/* ============================================================
   style.css — Date Calculator Styles (English version)
   ============================================================ */

/* ---------- Reset & Base ---------- */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', 'PingFang SC', Roboto, 'Helvetica Neue', sans-serif;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: linear-gradient(145deg, #f7f9fc 0%, #e9edf3 100%);
    padding: 20px;
}

/* ---------- Card ---------- */
.calculator {
    max-width: 820px;
    width: 100%;
    background: rgba(255, 255, 255, 0.75);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-radius: 48px;
    box-shadow:
        0 20px 60px rgba(0, 20, 40, 0.12),
        0 8px 24px rgba(0, 0, 0, 0.04),
        inset 0 1px 0 rgba(255, 255, 255, 0.7);
    padding: 40px 36px 44px;
    border: 1px solid rgba(255, 255, 255, 0.5);
    transition: all 0.25s ease;
}

/* ---------- Header ---------- */
.header {
    display: flex;
    align-items: center;
    gap: 14px;
    margin-bottom: 32px;
}

.header h1 {
    font-size: 28px;
    font-weight: 600;
    color: #1a2639;
    letter-spacing: -0.3px;
    background: linear-gradient(135deg, #1a2639, #3c4a5e);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.header .icon {
    font-size: 32px;
    line-height: 1;
}

/* ---------- Tabs ---------- */
.tabs {
    display: flex;
    gap: 8px;
    background: rgba(0, 0, 0, 0.04);
    border-radius: 60px;
    padding: 6px;
    margin-bottom: 32px;
    border: 1px solid rgba(255, 255, 255, 0.4);
}

.tab-btn {
    flex: 1;
    padding: 12px 10px;
    border: none;
    border-radius: 40px;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.25s ease;
    background: transparent;
    color: #4a5a6e;
    letter-spacing: 0.3px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

.tab-btn:hover {
    background: rgba(255, 255, 255, 0.5);
    color: #1a2639;
}

.tab-btn.active {
    background: #ffffff;
    color: #1a2639;
    box-shadow: 0 4px 16px rgba(0, 20, 40, 0.08);
    font-weight: 600;
}

/* ---------- Panels ---------- */
.panel {
    display: none;
    animation: fadeSlide 0.3s ease forwards;
}

.panel.active {
    display: block;
}

@keyframes fadeSlide {
    0% { opacity: 0; transform: translateY(10px); }
    100% { opacity: 1; transform: translateY(0); }
}

/* ---------- Form ---------- */
.form-group {
    display: flex;
    flex-wrap: wrap;
    align-items: flex-end;
    gap: 16px 20px;
    margin-bottom: 24px;
}

.form-group .field {
    flex: 1 1 180px;
    min-width: 140px;
}

.form-group .field label {
    display: block;
    font-size: 13px;
    font-weight: 500;
    color: #4a5a6e;
    margin-bottom: 6px;
    letter-spacing: 0.2px;
}

.form-group .field input {
    width: 100%;
    padding: 12px 16px;
    border: 1.5px solid #dce2ec;
    border-radius: 16px;
    font-size: 15px;
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(4px);
    transition: all 0.2s ease;
    color: #1a2639;
    font-family: inherit;
    outline: none;
}

.form-group .field input:focus {
    border-color: #6c8cff;
    box-shadow: 0 0 0 4px rgba(108, 140, 255, 0.15);
    background: #ffffff;
}

.form-group .field input[type="date"] {
    color-scheme: light;
    cursor: pointer;
}

.form-group .field input[type="number"] {
    -moz-appearance: textfield;
}
.form-group .field input[type="number"]::-webkit-inner-spin-button,
.form-group .field input[type="number"]::-webkit-outer-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

/* ---------- Buttons ---------- */
.btn {
    padding: 12px 28px;
    border: none;
    border-radius: 40px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    display: inline-flex;
    align-items: center;
    gap: 10px;
    background: #1a2639;
    color: #fff;
    box-shadow: 0 4px 16px rgba(26, 38, 57, 0.2);
    letter-spacing: 0.3px;
    flex-shrink: 0;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 28px rgba(26, 38, 57, 0.25);
    background: #2c3d5a;
}

.btn:active {
    transform: translateY(0);
    box-shadow: 0 2px 8px rgba(26, 38, 57, 0.15);
}

.btn-group {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-top: 8px;
}

/* ---------- Result ---------- */
.result {
    margin-top: 28px;
    padding: 24px 28px;
    border-radius: 24px;
    background: rgba(255, 255, 255, 0.6);
    backdrop-filter: blur(8px);
    border: 1px solid rgba(255, 255, 255, 0.8);
    box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.6);
    transition: all 0.2s ease;
}

.result .label {
    font-size: 13px;
    font-weight: 500;
    color: #6a7a8e;
    letter-spacing: 0.5px;
    text-transform: uppercase;
    margin-bottom: 4px;
}

.result .value {
    font-size: 34px;
    font-weight: 600;
    color: #1a2639;
    letter-spacing: -0.5px;
    line-height: 1.3;
    word-break: break-word;
}

.result .value .highlight {
    color: #4a7aff;
}

.result .sub {
    font-size: 16px;
    font-weight: 400;
    color: #5a6a7e;
    margin-top: 4px;
}

.result .sub .highlight {
    color: #1a2639;
    font-weight: 500;
}

.result-empty {
    color: #8a9aaa;
    font-size: 16px;
    font-weight: 400;
}

/* ---------- Quick Actions ---------- */
.quick-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 12px;
}

.quick-actions .chip {
    padding: 6px 18px;
    border-radius: 40px;
    border: 1.5px solid #dce2ec;
    background: transparent;
    font-size: 14px;
    font-weight: 500;
    color: #3c4a5e;
    cursor: pointer;
    transition: all 0.15s ease;
    font-family: inherit;
}

.quick-actions .chip:hover {
    background: #ffffff;
    border-color: #6c8cff;
    color: #1a2639;
    box-shadow: 0 2px 8px rgba(108, 140, 255, 0.15);
}

.quick-actions .chip:active {
    transform: scale(0.96);
}

/* ---------- Responsive ---------- */
@media (max-width: 600px) {
    .calculator {
        padding: 24px 18px 30px;
        border-radius: 32px;
    }
    .header h1 { font-size: 22px; }
    .header .icon { font-size: 26px; }
    .tab-btn { font-size: 14px; padding: 10px 6px; }
    .form-group .field { flex: 1 1 100%; min-width: 0; }
    .result .value { font-size: 26px; }
    .btn { width: 100%; justify-content: center; padding: 14px; }
    .btn-group { flex-direction: column; }
}

@media (max-width: 420px) {
    .calculator { padding: 18px 12px 24px; border-radius: 24px; }
    .result { padding: 18px 16px; }
    .result .value { font-size: 22px; }
}