:root {
    /* Color Palette - 仙女粉色系 */
    --color-bg-start: #FFF0F3;
    --color-bg-end: #FFE4E8;
    --color-bg: #FFFFFF;
    --color-bg-card: rgba(255, 255, 255, 0.75);
    --color-text-primary: #4A4A4A;
    --color-text-secondary: #8E8E93;
    --color-primary: #FF758C;
    --color-primary-hover: #FF5A76;
    --color-border: rgba(255, 117, 140, 0.15);
    
    /* Spacing */
    --sp-1: 4px;
    --sp-2: 8px;
    --sp-3: 12px;
    --sp-4: 16px;
    --sp-6: 24px;
    --sp-8: 32px;
    
    /* Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    
    /* Animation */
    --ease-spring: cubic-bezier(0.25, 0.8, 0.25, 1);
}

@media (prefers-color-scheme: dark) {
    :root {
        --color-bg-start: #2A1A1E;
        --color-bg-end: #1A1012;
        --color-bg: #1A1012;
        --color-bg-card: rgba(45, 25, 30, 0.7);
        --color-text-primary: #F5F5F7;
        --color-text-secondary: #A09A9B;
        --color-border: rgba(255, 117, 140, 0.2);
        --color-primary: #FF6B8B;
        --color-primary-hover: #FF8BA5;
    }
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial, sans-serif;
    background: linear-gradient(135deg, var(--color-bg-start) 0%, var(--color-bg-end) 100%);
    color: var(--color-text-primary);
    -webkit-font-smoothing: antialiased;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: env(safe-area-inset-top) var(--sp-4) env(safe-area-inset-bottom) var(--sp-4);
}

/* UI Components */
.container {
    max-width: 800px;
    width: 100%;
    margin-top: var(--sp-8);
}

.header {
    text-align: center;
    margin-bottom: var(--sp-6);
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
}

.header h1 {
    font-size: 32px;
    font-weight: 600;
    letter-spacing: -0.5px;
}

.card-glass {
    background: var(--color-bg-card);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--sp-6);
    box-shadow: 0 4px 24px rgba(0,0,0,0.04);
}

/* Upload Area */
.upload-area {
    border: 2px dashed var(--color-border);
    border-radius: var(--radius-md);
    padding: var(--sp-8);
    text-align: center;
    cursor: pointer;
    transition: all 0.3s var(--ease-spring);
    margin-bottom: var(--sp-6);
}

.upload-area:hover {
    border-color: var(--color-primary);
    background: rgba(0, 122, 255, 0.05);
}

/* Controls */
.controls-group {
    margin-bottom: var(--sp-6);
}

.controls-group h3 {
    font-size: 14px;
    color: var(--color-text-secondary);
    margin-bottom: var(--sp-3);
    font-weight: 500;
}

.segment-control {
    display: flex;
    background: rgba(118, 118, 128, 0.12);
    border-radius: var(--radius-sm);
    padding: 2px;
}

.segment-btn {
    flex: 1;
    background: transparent;
    border: none;
    padding: var(--sp-2) var(--sp-4);
    border-radius: 6px;
    font-size: 14px;
    font-weight: 500;
    color: var(--color-text-primary);
    cursor: pointer;
    transition: background 0.2s var(--ease-spring);
}

.segment-btn.active {
    background: var(--color-bg);
    box-shadow: 0 3px 8px rgba(0,0,0,0.12), 0 3px 1px rgba(0,0,0,0.04);
}

.custom-input {
    flex: 1;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    padding: var(--sp-2) var(--sp-3);
    font-size: 14px;
    background: var(--color-bg);
    color: var(--color-text-primary);
    outline: none;
    transition: border-color 0.2s;
    width: 0; /* allows flex: 1 to work properly */
}

.custom-input:focus {
    border-color: var(--color-primary);
}

/* Toggle Switch */
.toggle-switch {
    display: flex;
    align-items: center;
    gap: var(--sp-3);
    cursor: pointer;
}

.toggle-bg {
    width: 40px;
    height: 24px;
    background: rgba(120, 120, 128, 0.32);
    border-radius: 12px;
    position: relative;
    transition: background 0.3s;
}

.toggle-knob {
    width: 20px;
    height: 20px;
    background: white;
    border-radius: 50%;
    position: absolute;
    top: 2px;
    left: 2px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.2);
    transition: transform 0.3s var(--ease-spring);
}

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

.toggle-input:checked + .toggle-bg .toggle-knob {
    transform: translateX(16px);
}

.toggle-input {
    display: none;
}

/* Colors List */
.color-options {
    display: flex;
    gap: var(--sp-3);
    margin-top: var(--sp-3);
    opacity: 0.5;
    pointer-events: none;
    transition: opacity 0.3s;
}

.color-options.active {
    opacity: 1;
    pointer-events: auto;
}

.color-btn {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    border: 2px solid transparent;
    cursor: pointer;
    box-shadow: 0 2px 6px rgba(0,0,0,0.1);
    transition: transform 0.2s var(--ease-spring);
}

.color-btn:hover {
    transform: scale(1.1);
}

.color-btn.active {
    border: 2px solid var(--color-text-primary);
    transform: scale(1.1);
}

/* Workspace */
.workspace {
    display: none;
    gap: var(--sp-6);
    flex-direction: column;
}

.editor-container {
    height: 400px;
    background: #e9ecef;
    border-radius: var(--radius-md);
    overflow: hidden;
    position: relative;
}

/* Buttons */
.btn-primary {
    background: var(--color-primary);
    color: white;
    border: none;
    padding: var(--sp-3) var(--sp-6);
    border-radius: var(--radius-lg);
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    width: 100%;
    transition: all 0.2s var(--ease-spring);
}

.btn-primary:hover {
    background: var(--color-primary-hover);
    transform: scale(0.98);
}

.btn-primary:active {
    transform: scale(0.95);
}

.btn-secondary {
    background: rgba(118, 118, 128, 0.12);
    color: var(--color-text-primary);
    border: none;
    padding: var(--sp-3) var(--sp-6);
    border-radius: var(--radius-lg);
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    flex: 1;
    transition: all 0.2s var(--ease-spring);
}

.btn-secondary:hover {
    background: rgba(118, 118, 128, 0.2);
    transform: scale(0.98);
}

.btn-secondary:active {
    transform: scale(0.95);
}

@keyframes fade-in-up {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.animate-fade-in {
    animation: fade-in-up 0.5s var(--ease-spring) forwards;
}

/* Loader */
.loader-overlay {
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    background: rgba(255,255,255,0.8);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 10;
    backdrop-filter: blur(4px);
    display: none;
}

.loader-spinner {
    width: 40px; height: 40px;
    border: 4px solid var(--color-border);
    border-top-color: var(--color-primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: var(--sp-3);
}

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

/* Size helper */
.size-helper {
    position: absolute;
    bottom: var(--sp-4);
    left: 50%;
    transform: translateX(-50%);
    background: rgba(0,0,0,0.6);
    color: white;
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 12px;
    z-index: 5;
    pointer-events: none;
}

/* Toast Notification */
.toast {
    position: fixed;
    top: calc(env(safe-area-inset-top, 24px) + var(--sp-4));
    left: 50%;
    transform: translateX(-50%) translateY(-100px);
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    color: var(--color-primary);
    padding: var(--sp-3) var(--sp-6);
    border-radius: var(--radius-lg);
    box-shadow: 0 8px 32px rgba(255, 117, 140, 0.2);
    font-weight: 500;
    font-size: 14px;
    z-index: 1000;
    opacity: 0;
    transition: all 0.5s var(--ease-spring);
    text-align: center;
    line-height: 1.5;
    white-space: pre-line;
    border: 1px solid var(--color-border);
}

.toast.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

/* Mobile Optimizations for PWA */
@media screen and (max-width: 768px) {
    .container {
        margin-top: 0;
        padding-top: env(safe-area-inset-top);
    }
    
    body {
        padding: 0;
        background: linear-gradient(135deg, var(--color-bg-start) 0%, var(--color-bg-end) 100%);
    }

    .card-glass {
        border-radius: 0;
        border-left: none;
        border-right: none;
        border-bottom: none;
        box-shadow: none;
        padding: var(--sp-4);
        flex: 1;
        display: flex;
        flex-direction: column;
    }

    .header {
        margin-top: var(--sp-4);
        margin-bottom: var(--sp-4);
    }

    .header h1 {
        font-size: 24px;
    }

    .editor-container {
        height: 60vh; /* Make the editor take up more screen space on mobile */
    }

    .controls-group {
        margin-bottom: var(--sp-4);
    }

    .segment-btn {
        padding: var(--sp-3) var(--sp-2); /* larger touch targets */
    }
}

/* Install Guide */
.install-guide {
    background: rgba(255, 117, 140, 0.08);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    margin-bottom: var(--sp-4);
    padding: var(--sp-3);
    animation: fade-in-up 0.5s var(--ease-spring) forwards;
}

.install-guide-content {
    display: flex;
    align-items: center;
    gap: var(--sp-3);
}

.install-text {
    display: flex;
    flex-direction: column;
    flex: 1;
}

.install-text strong {
    font-size: 14px;
    color: var(--color-primary);
    margin-bottom: 2px;
}

.install-text span {
    font-size: 12px;
    color: var(--color-text-secondary);
    line-height: 1.4;
}

.close-btn {
    background: none;
    border: none;
    font-size: 20px;
    color: var(--color-text-secondary);
    cursor: pointer;
    padding: 0;
    line-height: 1;
}

/* Action Sheet */
.action-sheet-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.4);
    z-index: 2000;
    backdrop-filter: blur(4px);
    -webkit-backdrop-filter: blur(4px);
    animation: fade-in 0.3s ease forwards;
}

.action-sheet {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background: var(--color-bg-card);
    border-radius: 20px 20px 0 0;
    padding: var(--sp-4) var(--sp-4) env(safe-area-inset-bottom) var(--sp-4);
    box-shadow: 0 -4px 24px rgba(0,0,0,0.1);
    transform: translateY(100%);
    animation: slide-up 0.4s var(--ease-spring) forwards;
}

.sheet-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--sp-4);
}

.sheet-header h3 {
    font-size: 18px;
    font-weight: 600;
}

.sheet-body {
    display: flex;
    flex-direction: column;
    gap: var(--sp-3);
    margin-bottom: var(--sp-3);
}

.sheet-btn {
    display: flex;
    align-items: center;
    gap: var(--sp-3);
    background: rgba(118, 118, 128, 0.08);
    border: none;
    padding: var(--sp-3);
    border-radius: var(--radius-lg);
    cursor: pointer;
    text-align: left;
    transition: all 0.2s;
}

.sheet-btn.primary-sheet-btn {
    background: rgba(255, 117, 140, 0.1);
    border: 1px solid var(--color-border);
}

.sheet-btn-text {
    display: flex;
    flex-direction: column;
}

.sheet-btn-text strong {
    font-size: 15px;
    color: var(--color-text-primary);
    margin-bottom: 2px;
}

.sheet-btn.primary-sheet-btn .sheet-btn-text strong {
    color: var(--color-primary);
}

.sheet-btn-text span {
    font-size: 12px;
    color: var(--color-text-secondary);
}

@keyframes fade-in {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes slide-up {
    from { transform: translateY(100%); }
    to { transform: translateY(0); }
}

/* Welcome Screen */
.welcome-screen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: var(--color-bg-card);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    z-index: 9999;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: opacity 0.8s var(--ease-spring), visibility 0.8s;
}

.welcome-screen.fade-out {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
}

.welcome-content {
    text-align: center;
    animation: slideUpFade 1s var(--ease-spring) forwards;
}

.welcome-title {
    font-size: 32px;
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: 12px;
    background: linear-gradient(135deg, var(--color-primary), #FFB7C5);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.welcome-subtitle {
    font-size: 15px;
    color: var(--color-text-secondary);
}

@keyframes slideUpFade {
    0% {
        opacity: 0;
        transform: translateY(20px) scale(0.95);
    }
    100% {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}