/*
    Handbook CSS - A Professional Refactor
    ---------------------------------------------
    This stylesheet has been completely rewritten with a modern,
    component-based architecture using CSS Custom Properties for a
    scalable and maintainable design system. The visual and
    interactive experience remains identical to the original.
*/

/* ==========================================================================
   1. FOUNDATION & DESIGN TOKENS
   ========================================================================== */

/* --- Font Import --- */
@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@400;600;700&display=swap');

:root {
    /* Base Palette (Light Mode) */
    --c-bg: #F8F9FA;
    --c-surface: #FFFFFF;
    --c-text-primary: #1a1a1a;
    --c-text-secondary: #5a646e;
    --c-accent: #0077ff;
    --c-border: #e9ecef;
    --c-shadow-color: rgba(0, 4, 48, 0.05);

    /* UI Feedback Colors */
    --c-success: #28a745;
    --c-error: #dc3545;
    --c-info: #17a2b8;
    --c-light-text-on-accent: #ffffff;
    
    /* Typography */
    --font-primary: 'Poppins', sans-serif;
    --fw-regular: 400;
    --fw-semibold: 600;
    --fw-bold: 700;

    /* Spacing & Sizing */
    --space-xs: 0.5rem;   /* 8px */
    --space-sm: 0.75rem;  /* 12px */
    --space-md: 1rem;     /* 16px */
    --space-lg: 1.5rem;   /* 24px */
    --space-xl: 2rem;     /* 32px */
    --space-xxl: 2.5rem;  /* 40px */
    
    /* Borders & Radii */
    --radius-sm: 8px;
    --radius-md: 16px;
    --radius-lg: 24px;
    --radius-full: 50px;
    --border-width: 1px;

    /* Shadows */
    --shadow-sm: 0 4px 15px var(--c-shadow-color);
    --shadow-md: 0 8px 30px var(--c-shadow-color);
    --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.2);

    /* Transitions */
    --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-medium: 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-playful: 0.6s cubic-bezier(0.34, 1.56, 0.64, 1);
}

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

html {
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-primary);
    background: var(--c-bg);
    color: var(--c-text-primary);
    transition: background 0.5s ease, color 0.5s ease, background-image 0.5s ease;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    background-attachment: fixed;
}

h1, h2, h3 {
    font-weight: var(--fw-bold);
    color: var(--c-text-primary);
}

p {
    color: var(--c-text-secondary);
    line-height: 1.6;
}

a {
    color: var(--c-accent);
    text-decoration: none;
    transition: opacity var(--transition-fast);
}

a:hover {
    opacity: 0.8;
}

input, button {
    font-family: inherit;
    font-size: inherit;
    color: inherit;
}

/* ==========================================================================
   2. THEMES
   ========================================================================== */

body.dark-mode {
    --c-bg: #121212; --c-surface: #1E1E1E; --c-text-primary: #EAEAEA;
    --c-text-secondary: #888888; --c-accent: #00A6ED; --c-border: #2c2c2c;
    --c-shadow-color: rgba(0, 0, 0, 0.2);
}
body.cream-mode {
    --c-bg: #FDF8E1; --c-surface: #FFFBF0; --c-text-primary: #6B4F4F;
    --c-text-secondary: #9E8B7D; --c-accent: #C19A6B; --c-border: #EFE8D0;
    --c-shadow-color: rgba(107, 79, 79, 0.08);
}
body.pop-blue-mode {
    --c-bg: #F1FAEE; --c-surface: #ffffff; --c-text-primary: #1D3557;
    --c-text-secondary: #457B9D; --c-accent: #E63946; --c-border: #a8dadc4d;
    --c-shadow-color: rgba(29, 53, 87, 0.08);
}
body.pop-green-mode {
    --c-bg: #E8FDF0; --c-surface: #ffffff; --c-text-primary: #004D40;
    --c-text-secondary: #006A57; --c-accent: #FF6B6B; --c-border: #b2f7c24d;
    --c-shadow-color: rgba(0, 77, 64, 0.08);
}
body.sunset-mode {
    --c-bg: #FFF4E8; --c-surface: #ffffff; --c-text-primary: #5E376D;
    --c-text-secondary: #A16A70; --c-accent: #FF7B54; --c-border: #ffecd94d;
    --c-shadow-color: rgba(94, 55, 109, 0.08);
}
body.midnight-mode {
    --c-bg: #0F172A; --c-surface: #1E293B; --c-text-primary: #E2E8F0;
    --c-text-secondary: #94A3B8; --c-accent: #818CF8; --c-border: #334155;
    --c-shadow-color: rgba(0, 0, 0, 0.2);
}

/* --- Gradient Themes --- */
body.sunny-meadow-mode {
    --c-bg: #FCF9E8;
    --c-surface: #FFFFFF;
    --c-text-primary: #5c5221;
    --c-text-secondary: #857c58;
    --c-accent: #E07A5F;
    --c-border: #f2e9c2;
    --c-shadow-color: rgba(107, 79, 79, 0.08);
    background-image: linear-gradient(160deg, rgba(246, 211, 101, 0.2) 0%, rgba(253, 160, 133, 0.15) 100%);
}
body.ocean-breeze-mode {
    --c-bg: #E6F7F9;
    --c-surface: #FFFFFF;
    --c-text-primary: #0b4f6c;
    --c-text-secondary: #247b7b;
    --c-accent: #17A2B8;
    --c-border: #cceef2;
    --c-shadow-color: rgba(29, 53, 87, 0.08);
    background-image: linear-gradient(160deg, rgba(91, 36, 122, 0.1) 0%, rgba(27, 206, 223, 0.15) 100%);
}
body.starry-night-mode {
    --c-bg: #192b33;
    --c-surface: rgba(255, 255, 255, 0.07);
    --c-text-primary: #ffffff;
    --c-text-secondary: rgba(255, 255, 255, 0.7);
    --c-border: rgba(255, 255, 255, 0.15);
    --c-shadow-color: rgba(0, 0, 0, 0.25);
    --c-accent: #a3bded;
    background-image: linear-gradient(135deg, rgba(15, 32, 39, 0.5) 0%, rgba(32, 58, 67, 0.7) 50%, rgba(44, 83, 100, 0.7) 100%);
}


/* ==========================================================================
   3. LAYOUT
   ========================================================================== */
.page-container {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    animation: fadeIn 0.5s ease-in-out;
}

.page-main-content {
    padding: 100px var(--space-xl) var(--space-xl) var(--space-xl);
    width: 100%;
    max-width: 800px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: var(--space-xxl);
}

.page-title {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: var(--space-md);
}

#home-page main {
    flex-grow: 1;
    display: grid;
    place-content: center;
    text-align: center;
    padding: var(--space-xl);
}

#home-page footer {
    padding: var(--space-xl);
    width: 100%;
    max-width: 600px;
    margin: 0 auto;
    text-align: center;
}

/* ==========================================================================
   4. COMPONENTS
   ========================================================================== */

/* --- Header & Theme Manager --- */
header {
    position: fixed;
    top: 20px;
    left: 20px;
    right: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 44px;
    z-index: 100;
    transition: transform var(--transition-medium);
}
header.header-hidden {
    transform: translateY(calc(-100% - 30px));
}
#theme-manager {
    display: flex;
    align-items: center;
    background-color: color-mix(in srgb, var(--c-surface) 80%, transparent);
    backdrop-filter: blur(10px);
    border-radius: var(--radius-full);
    box-shadow: var(--shadow-sm);
    border: var(--border-width) solid var(--c-border);
    transition: all var(--transition-playful);
}
.theme-switcher {
    display: flex;
    gap: var(--space-xs);
    padding: 0 var(--space-xs);
    max-width: 0;
    opacity: 0;
    overflow: hidden;
    transition: max-width var(--transition-medium), opacity 0.2s ease, padding var(--transition-medium);
}
#theme-manager.themes-visible .theme-switcher {
    max-width: 450px;
    opacity: 1;
    padding: var(--space-xs);
}
.theme-switcher button {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    border: 2px solid var(--c-border);
    cursor: pointer;
    transition: all var(--transition-playful);
    flex-shrink: 0;
}
.theme-switcher button:hover {
    transform: scale(1.15) rotate(15deg);
}
.theme-switcher button.active {
    border-color: var(--c-accent);
    transform: scale(1.25) rotate(-5deg);
    box-shadow: 0 0 12px color-mix(in srgb, var(--c-accent) 60%, transparent);
}
#toggle-themes-btn .arrow-icon {
    transition: transform var(--transition-medium);
}
#theme-manager.themes-visible .arrow-icon {
    transform: rotate(180deg);
}
#light-btn { background-color: #F8F9FA; }
#dark-btn  { background-color: #121212; }
#cream-btn { background-color: #FDF8E1; }
#pop-blue-btn { background-color: #F1FAEE; }
#pop-green-btn { background-color: #E8FDF0; }
#sunset-btn { background-color: #FFF4E8; }
#midnight-btn { background-color: #0F172A; }
#sunny-meadow-btn { background: linear-gradient(135deg, #f6d365, #fda085); }
#ocean-breeze-btn { background: linear-gradient(135deg, #5b247a, #1bcedf); }
#starry-night-btn { background: linear-gradient(135deg, #0f2027, #2c5364); }

/* --- Buttons --- */
.icon-btn {
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
    color: var(--c-text-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: color var(--transition-fast), transform var(--transition-fast);
}
.icon-btn svg {
    stroke: currentColor;
}
.icon-btn:hover {
    color: var(--c-accent);
    transform: scale(1.1);
}
.icon-btn:active {
    transform: scale(1);
}

/* --- Card --- */
.card {
    background-color: var(--c-surface);
    border-radius: var(--radius-lg);
    border: var(--border-width) solid var(--c-border);
    padding: var(--space-lg);
    transition: all var(--transition-medium);
}

/* --- Logo & SOTD --- */
.logo-container {
    cursor: pointer;
    transition: transform var(--transition-playful);
    animation: popIn 0.8s var(--transition-playful) backwards;
    margin-bottom: var(--space-xl);
}
.logo-container:active {
    transform: scale(0.95) rotate(-3deg);
}
.main-icon {
    fill: var(--c-accent);
    transition: fill var(--transition-medium);
    margin-bottom: var(--space-xs);
}
.logo-container h1 {
    font-size: clamp(2.5rem, 8vw, 3.5rem);
    font-weight: var(--fw-bold);
}
.logo-container:hover .main-icon {
    fill: var(--c-text-primary);
}
.sotd-wrapper {
    margin-top: -1rem;
    margin-bottom: var(--space-xl);
    display: grid;
    place-items: center;
    animation: fadeIn 1s 0.5s ease backwards;
}
.sotd-label {
    font-size: 0.8rem;
    font-weight: var(--fw-semibold);
    color: var(--c-text-secondary);
    margin-bottom: var(--space-xs);
    letter-spacing: 0.5px;
}
#sotd-card, .flashcard-container {
    width: 100%;
    perspective: 1500px;
    cursor: pointer;
}
#sotd-card { max-width: 320px; height: 80px; }
#sotd-card .sotd-card-inner, .flashcard-container .flashcard {
    position: relative;
    width: 100%;
    height: 100%;
    transition: transform 0.8s var(--transition-playful);
    transform-style: preserve-3d;
}
#sotd-card.is-flipped .sotd-card-inner, .flashcard-container.is-flipped .flashcard {
    transform: rotateY(180deg);
}
.sotd-front, .sotd-back, .flashcard-front, .flashcard-back {
    position: absolute;
    width: 100%;
    height: 100%;
    inset: 0;
    backface-visibility: hidden;
    display: grid;
    place-content: center;
    padding: var(--space-xl);
    border-radius: var(--radius-lg);
    background: var(--c-surface);
    border: var(--border-width) solid var(--c-border);
    box-shadow: var(--shadow-md);
    text-align: center;
}
.sotd-back, .flashcard-back {
    transform: rotateY(180deg);
}
#sotd-name { font-size: 1.2rem; font-weight: var(--fw-semibold); }
#sotd-desc { font-size: 0.9rem; }


/* --- Search --- */
.search-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-sm);
}
.search-helper {
    font-size: 0.9rem;
    color: var(--c-text-secondary);
    margin-bottom: var(--space-xs);
    transition: all var(--transition-fast);
}
.search-helper.hidden {
    opacity: 0;
}
.search-form {
    position: relative;
    width: 100%;
}
.search-form input, .language-search-container input {
    width: 100%;
    padding: var(--space-md) 1.75rem;
    font-size: 1rem;
    background-color: var(--c-surface);
    border: var(--border-width) solid var(--c-border);
    border-radius: var(--radius-full);
    outline: none;
    transition: all var(--transition-medium);
}
.search-form input {
    padding-right: 4rem;
}
.search-form input::placeholder, .language-search-container input::placeholder {
    color: var(--c-text-secondary);
    opacity: 0.7;
}
.search-form input:focus, .language-search-container input:focus {
    border-color: var(--c-accent);
    box-shadow: 0 0 0 4px color-mix(in srgb, var(--c-accent) 20%, transparent);
}
.search-clear-btn {
    position: absolute;
    right: var(--space-md);
    top: 50%;
    transform: translateY(-50%);
    opacity: 0;
    pointer-events: none;
    transition: all var(--transition-fast);
}
.search-clear-btn.visible {
    opacity: 1;
    transform: translateY(-50%) scale(1);
    pointer-events: auto;
}
.language-search-container {
    width: 100%;
    max-height: 0;
    opacity: 0;
    transform: translateY(-10px);
    transition: all var(--transition-medium);
    overflow: hidden;
}
.language-search-container.visible {
    max-height: 100px;
    opacity: 1;
    transform: translateY(0);
}

/* --- Footer Links --- */
.footer-links {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: var(--space-md);
    margin-top: var(--space-xl);
}
.footer-link-btn {
    font-size: 0.8rem;
    font-weight: var(--fw-semibold);
    padding: 0.6rem 1.2rem;
    border-radius: var(--radius-full);
    background-color: var(--c-surface);
    color: var(--c-text-secondary);
    border: var(--border-width) solid var(--c-border);
    transition: all var(--transition-fast);
}
.footer-link-btn:hover {
    background-color: var(--c-accent);
    color: var(--c-light-text-on-accent);
    border-color: var(--c-accent);
    transform: translateY(-2px);
    box-shadow: 0 4px 10px var(--c-shadow-color);
}
.footer-link-btn:active {
    transform: translateY(-1px);
}
.copyright {
    font-size: 0.8rem;
    color: var(--c-text-secondary);
    opacity: 0.7;
}

/* --- Account Page Components --- */
.account-profile { display: flex; align-items: center; gap: var(--space-lg); }
.account-avatar {
    width: 80px; height: 80px;
    border-radius: 50%; background-color: var(--c-accent);
    color: var(--c-light-text-on-accent); display: grid; place-content: center;
    font-size: 2rem; font-weight: var(--fw-bold); flex-shrink: 0;
    transition: background-color var(--transition-medium);
}
.account-name { font-size: 2.25rem; margin-bottom: 0.25rem; }
.membership-date { font-size: 0.9rem; }

.subscription-box-link { display: flex; justify-content: space-between; align-items: center; }
.manage-sub-button {
    font-weight: var(--fw-semibold); font-size: 0.9rem;
    padding: 0.75rem 1.25rem; border-radius: var(--radius-full);
    color: var(--c-accent); border: var(--border-width) solid var(--c-accent);
}
.manage-sub-button:hover { background-color: var(--c-accent); color: var(--c-light-text-on-accent); opacity: 1; }
.manage-sub-button:active { transform: scale(0.97); }

.stats-container { display: flex; justify-content: center; gap: clamp(2rem, 10vw, 4rem); text-align: center; }
.stat-item { cursor: pointer; transition: transform var(--transition-fast); }
.stat-item:hover { transform: translateY(-5px); }
.stat-number { font-size: 2.5rem; font-weight: var(--fw-bold); color: var(--c-accent); transition: color var(--transition-medium); }
.stat-item:hover .stat-number { color: var(--c-text-primary); }
.stat-label { font-size: 0.9rem; }

.group-management-container h3 { font-size: 1.75rem; margin-bottom: var(--space-lg); text-align: center; }
.member-list { display: flex; flex-direction: column; gap: 0.75rem; margin-bottom: var(--space-xl); }
.member-item {
    display: flex; justify-content: space-between; align-items: center; padding: var(--space-md);
    background-color: color-mix(in srgb, var(--c-surface) 50%, var(--c-bg));
    border-radius: var(--radius-md); border: var(--border-width) solid var(--c-border);
    transition: all 0.3s ease, opacity 0.5s ease; opacity: 0; transform: translateY(10px);
    animation: fadeIn 0.5s ease forwards;
}
.member-item:hover { transform: translateY(10px) translateX(5px); box-shadow: -5px 5px 20px var(--c-shadow-color); border-color: color-mix(in srgb, var(--c-border) 50%, var(--c-accent)); }
.member-item.removing { opacity: 0; transform: translateX(-20px); }
.member-actions { display: flex; align-items: center; gap: var(--space-md); }
.member-role { font-size: 0.8rem; font-weight: var(--fw-semibold); padding: 0.3rem 0.6rem; border-radius: var(--radius-sm); background-color: var(--c-border); color: var(--c-text-secondary); }
.member-role.admin { background-color: var(--c-accent); color: var(--c-light-text-on-accent); }
.remove-member-btn { color: var(--c-text-secondary); }
.remove-member-btn:hover { color: var(--c-error); background-color: color-mix(in srgb, var(--c-error) 15%, transparent); border-radius: 50%; }

.add-member-form { display: flex; gap: var(--space-md); }
.add-member-form input { flex-grow: 1; border-radius: var(--radius-md); padding: 0.75rem 1rem; }
.add-member-form input.error { animation: shake 0.5s ease-in-out; border-color: var(--c-error); }
.add-member-form button {
    font-weight: var(--fw-semibold); font-size: 1rem; padding: 0.75rem var(--space-lg); border: none;
    border-radius: var(--radius-md); background-color: var(--c-accent); color: var(--c-light-text-on-accent);
    cursor: pointer; transition: all var(--transition-fast);
}
.add-member-form button:hover { opacity: 0.85; transform: translateY(-2px); }
.add-member-form button:active { transform: translateY(0); opacity: 1; }
.add-member-form button:disabled { opacity: 0.6; cursor: wait; }

.account-actions { display: flex; justify-content: center; }
.logout-button {
    color: var(--c-text-secondary); font-size: 1rem; cursor: pointer; padding: var(--space-xs) var(--space-md);
    border-radius: var(--radius-md); transition: all var(--transition-fast);
    background: none; border: none; font-weight: var(--fw-regular);
}
.logout-button:hover { color: var(--c-error); background-color: color-mix(in srgb, var(--c-error) 10%, transparent); }

/* --- Popups & Toasts --- */
.popup-overlay {
    position: fixed; inset: 0; background-color: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(8px); display: grid; place-items: center; z-index: 1000;
    opacity: 0; transition: opacity 0.3s ease-in-out; pointer-events: none;
}
.popup-overlay.show { opacity: 1; pointer-events: auto; }
.popup-content {
    background: var(--c-surface); padding: var(--space-xxl) var(--space-xl); border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg); max-width: 90vw; width: 420px;
    text-align: center; position: relative; transform: scale(0.9); transition: all var(--transition-playful);
}
.popup-overlay.show .popup-content { transform: scale(1); }
.popup-close-btn { position: absolute; top: var(--space-md); right: var(--space-md); }

#toast-container { position: fixed; bottom: 20px; right: 20px; z-index: 2000; display: flex; flex-direction: column; gap: 10px; }
.toast {
    padding: 14px 22px; border-radius: var(--radius-md); font-weight: var(--fw-semibold);
    color: var(--c-light-text-on-accent); box-shadow: 0 5px 25px rgba(0,0,0,0.15);
    opacity: 0; transform: translateX(calc(100% + 20px));
    transition: all 0.6s cubic-bezier(0.68, -0.6, 0.27, 1.55);
}
.toast.show { opacity: 1; transform: translateX(0); }
.toast.toast-success { background-color: var(--c-success); }
.toast.toast-error { background-color: var(--c-error); }
.toast.toast-info { background-color: var(--c-info); }

/* --- Practice Page --- */
.practice-container {
    display: flex; flex-direction: column; align-items: center; justify-content: center;
    gap: var(--space-xxl); width: 100%; max-width: 500px; flex-grow: 1; padding: var(--space-xl); margin: 0 auto;
}
.flashcard-container { height: 280px; }
.flashcard-term { font-size: 2.25rem; font-weight: var(--fw-bold); min-height: 44px; }
.flashcard-definition { font-size: 1.25rem; min-height: 30px; }
.practice-controls { display: flex; gap: var(--space-sm); align-items: center; justify-content: center; flex-wrap: wrap; }
.practice-btn {
    font-size: 1rem; font-weight: var(--fw-semibold);
    padding: 0.75rem var(--space-lg); border-radius: var(--radius-full);
    border: var(--border-width) solid var(--c-border); background-color: var(--c-surface);
    color: var(--c-text-primary); cursor: pointer; transition: all var(--transition-fast);
}
.practice-btn:hover { transform: translateY(-3px); border-color: var(--c-accent); box-shadow: var(--shadow-sm); }
.practice-btn:active { transform: translateY(0); }
.practice-btn.shuffle { background-color: var(--c-accent); color: var(--c-light-text-on-accent); border-color: var(--c-accent); }
.practice-btn.known { background-color: var(--c-success); color: var(--c-light-text-on-accent); border-color: var(--c-success); }
.card-counter { color: var(--c-text-secondary); font-weight: var(--fw-semibold); }

/* --- Subscription Page --- */
.subscription-page-main { padding: 120px 0 60px 0; }
.subscription-container { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: var(--space-xxl); max-width: 1100px; margin: 0 auto 3rem; padding: 0 var(--space-xl); }
.tier-box {
    background-color: var(--c-surface); border: var(--border-width) solid var(--c-border);
    border-radius: var(--radius-lg); padding: var(--space-xxl) var(--space-xl); display: flex;
    flex-direction: column; transition: all var(--transition-medium);
    box-shadow: 0 4px 20px var(--c-shadow-color); position: relative;
}
.tier-box:hover { transform: translateY(-8px); box-shadow: var(--shadow-md); }
.tier-box.recommended { border-color: var(--c-accent); }
.tier-badge {
    position: absolute; top: var(--space-lg); right: var(--space-lg);
    background-color: var(--c-accent); color: var(--c-light-text-on-accent);
    padding: 0.3rem var(--space-xs); font-size: 0.8rem; font-weight: var(--fw-bold);
    border-radius: var(--radius-full);
}
.tier-header { text-align: center; margin-bottom: var(--space-lg); }
.tier-name { font-size: 1.75rem; }
.tier-price { font-size: 1.25rem; color: var(--c-text-secondary); }
.tier-price span { font-size: 3.5rem; color: var(--c-text-primary); }
.tier-description { text-align: center; color: var(--c-text-secondary); margin-bottom: var(--space-xl); min-height: 40px; font-size: 0.9rem; }
.tier-perks { list-style: none; margin-bottom: var(--space-xl); flex-grow: 1; padding: 0; }
.tier-perks li {
    padding: 0.85rem 0; border-bottom: var(--border-width) solid var(--c-border);
    color: var(--c-text-primary); font-size: 0.95rem;
    opacity: 0; transform: translateY(10px); animation: fadeIn 0.5s ease forwards;
}
.tier-perks li::before { content: '✓'; color: var(--c-accent); margin-right: var(--space-sm); font-weight: var(--fw-bold); }
.tier-button {
    width: 100%; padding: 1.1rem; font-size: 1rem; font-weight: var(--fw-semibold);
    color: var(--c-light-text-on-accent); background-color: var(--c-text-primary);
    border: none; border-radius: var(--radius-full); cursor: pointer;
    transition: all var(--transition-fast); margin-top: auto;
}
.tier-button:hover { opacity: 0.85; transform: translateY(-3px); box-shadow: 0 6px 20px color-mix(in srgb, var(--c-text-primary) 30%, transparent); }
.tier-button:active { transform: translateY(0); opacity: 1; }
.tier-button:disabled { background-color: var(--c-border); color: var(--c-text-secondary); cursor: not-allowed; }
.tier-button:disabled:hover { transform: none; box-shadow: none; opacity: 1; }
.tier-box.recommended .tier-button { background-color: var(--c-accent); }
.tier-box.recommended .tier-button:hover { box-shadow: 0 6px 20px color-mix(in srgb, var(--c-accent) 30%, transparent); }

/* ==========================================================================
   5. ANIMATIONS & MEDIA QUERIES
   ========================================================================== */
@keyframes fadeIn { from { opacity: 0; transform: translateY(15px); } to { opacity: 1; transform: translateY(0); } }
@keyframes popIn { from { opacity: 0; transform: scale(0.8); } to { opacity: 1; transform: scale(1); } }
@keyframes shake { 0%, 100% { transform: translateX(0); } 10%, 30%, 50%, 70%, 90% { transform: translateX(-5px); } 20%, 40%, 60%, 80% { transform: translateX(5px); } }

/* --- Staggered Animations --- */
.tier-perks li:nth-child(1) { animation-delay: 0.1s; }
.tier-perks li:nth-child(2) { animation-delay: 0.2s; }
.tier-perks li:nth-child(3) { animation-delay: 0.3s; }
.tier-perks li:nth-child(4) { animation-delay: 0.4s; }
.tier-perks li:nth-child(5) { animation-delay: 0.5s; }

.member-item:nth-child(1) { animation-delay: 0.05s; }
.member-item:nth-child(2) { animation-delay: 0.1s; }
.member-item:nth-child(3) { animation-delay: 0.15s; }
.member-item:nth-child(4) { animation-delay: 0.2s; }
.member-item:nth-child(5) { animation-delay: 0.25s; }


/* --- Media Queries --- */
@media (max-width: 768px) {
    .page-main-content { padding-top: 80px; }
    .add-member-form { flex-direction: column; }
    .page-title { font-size: 2rem; }
}