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

:root {
    --bg-primary: #e8e4d9;
    --bg-secondary: #f5f2ea;
    --text-primary: #2c2416;
    --text-secondary: #6b5d4f;
    --accent: #6aaa64;
    --accent-dark: #538d4e;
    --shadow-light: rgba(255, 255, 255, 0.8);
    --shadow-dark: rgba(0, 0, 0, 0.2);
    --card-bg: #f9f7f0;
    --border-color: #d4cfc0;
}

[data-theme="dark"] {
    --bg-primary: #121213;
    --bg-secondary: #1a1a1b;
    --text-primary: #d7dadc;
    --text-secondary: #818384;
    --accent: #538d4e;
    --accent-dark: #6aaa64;
    --shadow-light: rgba(255, 255, 255, 0.05);
    --shadow-dark: rgba(0, 0, 0, 0.5);
    --card-bg: #2a2a2b;
    --border-color: #3a3a3c;
}

body {
    font-family: 'Poppins', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    padding: 20px;
    transition: background 0.3s ease, color 0.3s ease;
}

.container {
    max-width: 800px;
    margin: 0 auto;
}

header {
    text-align: center;
    margin-bottom: 40px;
}

h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 10px;
    text-shadow: 3px 3px 6px var(--shadow-dark);
    letter-spacing: 2px;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1rem;
    font-weight: 400;
}

.controls {
    display: flex;
    justify-content: flex-end;
    margin-bottom: 30px;
    gap: 15px;
    flex-wrap: wrap;
}

.theme-toggle {
    background: var(--card-bg);
    border: 2px solid var(--border-color);
    border-radius: 30px;
    padding: 10px 20px;
    cursor: pointer;
    font-family: 'Poppins', sans-serif;
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-primary);
    box-shadow: 
        -3px -3px 6px var(--shadow-light),
        3px 3px 6px var(--shadow-dark);
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 8px;
    white-space: nowrap;
}

.theme-toggle:hover {
    transform: translateY(-2px);
    box-shadow: 
        -4px -4px 8px var(--shadow-light),
        4px 4px 8px var(--shadow-dark);
}

.theme-toggle:active {
    transform: translateY(0);
    box-shadow: 
        inset 2px 2px 4px var(--shadow-dark),
        inset -2px -2px 4px var(--shadow-light);
}

.icon {
    width: 20px;
    height: 20px;
    stroke: currentColor;
    fill: none;
    stroke-width: 1.5;
    flex-shrink: 0;
}

.icon-sm {
    width: 16px;
    height: 16px;
    stroke: currentColor;
    fill: none;
    stroke-width: 1.5;
    flex-shrink: 0;
}

.answer-card {
    background: var(--card-bg);
    border-radius: 20px;
    padding: 40px;
    margin-bottom: 40px;
    box-shadow: 
        -8px -8px 16px var(--shadow-light),
        8px 8px 16px var(--shadow-dark);
    border: 1px solid var(--border-color);
}

.date-label {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 15px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.answer-display {
    display: flex;
    gap: 8px;
    justify-content: center;
    margin-bottom: 20px;
}

.letter-box {
    width: 62px;
    height: 62px;
    background: var(--accent);
    border: 3px solid var(--accent-dark);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    font-weight: 700;
    text-transform: uppercase;
    color: white;
    box-shadow: 
        inset -2px -2px 4px rgba(255, 255, 255, 0.2),
        inset 2px 2px 4px rgba(0, 0, 0, 0.3),
        4px 4px 10px var(--shadow-dark);
    animation: flipIn 0.3s ease;
    animation-fill-mode: backwards;
}

.letter-box:nth-child(1) { animation-delay: 0.1s; }
.letter-box:nth-child(2) { animation-delay: 0.2s; }
.letter-box:nth-child(3) { animation-delay: 0.3s; }
.letter-box:nth-child(4) { animation-delay: 0.4s; }
.letter-box:nth-child(5) { animation-delay: 0.5s; }

.meta-info {
    display: flex;
    justify-content: space-around;
    flex-wrap: wrap;
    gap: 15px;
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-bottom: 20px;
}

.meta-item {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.meta-label {
    font-weight: 600;
    margin-bottom: 5px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.meta-value {
    font-family: 'Fira Code', monospace;
    color: var(--text-primary);
}

.share-section {
    display: flex;
    justify-content: center;
    gap: 10px;
    flex-wrap: wrap;
}

.btn {
    background: var(--card-bg);
    border: 2px solid var(--border-color);
    border-radius: 12px;
    padding: 10px 20px;
    cursor: pointer;
    font-family: 'Poppins', sans-serif;
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-primary);
    box-shadow: 
        -3px -3px 6px var(--shadow-light),
        3px 3px 6px var(--shadow-dark);
    transition: all 0.2s ease;
    white-space: nowrap;
    display: flex;
    align-items: center;
    gap: 6px;
}

.btn:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 
        -4px -4px 8px var(--shadow-light),
        4px 4px 8px var(--shadow-dark);
}

.btn:active:not(:disabled) {
    transform: translateY(0);
    box-shadow: 
        inset 2px 2px 4px var(--shadow-dark),
        inset -2px -2px 4px var(--shadow-light);
}

.btn-today {
    background: var(--accent);
    color: white;
    border-color: var(--accent-dark);
}

.btn-today:hover {
    transform: translateY(-2px);
    box-shadow: 
        -4px -4px 8px var(--shadow-light),
        4px 4px 8px var(--shadow-dark);
}

.btn-today:active {
    transform: translateY(0);
    box-shadow: 
        inset 2px 2px 4px rgba(0, 0, 0, 0.3),
        inset -2px -2px 4px rgba(255, 255, 255, 0.2);
}

.calendar-card {
    background: var(--card-bg);
    border-radius: 20px;
    padding: 30px;
    box-shadow: 
        -8px -8px 16px var(--shadow-light),
        8px 8px 16px var(--shadow-dark);
    border: 1px solid var(--border-color);
}

.calendar-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    flex-wrap: wrap;
    gap: 15px;
}

.calendar-title-group {
    display: flex;
    align-items: center;
    gap: 10px;
}

.calendar-controls {
    display: flex;
    gap: 10px;
    align-items: center;
}

.custom-select {
    position: relative;
}

.select-display {
    background: var(--bg-secondary);
    border: 2px solid var(--border-color);
    border-radius: 10px;
    padding: 10px 15px;
    cursor: pointer;
    font-family: 'Poppins', sans-serif;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    box-shadow: 
        inset 2px 2px 4px var(--shadow-dark),
        inset -2px -2px 4px var(--shadow-light);
    transition: all 0.2s ease;
    min-width: 140px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    user-select: none;
    gap: 12px;
}

.select-display:hover {
    border-color: var(--accent);
}

.select-display.open {
    border-color: var(--accent);
    box-shadow: 
        inset 2px 2px 4px var(--shadow-dark),
        inset -2px -2px 4px var(--shadow-light),
        0 0 0 3px rgba(106, 170, 100, 0.2);
}

.select-arrow {
    width: 16px;
    height: 16px;
    stroke: var(--text-secondary);
    fill: none;
    stroke-width: 1.5;
    transition: transform 0.3s ease;
    flex-shrink: 0;
}

.select-display.open .select-arrow {
    transform: rotate(180deg);
}

.select-dropdown {
    position: absolute;
    top: calc(100% + 8px);
    left: 0;
    right: 0;
    background: var(--card-bg);
    border: 2px solid var(--border-color);
    border-radius: 12px;
    padding: 8px;
    box-shadow: 
        -6px -6px 12px var(--shadow-light),
        6px 6px 12px var(--shadow-dark);
    z-index: 1000;
    max-height: 280px;
    overflow-y: auto;
    display: none;
    scrollbar-width: thin;
    scrollbar-color: var(--accent) var(--bg-secondary);
}

.select-dropdown::-webkit-scrollbar {
    width: 8px;
}

.select-dropdown::-webkit-scrollbar-track {
    background: var(--bg-secondary);
    border-radius: 10px;
    margin: 4px;
}

.select-dropdown::-webkit-scrollbar-thumb {
    background: var(--accent);
    border-radius: 10px;
    border: 2px solid var(--bg-secondary);
}

.select-dropdown::-webkit-scrollbar-thumb:hover {
    background: var(--accent-dark);
}

.select-dropdown.open {
    display: block;
    animation: dropDown 0.2s ease;
}

.select-option {
    padding: 10px 15px;
    cursor: pointer;
    border-radius: 8px;
    transition: all 0.15s ease;
    font-weight: 500;
}

.select-option:hover {
    background: var(--accent);
    color: white;
}

.select-option.selected {
    background: var(--bg-secondary);
    font-weight: 600;
}

.nav-btn {
    background: var(--bg-secondary);
    border: 2px solid var(--border-color);
    border-radius: 8px;
    width: 40px;
    height: 40px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-primary);
    box-shadow: 
        -3px -3px 6px var(--shadow-light),
        3px 3px 6px var(--shadow-dark);
    transition: all 0.2s ease;
}

.nav-btn:hover {
    box-shadow: 
        -4px -4px 8px var(--shadow-light),
        4px 4px 8px var(--shadow-dark);
}

.nav-btn:active {
    box-shadow: 
        inset 2px 2px 4px var(--shadow-dark),
        inset -2px -2px 4px var(--shadow-light);
}

.calendar-grid {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 8px;
    margin-top: 15px;
}

.day-label {
    text-align: center;
    font-weight: 600;
    font-size: 0.85rem;
    color: var(--text-secondary);
    padding: 10px 0;
}

.day-cell {
    aspect-ratio: 1;
    background: var(--bg-secondary);
    border: 2px solid var(--border-color);
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.2s ease;
    box-shadow: 
        -2px -2px 4px var(--shadow-light),
        2px 2px 4px var(--shadow-dark);
}

.day-cell:hover:not(.empty):not(.disabled) {
    background: var(--accent);
    color: white;
    transform: scale(1.05);
    box-shadow: 
        -3px -3px 6px var(--shadow-light),
        3px 3px 6px var(--shadow-dark);
}

.day-cell.empty {
    background: transparent;
    border: none;
    box-shadow: none;
    cursor: default;
}

.day-cell.disabled {
    opacity: 0.3;
    cursor: not-allowed;
    background: var(--bg-secondary);
}

.day-cell.selected {
    background: var(--accent);
    color: white;
    border-color: var(--accent-dark);
    box-shadow: 
        inset -2px -2px 4px rgba(255, 255, 255, 0.2),
        inset 2px 2px 4px rgba(0, 0, 0, 0.3);
}

.day-cell.today {
    border-color: var(--accent);
    font-weight: 700;
}

.loading {
    text-align: center;
    color: var(--text-secondary);
    font-style: italic;
}

.error {
    background: #d32f2f;
    color: white;
    padding: 15px;
    border-radius: 10px;
    margin-bottom: 20px;
    box-shadow: 4px 4px 10px var(--shadow-dark);
}

.success-toast {
    position: fixed;
    bottom: 30px;
    right: 30px;
    background: var(--accent);
    color: white;
    padding: 15px 25px;
    border-radius: 12px;
    box-shadow: 4px 4px 15px var(--shadow-dark);
    font-weight: 600;
    animation: slideIn 0.3s ease, slideOut 0.3s ease 2.7s;
    z-index: 1000;
    display: flex;
    align-items: center;
    gap: 10px;
}

.footer {
    text-align: center;
    margin-top: 60px;
    padding: 40px 20px 20px;
    color: var(--text-secondary);
    font-size: 0.9rem;
    border-top: 1px solid var(--border-color);
}

.footer-text {
    margin-bottom: 10px;
    line-height: 1.6;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
    gap: 5px;
}

.footer-link {
    color: var(--accent);
    text-decoration: none;
    font-weight: 600;
    transition: color 0.2s ease;
    display: inline-flex;
    align-items: center;
    gap: 5px;
}

.footer-link:hover {
    color: var(--accent-dark);
}

.footer-copyright {
    font-size: 0.85rem;
    color: var(--text-secondary);
    opacity: 0.7;
    margin-top: 10px;
}

.heart {
    color: #e74c3c;
    animation: heartbeat 1.5s ease-in-out infinite;
    display: inline-block;
}

.separator {
    margin: 0 5px;
    opacity: 0.5;
}

.github-icon {
    width: 16px;
    height: 16px;
    fill: currentColor;
    vertical-align: middle;
}

@keyframes flipIn {
    from {
        transform: rotateX(-90deg);
        opacity: 0;
    }
    to {
        transform: rotateX(0);
        opacity: 1;
    }
}

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

@keyframes slideIn {
    from {
        transform: translateX(400px);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

@keyframes slideOut {
    from {
        transform: translateX(0);
        opacity: 1;
    }
    to {
        transform: translateX(400px);
        opacity: 0;
    }
}

@keyframes heartbeat {
    0%, 100% {
        transform: scale(1);
    }
    10%, 30% {
        transform: scale(1.1);
    }
    20%, 40% {
        transform: scale(1);
    }
}

@media (max-width: 600px) {
    h1 {
        font-size: 2rem;
    }

    .answer-card {
        padding: 25px;
    }

    .letter-box {
        width: 50px;
        height: 50px;
        font-size: 1.5rem;
    }

    .calendar-card {
        padding: 20px;
    }

    .controls {
        justify-content: center;
    }

    .calendar-header {
        flex-direction: column;
        align-items: stretch;
    }

    .calendar-title-group {
        justify-content: center;
    }

    .calendar-controls {
        justify-content: center;
    }

    .success-toast {
        right: 20px;
        left: 20px;
        bottom: 20px;
    }
}