: 50%;
    width: 50px;
    height: 50px;
    animation: spin 1s linear infinite;
    margin: 0 auto 1rem;
}
@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}
#status-message {
    font-size: 1.1rem;
    font-weight: 500;
}
.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--color-gray-200);
    border-radius: 4px;
    margin-top: 1rem;
    overflow: hidden;
}
.progress-fill {
    height: 100%;
    background: var(--color-primary);
    width: 0%;
    transition: width 0.3s;
}

/* Result */
.result-section {
    padding: 2rem 0;
}
.result-container {
    background: var(--color-gray-50);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    box-shadow: var(--box-shadow);
}
.before-after-slider {
    position: relative;
    overflow: hidden;
    border-radius: var(--border-radius);
    aspect-ratio: 1 / 1;
    max-height: 600px;
    background: repeating-conic-gradient(var(--color-gray-200) 0% 25%, var(--color-white) 0% 50%) 0 0 / 20px 20px;
}
.image-wrapper {
    position: relative;
    width: 100%;
    height: 100%;
}
#result-image {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: contain;
    display: block;
}
.checkerboard {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: repeating-conic-gradient(var(--color-gray-200) 0% 25%, var(--color-white) 0% 50%) 0 0 / 20px 20px;
    z-index: -1;
}
.slider-handle {
    position: absolute;
    top: 0;
    left: 50%;
    width: 4px;
    height: 100%;
    background: var(--color-primary);
    cursor: ew-resize;
    z-index: 10;
    transform: translateX(-50%);
}
.slider-handle::before {
    content: "◀";
    position: absolute;
    top: 50%;
    left: -2rem;
    transform: translateY(-50%);
    font-size: 2rem;
    color: var(--color-primary);
}
.slider-handle::after {
    content: "▶";
    position: absolute;
    top: 50%;
    right: -2rem;
    transform: translateY(-50%);
    font-size: 2rem;
    color: var(--color-primary);
}

.result-controls {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-top: 1.5rem;
    flex-wrap: wrap;
}

/* Features */
.features {
    padding: 3rem 0;
    background: var(--color-gray-50);
}
.features h2 {
    text-align: center;
    margin-bottom: 2rem;
    color: var(--color-primary);
}
.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
}
.feature {
    text-align: center;
}
.feature-icon {
    font-size: 2.5rem;
    display: block;
    margin-bottom: 0.5rem;
}
.feature h3 {
    font-size: 1.2rem;
}

/* Privacy & FAQ */
.privacy,
.faq {
    padding: 2rem 0;
}
.privacy h2,
.faq h2 {
    text-align: center;
    color: var(--color-primary);
    margin-bottom: 1rem;
}
.faq details {
    margin: 0.5rem 0;
    padding: 0.5rem 0;
    border-bottom: 1px solid var(--color-gray-200);
}
.faq summary {
    cursor: pointer;
    font-weight: 600;
    padding: 0.5rem 0;
}
.faq summary:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}
.faq p {
    padding: 0.5rem 0 1rem 1.5rem;
}

/* Footer */
.footer {
    background: var(--color-gray-900);
    color: var(--color-white);
    padding: 2rem 0;
    text-align: center;
}
.footer a {
    color: var(--color-secondary-light);
    text-decoration: none;
}
.footer a:hover {
    text-decoration: underline;
}