/* Root variables */
:root {
    --bg-primary: #FAF9F7;
    --bg-secondary: #FFFFFF;
    --text-primary: #2B2B2B;
    --text-secondary: #6B6B6B;
    --border-color: #E5E5E5;
    --period-color: #E8897A;
    --fertile-color: #A8C8A0;
    --ovulation-color: #F4B860;
    --neutral-color: #F5F5F5;
    --today-outline: #2B2B2B;
    --btn-primary: #2B2B2B;
    --btn-hover: #1A1A1A;
}

[data-theme="dark"] {
    --bg-primary: #1A1A1A;
    --bg-secondary: #2B2B2B;
    --text-primary: #FAF9F7;
    --text-secondary: #B0B0B0;
    --border-color: #3A3A3A;
    --neutral-color: #2B2B2B;
    --today-outline: #FAF9F7;
    --btn-primary: #FAF9F7;
    --btn-hover: #E5E5E5;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background 0.3s ease, color 0.3s ease;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 32px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border-color);
}

h1 {
    font-size: 24px;
    font-weight: 600;
}

.theme-toggle {
    background: none;
    border: 1px solid var(--border-color);
    padding: 8px 12px;
    border-radius: 8px;
    cursor: pointer;
    font-size: 18px;
    transition: border-color 0.2s ease;
}

.theme-toggle:hover {
    border-color: var(--text-secondary);
}

/* Input Section */
.input-section {
    background: var(--bg-secondary);
    padding: 20px;
    border-radius: 12px;
    margin-bottom: 32px;
    border: 1px solid var(--border-color);
}

.input-section label {
    display: block;
    margin-bottom: 8px;
    font-size: 14px;
    color: var(--text-secondary);
}

.input-section input[type="date"] {
    width: 100%;
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 16px;
    margin-bottom: 16px;
    background: var(--bg-primary);
    color: var(--text-primary);
}

.btn-primary {
    width: 100%;
    padding: 12px;
    background: var(--btn-primary);
    color: var(--bg-primary);
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    transition: background 0.2s ease;
}

.btn-primary:hover {
    background: var(--btn-hover);
}

.btn-primary:active {
    transform: scale(0.98);
}

/* Calendar Section */
.calendar-section {
    background: var(--bg-secondary);
    padding: 20px;
    border-radius: 12px;
    margin-bottom: 32px;
    border: 1px solid var(--border-color);
}

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

.calendar-header h2 {
    font-size: 18px;
    font-weight: 600;
}

.nav-btn {
    background: none;
    border: 1px solid var(--border-color);
    padding: 8px 16px;
    border-radius: 8px;
    cursor: pointer;
    font-size: 16px;
    color: var(--text-primary);
    transition: border-color 0.2s ease;
}

.nav-btn:hover {
    border-color: var(--text-secondary);
}

.calendar-grid {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 8px;
    margin-bottom: 20px;
}

.calendar-day {
    aspect-ratio: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 8px;
    font-size: 14px;
    cursor: pointer;
    transition: transform 0.1s ease;
    position: relative;
}

.calendar-day:hover {
    transform: scale(1.05);
}

.calendar-day.day-label {
    font-weight: 600;
    color: var(--text-secondary);
    cursor: default;
    font-size: 12px;
}

.calendar-day.day-label:hover {
    transform: none;
}

.calendar-day.other-month {
    color: var(--text-secondary);
    opacity: 0.3;
}

.calendar-day.period {
    background: var(--period-color);
    color: white;
}

.calendar-day.fertile {
    background: var(--fertile-color);
    color: white;
}

.calendar-day.ovulation {
    background: var(--ovulation-color);
    color: white;
}

.calendar-day.neutral {
    background: var(--neutral-color);
    color: var(--text-primary);
}

.calendar-day.today {
    outline: 2px solid var(--today-outline);
    outline-offset: 2px;
}

/* Legend */
.legend {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    padding-top: 16px;
    border-top: 1px solid var(--border-color);
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 13px;
    color: var(--text-secondary);
}

.legend-box {
    width: 20px;
    height: 20px;
    border-radius: 4px;
}

.legend-box.period {
    background: var(--period-color);
}

.legend-box.fertile {
    background: var(--fertile-color);
}

.legend-box.ovulation {
    background: var(--ovulation-color);
}

.legend-box.neutral {
    background: var(--neutral-color);
}

/* History Section */
.history-section {
    background: var(--bg-secondary);
    padding: 20px;
    border-radius: 12px;
    margin-bottom: 32px;
    border: 1px solid var(--border-color);
}

.history-section h3 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 16px;
}

.history-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.history-item {
    padding: 12px;
    background: var(--bg-primary);
    border-radius: 8px;
    border: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.history-item .date {
    font-weight: 500;
}

.history-item .info {
    font-size: 13px;
    color: var(--text-secondary);
}

.empty-state {
    text-align: center;
    color: var(--text-secondary);
    font-size: 14px;
    padding: 24px;
}

/* Notification Section */
.notification-section {
    background: var(--bg-secondary);
    padding: 20px;
    border-radius: 12px;
    margin-bottom: 32px;
    border: 1px solid var(--border-color);
}

.notification-section h3 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 8px;
}

.notification-info {
    font-size: 13px;
    color: var(--text-secondary);
    margin-bottom: 16px;
}

.phone-input-group {
    margin-bottom: 16px;
}

.phone-input-group label {
    display: block;
    margin-bottom: 8px;
    font-size: 14px;
    color: var(--text-secondary);
}

.phone-input-group input[type="tel"] {
    width: 100%;
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 16px;
    background: var(--bg-primary);
    color: var(--text-primary);
}

.btn-secondary {
    padding: 10px 16px;
    background: none;
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: border-color 0.2s ease;
    margin-right: 8px;
}

.btn-secondary:hover {
    border-color: var(--text-secondary);
}

.btn-secondary:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-secondary:disabled:hover {
    border-color: var(--border-color);
}

/* Mobile Responsive */
@media (max-width: 600px) {
    .container {
        padding: 16px;
    }

    h1 {
        font-size: 20px;
    }

    .calendar-grid {
        gap: 4px;
    }

    .calendar-day {
        font-size: 12px;
    }

    .legend {
        flex-direction: column;
        gap: 8px;
    }

    .btn-secondary {
        width: 100%;
        margin-right: 0;
        margin-bottom: 8px;
    }
}

/* Focus states for keyboard navigation */
button:focus-visible,
input:focus-visible {
    outline: 2px solid var(--btn-primary);
    outline-offset: 2px;
}

.calendar-day:focus-visible {
    outline: 2px solid var(--btn-primary);
    outline-offset: 2px;
}